Guide for Industrial Waste Management
Protecting Land Ground Water Surface Water Air
Building Partnerships Introduction
EPA’s Guide for Industrial Waste Management Introduction
Welcome to EPA’s Guide for Industrial Waste Management. The pur- pose of the Guide is to provide facility managers, state and tribal regulators, and the interested public with recommendations and tools to better address the management of land-disposed, non-haz- ardous industrial wastes. The Guide can help facility managers make environmentally responsible decisions while working in partnership with state and tribal regulators and the public. It can serve as a handy implementation reference tool for regulators to complement existing programs and help address any gaps. The Guide can also help the public become more informed and more knowledgeable in addressing waste management issues in the community.
In the Guide, you will find: • Considerations for siting industrial waste management units • Methods for characterizing waste constituents • Fact sheets and Web sites with information about individual waste constituents • Tools to assess risks that might be posed by the wastes • Principles for building stakeholder partnerships • Opportunities for waste minimization • Guidelines for safe unit design • Procedures for monitoring surface water, air, and ground water • Recommendations for closure and post-closure care Each year, approximately 7.6 billion tons of industrial solid waste are generated and disposed of at a broad spectrum of American industrial facilities. State, tribal, and some local governments have regulatory responsibility for ensuring proper management of these wastes, and their pro- grams vary considerably. In an effort to establish a common set of industrial waste management guidelines, EPA and state and tribal representatives came together in a partnership and developed the framework for this voluntary Guide. EPA also convened a focus group of industry and public interest stakeholders chartered under the Federal Advisory Committee Act to provide advice throughout the process. Now complete, we hope the Guide will complement existing regulatory programs and provide valuable assistance to anyone interested in industrial waste management.
vii. Introduction
What Are the Underlying Principles of the Guide? When using the Guide for Industrial Waste Management, please keep in mind that it reflects four underlying principles: • Protecting human health and the environment. The purpose of the Guide is to pro- mote sound waste management that protects human health and the environment. It takes a multi-media approach that emphasizes surface-water, ground-water, and air protection, and presents a comprehensive framework of technologies and practices that make up an effective waste management system. • Tailoring management practices to risks. There is enormous diversity in the type and nature of industrial waste and the environmental settings in which it is managed. The Guide provides conservative management recommendations and simple-to-use modeling tools to tailor management practices to waste- and location-specific risks. It also identifies in-depth analytic tools to conduct more comprehensive site-specific analyses. • Affirming state and tribal leadership. States, tribes, and some local governments have primary responsibility for adopting and implementing programs to ensure proper management of industrial waste. This Guide can help states, tribes, and local govern- ments in carrying out those programs. Individual states or tribes might have more stringent or extensive regulatory requirements based on local or regional conditions or policy considerations. The Guide complements, but does not supersede, those regula- tory programs; it can help you make decisions on meeting applicable regulatory requirements and filling potential gaps. Facility managers and the public should con- sult with the appropriate regulatory agency throughout the process to understand regu- latory requirements and how to use this Guide. • Fostering partnerships. The public, facility managers, state and local governments, and tribes share a common interest in preserving quality neighborhoods, protecting the environment and public health, and enhancing the economic well-being of the commu- nity. The Guide can provide a common technical framework to facilitate discussion and help stakeholders work together to achieve meaningful environmental results.
What Can I Expect to Find in the Guide? The Guide for Industrial Waste Management is available in both hard-copy and electronic ver- sions. The hard-copy version consists of five volumes. These include the main volume and four supporting documents for the ground-water and air fate-and-transport models that were devel- oped by EPA specifically for this Guide. The main volume presents comprehensive information and recommendations for use in the management of land-disposed, non-hazardous industrial waste that includes siting the waste management unit, characterizing the wastes that will be disposed in it, designing and constructing the unit, and safely closing it. The other four vol- umes are the user’s manuals and background documents for the ground-water fate-and-trans- port model—the Industrial Waste Evaluation Model (IWEM)—and the air fate-and-transport model—the Industrial Waste Air Model (IWAIR).
viii. Introduction
The electronic version of the Guide, which can be obtained either on CD-ROM or from EPA’s Web site
What Wastes Does the Guide Address? The Guide for Industrial Waste Management addresses non-hazardous industrial waste subject to Subtitle D of the Resource Conservation and Recovery Act (RCRA). The reader is referred to the existence of 40 CFR Part 257, Subparts A and B, which provide federal requirements for non-hazardous industrial waste facilities or practices. Under RCRA, a waste is defined as non- hazardous if it does not meet the definition of hazardous waste and is not subject to RCRA Subtitle C regulations. Defining a waste as non-hazardous under RCRA does not mean that the management of this waste is without risk. This Guide is primarily intended for new industrial waste management facilities and units, such as new landfills, new waste piles, new surface impoundments, and new land application units. Chapter 7B–Designing and Installing Liners, and Chapter 4–Considering the Site, are clearly directed toward new units. Other chapters, such as Chapter 8–Operating the Waste Management System, Chapter 9–Monitoring Performance, Chapter 10–Taking Corrective Action, Chapter 11–Performing Closure and Post-Closure Care, while primarily intended for new units, can provide helpful information for existing units as well.
What Wastes Does the Guide Not Address? The Guide for Industrial Waste Management is not intended to address facilities that primarily handle the following types of waste: household or municipal solid wastes, which are managed in facilities regulated by 40 CFR Part 258; hazardous wastes, which are regulated by Subtitle C of RCRA; mining and some mineral processing wastes; and oil and gas production wastes; mixed wastes, which are solid wastes mixed with radioactive wastes; construction and demoli- tion debris; and non-hazardous wastes that are injected into the ground by the use of shallow underground injection wells (these injection wells fall under the Underground Injection Control (UIC) Program).
ix. Introduction
Furthermore, while the Guide provides many tools for assessing appropriate industrial waste management, the information provided is not intended for use as a replacement for other exist- ing EPA programs. For example, Tier 1 ground-water risk criteria can be a useful conservative screening tool for certain industrial wastes that are to be disposed in new landfills, surface impoundments, waste piles, or land application units, as intended by the Guide. These ground-water risk criteria, however, cannot be used as a replacement for sewage sludge stan- dards, hazardous waste identification exit criteria, hazardous waste treatment standards, MCL drinking water standards, or toxicity characteristics to identify when a waste is hazardous—all of which are legally binding and enforceable. In a similar manner, the air quality tool in this Guide does not and cannot replace Clean Air Act Title V permit conditions that may apply to industrial waste disposal units. The purpose of this Guide is to help industry, state, tribal, and environmental representatives by providing a wealth of information that relays and defers to existing legal requirements.
What is the Relationship Between This Guide and Statutory or Regulatory Provisions? Please recognize that this is a voluntary guidance document, not a regulation, nor does it change or substitute for any statutory or regulatory provisions. This document presents techni- cal information and recommendations based on EPA’s current understanding of a range of issues and circumstances involved in waste management The statutory provisions and EPA reg- ulations contain legally binding requirements, and to the extent any statute or regulatory provi- sion is cited in the Guide, it is that provision, not the Guide, which is legally binding and enforceable. Thus, this Guide does not impose legally binding requirements, nor does it confer legal rights or impose legal obligations on anyone or implement any statutory or regulatory provisions. When a reference is made to a RCRA criteria, for example, EPA does not intend to convey that any recommended actions, procedures, or steps discussed in connection with the reference are required to be taken. Those using this Guide are free to use and accept other technically sound approaches. The Guide contains information and recommendations designed to be useful and helpful to the public, the regulated community, states, tribes, and local gov- ernments. The word “should” as used in the Guide is intended solely to recommend particular action and does not connote a requirements. Similarly, examples are presented as recommenda- tions or demonstrations, not as requirements. To the extent any products, trade name, or com- pany appears in the Guide, their mention does not constitute or imply endorsement or recommendation for use by either the U.S. Government or EPA. Interested parties are free to raise questions and objections about the appropriateness of the application of the examples presented in the Guide to a particular situation.
x. Part I Getting Started
Chapter 1 Understanding Risk and Building Partnerships Contents
I. Understanding Risk Assessment ...... 1 - 1 A. Introduction to Risk Assessment ...... 1 - 1 B. Types of Risk...... 1 - 2 C. Assessing Risk...... 1 - 3 1. Hazard Identification ...... 1 - 5 2. Exposure Assessment: Pathways, Routes, and Estimation ...... 1 - 5 3. Risk Characterization ...... 1 - 8 4. Tiers for Assessing Risk...... 1 - 10 D. Results ...... 1 - 10
II. Information on Environmental Releases...... 1 - 11
III. Building Partnerships...... 1 - 11 A. Develop a Partnership Plan...... 1 - 12 B. Inform the State and Public About New Facilities or Significant Changes in Facility Operating Plans ...... 1 - 13 C. Make Knowledgeable and Responsible People Available for Sharing Information ...... 1 - 16 D. Provide Information About Facility Operations...... 1 - 16
Understanding Risk and Building Partnerships Activity List...... 1 - 19
Resources ...... 1 - 20
Appendix ...... 1 - 22
Tables: Table 1: Effective Methods for Public Notification ...... 1- 14
Figures: Figure 1: Multiple Exposure Pathways/Routes...... 1 - 7 Getting Started—Understanding Risk and Building Partnerships
Understanding Risk and Building Partnerships
This chapter will help you: • Understand the basic principles of risk assessment and the science behind it. • Build partnerships between a company that generates and man- ages waste, the community within which the company lives and works, and the state agency that regulates the company in order to build trust and credibility among all parties. esidents located near waste man- A. Introduction to Risk agement units want to understand Assessment the management activities taking This Guide provides simple-to-use risk place in their neighborhoods. They assessment tools that can assist in determining want to know that waste is being the appropriate waste management practices Rmanaged safely, without danger to public for surface impoundments, landfills, waste health or the environment. This requires an piles, and land application units. The tools understanding of the basic principles of risk estimate potential human health impacts from assessment and the science behind it. a waste management unit by modeling two Opportunities for dialogue between facilities, possible exposure pathways: releases through states, tribes, and concerned citizens, includ- volatile air emissions and contaminant migra- ing a discussion of risk factors, should take tion into ground water. Although using the place before decisions are made. Remember, tools is simple, it is still essential to under- successful partnerships are an ongoing activity. stand the basic concepts of risk assessment to be able to interpret the results and understand the nature of any uncertainties associated with I. Understanding the analysis. This section provides a general overview of the scientific principles underly- Risk Assessment ing the methods for quantifying cancer and Environmental risk communication skills are critical to successful partnerships between This chapter will help address the fol- companies, state regulators, the public, and lowing questions. other stakeholders. As more environmental management decisions are made on the basis • What is risk and how is it assessed? of risk, it is increasingly important for all inter- • What are the benefits of building ested parties to understand the science behind partnerships? risk assessment. Encouraging public participa- tion in environmental decision-making means • What methods have been successful ensuring that all interested parties understand in building partnerships? the basic principles of risk assessment and can • What is involved in preparing a converse equally on the development of stakeholder meeting? assumptions that underlie the analysis.
1-1 Getting Started—Understanding Risk and Building Partnerships
noncancer risk. Ultimately, understanding the Noncancer risk encompasses a diverse set of scientific principles will lead to more effective effects or endpoints, such as weight loss, use of the provided tools. enzyme changes, reproductive and develop- mental abnormalities, and respiratory reac- tions. Noncancer risk is generally assessed by B. Types of Risk comparing the exposure or average intake of a Risk is a concept used to describe situa- chemical with a corresponding reference (a tions or circumstances that pose a hazard to health benchmark), thereby creating a ratio. people or things they value. People encounter The ratio so generated is referred to as the a myriad of risks during common everyday hazard quotient (HQ). An HQ that is greater activities, such as driving a car, investing than 1 indicates that the exposure level is money, and undergoing certain medical pro- above the protective level of the health bench- cedures. By definition, risk is comprised of mark, whereas, an HQ less than 1 indicates two components: the probability that an that the exposure is below the protective level adverse event will occur and the magnitude established by the health benchmark. of the consequences of that adverse event. In It is important to understand that exposure capturing these two components, risk is typi- to a chemical does not necessarily result in an cally stated in terms of the probability (e.g., adverse health effect. A chemical’s ability to one chance in one million) of a specific initiate a harmful health effect depends on harmful “endpoint” (e.g., accident, fatality, the toxicity of the chemical as well as the cancer). route (e.g., ingestion, inhalation) and dose In the context of environmental manage- (the amount that a human intakes) of the ment and this section in the Guide, risk is exposure. Health benchmark values are used defined as the probability or likelihood that to quantify a chemical’s possible toxicity and public health might be unacceptably impact- ability to induce a health effect, and are ed from exposure to chemicals contained in derived from toxicity data. They represent a waste management units. The risk endpoints “dose-response”1 estimate that relates the like- resulting from the exposure are typically lihood and severity of adverse health effects grouped into two major consequence cate- to exposure and dose. The health benchmark gories: cancer risk and noncancer risk. is used in combination with an individual’s exposure level to determine if there is a risk. The cancer risk category captures risks Because individual chemicals generate differ- associated with exposure to chemicals that ent health effects at different doses, bench- might initiate cancer. To determine a cancer marks are chemical specific; additionally, risk, one must calculate the probability of an since health effects are related to the route of individual developing any type of cancer dur- exposure and the timing of the exposure, ing his or her lifetime from exposure to car- health benchmarks are specific to the route cinogenic hazards. Cancer risk is generally and the duration (acute, subchronic, or expressed in scientific notation; in this nota- chronic) of the exposure. The definitions of tion, the chance of 1 person in 1,000,000 of acute, subchronic, and chronic exposures developing cancer would be expressed as 1 x vary, but acute typically implies an exposure 10-6 or 1E-6. of less than one day, subchronic generally The noncancer risk category is essentially a indicates an exposure of a few weeks to a few catch-all category for the remaining health months, and chronic exposure can span peri- effects resulting from chemical exposure. ods of several months to several years.
1 Dose-response is the correlative relationship between the dose of a chemical received by a subject and the degree of response to that exposure. 1-2 Getting Started—Understanding Risk and Building Partnerships
The health benchmark for carcinogens is called the cancer slope factor. A cancer slope Example of Health Benchmarks for factor (CSF) is defined as the upper-bound2 Acrylonitrile estimate of the probability of a response per Chronic: unit intake of a chemical over a lifetime and is inhalation CSF: 0.24 (mg/kg-d) expressed in units of (mg/kg-d). The slope fac- oral CSF: 0.54 (mg/kg-d) tor is used to estimate an upper-bound proba- RfC: 0.002 mg/m3 bility of an individual developing cancer as a RfD: 0.001 mg/kg-d result of a lifetime of exposure to a particular concentration of a carcinogen. Subchronic: RfC: 0.02 mg/m3 A reference dose (RfD) for oral exposure and reference concentration (RfC) for inhala- Acute: tion exposure are used to evaluate noncancer ATSDR MRL: 0.22 mg/m3 effects. The RfD and RfC are estimates of daily exposure levels to individuals (including sen- sitive populations) that are likely to be with- source is the Agency for Toxic Substances and out an appreciable risk of deleterious effects Disease Registry (ATSDR)
2 Upper-bound is a number that is greater than or equal to any number in a set.
1-3 Getting Started—Understanding Risk and Building Partnerships
Sources for Health Benchmarks by calling 1-800-553-IRIS or accessing their Website at
guidance for making management decisions by and identifying the extent of exposure for indi- providing one of the inputs to the decision viduals or populations at risk. making process. Risk assessment furnishes ben- Performing a risk assessment is complex and eficial information for a variety of situations, requires knowledge in a number of scientific such as determining the appropriate pollution disciplines. Experts in several areas, such as control systems for an industrial site, predicting toxicology, geochemistry, environmental engi- the appropriateness of different waste manage- neering, and meteorology, can be involved in ment options or alternative waste management performing a risk assessment. For the purpose unit configurations, or identifying exposures of this section, and for brevity, the basic com- that might require additional attention. ponents important to consider when assessing The risk assessment process involves data risk are summarized in three main categories collection activities, such as identifying and listed below. A more extensive discussion of characterizing the source of the environmental these components can be found in the refer- pollutant, determining the transport of the pol- ences listed at the end of this section. The lutant once it is released into the environment, three main categories are: determining the pathways of human exposure,
1-4 Getting Started—Understanding Risk and Building Partnerships
1. Hazard Identification: identifying produce greater volatile releases than units in and characterizing the source of the a cool, wet, non-windy climate. potential risk (e.g., chemicals man- aged in a waste management unit). 2. Exposure Assessment: 2. Exposure Assessment: determining Pathways, Routes, and the exposure pathways and exposure Estimation routes from the source to an individual. Individuals and populations can come into 3. Risk Characterization: integrating contact with environmental pollutants by a the results of the exposure assess- variety of exposure mechanisms and process- ment with information on who is es. The mere presence of a hazard, such as potentially at risk (e.g., location of toxic chemicals in a waste management unit, the person, body weights) and chem- does not denote the existence of a risk. ical toxicity information. Exposure is the bridge between what is con- sidered a hazard and what actually presents a 1. Hazard Identification risk. Assessing exposure involves evaluating the potential or actual pathways for and For the purpose of the Guide, the source extent of human contact with toxic chemi- of the potential risk has already been identi- cals. The magnitude, frequency, duration, and fied: waste management units. However, route of exposure to a substance must be there must be a release of chemicals from a considered when collecting all of the data waste management unit for there to be expo- necessary to construct a complete exposure sure and risk. Chemicals can be released from assessment. waste management units by a variety of processes, including volatilization (where The steps for performing an exposure chemicals in vapor phase are released to the assessment include identifying the potentially air), leaching to ground water (where chemi- exposed population (receptors); pathways of cals travel through the ground to a ground- exposure; environmental media that transport water aquifer), particulate emission (where the contaminant; contaminant concentration chemicals attached to particulate matter are at a receptor point; and receptor’s exposure released in the air when the particulate mat- time, frequency, and duration. In a determin- ter becomes airborne), and runoff and ero- istic exposure assessment, single values are sion (where chemicals in soil water or assigned to each exposure variable. For exam- attached to soil particles move to the sur- ple, the length of time a person lives in the rounding area). same residence adjacent to the facility might be assumed to be 30 years. Alternatively, in a To consider these releases in a risk assess- probabilistic analysis, single values can be ment, information characterizing the waste replaced with probability distribution func- management unit is needed. Critical parame- tions that represent the range in real-world ters include the size of the unit and its loca- variability, as well as uncertainty. Using the tion. For example, larger units have the time in residence example, it might be found potential to produce larger releases. Units that 10 percent of the people adjacent to the located close to the water table might pro- facility live in their home for less than three duce greater releases to ground water than years, 50 percent less than six years, 90 per- units located further from the water table. cent less than 20 years, and 99 percent less Units located in a hot, dry, windy climate can than 27 years.
1-5 Getting Started—Understanding Risk and Building Partnerships
A probabilistic risk assessment is per- different types of media which are considered formed by running the equations that exposure pathways: air, soil, ground water, describe each distribution in a program in surface water, and biota (Figure 1). As a result conjunction with a Monte Carlo program. of this movement, a chemical can be present The Monte Carlo program randomly selects a in various environmental media, and human value from the designated distribution and exposure often results from multiple sources. mathematically treats it with numbers ran- The relative importance of an exposure path- domly selected from distributions for other way depends on the concentration of a chemi- parameters. This process is repeated a num- cal in the relevant medium and the rate of ber of times (e.g., 10,000 times) to generate a intake by the exposed individual. In a com- distribution of theoretical values. The person prehensive risk assessment, the risk assessor assessing risk then uses his or her judgement identifies all possible site-specific pathways to select the risk value (e.g., 50th or 90th through which a chemical could move and percentile). reach a receptor. The Guide provides tools to model the transport and movement of chemi- The output of the exposure assessment is a cals through two environmental pathways: air numerical estimate of exposure and intake of and ground water. a chemical by an individual. The intake infor- mation is then used in concert with chemical- The transport of a chemical in the environ- specific health benchmarks to quantify risks ment is facilitated by natural forces: wind and to human health. water are the primary physical processes for distributing contaminants. For example, Before gathering these data, it is important atmospheric transport is frequently caused by to understand what information is necessary ambient wind. The direction and speed of the for conducting an adequate exposure assess- wind determine where a chemical can be ment and what type of work might be found. Similarly, chemicals found in surface required. Exposures are commonly deter- water and ground water are carried by water mined by using mathematical models of currents or sediments suspended in the water. chemical fate and transport to determine chemical movement in the environment in The chemistry of the contaminants and of conjunction with models of human activity the surrounding environment, often referred patterns. The information required for per- to as the “system,” also plays a significant role forming the exposure assessment includes in determining the ultimate distribution of site-specific data such as soil type, meteoro- pollutants in the various types of media. logical conditions, ground-water pH, and Physical-chemical processes, including disso- location of the nearest receptor. Information lution/precipitation, volatilization, photolytic must be gathered for the two components of and hydrolytic degradation, sorption, and exposure assessment: exposure complexation, can influence the distribution pathways/routes and exposure quantifica- of chemicals among the different environ- tion/estimation. mental media and the transformation from one chemical form to another3. An important a. Exposure Pathways/Routes component of creating a conceptual model for performing a risk assessment is the identi- An exposure pathway is the course the fication of the relevant processes that occur in chemical takes from its source to the individ- a system. These complex processes depend ual or population it reaches. Chemicals cycle on the conditions at the site and specific in the environment by crossing through the chemical properties. 3 Kolluru, Rao (1996).
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into another chemical that is solu- ble and can be excreted. Some contaminants can also be absorbed by the skin. The skin is not very permeable and usually provides a sufficient barrier against most chemicals. Some chemicals, however, can pass through the skin in sufficient quantities to induce severe health effects. An example is carbon tetrachloride, which is readily absorbed through the skin and at certain doses can cause severe liver damage. The dermal route is typically consid- ered in worker scenarios in which the worker is actually performing activities that involve skin contact with the chemical of concern. The tools provided in the Guide do not address the dermal route of Figure 1. Multiple Exposure Pathways/Routes (National Research exposure. Council, “Frontiers in Assesssing Human Exposure,” 1991)
Whereas the exposure pathway dictates the b. Exposure Quantification/Estimation means by which a contaminant can reach an Once appropriate fate-and-transport mod- individual, the exposure route is the way in eling has been performed for each pathway, which that chemical comes in contact with providing an estimate of the concentration of the body. To generate a health effect, the a chemical at an exposure point, the chemical chemical must come in contact with the body. intake by a receptor must be quantified. In environmental risk assessment, three expo- Quantifying the frequency, magnitude, and sure routes are generally considered: inges- duration of exposures that result from the tion, inhalation, and dermal absorption. As transport of a chemical to an exposure point stated earlier, the toxicity of a chemical is spe- is critical to the overall assessment. For this cific to the dose received and its means of step, the risk assessor calculates the chemical- entry into the body. For example, a chemical specific exposures for each exposure pathway that is inhaled might prove to be toxic and identified. Exposure estimates are expressed result in a harmful health effect, whereas the in terms of the mass of a substance in contact same chemical might cause no reaction if with the body per unit body weight per unit ingested, or vice-versa. This phenomenon is time (e.g., milligrams of a chemical per kilo- due to the differences in physiological gram body weight per day, also expressed as response once a chemical enters the body. A mg/kg-day). chemical that is inhaled reaches the lungs and enters the blood system. A chemical that is The exposure quantification process ingested might be metabolized into a different involves gathering information in two main chemical that might result in a health effect or areas: the activity patterns and the biological
1-7 Getting Started—Understanding Risk and Building Partnerships
characteristics (e.g., body weight, inhalation Key Chemical Processes rate) of receptors. Activity patterns and bio- Sorption: the partitioning of a chemical between the liq- logical characteristics dictate the amount of a uid and solid phase determined by its affinity for adhering constituent that a receptor can intake and the to other solids in the system such as soils and sediment. dose that is received per kilogram of body The amount of chemical that “sorbs” to solids and does not weight. Chemical intake values are calculated move through the environment is dependent upon the using equations that include variables for characteristics of the chemical, the characteristics of the exposure concentration, contact rate, exposure surrounding soils and sediments, and the quantity of the frequency, exposure duration, body weight, chemical. A sorption coefficient is the measure of a chemi- and exposure averaging time. The values of cal’s ability to sorb. If too much of the chemical is present, some of these variables depend on the site the available binding sites on soils and sediments will be conditions and the characteristics of the filled and sorption will not continue. potentially exposed population. For example, the rate of oral ingestion of contaminated food Dissolution/precipitation: the taking in or coming out of is different for different subgroups of recep- solution by a substance. In dissolution a chemical is taken tors, which might include adults, children, into solution; precipitation is the formation of an insoluble area visitors, subsistence farmers, and subsis- solid. These processes are a function of the nature of the tence fishers. Children typically drink greater chemical and its surrounding environment and are depen- quantities of milk each day than adults per dent on properties such as temperature and pH. A chemical’s unit body weight. A subsistence fisher would solubility is characterized by a solubility product. Chemicals be at a greater risk than another area resident that tend to volatilize rapidly are not highly soluble. from the ingestion of contaminated fish. Degradation: the break down of a chemical into other Additionally, a child might have a greater rate substances in the environment. Some degradation processes of soil ingestion than an adult due to playing include biodegradation, hydrolysis, and photolysis. Not all outdoors or hand-to-mouth behavior patterns. degradation products have the same risk as the “parent” The activities of individuals also determine the compound. Although most degradation products present duration of exposure. A resident might live in less risk than the parent compound, some chemicals can the area for 20 years and be in the area for break down into “daughter” products that are more harmful more than 350 days each year. Conversely, a than the parent compound. In performing a risk assessment visitor or a worker will have shorter exposure it is important to consider what the daughter products of times. After the intake values have been esti- degradation might be. mated, they should be organized by popula- tion as appropriate (e.g., children, adult Bioaccumulation: the take up/ingestion and storage of a residents) so that the results in the risk char- substance into an organism. For substances that bioaccu- acterization can be reported for each popula- mulate, the concentrations of the substance in the organism tion group. To the extent feasible, site-specific can exceed the concentrations in the environment since the values should be used for estimating the expo- organism will store the substance and not excrete it. sures; otherwise, default values suggested by Volatilization: the partitioning of a compound into a the EPA in The Exposure Factors Handbook gaseous state. The volatility of a compound is dependent (EPA, 1995) can be used. on its water solubility and vapor pressure. The extent to which a chemical can partition into air is described by one 3. Risk Characterization of two constants: Henry's Law or Rauolt's Law. Other fac- In the risk-characterization process, the tors that are important to volatility are atmospheric temper- ature and waste mixing. health benchmark information (i.e., cancer slope factors, reference doses, reference concen-
1-8 Getting Started—Understanding Risk and Building Partnerships
trations) and the results of the exposure assess- ment unit might be underestimated. The EPA ment (estimated intake or dose by potentially has developed guidance outlined in the Risk exposed populations) are integrated to arrive at Assessment Guidance for Superfund, Volume I quantitative estimates of cancer and noncancer (U.S. EPA, 1989b) to assess the overall poten- risks. To characterize the potential noncarcino- tial for cancer and noncancer effects posed by genic effects, comparisons are made between multiple chemicals. The risk assessor, facility projected intake levels of substances and refer- manager, and other interested parties should ence dose or reference concentration values. To determine the appropriateness of adding the characterize potential carcinogenic effects, risk contribution of each chemical for each probabilities that an individual will develop pathway to calculate a cumulative cancer risk cancer over a lifetime are estimated from pro- or noncancer risk. The procedures for adding jected intake levels and the chemical-specific risks differ for carcinogenic and noncarcino- cancer slope factor value. This procedure is the genic effects. final calculation step. This step determines who The cancer-risk equation described in the is likely to be affected and what the likely adjacent box estimates the incremental indi- effects are. Because of all the assumptions vidual lifetime cancer risk for simultaneous inherent in calculating a risk, a risk characteri- exposure to several carcinogens and is based zation cannot be considered complete unless on EPA (1989a) guidance. The equation com- the numerical expressions of risk are accompa- bines risks by summing the risks to a recep- nied by explanatory text interpreting and quali- tor from each of the carcinogenic chemicals. fying the results. As shown in the text box, the risk characterization step is different for car- cinogens and noncarcinogens. Cancer Risk Equation for Multiple Substances ⌺ Calculating Risk RiskT = Riski Cancer Risks: where: Incremental risk of cancer = average RiskT = the total cancer risk, daily dose (mg/kg-day) * slope factor expressed as a unitless probability. (mg/kg-day) ⌺ Riski = the sum of the risk estimates Non-Cancer Risks: for all of the chemical risks. Hazard quotient = exposure or intake (mg/kg-day) or (mg/m3)/ RfD (mg/kg- 3 day) or RfC (mg/m ) Assessing cumulative effects from noncar- cinogens is more difficult and contains a greater amount of uncertainty than an assess- Another consideration during the risk- ment for carcinogens. As discussed earlier, characterization phase is the cumulative noncarcinogenic risk covers a diverse set of effects of multiple exposures. A given popula- health effects and different chemicals will tion can be exposed to multiple chemicals have different effects. To assess the overall from several exposure routes and sources. potential for noncarcinogenic effects posed by Multiple constituents might be managed in a more than one chemical, EPA developed a single waste management unit, for example, hazard index (HI) approach. The approach and by considering one chemical at a time, assumes that the magnitude of an adverse the risks associated with the waste manage-
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health effect is proportional to the sum of the using conservative, non-site specific hazard quotients of each of the chemicals assumptions provided by EPA. The investigated. In keeping with EPA’s Risk values are provided in “look-up Assessment Guidance, hazard quotients should tables” that serve as a quick and only be added for chemicals that have the straightforward means for assessing same critical effect (e.g., both chemicals affect risk. These values are calculated to be the liver or both initiate respiratory distress). protective over a broad range of con- As a result, an extensive knowledge of toxi- ditions and situations and are by cology is needed to sum the hazard quotients design very conservative. to produce a hazard index. Segregation of Tier 2 Evaluation hazard indices by effect and mechanism of • Represents a higher level of complex- action can be complex, time-consuming, and ity. will have some degree of uncertainty associat- ed with it. This analysis is not simple and • Moderate cost. should be performed by a toxicologist. • Provides the ability to input some site-specific data into the risk assess- 4. Tiers for Assessing Risk ment and thus provides a more accu- As part of the Guide, EPA has used a 3- rate representation of site risk. tiered approach for assessing risk associated • Uses relatively simplistic fate and with air and water releases from waste man- transport models. agement units. Under this approach, an Tier 3 Evaluation acceptable level of protection is provided across all tiers, but with each progressive tier • Provides a sophisticated risk assess- the level of uncertainty in the risk analysis is ment. reduced. Reducing the level of uncertainty in • Higher cost. the risk analysis might reduce the level of • Provides the maximum use of site- control required by a waste management unit specific data and thus provides the (if appropriate for the site), while maintaining most accurate representation of site an acceptable level of protection. The facility risk. performing the risk assessment accepts the higher costs associated with a more complex • Uses more complex fate-and-trans- risk assessment in return for greater certainty port models and analyses. and potentially reduced construction and operating costs. D. Results The advantages and relative costs of each tier are outlined below. The results of a risk assessment provide a basis for making decisions but are only one Tier 1 Evaluation element of input into the process of designing • Allows for a rapid but conservative a waste management unit. The risk assess- assessment. ment does not constitute the only basis for • Lower cost. management action. Other factors are also important, such as technical feasibility of • Requires minimal site data. options, public values, and economics. • Contaminant fate-and-transport and Understanding and interpreting the results exposure assumptions are developed for the purpose of making decisions also requires a thorough knowledge of the
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assumptions that were applied during the operators might wish to include TRI data in risk assessment. Ample documentation the facility’s information repository. TRI data, should be assembled to describe the scenarios however, are merely raw data. When estimat- that were evaluated for the risk assessment ing risk, other considerations need to be and any uncertainty associated with the esti- examined and understood too, such as the mate. Information that should be considered nature and characteristics of the specific facil- for inclusion in the risk assessment documen- ity and surrounding community. tation include: a description of the contami- In 1999, EPA promulgated a final rule that nants that were evaluated; a description of established alternate thresholds for several the risks that are present (i.e., cancer, non- persistent, bioaccumulative, and toxic (PBT) cancer); the level of confidence in the infor- chemicals (see 64 FR 58665; October 29, mation used in the assessment; the major 1999). In this rule, EPA has added seven factors driving the site risks; and the charac- chemicals to the EPCRA Section 313 list of teristics of the exposed population. The TRI chemicals and lowered the reporting results of a risk assessment are essentially thresholds for another 18 PBT chemicals and meaningless without the information on how chemical categories. For these 18 chemicals, they were generated. the alternate thresholds are significantly lower than the standard reporting thresholds of 25,000 pounds manufactured or processed, II. Information on and 10,000 pounds otherwise used. Environmental EPCRA is based on the belief that citizens have a right to know about potential environ- Releases mental risks caused by facility operations in There are several available sources of infor- their communities, including those posed as a mation that citizens can review to understand result of waste management. TRI data, there- chemical risk better and to review potential fore, provide yet another way for residents to environmental release from waste manage- learn about the waste management activities ment units in their communities. The taking place in their neighborhood and to Emergency Planning and Community Right- take a more active role in decisions that to-Know Act (EPCRA) of 1986 provides one potentially affect their health and environ- such resource. EPCRA created the Toxic ment. More information on TRI and access to Release Inventory (TRI) reporting program TRI data can be obtained from EPA’s Web site which requires facilities in designated
1-11 Getting Started—Understanding Risk and Building Partnerships
• Better understanding of waste man- ment activities best agement activities at an industrial address those con- facility. cerns. • Better understanding of facility, state, The first step in and community issues. developing a part- nership plan is to • Greater support of industry proce- work with the state dures and state policies. agency to under- • Reduced delays and costs associated stand what involve- with opposition and litigation. ment requirements • A positive image for a company and exist. Existing state relationship with the state and com- requirements deal- munity. ing with partnership plans must be followed. (Internet sites for all state environmental Regardless of the size or type of a facility’s agencies are available from
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ronmental organizations, and any individuals person who is available within the facility to in the community who have expressed inter- answer questions. est in the facility’s operations. What is involved in preparing a Using the information gathered during the interviews, facility representatives can devel- meeting with industry, community, op a list of the community’s concerns regard- and state representatives? ing the facility’s waste management activities. They can then begin to engage the communi- Meetings can be an effective means of giv- ty in discussions about how to address those ing and receiving comments and addressing concerns. These discussions can form the concerns. To publicize a meeting, the date, basis of a partnership plan. time, and location of the meeting should be placed in a local newspaper and/or advertised on the radio. To help ensure a successful dia- B. Inform the State and logue, meetings should be at times conve- Public About New nient for members of the community, such as Facilities or Significant early in the evenings during the week, or on weekends. An interpreter might need to be Changes in Facility obtained if the local community includes resi- Operating Plans dents whose primary language is not English. A facility’s decision to change its opera- Prior to a meeting, the facility representa- tions provides a valuable opportunity for tive should develop a waste management plan involvement. Notifying the state and public or come to the meeting prepared to describe of new units and proposed changes at exist- how the industrial waste from the facility will ing facilities gives these groups the opportu- be managed. A waste management plan pro- nity to identify applicable state requirements vides a starting point for public comment and and comment on matters that apply to them. input. Keep data presentations simple and provide information relevant to the audience. What are examples of effective Public speakers should be able to respond to methods for notifying the public? both general and technical questions. Also, the facility representative should review and Table 1 presents examples of effective be familiar with the concerns of groups or cit- methods for public notification and associat- izens who have ed advantages and disadvantages. The previously method used at a particular facility, and expressed an within a particular community, will depend interest in the on the type of information or issues that facility’s opera- need to be communicated and addressed. tions. In addi- Public notices usually provide the name and tion, it is address of the facility representative and a important to brief description of the change being consid- anticipate ques- ered. After a public notice is issued, a facility tions and plan can develop informative fact sheets to how best to explain proposed changes in more detail. respond to these Fact sheets and public notices can include questions at a the name and telephone number of a contact meeting.
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Table 1 Effective Methods for Public Notification Methods Features Advantages Disadvantages
Briefings Personal visit or phone call to Provides background information. Requires time. key officials or group leaders to Determines reactions before an issue announce a decision, provide “goes public.” Alerts key people to background information, or issues that might affect them. answer questions.
Mailing of key Mailing technical studies or Provides full and detailed information Costs money to print and technical reports or environmental reports to other to people who are most interested. mail. Some people might not environmental agencies, leaders of organized Often increases the credibility of read the reports. documents groups, or other interested parties. studies because they are fully visible.
News conferences Brief presentation to reporters, Stimulates media interest in a story. Reporters will only come if followed by a question-and- Direct quotations often appear in the announcement or presen- answer period, often television and radio. Might draw tation is newsworthy. Cannot accompanied by handouts of attention to an announcement or control how the story is pre- presenter’s comments. generate interest in public meetings. sented, although some direct quotations are likely.
Newsletters Brief description of what is going Provides more information than can Requires staff time. Costs on, usually issued at key intervals be presented through the media to money to prepare, print, and for all people who have shown those who are most interested. Often mail. Stories must be objec- interest. used to provide information prior to tive and credible, or people public meetings or key decision points. will react to the newsletters Helps to maintain visibility during as if they were propaganda. extended technical studies.
Newspaper inserts Much like a newsletter, but Reaches the entire community with Requires staff time to prepare distributed as an insert in a important information. Is one of the the insert, and distribution newspaper. few mechanisms for reaching everyone costs money. Must be pre- in the community through which you pared to newspaper’s layout can tell the story your way. specifications.
Paid advertisements Advertising space purchased in Effective for announcing meetings or Advertising space can be newspapers or on the radio or key decisions or as background costly. Radio and television television. material for future media stories. can entail expensive produc- tion costs to prepare the ad.
News releases A short announcement or news Might stimulate interest from the Might be ignored or not story issued to the media to get media. Useful for announcing read. Cannot control how interest in media coverage of the meetings or major decisions or as the information is used. story. background material for future media stories.
Presentations to civic Deliver presentations, enhanced Stimulates communication with key Few disadvantages, except and technical groups with slides or overheads, to key community groups. Can also provide some groups can be hostile. community groups. in-depth responses.
Press kits A packet of information Stimulates media interest in the story. Few disadvantages, except distributed to reporters. Provides background information that cannot control how the reporters can use for future stories. information is used and might not be read.
Advisory groups and A group of representatives of key Promotes communication between Potential for controversy task forces interested parties is established. key constituencies. Anticipates public exists if “advisory” recom- Possibly a policy, technical, or reaction to publications or decisions. mendations are not followed. citizen advisory group. Provides a forum for reaching Requires substantial commit- consensus. ment of staff time to provide support to committees.
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Table 1 Effective Methods for Public Notification (cont.) Methods Features Advantages Disadvantages
Focus groups Small discussion groups Provides in-depth reaction to ideas or Gets reactions, but no established to give “typical” decisions. Good for predicting knowledge of how many reactions of the public. emotional reactions people share those reactions. Conducted by a professional Might be perceived as an facilitator. Several sessions can be effort to manipulate the conducted with different groups. public.
Telephone line Widely advertised phone number Gives people a sense that they know Is only as effective as the that handles questions or provides whom to call. Provides a one-step person answering the tele- centralized source of information. service of information. Can handle phone. Can be expensive. two-way communication.
Meetings Less formal meetings for people Highly legitimate forum for the public Unless a small-group discus- to present positions, ask to be heard on issues. Can be sion format is used, it permits questions, and so forth. structured to permit small group only limited dialogue. Can interaction— anyone can speak. get exaggerated positions or grandstanding. Requires staff time to prepare for meetings.
U.S. EPA 1990. Sites for Our Solid Waste: A Guidebook for Effective Public Involvement.
State representatives also should antici- • What are the construction plans for pate and be prepared to answer questions any proposed containment facilities? raised during the meeting. State representa- • What are the intended methods for tives should be prepared to answer ques- monitoring and detecting emissions tions on specific regulatory or compliance or potential releases? issues, as well as to address how the facility has been working in cooperation with the • What are the plans to address acci- state agency. The following are some ques- dental releases of chemicals or wastes tions that are often asked at meetings. at the site? • What are the risks to me associated • What are the plans for financial with the operations? assurance, closure, and post-closure care? • Who should I contact at the facility if I have a question or concern? • What are the applicable state regula- tions? • How will having the facility nearby benefit the area? • How long will it take to issue the permit? • Will there be any noticeable day-to- day effects on the community? • How will the permit be issued? • Which processes generate industrial • Who should I contact at the state waste, and what types of waste are agency if I have questions or con- generated? cerns about the facility? • How will the waste streams be treat- At the meeting, the facility representative ed or managed? should invite public and state comments on the proposed change(s), and tell community
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members where, and to whom, they should one-to-one. Similarly, workshops and briefin- send written comments. A facility can choose gs enable community members, state officials, to respond to comments in several ways. For and facility representatives to interact, ask example, telephone calls, additional fact questions, and learn about the activities at the sheets, or additional meetings can all be used facility. Web sites can also serve as a useful to address comments. Responding promptly tool for facility, state, and community repre- to residents’ comments and concerns demon- sentatives to share information and ask ques- strates an honest attempt to address them. tions.
C. Make Knowledgeable D. Provide Information and Responsible People About Facility Available for Sharing Operations Information Providing information about facility opera- Having a facility representative available to tions is an invaluable way to help the public answer the public’s questions and provide understand waste management activities. information helps assure citizens that the Methods of informing communities include facility is actively listening to their concerns. conducting facility tours; maintaining a pub- Having a state contact available to address the licly accessible information repository on site public’s concerns about the facility can also or at a convenient offsite public building such make sure that concerns are being heard and as a library; developing exhibits to explain addressed. operations; and distributing information through the publications of established orga- In addition to identifying a contact person, nizations. Examples of public involvement facilities and states should consider setting up activities are presented in the following pages. a telephone line staffed by employees for citi- zens to call and obtain information promptly Conduct facility tours. Scheduled facility about the facility. Opportunities for face-to- tours allow community members and state face interaction between community mem- representatives to visit the facility and ask bers and facility representatives include onsite questions about how it operates. By seeing a information offices, open houses, workshops, facility first-hand, residents learn how waste or briefings. is managed and can become more confident Information that it is being managed safely. Individual cit- offices function izens, local officials, interest groups, students, similarly to infor- and the media might want to take advantage mation reposito- of facility tours. In planning tours, determine ries, except that the maximum number of people that can be an employee is taken through the facility safely and think of present to answer ways to involve tour participants in what they questions. Open are seeing, such as providing hands-on houses are infor- demonstrations. It is also a good idea to have mal meetings on facility representatives available to answer site where resi- technical questions in an easy-to-understand dents can talk to manner. company officials
1-16 Getting Started—Understanding Risk and Building Partnerships
Maintain a publicly accessible informa- concern. When developing exhibits, identify tion repository. An information repository is the target audience, clarify which issue or simply a collection of documents describing aspect of the facility’s operations will be the the facility and its activities. It can include exhibit’s focus, and determine where the background information on the facility, the exhibit will be displayed. Public libraries, partnership plan (if developed), permits to convention halls, community events, and manage waste on site, fact sheets, and copies shopping centers are all good, highly visible of relevant guidance and regulations. The locations for an exhibit. repository should be in a convenient, publicly Use publications and mailing lists of accessible place. Repositories are often main- established local organizations. Existing tained on site in a public “reading room” or groups and publications often provide access off site at a public library, town hall, or public to established communication networks. Take health office. Facilities should publicize the advantage of these networks to minimize the existence, location, and hours of the reposito- time and expense required to develop mailing ry and update the information regularly. lists and organize meetings. Civic or environ- Develop exhibits that explain facility mental groups, rotary clubs, religious organi- operations. Exhibits are visual displays, such zations, and local trade associations might as maps, charts, diagrams, or photographs, have regular meetings, newsletters, newspa- accompanied by brief text. They can provide pers, magazines, or mailing lists that could be technical information in an easily under- useful in reaching interested members of the standable way and an opportunity to illus- community. trate creatively and informatively issues of
1-17 Getting Started—Understanding Risk and Building Partnerships
American Chemistry Council’s Association’s (AF&PA’s) belief that “sound environ- Responsible Care® mental policy and sound business practice go hand in hand” fueled the establishment of the To address citizens’ concerns about the manu- Sustainable Forestry Initiative (SFI). Established in facture, transport, use, and disposal of chemical 1995, the SFI outlines principles and objectives for products, the American Chemistry Council (ACC) environmental stewardship with which all AF&PA launched its Responsible Care® program in 1988. members must comply in order to retain member- To maintain their membership in ACC, companies ship. SFI encourages protecting wildlife habitat must participate in the Responsible Care® pro- and water quality, reforesting harvested land, and gram. One of the key components of the program conserving ecologically sensitive forest land. SFI is recognizing and responding to community con- recognizes that continuous public involvement is cerns about chemicals and facility operations. crucial to its ultimate goal of “ensuring that future ACC member are committed to fostering an generations of Americans will have the same abun- open dialogue with residents of the communities in dant forests that we enjoy today.” which they are located. To do this, member compa- The SFI stresses the importance of reaching out nies are required to address community concerns in to the public through toll-free information lines, two ways: (1) by developing and maintaining com- environmental education, private and public sector munity outreach programs, and (2) by assuring that technical assistance programs, workshops, videos, each facility has an emergency response program in and other means. To help keep the public place. For example, member companies provide informed of achievements in sustainable forestry, information about their waste minimization and members report annually on their progress, and emissions reduction activities, as well as provide AF&PA distributes the resulting publication to convenient ways for citizens to become familiar interested parties. In addition, AF&PA runs two with the facility, such as tours. Many companies national forums a year, which bring together log- also set up Community Advisory Panels. These gers, landowners, and senior industry representa- panels provide a mechanism for dialogue on issues tives to review progress toward SFI objectives. between plants and local communities. Companies must also develop written emergency response Many AF&PA state chapters have developed plans that include information about how to com- additional activities to inform the public about the municate with members of the public and consider SFI. For example, in New Hampshire, AF&PA their needs after an emergency. published a brochure about sustainable forestry and used it to brief local sawmill officials and the Responsible Care® is just one example of how media. In Vermont, a 2-hour interactive television public involvement principles can be incorporated session allowed representatives from industry, pub- into everyday business practices. The program also lic agencies, environmental organizations, the aca- shows how involving the public makes good busi- demic community, and private citizens to share ness sense. For more information about their views on sustainable forestry. Furthermore, in Responsible Care®, contact ACC at 703 741-5000. West Virginia, AF&PA formed a Woodland Owner Education Committee to reach out to nonindustrial AF&PA’s Sustainable Forestry private landowners. Initiative For more information about the SFI, contact AF&PA at 800 878-8878, or visit the Web site Public concern about the future of America’s
1-18 Getting Started—Understanding Risk and Building Partnerships
Understanding Risk and Building Partnerships Activity List
You should consider the following activities in understanding risk and building partnerships between facilities, states, and community members when addressing potential waste management practices. ■ Understand the definition of risk. ■ Review sources for obtaining health benchmarks. ■ Understand the risk assessment process including the pathways and routes of potential exposure and how to quantify or estimate exposure. ■ Be familiar with the risk assessment process for cancer risks and non-cancer risks. ■ Develop exhibits that provide a better understanding of facility operations. ■ Identify potentially interested/affected people. ■ Notify the state and public about new facilities or significant changes in facility operating plans. ■ Set up a public meeting for input from the community. ■ Provide interpreters for public meetings. ■ Make knowledgeable and responsible people available for sharing information. ■ Develop a partnership plan based on information gathered in previous steps. ■ Provide tours of the facility and information about its operations. ■ Maintain a publicly accessible information repository or onsite reading room. ■ Develop environmental risk communication skills.
1-19 Getting Started—Understanding Risk and Building Partnerships
Resources
American Chemistry Council. 2001 Guide to Community Advisory Panels.
American Chemistry Council. Revised 2001. Environmental Justice and Your Community: A Plant Manager’s Introduction.
American Chemistry Council. Responsible Care® Overview Brochure.
Council in Health and Environmental Science, ENVIRON Corporation. 1986. Elements of Toxicology and Chemical Risk Assessment.
Executive Order 12898. 1994. Federal Actions to Address Environmental Justice in Minority Populations and Low-income Populations. February.
Holland, C.D., and R.S. Sielken, Jr. 1993. Quantitative Cancer Modeling and Risk Assessment.
Kolluru, Rao, Steven Bartell, et al. 1996. Risk Assessment and Management Handbook: For Environmental, Health, and Safety Professionals.
Louisiana Department of Environmental Quality. 1994. Final Report to the Louisiana Legislature on Environmental Justice.
Lu, Frank C. 1996. Basic Toxicology: Fundamentals, Target Organs, and Risk Assessment.
National Research Council. 1983. Risk Assessment in the Federal Government: Managing the Process.
Public Participation and Accountability Subcommittee of the National Environmental Justice Advisory Council (A Federal Advisory Committee to the U.S. EPA). 1996. The Model Plan for Public Participation. November.
Texas Natural Resource Conservation Commission. 1993. Texas Environmental Equity and Justice Task Force Report: Recommendations to the Texas Natural Resource Conservation Commission.
Travis, C.C. 1988. Carcinogenic Risk Assessment.
U.S. EPA. 1996a. RCRA Public Involvement Manual. EPA530-R-96-007.
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Resources (cont.)
U.S. EPA. 1996b. 1994 Toxics Release Inventory: Public Data Release, Executive Summary. EPA745-S- 96-001.
U.S. EPA. 1995a. Decision-maker’s Guide to Solid Waste Management, Second Edition. EPA530-R-95- 023.
U.S. EPA. 1995b. The Exposure Factors Handbook. EPA600-P-95-002A-E.
U.S. EPA. 1995c. OSWER Environmental Justice Action Agenda. EPA540-R-95-023.
U.S. EPA. 1992. Environmental Equity: Reducing Risk for all Communities. EPA230-R-92-008A.
U.S. EPA. 1990. Sites for our Solid Waste: A Guidebook for Effective Public Involvement. EPA530- SW-90-019.
U.S. EPA. 1989a. Chemical Releases and Chemical Risks: A Citizen’s Guide to Risk Screening. EPA560- 2-89-003.
U.S. EPA. 1989b. Risk Assessment Guidance for Superfund. EPA540-1-89-002.
U.S. Government Accounting Office. 1995. Hazardous and Nonhazardous Waste: Demographics of People Living Near Waste Facilities. GAO/RCED-95-84.
Ward, R. 1995. Environmental Justice in Louisiana: An Overview of the Louisiana Department of Environmental Quality’s Environmental Justice Program.
Western Center for Environmental Decision-Making. 1996. Public Involvement in Comparative Risk Projects: Principles and Best Practices: A Source Book for Project Managers.
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Appendix
1-22 Getting Started—Understanding Risk and Building Partnerships
1-23 Part I Getting Started
Chapter 2 Characterizing Waste Contents
I. Waste Characterization Through Process Knowledge...... 2 - 2
II. Waste Characterization Through Leachate Testing ...... 2 - 3 A. Sampling and Analysis Plan ...... 2 - 4 1. Representative Waste Sampling...... 2 - 6 2. Representative Waste Analysis ...... 2 - 8 B. Leachate Test Selection ...... 2 - 9 1. Toxicity Characteristic Leaching Procedure (TCLP) ...... 2 - 10 2. Synthetic Precipitation Leaching Procedure (SPLP)...... 2 - 11 3. Multiple Extraction Procedure (MEP) ...... 2 - 12 4. Shake Extraction of Solid Waste with Water or Neutral Leaching Procedure ...... 2 - 13
III. Waste Characterization of Volatile Organic Emissions ...... 2 - 13
Waste Characterization Activity List ...... 2 - 15
Resources ...... 2 - 16
Appendix ...... 2 - 18 Getting Started—Characterizing Waste
Characterizing Waste This chapter will help you: • Understand the industrial processes that generate a waste. • Determine the waste’s physical and chemical properties. • Estimate constituent leaching to facilitate ground-water risk analysis. • Quantify total constituent concentrations to facilitate air emissions analysis. ing, or some combination of the two to esti- nderstanding the physical and mate waste generation rates and waste con- chemical properties of a waste stituent concentrations. To the extent that the using sampling and analysis waste is not highly variable, the use of process techniques is the cornerstone knowledge can be a sound approach to waste upon which subsequent steps in characterization and can prove more reason- the Guide are built. It is necessary for gauging U able and cost effective than frequent sampling what risks a waste might pose to surface water, of the waste. It is important to note, however, ground water, and air and drives waste man- that owners or operators using process knowl- agement unit design and operating decisions. edge to characterize a waste in lieu of testing Knowing the composition of the waste is also are still responsible for the accuracy of their necessary when determining the constituents determinations. No matter what approach is for which to test. And, as discussed in Chapter used in characterizing a waste, the goal is to 3–Integrating Pollution Prevention, knowledge maximize the available knowledge that is nec- of the physical and chemical properties of the essary to make the important decisions waste is crucial in identifying pollution pre- described in later chapters of the Guide. Also, vention opportunities. as changes are made to the industrial process- In many instances, you can use knowledge es or waste management practices, it might be of waste generation processes, analytical test- necessary to recharacterize a waste in order to accurately make waste management decisions and evaluate risk. This chapter will help you address the In considering the use of process knowl- following questions: edge or analytical testing, it is important to • How can process knowledge be used note that the ground water and air emissions to characterize a waste? models that accompany the Guide use con- stituent concentrations to estimate risk. Input • Which constituent concentrations requires specific concentrations which cannot should be quantified? be precisely estimated solely by knowledge of • Which type of leachate test should be the processes that generate the waste. Further, used? when wastes are placed in a waste manage- ment unit, such as a landfill or surface
2-1 Getting Started—Characterizing Waste
impoundment, they are subjected to various waste characteristics such as the physical physical, chemical, and biological processes state of the waste, the volume of waste pro- that can result in the creation of new com- duced, and the general composition of the pounds in the waste, changes in the mass and waste. In addition, many industries have volume of the waste, and the creation of dif- thoroughly tested and characterized their ferent phases within the waste and within the wastes over time, therefore it might be benefi- landfill or impoundment. In order to accu- cial to contact your trade association to deter- rately predict the concentration of the conta- mine if waste characterizations have already minants in the leachate, these changes must been performed and are available for process- be accounted for. es similar to yours. Additional resources can assist in waste characterization by providing Accurate waste management unit con- information on waste constituents and poten- stituent characterization is also necessary for tial concentrations. Some examples include: input to the modeling tools provided in the Guide. Because model input requires specific • Chemical engineering designs or data, model output will be based on the accu- plans for the process, showing racy of the data input. Process knowledge process input chemicals, expected alone (unless based on previous testing) might primary and secondary chemical not be sufficiently accurate to yield reliable reactions, and products. results. Leachate testing (discussed later in • Material Safety Data Sheets (MSDSs) this chapter), for example, will likely give you for materials involved. (Note that not a more precise assessment of waste con- all MSDSs contain information on all stituent concentrations than process knowl- constituents found in a product.) edge. Also note that whether you are using process knowledge, testing, or a combination • Manufacturer’s literature. of both, sources of model input data must be • Previous waste analyses. well documented so that an individual evalu- ating the modeling results understands the • Literature on similar processes. background supporting the assessment. • Preliminary testing results, if available. A material balance exercise using process knowledge can be useful in understanding I. Waste where wastes are generated within a process and in estimating concentrations of waste con- Characterization stituents particularly where analytical test data Through Process Knowledge A waste characterization begins with an understanding of the industrial processes that generate a waste. You must obtain enough information about the process to enable proper characterization of the waste, for example, by reviewing process flow diagrams or plans and determining all inputs and out- puts. You should also be familiar with other
2-2 Getting Started—Characterizing Waste
are limited. In a material balance, all input streams, such as raw materials fed into the What is process processes, and all output streams, such as knowledge? products produced and waste generated, are Process knowledge refers to detailed calculated. Flow diagrams can be used to iden- information on processes that generate tify important process steps and sources where wastes. It can be used to partly, or in wastes are generated. Characterizing wastes many cases completely, characterize using material balances can require consider- waste to ensure proper management. able effort and expense, but can help you to Process knowledge includes: develop a more complete picture of the waste generation process(es) involved. • Existing published or documented waste analysis data or studies con- Note that a thorough assessment of your ducted on wastes generated by production processes can also serve as the processes similar to that which gener- starting point for facility-wide waste reduc- ated the waste. tion, recycling, or pollution prevention efforts. Such an assessment will provide the • Waste analysis data obtained from information base to explore many opportuni- other facilities in the same industry. ties to reduce or recycle the volume or toxici- • Facility’s records of previously per- ty of wastes. Refer to Chapter 3–Integrating formed analyses. Pollution Prevention for ideas, tools, and ref- erences on how to proceed. While the use of process knowledge is to, or in place of, sampling and analysis, you attractive because of the cost savings associat- should clearly document the information ed with using existing information, you must used in your characterization assessment to ensure that this information accurately char- demonstrate to regulatory agencies, the pub- acterizes your wastes. If using process lic, and other interested parties that the infor- descriptions, published data, and document- mation accurately and completely ed studies to determine waste characteristics, characterizes the waste. The source of this the data should be scrutinized carefully to information should be clearly documented. determine if there are any differences between the processes in the studies and the waste generating process at your facility, that the studies are acceptable and accurate (i.e., II. Waste based on valid sampling and analytical tech- Characterization niques), and that the information is current. If there are discrepancies, or if you begin a Through new process or change any of the existing Leachate Testing processes at your facility (so that the docu- Although sampling and laboratory analysis mented studies and published data are no is not as economical and might not be as longer applicable), you are encouraged to convenient as using process knowledge, it consider performing additional sampling and does have advantages. The resulting data usu- laboratory analysis to accurately characterize ally provide the most accurate information the waste and ensure proper management. available on constituent concentration levels. Also, if process knowledge is used in addition
2-3 Getting Started—Characterizing Waste
Incomplete or mis-characterization of waste the results of the total compositional analysis can lead to improper waste management, inac- may be divided by twenty to convert the total curate modeling outputs, or erroneous deci- results into the maximum leachable concentra- sions concerning the type of unit to be used, tion1. This factor is derived from the 20:1 liq- liner selection, or choice of land application uid to solid ratio employed in the TCLP. This methods. Note that process knowledge allows is a conservative approach to estimating you to eliminate unnecessary or redundant leachate concentrations and does not factor in waste testing by helping you focus on which environmental influences, such as rainfall. If a constituents to measure in the waste. Again, waste has filterable liquid, then the concentra- thorough documentation of both the process tion of each phase (liquid and solid) must be knowledge used (e.g., studies, published data), determined. The following equation may be as well as the analytical data is important. used to calculate this value:2
The intent of leachate and extraction testing (V1)(C1) + (V2)(C2) is to estimate the leaching potential of con- V + 20V stituents of concern to water sources. It is 1 2 important to estimate leaching potential in Where: order to accurately estimate the quantity of V = Volume of the first phase (L) chemicals that could potentially reach ground- 1 or surface-water resources (e.g., drinking C1 = Concentration of the analyte of con- water supply wells, waters used for recre- cern in the first phase (mg/L) ation). The Industrial Waste Management V2 = Volume of the second phase (L) Evaluation Model (IWEM) developed for the Guide uses expected leachate concentrations C2 = Concentration of the analyte of con- for the waste management units as the basis cern in the second phase (mg/L) for liner system design recommendations. Because this is only a screening method for Leachate tests will allow you to accurately identifying an upper-bound TCLP leachate quantify the input terms for modeling. concentration, you should consult with your If the total concentration of all the con- state or local regulatory agency to determine stituents in a waste has been estimated using whether process knowledge can be used to process knowledge (which could include pre- accurately estimate maximum risk in lieu of vious testing data on wastes known to be very leachate testing. similar), estimates of the maximum possible concentration of these constituents in leachate A. Sampling and Analysis can be made using the dilution ratio of the leachate test to be performed. Plan One of the more critical elements in proper For example, the Toxicity Characteristic waste characterization is the plan for sampling Leachate Procedure (TCLP) allows for a total and analyzing the waste. The sampling plan is constituent analysis in lieu of performing the usually a written document that describes the test for some wastes. If a waste is 100 percent objectives and details of the individual tasks of solid, as defined by the TCLP method, then
1 This method is only appropriate for estimating maximum constituent concentration in leachate for non- liquid wastes (e.g., those wastes not discharged to a surface impoundment). For surface impoundments, the influent concentration of heavy metals can be assumed to be the maximum theoretical concentration of metals in the leachate for purposes of input to the ground-water modeling tool that accompanies this document. To estimate the leachate concentration of organic constituents in liquid wastes for modeling input, you will need to account for losses occurring within the surface impoundment before you can esti- mate the concentration in the leachate (i.e., an effluent concentration must be determined for organics). 2-4 2 Source: Office of Solid Waste Web site at
a sampling effort and how they will be per- itself. Reasons for obtaining samples from an formed. This plan should be carefully thought existing unit include, characterizing the waste out, well in advance of sampling. The more in the unit to determine if the new waste detailed the sampling plan, the less opportu- being added is compatible, checking to see if nity for error or misunderstanding during the composition of the waste is changing over sampling, analysis, and data interpretation. time due to various chemical and biological breakdown processes, or characterizing the To ensure that the sampling plan is waste in the unit or the leachate from the designed properly, a wide range of personnel unit to give an indication of expected concen- should be consulted. It is important that the trations in leachate from a new unit. following individuals are involved in the development of the sampling plan to ensure The sampling plan must be correctly that the results of the sampling effort are pre- defined and organized in order to get an cise and accurate enough to properly charac- accurate estimation of the characteristics of terize the waste: the waste. Both an appropriate sample size and proper sampling techniques are neces- • An engineer who understands the sary. If the sampling process is carried out manufacturing processes. correctly, the sample will be representative • An experienced member of the sam- and the estimates it generates will be useful pling team. for making decisions concerning proper man- • The end user of the data. agement of the waste and for assessing risk. • A senior analytical chemist. In developing a sampling plan, accuracy is of primary concern. The goal of sampling is to • A statistician. get an accurate estimate of the waste’s charac- • A quality assurance representative. teristics from measuring the sample’s charac- teristics. The main controlling factor in It is also advisable that you consult the deciding whether the estimates will be accu- analytical laboratory to be used when devel- rate is how representative the sample is (dis- oping your sampling plan. cussed in the following section). Using a small Background information on the processes sample increases the possibility that the sam- that generate the waste and the type and ple will not be representative, but a sample characteristics of the waste management unit that is larger than the minimum calculated is essential for developing a sound sampling sample size does not necessarily increase the plan. Knowledge of the unit location and sit- probability of getting a representative sample. uation (e.g., geology, exposure of the waste to As you are developing the sampling plan, you the elements, local climatic conditions) will should address the following considerations: assist in determining correct sample size and sampling method. Sampling plan design will • Data quality objectives. depend on whether you are sampling a waste • Determination of a representative prior to disposal in a waste management unit sample. or whether you are sampling waste from an existing unit. When obtaining samples from • Statistical methods to be employed in an existing unit, care should be taken to the analyses. avoid endangering the individuals collecting • Waste generation and handling the samples and to prevent damaging the unit processes.
2-5 Getting Started—Characterizing Waste
• Constituents/parameters to be sampled. Background Document (U.S. EPA 2002). The LCTV tables also are included in the IWEM • Physical and chemical properties of Technical Background Document and the model the waste. on the CD-ROM version of this Guide, and • Accessibility of the unit. can be used as a starting point to help you • Sampling equipment, methods, and determine which constituents to measure. It sample containers. is not recommended that you sample for all of the organic chemicals and metals listed in • Quality assurance and quality control the tables, but rather use these tables as a (e.g., sample preservation and han- guide in conjunction with knowledge con- dling requirements). cerning the waste generating practices to • Chain-of-custody. determine which constituents to measure. • Health and safety of employees. 1. Representative Waste Many of these considerations are discussed Sampling below. Additional information on data quality objectives and quality assurance and quality The first step in any analytical testing control can be found in Test Methods for process is to obtain a sample that is represen- Evaluating Solid Waste, Physical/Chemical tative of the physical and chemical composi- Methods—SW-846 (U.S. EPA, 1996e), Guidance tion of a waste. The term “representative for the Data Quality Objectives Process (U.S. sample” is commonly used to denote a sample EPA, 1996b), Guidance on Quality Assurance that has the same properties and composition Project Plans (U.S. EPA, 1998a), and Guidance in the same proportions as the population for the Data Quality Assessment: Practical from which it was collected. Finding one sam- Methods for Data Analysis (U.S. EPA, 1996a).3 ple which is representative of the entire waste can be difficult unless you are dealing with a A determination as to the constituents that homogenous waste. Because most industrial will be measured can be based on process wastes are not homogeneous, many different knowledge to narrow the focus and expense factors should be considered in obtaining of performing the analyses. Analyses should samples. Examples of some of the factors that be performed for those constituents that are should be considered include: reasonably expected to be in the waste at detectable levels (i.e., test method detection • Physical state of the waste. The levels). Note that the Industrial Waste physical state of the waste affects Management Evaluation Model (IWEM) that most aspects of a sampling effort. The accompanies this document recommends sampling device will vary according liner system designs, if necessary, or the to whether the sample is liquid, solid, appropriateness of land application based on gas, or multiphasic. It will also vary calculated protective leachate thresholds according to whether the liquid is (Leachate Concentration Threshold Values or viscous or free-flowing, or whether LCTVs) for various constituents that are like- the solid is hard, soft, powdery, ly to be found in industrial waste and pose monolithic, or clay-like. hazards at certain levels to people and the • Composition of the waste. The environment. The constituents that are evalu- samples should represent the average ated are listed in Table 1.2 of the Industrial concentration and variability of the Waste Management Evaluation Model Technical waste in time or over space.
3 These and other EPA publications can be found at the National Environmental Publications Internet site (NEPIS) at
• Waste generation and han- dling processes. Processes to More information on Test Methods consider include: if the waste for Evaluating Solid Waste, Physical/ is generated in batches; if Chemical Methods—SW-846 there is a change in the raw EPA has begun replacing requirements mandat- materials used in a manufac- ing the use of specific measurement methods or turing process; if waste com- technologies with a performance-based measure- position can vary substantially ment system (PBMS). The goal of PBMS is to as a function of process tem- reduce regulatory burden and foster the use of peratures or pressures; and if innovative and emerging technologies or meth- storage time affects the waste’s ods. The PBMS establishes what needs to be characteristics/composition. accomplished, but does not prescribe specifically • Transitory events. Start-up, how to do it. In a sampling situation, for exam- shut-down, slow-down, and ple, PBMS would establish the data needs, the maintenance transients can level of uncertainty acceptable for making deci- result in the generation of a sions, and the required supporting documenta- waste that is not representative tion; a specific test method would not be of the normal waste stream. If prescribed. This approach allows the analyst the a sample was unknowingly flexibility to select the most appropriate and cost collected at one of these inter- effective test methods or technologies to comply vals, incorrect conclusions with the criteria. Under PBMS, the analyst is could be drawn. required to demonstrate the accuracy of the mea- You should consult with your state or surement method using the specific matrix that is local regulatory agency to identify any being analyzed. SW-846 serves only as a guidance legal requirements or preferences before document and starting point for determining initiating sampling efforts. Refer to which test method to use. Chapter 9 of the EPA’s SW-846 test SW-846 provides state-of-the-art analytical test methods document (see side bar) for methods for a wide array of inorganic and organic detailed guidance on planning, imple- constituents, as well as procedures for field and menting, and assessing sampling events. laboratory quality control, sampling, and charac- To ensure that the chemical infor- teristics testing. The methods are intended to pro- mation obtained from waste sampling mote accuracy, sensitivity, specificity, precision, efforts is accurate, it must be unbiased and comparability of analyses and test results. and sufficiently precise. Accuracy is For assistance with the methods described in SW- usually achieved by incorporating 846, call the EPA Method Information some form of randomness into the Communication Exchange (MICE) Hotline at 703 sample selection process and by select- 676-4690 or send an e-mail to [email protected]. ing an appropriate number of samples. The text of SW-846 is available online at: Since most industrial wastes are het-
2-7 Getting Started—Characterizing Waste
or points in all batches of waste from which a If sampling is restricted, the sampling strat- sample could be collected) are identified, and egy should, at a minimum, take sufficient a suitable number of samples is randomly samples to address the potential vertical varia- selected from the population. tions in the waste in order to be considered representative. This is because contained The appropriate number of samples to wastes tend to display vertical, rather than employ in a waste characterization is at least horizontal, non-random heterogeneity due to the minimum number of samples required to settling or the layering of solids and denser generate a precise estimate of the true mean liquid phases. Also, care should be taken concentration of a chemical contaminant in a when performing representative sampling of a waste. A number of mathematical formulas landfill, waste pile, or surface impoundment exist for determining the appropriate number to minimize any potential to create hazardous of samples depending on the statistical preci- conditions. (It is possible that the improper sion required. Further information on sam- use of intrusive sampling techniques, such as pling designs and methods for calculating the use of augers, could accelerate leaching by required sample sizes and optimal distribu- creating pathways or tunnels that can acceler- tion of samples can be found in Gilbert ate leachate movement to ground water.) (1987), Winer (1971), and Cochran (1977) and Chapter 9 of EPA SW-846. To facilitate characterization efforts, consult with state and local regulatory agencies and a The type of sampling plan developed will qualified professional to select a sampling plan vary depending on the sampling location. and determine the appropriate number of sam- Solid wastes contained in a landfill or waste ples, before beginning sampling efforts. You pile can be best sampled using a three- should also consider conducting a detailed dimensional random sampling strategy. This waste-stream specific characterization so that involves establishing an imaginary three- the information can be used to conduct waste dimensional grid or sampling points in the reduction and waste minimization activities. waste and then using random-number tables or random-number generators to select points Additional information concerning sam- for sampling. Hollow-stem augers combined pling plans, strategies, methods, equipment, with split-spoon samplers are frequently and sampling quality assurance and quality appropriate for sampling landfills. control is available in Chapters 9 and 10 of the SW-846 test methods document. Electronic If the distribution of waste components is versions of these chapters have been included known or assumed for liquid or semi-solid on the CD-ROM version of the Guide. wastes in surface impoundments, then a two- dimensional simple random sampling strategy might be appropriate. In this strategy, the top 2. Representative Waste Analysis surface of the waste is divided into an imagi- After a representative sample has been col- nary grid and grid sections are selected using lected, it must be properly preserved to main- random-number tables or random-number tain the physical and chemical properties that generators. Each selected grid point is then it possessed at the time of collection. Sample sampled in a vertical manner along the entire types, sample containers, container prepara- length from top to bottom using a sampling tion, and sample preservation methods are device such as a weighted bottle, a drum critical for maintaining the integrity of the thief, or Coliwasa. sample and obtaining accurate results. Preservation and holding times are also
2-8 Getting Started—Characterizing Waste
important factors to consider and will vary ommendations or requirements of your state depending on the type of constituents being and local regulatory agencies. measured (e.g., VOCs, heavy metals, hydro- When selecting the most appropriate ana- carbons) and the waste matrix (e.g., solid, lytical tests, consider at a minimum the phys- liquid, semi-solid). ical state of the sample, the constituents to be The analytical chemist then develops an analyzed, detection limits, and the specified analytical plan which is appropriate for the holding times of the analytical methods.4 It sample to be analyzed, the constituents to be might not be cost-effective or useful to con- analyzed, and the end use of the information duct a test with detection limits at or greater required. The laboratory should have standard than the constituent concentrations in a operating procedures available for review for waste. Process knowledge can help you pre- the various types of analyses to be performed dict whether the concentrations of certain and for all associated methods needed to com- constituents are likely to fall below the detec- plete each analysis, such as instrument main- tion limits for anticipated methods. tenance procedures, sample handling After assessing the state of the waste, assess procedures, and sample documentation proce- the environment of the waste management dures. In addition, the laboratory should have unit in which the waste will be placed. For a laboratory quality assurance/quality control example, an acidic environment might statement available for review which includes require a different test than a non-acidic envi- all key personnel qualifications. ronment in order to best reflect the condi- The SW-846 document contains informa- tions under which the waste will actually tion on analytical plans and methods. leach. If the waste management unit is a Another useful source of information regard- monofill, then the characteristics of the waste ing the selection of analytical methods and will determine most of the unit’s conditions. quality assurance/quality control procedures Conversely, if many different wastes are being for various compounds is the Office of Solid co-disposed, then the conditions created by Waste Methods Team home page at
4 There are several general categories of phases in which samples can be categorized: solids, aqueous, sludges, multiphase samples, ground water, and oil and organic liquid. You should select a test that is designed for the specific sample type. 2-9 Getting Started—Characterizing Waste
the co-disposed wastes must be considered, sult with state and local regulatory agencies including the constituents that can be leached and/or a laboratory that is familiar with by the subject waste. leachate testing methods to identify the most appropriate test and test method procedures A qualified laboratory should always be used for your waste and sample type. when conducting analytical testing. The labora- tory can be in-house or independent. When using independent laboratories, ensure that 1. Toxicity Characteristic Leaching they are qualified and competent to perform Procedure (TCLP) the required tests. Some laboratories might be The TCLP 6 is the test method used to deter- proficient in one test but not another. You mine whether a waste is hazardous due to its should consult with the laboratory before final- characteristics as defined in the Resource izing your test selection to make certain that Conservation and Recovery Act (RCRA), 40 the test can be performed. When using analyti- CFR Part 261. The TCLP estimates the leacha- cal tests that are not frequently performed, bility of certain toxicity characteristic hazardous additional quality assurance and quality control constituents from solid waste under a defined practices might need to be implemented to set of laboratory conditions. It evaluates the ensure that the tests are conducted correctly leaching of metals, volatile and semi-volatile and that the results are accurate. organic compounds, and pesticides from A brief summary of the TCLP and three wastes. The TCLP was developed to simulate other commonly used leachate tests is provid- the leaching of constituents into ground water ed below (procedures for the EPA test meth- under conditions found in municipal solid ods are included in SW-846 and for the waste (MSW) landfills. The TCLP does not sim- ASTM method in the Annual Book of ASTM ulate the release of contaminants to non-ground Standards). These summaries are provided as water pathways. The TCLP is most commonly background and are not meant to imply that used by EPA, state, and local agencies to classify these are the only tests that can be used to waste. It is also used to determine compliance accurately predict leachate potential. Other with some land disposal restrictions (LDRs) for leachate tests have been developed and might hazardous wastes. The TCLP can be found as be suitable for testing your waste. The table EPA Method 1311 in SW-846.7 A copy of in the appendix at the end of this chapter Method 1311 has been included on the CD- provides a summary of over 20 leachate tests ROM version of the Guide. that have been designed to estimate the For liquid wastes, (i.e., those containing potential for contaminant release, including less than 0.5 percent dry solid material) the several developed by ASTM.5 You should con- waste after filtration through a glass fiber fil-
5 EPA has only reviewed and evaluated those test methods found in SW-846. The EPA has not reviewed or evaluated the other test methods and cannot recommend use of any test methods other than those found in SW-846. 6 EPA is undertaking a review of the TCLP test and how it is used to evaluate waste leaching (described in the Phase IV Land Disposal Restrictions rulemaking, 62 Federal Register 25997; May 26, 1998). EPA anticipates that this review will examine the effects of a number of factors on leaching and on approaches to estimating the likely leaching of a waste in the environment. These factors include pH, liquid to solid ratios, matrix effects and physical form of the waste, effects of non-hazardous salts on the leachability of hazardous metal salts, and others. The effects of these factors on leaching might or might not be well reflected in the leaching tests currently available. At the conclusion of the TCLP review, EPA is likely to issue revisions to this guidance that reflect a more complete understanding of waste constituent leaching under a variety of management conditions. 2-10 7 The TCLP was developed to replace the Extraction Procedure Toxicity Test method which is designated as EPA Method 1310 in SW-846. Getting Started—Characterizing Waste
ter is defined as the TCLP extractant. The in a municipal landfill, this test might not be concentrations of constituents in the liquid appropriate for your waste because the leach- extract are then determined. ing potential for the same chemical can be quite different depending on a number of fac- For wastes containing greater than or equal tors. These factors include the characteristics to 0.5 percent solids, the liquid, if any, is sep- of the leaching fluid, the form of the chemical arated from the solid phase and stored for in the solids, the waste matrix, and the dis- later analysis. The solids must then be posal conditions. reduced to particle size, if necessary. The solids are extracted with an acetate buffer Although the TCLP is the most commonly solution. A liquid-to-solid ratio of 20:1 by used leachate test for estimating the actual weight is used for an extraction period of 18 leaching potential of wastes, you should not ± 2 hours. After extraction, the solids are fil- automatically default to it in all situations or tered from the liquid through a glass fiber fil- conditions and for all types of wastes. While ter and the liquid extract is combined with the TCLP test might be conservative under any original liquid fraction of the wastes. some conditions (i.e., overestimates leaching Analyses are then conducted on the liquid fil- potential), it might underestimate leaching trate/leachate to determine the constituent under other extreme conditions. In a landfill concentrations. that has primarily alkaline conditions, the TCLP is not likely to be the optimal method To determine if a waste is hazardous because the TCLP is designed to replicate because it exhibits the toxicity characteristic leaching in an acidic environment. For mate- (TC), the TCLP method is used to generate rials that pose their greatest hazard when leachate under controlled conditions as dis- exposed to alkaline conditions (e.g., metals cussed above. If the TCLP liquid extract con- such as arsenic and antimony), use of the tains any of the constituents listed in Table 1 TCLP might underestimate the leaching of 40 CFR Part 261 at a concentration equal potential. When the conditions of your waste to or greater than the respective value in the management unit are very different from the table, the waste is considered to be a TC haz- conditions that the TCLP test simulates, ardous waste, unless exempted or excluded another test might be more appropriate. under Part 261. Although the TCLP test was Further, the TCLP might not be appropriate designed to determine if a waste is hazardous, for analyzing oily wastes. Oil phases can be the importance of its use for waste characteri- difficult to separate (e.g., it might be impossi- zation as discussed in this chapter is to ble to separate solids from oil), oily material understand the parameters to be considered can obstruct the filter (often resulting in an in properly managing the wastes. underestimation of constituents in the You should check with state and local reg- leachate), and oily materials can yield both ulatory agencies to determine whether the oil and aqueous leachate which must be ana- TCLP is likely to be the best test for evaluat- lyzed separately.8 ing the leaching potential of a waste or if another test might better predict leaching 2. Synthetic Precipitation under the anticipated waste management conditions. Because the test was developed by Leaching Procedure (SPLP) EPA to determine if a waste is hazardous The SPLP (designated as EPA Method 1312 (according to 40 CFR 261.24) and focused in SW-846) is currently used by several state on simulating leaching of solid wastes placed agencies to evaluate the leaching of con-
8 SW-846 specifies several procedures that should be followed when analyzing oily wastes.
2-11 Getting Started—Characterizing Waste
and TCLP, some paint and oily wastes might clog the filters used to separate the liquid extract from the solids prior to analysis, resulting in under reporting of the extractable constituent concentrations.
3. Multiple Extraction Procedure (MEP) The MEP (designated as EPA Method 1320 in SW-846) was designed to simulate the stituents from wastes. The SPLP was designed leaching that a waste will undergo from repeti- to estimate the leachability of both organic tive precipitation of acid rain on a landfill to and inorganic analytes present in liquids, soils, determine the highest concentration of each and wastes. The SPLP was originally designed constituent that is likely to leach in a real to assess how clean a soil was under EPA’s world environment. Currently, the MEP is used Clean Closure Program. Even though the fed- in EPA’s hazardous waste delisting program. A eral hazardous waste program, did not adopt copy of Method 1320 has been included on it for use, the test can still estimate releases the CD-ROM version of the Guide. from wastes placed in a landfill and subject to The MEP can be used to evaluate liquid, acid rain. There might be, however, important solid, and multiphase samples. Waste sam- differences between soil as a constituent ples are extracted according to the Extraction matrix (for which the SPLP is primarily used) Procedure (EP) Toxicity Test (Method 1310 and the matrix of a generated industrial waste. of SW-846). The EP test is also very similar A copy of Method 1312 has been included on to the TCLP Method 1311. A copy of Method the CD-ROM version of the Guide. 1310 has been included on the CD- ROM The SPLP is very similar to the TCLP version of the Guide. Method 1311. Waste samples containing In the MEP, liquid wastes are filtered solids and liquids are handled by separating through a glass fiber filter prior to testing. the liquids from the solid phase, and then Waste samples containing both solids and liq- reducing solids to particle size. The solids are uids are handled by separating the liquids then extracted with a dilute sulfuric from the solid phase, and then reducing the acid/nitric acid solution. A liquid-to-solid solids to particle size. The solids are then ratio of 20:1 by weight is used for an extrac- extracted using an acetic acid solution. A liq- tion period of 18±2 hours. After extraction, uid- to-solid ratio of 16:1 by weight is used the solids are filtered from the liquid extract for an extraction period of 24 hours. After and the liquid extract is combined with any extraction, the solids are filtered from the liq- original liquid fraction of the wastes. uid extract, and the liquid extract is combined Analyses are then conducted on the liquid fil- with any original liquid fraction of the waste. trate/leachate to determine the constituent concentrations. The solids portion of the sample that remains after application of Method 1310 are The sulfuric acid/nitric acid extraction then re-extracted using a dilute sulfuric solution used in the SPLP was selected to acid/nitric acid solution. As in the SPLP, this simulate leachate generation, in part, from acidic solution was selected to simulate acid rain. Also note that in both the SPLP
2-12 Getting Started—Characterizing Waste
leachate generation, in part, from acid rain. solid ratio of 20:1 by weight is used. After This time a liquid-to-solid ratio of 20:1 by agitation the solids are filtered from the liquid weight is used for an extraction period of 24 extract, and the liquid is analyzed. hours. After extraction, the solids are once The water extraction is meant to simulate again filtered from the liquid extract, and the conditions where the solid waste is the domi- liquid extract is combined with any original nant factor in determining the pH of the liquid fraction of the waste. extract. This test, however, has only been These four steps are repeated eight addi- approved for certain inorganic constituents, tional times. If the concentration of any con- and is not applicable to organic substances stituent of concern increases from the 7th or and volatile organic compounds (VOCs). A 8th extraction to the 9th extraction, the pro- copy of this procedure can be ordered by cedure is repeated until these concentrations calling ASTM at 610 832-9585 or online at decrease.
2-13 Getting Started—Characterizing Waste
unnecessary sampling costs. A thorough understanding of process knowledge can help you determine what is reasonably expected to be in the waste, so that it is not necessary to sample for unspecified constituents. Many tests have been developed for quan- titatively extracting volatile and semi-volatile organic constituents from various sample matrices. These tests tend to be highly dependent upon the physical characteristics of the sample. You should consult with state and local regulatory agencies before imple- menting testing. You can refer to SW-846 Method 3500B for guidance on the selection of methods for quantitative extraction or dilution of samples for analysis by one of the volatile or semi-volatile determinative meth- ods. After performing the appropriate extrac- tion procedure, further cleanup of the sample extract might be necessary if analysis of the extract is prevented due to interferences coextracted from the sample. Method 3600 of SW-846 provides additional guidance on cleanup procedures. Following sample preparation, a sample is ready for further analysis. Most analytical methods use either gas chromatography (GC), high performance liquid chromatogra- phy (HPLC), gas chromatography/mass spec- trometry (GC/MS), or high performance liquid chromatography/mass spectrometry (HPLC/MS). SW-846 is designed to allow the methods to be mixed and matched, so that sample preparation, sample cleanup, and analytical methods can be properly sequenced for the particular analyte and matrix. Again, you should consult with state and local regulatory agencies before finalizing the selected methodology.
2-14 Getting Started—Characterizing Waste
Waste Characterization Activity List
To determine constituent concentrations in a waste you should: ■ Assess the physical state of the waste using process knowledge. ■ Use process knowledge to identify constituents for further analysis. ■ Assess the environment in which the waste will be placed. ■ Consult with state and local regulatory agencies to determine any specific testing requirements. ■ Select an appropriate leachate test or organic constituent analysis based on the above information.
2-15 Getting Started—Characterizing Waste
Resources
ASTM. 1995. Annual Book of ASTM Standards.
ASTM. Standard Methods for Examination of Water and Wastewater.
ASTM. D-3987-85. Standard Test Method for Shake Extraction of Solid Waste with Water
California EPA. Handbook for the Analysis and Classification of Wastes.
California EPA. 1995. Preliminary Proposal to Require the TCLP in Lieu of the Waste Extraction Test. Memorandum to James Carlisle, Department of Toxics Substances Control, from Jon Marshack, California Regional Water Quality Control Board. December 18.
California EPA. 1994. Regulation Guidance: When Extraction Tests are Not Necessary.
California EPA. 1994. Regulation Guidance: TCLP vs. WET.
California EPA. 1993. Regulation Guidance: Lab Methods.
California EPA. 1993. Regulation Guidance: Self-Classification.
Cochran, W.G. 1977. Sampling Techniques. Third Edition. New York: John Wiley and Sons.
Dusing, D.C., Bishop, P.L., and Keener, T.C. 1992. Effect of Redox Potential on Leaching from Stabilized/Solidified Waste Materials. Journal of Air and Waste Management Association. 42:56. January.
Gilbert, R.O. 1987. Statistical Methods for Environmental Pollution Monitoring. New York: Van Nostrand Reinhold Company.
Kendall, Douglas. 1996. Impermanence of Iron Treatment of Lead-Contaminated Foundry Sand— NIBCO, Inc., Nacogdoches, Texas. National Enforcement Investigations Center Project PA9. April.
Kosson, D.S., H.A. van der Sloot, F. Sanchez, and A.C. Garrabrants. 2002. An Integrated Framework for Evaluating Leaching in Waste Management and Utilization of Secondary Materials. Environmental Engineering Science, In-press.
New Jersey Department of Environmental Protection. 1996. Industrial Pollution Prevention Trends in New Jersey.
2-16 Getting Started—Characterizing Waste
Resources (cont.)
Northwestern University. 1995. Chapter 4—Evaluation of Procedures for Analysis and Disposal of Lead- Based Paint-Removal Debris. Issues Impacting Bridge Painting: An Overview. Infrastructure Technology Institute. FHWA/RD/94/098. August.
U.S. EPA 2002. Industrial Waste Managment Evaluation (IWEM) Technical Background Document. EPA530-R-02-012.
U.S. EPA. 1998a. Guidance on Quality Assurance Project Plans: EPA QA/G-5. EPA600-R-98-018.
U.S. EPA. 1998b. Guidance on Sampling Designs to Support QA Project Plans. QA/G-5S
U.S. EPA. 1997. Extraction Tests. Draft.
U.S. EPA. 1996a. Guidance for the Data Quality Assessment: Practical Methods for Data Analysis: EPAQA/G-9. EPA600-R-96-084.
U.S. EPA. 1996b. Guidance for the Data Quality Objectives Process: EPA QA/G-4. EPA600-R-96-055.
U.S. EPA. 1996c. Hazardous Waste Characteristics Scoping Study.
U.S. EPA. 1996d. National Exposure Research Laboratory (NERL)-Las Vegas: Site Characterization Library, Volume 2.
U.S. EPA. 1996e. Test Methods for Evaluating Solid Waste Physical/Chemical Methods—SW846. Third Edition.
U.S. EPA. 1995. State Requirements for Non-Hazardous Industrial Waste Management Facilities.
U.S. EPA. 1993. Identifying Higher-Risk Wastestreams in the Industrial D Universe: The State Experience. Draft.
U.S. EPA. 1992. Facility Pollution Prevention Guide. EPA600-R-92-088.
U.S. EPA Science Advisory Board. 1991. Leachability Phenomena: Recommendations and Rationale for Analysis of Contaminant Release by the Environmental Engineering Committee. EPA-SAB-EEC-92-003.
Winer, B.J. 1971. Statistical Principles in Experimental Design. New York: McGraw-Hill.
2-17 Getting Started—Characterizing Waste
Appendix: Example Extraction Tests (Draft 9/30/97)
Test Method Leaching Fluid Liquid:Solid Maximum Number of Time of Comments Ratio Particle Size Extractions Extractions
I. Static Tests
A. Agitated Extraction Tests
Toxicity 0.1 N acetic acid solution, 20:1 9.5 mm 1 18 ±2 hours Co-disposal scenario might Characteristic pH 2.9, for alkaline wastes not be appropriate; no Leaching 0.1 N sodium acetate allowance for structural Procedure (1311) buffer solution, pH 5.0, integrity testing of for non-alkaline wastes monolithic samples
Extraction 0.5 N acetic acid (pH-5.0) 16:1 during 9.5 mm 1 24 hours High alkalinity samples can Procedure extraction result in variable data Toxicity Test (1310) 20:1 final dilution
ASTM D3987-85 ASTM IV reagent water 20:1 As in 1 18 hours Not validated for organics Shake Extraction environment of Solid Waste (as received) with Water
California WET 0.2 M sodium citrate 10:1 2.0 mm 1 48 hours Similar to EP, but sodium (pH- 5.0) citrate makes test more aggressive
Ultrasonic Distilled water 4:1 Ground 1 30 minutes New—little performance Agitation data Method for Accelerating Batch Leaching Test9
Alternative TCLP TCLP acetic acid solutions 20:1 <9.5 1 8 hours Uses heat to decrease for Construction, extraction time Demolition and Lead Paint Abatement Debris10
Extraction Soxhlet with THF and 100g:300mL 9.5 mm 3 24 hours (EP) Procedure for Oily toluene EP on remaining 20:1 Waste (1330) solids
Synthetic #1 Reagent water to pH 4.2 20:1 9.5 mm 1 18±2 hours ZHE option for organics Precipitation with nitric and sulfuric Leaching Procedure acids (60/40) (1312) #2 Regent water to pH 5.0 with nitric and sulfuric acids (60/40)
Equilibrium Leach Distilled water 4:1 150 mm 1 7 days Determines contaminants Test that have been insolubilized by solidification
9 Bisson, D.L.; Jackson D.R.; Williams K.R.; and Grube W.E. J. Air Waste Manage. Assoc., 41: 1348-1354. 10 Olcrest, R. A Representative Sampling and Alternative Analytical Toxic Characteristic Leachate Procedure 2-18 Method for Construction, Demolition, and Lead Paint Abatement Debris Suspected of Containing Leachable Lead, Appl. Occup. Environ. Hyg. 11(1), January 1996. Getting Started—Characterizing Waste
Test Method Leaching Fluid Liquid:Solid Maximum Number of Time of Comments Ratio Particle Size Extractions Extractions
B. Non-Agitated Extraction Tests
Static Leach Test Can be site specific, 3 VOL/surface 40 mm2 1 >7 days Series of optional steps Method (material standard leachates: water, 10 cm surface area increasing complexity of characteristic brine, silicate/bicarbonate analysis centre- 1)
High Temperature Same as MCC-1 (conducted VOL/Surface 40 mm2 1 >7 Days Series of optional steps Static Leach Tests at 100°C) 10 cm Surface Area increasing complexity of Method (material analysis characterization centre-2)
C. Sequential Chemical Extraction Tests
Sequential 0.04 m acetic acid 50:1 9.5 mm 15 24 hours per Extraction Tests extraction
D. Concentration Build-Up Test
Sequential 5 leaching solutions of Varies from 150 mm 5 Varies 3 or Examines partitioning of Chemical increasing acidity 16.1 to 40.1 14 days metals into different Extraction fractions or chemicals forms
Standard Leach DI water SYN Landfill 10:1, 5:1, As in 3 3 or 14 days Sample discarded after each Test, Procedure C 7.5:1 environment leach, new sample added to (Wisconsin) existing leachate
II. Dynamic Tests (Leaching Fluid Renewed)
A. Serial Batch (Particle)
Multiple Extraction Same as EP TOX, then 20:1 9.5 mm 9 (or more) 24 hours per Procedure (1320) with synthetic acid rain extraction (sulfuric acid, nitric acid in 60:40% mixture)
Monofill Waste Distilled/deionized water 10:1 per 9.5 mm or 4 18 hours per Extraction or other for specific site extraction monolith extraction Procedures
Graded Serial Batch Distilled water Increases N/A >7 Until steady (U.S. Army) from 2:1 to state 96:1
Sequential Batch Type IV reagent water 20:1 As in 10 18 hours Ext. of Waste with environment Water ASTM D-4793-93
2-19 Getting Started—Characterizing Waste
Test Method Leaching Fluid Liquid:Solid Maximum Number of Time of Comments Ratio Particle Size Extractions Extractions
Use of Chelating Demineralized water with 50 or 100 <300 µm 1 18, 24, or Experimental test based on Agent to Determine EDTA, sample to a final 48 hours Method 7341 the Metal pH of 7±0.5 Availability for Leaching Soils and Wastes11
B. Flow Around Tests
IAEA Dynamic DI water/site water N/A One face >19 >6 months Leach Test prepared (International Atomic Energy Agency)
Leaching Tests on 0.1N acetic acid 20:1 0.6 µm-70µm 1 24 hours S/S technologies most valid Solidified Products12 (Procedure A) when applied to wastes 2:1 (6 hrs.) contaminated by inorganic & 10:1 pollutants (18 hrs.) (Procedure B)
DLT DI water N/A Surface 18 196 days washing
C. Flow Through Tests
ASTM D4874-95 Type IV reagent water One void 10 mm 1 24 hours Column Test volume
III. Other Tests
MCC-5s Soxhlet DI/site water 100:1 Out and 1 0.2 ml/min Test (material washed characteristic center)
ASTM C1308-95 Only applicable if diffusion Accelerated Leach is dominant leaching Test13 mechanism
Generalized Acid Acetic acid 20:1 Able to pass 1 48 hours Quantifies the alkalinity of Neutralization through an binder and characterizes Capacity Test14 ASTM No. 40 buffering chemistry sieve
Acid Neutralization HNO3, solutions of 3:1 150 mm 1 48 hours per Capacity increasing strength extraction
11 Garrabrants, A.C. and Koson, D.S.; Use of Chelating Agent to Determine the Metal Availability for Leaching from Soils and Wastes, unpublished. 12 Leaching Tests on Solidified Products; Gavasci, R., Lombardi, F., Polettine, A., and Sirini, P. 13 C1308-95 Accelerated Leach Test for Diffusive Releases from Solidified Waste and a Computer Program to Model Diffusive, Fractional Leaching from Cylindrical Wastes. 2-20 14 Generalized Acid Neutralization capacity Test; Isenburg, J. and Moore, M. Part I Getting Started
Chapter 3 Integrating Pollution Prevention Contents
I. Benefits of Pollution Prevention...... 3 - 3
II. Implementing Pollution Prevention ...... 3 - 5 A. Source Reduction ...... 3 - 5 B. Recycling ...... 3 - 7 C. Treatment ...... 3 - 8
III. Where to Find Out More: Technical and Financial Assistance ...... 3 - 10
Integrating Pollution Prevention Activity List ...... 3 - 14
Resources ...... 3 - 15
Figure 1: Waste Management Hierarchy...... 3 - 2 Getting Started—Integrating Pollution Prevention
Integrating Pollution Prevention
This chapter will help you: • Consider pollution prevention options when designing a waste management system. Pollution prevention will reduce waste dis- posal needs and can minimize impacts across all environmental media. Pollution prevention can also reduce the volume and toxi- city of waste. Lastly, pollution prevention can ease some of the burdens, risks, and liabilities of waste management.
among industry, the public, and regulatory ollution prevention describes a vari- agencies. It can also reduce liabilities and risks ety of practices that go beyond tra- associated with releases from waste manage- ditional environmental compliance ment units and closure and post-closure care or single media permits for water, of waste management units. air, or land disposal and begin to Paddress the concept of sustainability in the Pollution prevention is comprehensive. use and reuse of natural resources. Adopting It emphasizes a life-cycle approach to assess- pollution prevention policies and integrating ing a facility’s physical plant, production pollution prevention into operations provide processes, and products to identify the best opportunities to reduce the volume and toxic- opportunities to minimize environmental ity of wastes, reduce waste disposal needs, impacts across all media. This approach also and recycle and reuse materials formerly han- ensures that actions taken in one area will not dled as wastes. In addition to potential sav- increase environmental problems in another ings on waste management costs, pollution area, such as reducing wastewater discharges prevention can help improve the interactions but increasing airborne emissions of volatile organic compounds. Pollution prevention requires creative problem solving by a broad This chapter will help address the fol- cross section of employees to help achieve lowing questions. environmental goals. In addition to the envi- ronmental benefits, implementing pollution • What are some of the benefits of pol- prevention can often benefit a company in lution prevention? many other ways. For example, redesigning • Where can assistance in identifying production processes or finding alternative and implementing specific pollution material inputs can also improve product prevention options be obtained? quality, increase efficiency, and conserve raw materials. Some common examples of pollu- tion prevention activities include: redesigning
3-1 Getting Started—Intregrating Pollution Prevention
processes or products to reduce raw material ated with the release of such substances, pol- needs and the volume of waste generated; lutants, or contaminants. replacing solvent based cleaners with aqueous Recycling requires an examination of based cleaners or mechanical cleaning sys- waste streams and production processes to tems; and instituting a reverse distribution identify opportunities. Recycling and benefi- system where shipping packaging is returned cially reusing wastes can help reduce disposal to the supplier for reuse rather than discard. costs, while using or reusing recycled materi- The Pollution Prevention Act of 1990 als as substitutes for feedstocks can reduce established a national policy to first, prevent raw materials costs. Materials exchange pro- or reduce waste at the point of generation grams can assist in finding uses for recycled (source reduction); second, recycle or reuse materials and in identifying effective substi- waste materials; third, treat waste; and finally, tutes for raw materials. Recycling not only dispose of remaining waste in an environ- helps reduce the overall amount of waste sent mentally protective manner (see Figure 1). for disposal, but also helps conserve natural Some states and many local governments resources by replacing the need for virgin have adopted similar policies, often with materials. more specific and measurable goals. Treatment can reduce the volume and Source Reduction means any practice toxicity of a waste. Reducing a waste’s volume which (i) reduces the amount of any sub- and toxicity prior to final disposal can result stance, pollutant, or contaminant entering in long-term cost savings. There are a consid- any wastestream or otherwise released into erable number of levels and types of treat- the environment, prior to recycling, treat- ment from which to choose. Selecting the ment, or disposal; and (ii) reduces the risks right treatment option can help simplify dis- to public health and the environment associ- posal options and limit future liability.
Figure 1. Waste Management Hierarchy
3-2 Getting Started—Integrating Pollution Prevention
Over the past 10 years, interest in all aspects to land application can provide the flexibility to of pollution prevention has blossomed, and use land application and ensure that the prac- governments, businesses, academic and tice will be protective of human health and the research institutions, and individual citizens environment and limit future liabilities. have dedicated greater resources to it. Many industries are adapting pollution prevention practices to fit their individual operations. Pollution prevention can be successful when I. Benefits of flexible problem-solving approaches and solu- Pollution tions are implemented. Fitting these steps into your operation’s business and environmental Prevention goals will help ensure your program’s success. Pollution prevention activities benefit Throughout the Guide several key steps are industry, states, and the public by protecting highlighted that are ideal points for imple- the environment and reducing health risks, menting pollution prevention to help reduce and also provide businesses with financial and waste management costs, increase options, or strategic benefits. reduce potential liabilities by reducing risks Protecting human health and the envi- that the wastes might pose. For example: ronment. By reducing the amount of contami- Waste characterization is a key compo- nants released into the environment and the nent of the Guide. It is also a key component volume of waste requiring disposal, pollution of a pollution prevention opportunity assess- prevention activities protect human health and ment. An opportunity assessment, however, is the environment. Decreasing the volume or more comprehensive since it also covers mate- toxicity of process materials and wastes can rial inputs, production processes, operating reduce worker exposure to potentially harmful practices, and potentially other areas such as constituents. Preventing the release and dis- inventory control. When characterizing a posal of waste constituents to the environment waste, consider expanding the opportunity also reduces human and wildlife exposure and assessment to cover these aspects of the busi- habitat degradation. Reduced consumption of ness. An opportunity assessment can help raw materials and energy conserves precious identify the most efficient, cost-effective, and natural resources. Finally reducing the volume environmentally friendly combination of of waste generated decreases the need for con- options, especially when planning new prod- struction of new waste management facilities, ucts, new or changed waste management prac- preserving land for other uses such as recre- tices, or facility expansions. ation or wildlife habitat. Land application of waste might be a pre- Cost savings. Many pollution prevention ferred waste management option because land activities make industrial processes and equip- application units can manage wastes with high ment more resource-efficient. This increased liquid content, treat wastes through biodegra- production efficiency saves raw material and dation, and improve soils due to the organic labor costs, lowers maintenance costs due to material in the waste. Concentrations of con- newer equipment, and potentially lowers over- stituents might limit the ability to take full sight costs due to process simplification. When advantage of land application. Reducing the planning pollution prevention activities, con- concentrations of constituents in the waste sider the cost of the initial investment for before it is generated or treating the waste prior audits, equipment, and labor. This cost will
3-3 Getting Started—Intregrating Pollution Prevention
vary depending on health-related costs from lost work days, the size and com- health insurance, and disability payments. plexity of waste Lower liability. A well-operated unit mini- reduction activi- mizes releases, accidents, and unsafe waste- ties. In addition, handling practices. Reducing the volume and consider the pay- toxicity of waste decreases the impact of these back time for the events if they occur. Reducing potential liabili- investment. ties decreases the likelihood of litigation and Prioritize pollution cleanup costs. prevention activi- ties to maximize Higher product quality. Many corporations cost savings and have found that higher product quality results health and envi- from some pollution prevention efforts. A sig- ronmental benefits. nificant part of the waste in some operations consists of products that fail quality inspec- Simpler design and operating conditions. tions, so minimizing waste in those cases is Reducing the risks associated with wastes can inextricably linked with process changes that allow wastes to be managed under less strin- improve quality. Often, managers do not realize gent design and operating conditions. For how easy or technically feasible such changes example, the ground-water tool in Chapter 7, are until the drive for waste reduction leads to Section A – Assessing Risk might indicate that exploration of the possibilities. a composite liner is recommended for a specif- ic waste stream. A pollution prevention oppor- Building community relations. Honesty tunity assessment also might imply that by and openness can strengthen credibility implementing a pollution prevention activity between industries, communities, and regula- that lowers the concentrations of one or two tory agencies. If you are implementing a pollu- problematic waste constituents in that waste tion prevention program, make people aware stream, a compacted clay liner can provide of it. Environmental protection and economic sufficient protection. When the risks associat- growth can be compatible objectives. ed with waste disposal are reduced, the long- Additionally, dialogue among all parties in the term costs of closure and post-closure care can development of pollution prevention plans can also be reduced. help identify and address concerns. Improved work- er safety. Processes involving less toxic and less physically dangerous materials can improve worker safety by reducing work-related injuries and illnesses. In addition to strength- ening morale, improved worker safety also reduces
3-4 Getting Started—Integrating Pollution Prevention
ifications; process or procedure modifica- II. Implementing tions; reformulations or redesign of products; Pollution substitution of raw materials; and improve- ments in housekeeping, maintenance, train- Prevention ing, or inventory control. When implementing pollution prevention, Reformulation consider a combination of options that best or redesign of fits your facility and its products. There are a products. One number of steps common to implementing source reduction any facility-wide pollution prevention effort. option is to refor- An essential starting point is to make a clear mulate or redesign commitment to identifying and taking advan- products and tage of pollution prevention opportunities. processes to incor- Seek the participation of interested partners, porate materials develop a policy statement committing the more likely to pro- industrial operation to pollution prevention, duce lower-risk and organize a team to take responsibility for wastes. Some of the it. As a next step, conduct a thorough pollu- most common tion prevention opportunity assessment. Such practices include eliminating metals from an assessment will help set priorities accord- inks, dyes, and paints; reformulating paints, ing to which options are the most promising. inks, and adhesives to eliminate synthetic Another feature common to many pollution organic solvents; and replacing chemical- prevention programs is measuring the pro- based cleaning solvents with water-based or gram’s progress. citrus-based products. Using raw materials The actual pollution prevention practices free from even trace quantities of contami- implemented are the core of a program. The nants, whenever possible, can also help following sections give a brief overview of reduce waste at the source. these core activities: source reduction, recy- When substituting materials in an industri- cling, and treatment. To find out more, con- al process, it is important to examine the tact some of the organizations listed effect on the entire waste stream to ensure throughout this chapter. that the overall risk is being reduced. Some changes can shift contaminants to another medium rather than actually reduce waste A. Source Reduction generation. Switching from solvent-based to As defined in the Pollution Prevention Act water-based cleaners, for example, will of 1990, source reduction means any practice reduce solvent volume and disposal cost, but which (i) reduces the amount of any haz- is likely to dramatically increase wastewater ardous substance, pollutant, or contaminant volume. Look at the impact of wastewater entering any wastestream or otherwise generation on effluent limits and wastewater released into the environment, prior to recy- treatment sludge production. cling, treatment, or disposal; and (ii) reduces Technological modifications. the hazards to public health and the environ- Newer ment associated with the release of such sub- process technologies often include better stances, pollutants, or contaminants. The waste reduction features than older ones. For term includes equipment or technology mod- industrial processes that predate considera-
3-5 Getting Started—Intregrating Pollution Prevention
tion of waste and risk reduction, adopting waste reduction program, especially one fea- new procedures or upgrading equipment can turing good housekeeping procedures. Case reduce waste volume, toxicity, and manage- study data indicate that effective employee ment costs. Some examples include redesign- training programs can reduce waste disposal ing equipment to cut losses during batch volumes by 10 to 40 percent.1 changes or during cleaning and maintenance, Regularly scheduled maintenance and changing to mechanical cleaning devices to plant inspections are also useful. Maintenance avoid solvent use, and installing more energy- helps avoid the large cleanups and disposal and material-efficient equipment. State tech- operations that can result from equipment nical assistance centers, trade associations, failure. Routine maintenance also ensures that and other organizations listed in this chapter equipment is operating at peak efficiency, sav- can help evaluate the potential advantages ing energy, time, and materials. Regularly and savings of such improvements. scheduled or random, unscheduled plant In-process recycling (reuse). In-process inspections help identify potential problems recycling involves the reuse of materials, such before they cause waste management prob- as cutting scraps, as inputs to the same lems. They also help identify areas where process from which they came, or uses them improving the efficiency of materials manage- in other processes or for other uses in the ment and handling practices is possible. If facility. This furthers waste reduction goals by possible, plant inspections, periodically per- reducing the need for treatment or disposal formed by outside inspectors who are less and by conserving energy and resources. A familiar with day-to-day plant operations, can common example of in-process recycling is bring attention to areas for improvement that the reuse of wastewater. are overlooked by employees accustomed to the plant’s routine practices. Good housekeeping procedures. Some of the easiest, most cost-effective, and most wide- Storing large volumes of raw materials ly used waste reduction techniques are simple increases the risk of an accidental spill and improvements in housekeeping. Accidents and the likelihood that the materials will not be spills generate avoidable disposal hazards and used due to changes in production schedules, expenses. They are less likely to occur in new product formulations, or material degra- clean, neatly organized facilities. dation. Companies are sometimes forced to dispose of materials whose expiration dates Good housekeeping techniques that reduce have passed or that are no longer needed. the likelihood of accidents and spills include Efficient inventory control allows a facility to training employees to manage waste and avoid stocking materials in excess of its abili- materials properly; keeping aisles wide and ty to use them, thereby decreasing disposal free of obstructions; clearly labeling contain- volume and cost. Many companies have suc- ers with content, handling, storage, expira- cessfully implemented “just-in-time” manu- tion, and health and safety information; facturing systems to avoid the costs and risks spacing stored materials to allow easy access; associated with maintaining a large onsite surrounding storage areas with containment inventory. In a “just-in-time” manufacturing berms to control leaks or spills; and segregat- system, raw materials arrive as they are need- ing stored materials to avoid cross-contami- ed and only minimal inventories are main- nation, mixing of incompatible materials, and tained on site. unwanted reactions. Proper employee train- ing is crucial to implementing a successful
1 Freeman, Harry. 1995. Industrial Pollution Prevention Handbook. McGraw-Hill, Inc. p. 13.
3-6 Getting Started—Integrating Pollution Prevention
Segregating waste streams is another good simply publish lists of generators, materials, housekeeping procedure that enables a facili- and buyers. Some waste exchanges also spon- ty to avoid contaminating lower risk wastes sor workshops and conferences to discuss with hazardous constituents from another waste-related regulations and to exchange source. Based on a waste characterization information. More than 60 waste and materials study, it might be more efficient and cost- exchanges operate in North America. Below effective to manage wastes separately by recy- are four examples of national, state, and local cling some, and treating or disposing of exchange programs. Each program’s Web site others. Waste segregation can also help also provides links to other regional, national, reduce the risks associated with handling and international materials exchange net- waste. Separating waste streams allows some works. materials to be reused, resulting in additional • EPA’s Jobs Through Recycling (JTR) cost savings. Emerging markets for recovered Web site
3-7 Getting Started—Intregrating Pollution Prevention
recycled materials, such as fill or Portland est recovered material content level practica- cement, not only avoiding disposal costs but ble. As of January 2001, EPA has designated also generating revenue. Other examples of 54 items within eight product categories beneficial use include using wastewaters and including items such as retread tires, cement sludges as soil amendments (see Chapter 7, and concrete containing coal fly ash and Section C–Designing a Land Application ground granulated blast furnace slag, traffic Program) and using foundry sand in asphalt, barricades, playground surfaces, landscaping concrete, and roadbed construction. products, and nonpaper office products like binders and toner cartridges. While directed Many regulatory agencies require approval primarily at federal, state, and local procuring of planned beneficial use activities and may agencies, CPG information is helpful to every- require testing of the materials to be reused. one interested in purchasing recycled-content Others may allow certain wastes to be desig- products. For further information on the CPG nated for beneficial use, as long as the required program, visit:
3-8 Getting Started—Integrating Pollution Prevention
• Immobilization: • Stabilization Encapsulation • Vitrification Thermoplastic binding • Extraction: • Carbon absorption: Solvent extraction Granular activated carbon (GAC) Critical extraction Powdered activated carbon (PAC) • High temperature metal recovery • Distillation: (HTMR) Batch distillation Fractionation Biological treatment can be divided into two Thin film extraction categories–aerobic and anaerobic. Aerobic bio- Steam stripping logical treatment uses oxygen-requiring Thermal drying microorganisms to decompose organic and non-metallic constituents into carbon dioxide, • Filtration water, nitrates, sulfates, simpler organic prod- • Evaporation/volatilization ucts, and cellular biomass (i.e., cellular growth and reproduction). Anaerobic biological treat- • Grinding ment uses microorganisms, in the absence of • Shredding oxygen, to transform organic constituents and • Compacting nitrogen-containing compounds into oxygen and methane gas (CH4(g)). Anaerobic biologi- • Solidification/addition of absorbent cal treatment typically is performed in an material enclosed digestor unit. Listed below are a few Chemical treatment involves altering a examples of biological treatment. waste’s chemical composition, structure, and • Aerobic: properties through chemical reactions. Activated sludge Chemical treatment can consist of mixing the Aerated lagoon waste with other materials (reagents), heating Trickling filter the waste to high temperatures, or a combi- Rotating biological contactor (RBC) nation of both. Through chemical treatment, waste constituents can be recovered or • Anaerobic digestion destroyed. Listed below are a few examples of The range of treatment methods from chemical treatment. which to choose is as diverse as the range of • Neutralization wastes to be treated. More advanced treat- ment will generally be more expensive, but • Oxidation by reducing the quantity and risk level of the • Reduction waste, costs might be reduced in the long run. Savings could come from not only lower • Precipitation disposal costs, but also lower closure and • Acid leaching post-closure care costs. Treatment and post- treatment waste management methods can be • Ion exchange selected to minimize both total cost and envi- • Incineration ronmental impact, keeping in mind that treat- ment residuals, such as sludges, are wastes • Thermal desorption themselves that will need to be managed.
3-9 Getting Started—Intregrating Pollution Prevention
3-10 Getting Started—Integrating Pollution Prevention
and waste reduction alternatives for tains a collection of EPA non-regula- specific industry sectors. tory documents related to waste
3-11 Getting Started—Intregrating Pollution Prevention
technologies by providing technical nesses develop, review, or evaluate information, financing, training, and facility waste reduction plans. State other services. The NIST Web site waste reduction programs frequently
3-12 Getting Started—Integrating Pollution Prevention
• Workshops, seminars, and training. State agencies, trade associations, and other organizations conduct work- shops, seminars, and technical train- ing on waste reduction. These events provide information, identify resources, and facilitate networking. • Grants and loans. A number of states distribute funds to independent groups that conduct waste reduction activities. These groups often use such support to fund research and to run demonstration and pilot projects.
3-13 Getting Started—Intregrating Pollution Prevention
Integrating Pollution Prevention Activity List
To address pollution prevention you should: ■ Make waste management decisions by considering the priorities set by the full range of pollution prevention options—first, source reduction; second, reuse and recycling; third, treatment; last, dis- posal. ■ Explore the cost savings and other benefits available through activities that integrate pollution pre- vention. ■ Develop a waste reduction policy. ■ Conduct a pollution prevention opportunity assessment of facility processes. ■ Research potential pollution prevention activities. ■ Consult with public and private agencies and organizations providing technical and financial assis- tance for pollution prevention activities. ■ Plan and implement activities that integrate pollution prevention.
3-14 Getting Started—Integrating Pollution Prevention
Resources
Erickson, S. and King, B. 1999. Fundamentals of Environmental Management. John Wiley and Sons, Inc.
Freeman, Harry. 1995. Industrial Pollution Prevention Handbook. McGraw-Hill, Inc.
“Green Consumerism: Commitment Remains Strong Despite Economic Pessimism.” 1992. Cambridge Reports. Research International. (October).
Habicht, F. Henry. 1992. U.S. EPA Memorandum on EPA Definition of Pollution Prevention (May).
Higgins, Thomas E., ed. 1995. Pollution Prevention Handbook. CRC-Lewis Publishers.
“Moving from Industrial Waste to Coproducts.” 1997. Biocycle. (January)
National Pollution Prevention Roundtable. 1995. The Pollution Prevention Yellow Pages.
Pollution Prevention Act of 1990. (42 U.S.C. 13101 et seq., Pub.L. 101-508, November 5, 1990).
Rossiter, Alan P., ed. 1995. Waste Minimization Through Process Design. McGraw-Hill, Inc.
U.S. EPA. 2001. Pollution Prevention Clearinghouse: Quarterly List of Pollution Prevention Publications, Winter 2001. EPA742-F-01-004.
U.S. EPA. 1998. Project XL: Good for the Environment, Good for Business, Good for Communities. EPA100–F-98-008.
U.S. EPA. 1997. Developing and Using Production Adjusted Measurements of Pollution Prevention. EPA600-R-97-048.
U.S. EPA. 1997. Guide to Accessing Pollution Prevention Information Electronically. EPA742-B-97-003
U.S. EPA. 1997. Pollution Prevention 1997: A National Progress Report. EPA742-R-97-001.
U.S. EPA. 1997. Technical Support Document for Best Management Practices Programs—Spent Pulping Liquor Management, Spill Prevention, and Control.
U.S. EPA. 1996. Environmental Accounting Project: Quick Reference Fact Sheet. EPA742-F-96-001.
3-15 Getting Started—Intregrating Pollution Prevention
Resources (cont.)
U.S. EPA. 1996. Profiting from Waste Reduction in Your Small Business. EPA742-B-88-100.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Paints and Coatings. EPA600-S-95-009.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Bourbon Whiskey. EPA600-S-95-010.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Automotive Battery Separators. EPA600-S-95-011.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Automotive Lighting Equipment and Accessories. EPA600-S-95-012.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Locking Devices. EPA600-S-95-013.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Combustion Engine Piston Rings. EPA600-S-95-015.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Metal Fasteners.EPA600-S-95-016.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Stainless Steel Pipes and Fittings. EPA600-S-95-017.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Outboard Motors. EPA600-S-95-018.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Electroplated Truck Bumpers. EPA600-S-95-019.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Printed Circuit Board Plant.EPA600-S-95-020.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Folding Paperboard Cartons. EPA600-S-95-021.
3-16 Getting Started—Integrating Pollution Prevention
Resources (cont.)
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Rebuilt Industrial Crankshafts. EPA600-S-95-022.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Pressure-sensitive Adhesive Tape. EPA600-S-95-023.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Wooden Cabinets. EPA600-S-95-024.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Power Supplies. EPA600-S-95-025.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Food Service Equipment. EPA600-S-95-026.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Metal Parts Coater. EPA600-S-95-027.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Gear Cases for Outboard Motors. EPA600-S-95-028.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Electrical Load Centers. EPA600-S-95-029.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Pharmaceuticals. EPA600-S-95-030.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of Aircraft Landing Gear. EPA600-S-95-032.
U.S. EPA. 1995. EPA Standards Network Fact Sheet: Role of Voluntary Standards. EPA741-F-95-005.
U.S. EPA. 1995. Introduction to Pollution Prevention: Training Manual. EPA742-B-95-003.
U.S. EPA. 1995. Recent Experience in Encouraging the Use of Pollution Prevention in Enforcement Settlements: Final Report. EPA300-R-95-006.
U.S. EPA. 1995. Recycling Means Business. EPA530-K-95-005.
3-17 Getting Started—Intregrating Pollution Prevention
Resources (cont.)
U.S. EPA. 1994. Final Best Demonstrated Available Technology (BDAT) Background Document for Universal Standards, Volume B: Universal Standards for Wastewater forms of Listed Hazardous Wastes, Section 5, Treatment Performance Database. EPA530-R-95-033.
U.S. EPA. 1994. Review of Industrial Waste Exchanges. EPA530-K-94-003.
U.S. EPA. 1993. Guidance Manual for Developing Best Management Practices. EPA833-B-93-004.
U.S. EPA. 1993. Primer for Financial Analysis of Pollution Prevention Projects. EPA600-R-93-059.
U.S. EPA. 1992. Facility Pollution Prevention Guide. EPA600-R-92-008.
U.S. EPA. 1992. Practical Guide to Pollution Prevention Planning for the Iron and Steel Industries. EPA742-B-92-100
U.S. EPA. 1991. Pollution Prevention Strategy. EPA741-R-92-001.
U.S. EPA. 1991. Treatment Technology Background Document; Third Third; Final. EPA530-SW-90- 059Z.
U.S. EPA. 1990. Guide to Pollution Prevention: Printed Circuit Board Manufacturing Industry. EPA625- 7-90-007
U.S. EPA. 1990. Waste Minimization: Environmental Quality with Economic Benefits. EPA530-SW-90- 044.
U.S. EPA. 1989. Treatment Technology Background Document; Second Third; Final. EPA530-SW-89- 048A.
3-18 Part I Getting Started
Chapter 4 Considering the Site Contents
I. General Siting Considerations ...... 4 - 3 A. Floodplains...... 4 - 3 B. Wetlands...... 4 - 6 C. Active Fault Areas ...... 4 - 10 D. Seismic Impact Zones ...... 4 - 12 E. Unstable Areas ...... 4 - 14 F. Airport Vicinities...... 4 - 18 G. Wellhead Protection Areas ...... 4 - 19
II. Buffer Zone Considerations ...... 4 - 20 A. Recommended Buffer Zones ...... 4 - 21 B. Additional Buffer Zones ...... 4 - 22
III. Local Land Use and Zoning Considerations...... 4 - 23
IV. Environmental Justice Considerations ...... 4 - 23
Considering the Site Activity List ...... 4 - 25
Resources ...... 4 - 27
Appendix: State Buffer Zone Considerations ...... 4 - 30
Tables: Table 1: Examples of Improvement Techniques for Liquefiable Soil Foundation Conditions ...... 4 - 12 Getting Started—Considering the Site
Considering the Site This chapter will help you: • Become familiar with environmental, geological, and manmade fea- tures that influence siting decisions. • Identify nearby areas or land uses that merit buffer zones and place your unit an appropriate distance from them. • Comply with local land use and zoning restrictions, including any amendments occurring during consideration of potential sites. • Understand existing environmental justice issues as you consider a new site. • Avoid siting a unit in hydrologic or geologic problem areas, without first designing the unit to address conditions in those areas. earthquake zones, unstable soils, and areas at any hydrologic and geologic risk for subsurface movement need to be settings can be effectively uti- taken into account just as they would be lized for protective waste when siting and constructing a manufactur- management. There are, ing plant or home. Catastrophic events asso- however, some hydrologic ciated with these locations could seriously and geologic conditions that are best avoided M damage or destroy a waste management unit, all together if possible. If they cannot be release contaminants into the environment, avoided, special design and construction pre- and add substantial expenses for cleanup, cautions can minimize risks. Floodplains, repair, or reconstruction. If problematic site conditions cannot be avoided, engineering This chapter will help address the follow- design and construction techniques can ing questions: address some of the concerns raised by locat- • What types of sites need special consid- ing a unit in these areas. eration? Many state, local, and tribal governments • How will I know whether my waste require buffer zones between waste manage- management unit is in an area requir- ment units and other nearby land uses. Even ing special consideration? if buffer zones are not required, they can still provide benefits now and in the future. Buffer • Why should I be concerned about sit- zones provide time and space to contain and ing a waste management unit in such remediate accidental releases before they areas? reach sensitive environments or sensitive • What actions can I take if I plan to site populations. Buffer zones also help maintain a unit in these areas? good community relations by reducing dis- ruptions associated with noise, traffic, and
4-1 Getting Started—Considering the Site
wind-blown dust, often the source of serious be required prior to the disturbance of any neighborhood concerns. land area or before property titles are trans- ferred. An ESA is the process of determining In considering impacts on the surrounding whether contamination is present on a parcel community, it is important to understand of property. You should check with the EPA whether the community, especially one with a regional office and state or local authorities to large minority and low income population, determine if there are any ESA requirements already faces significant environmental prior to siting a new unit or expanding an impacts from existing industrial activities. You existing unit. If there are no requirements, should develop an understanding of the com- you might want to consider performing an munity’s current environmental problems and ESA in order to ensure that there are no cont- work together to develop plans that can amination problems at the site. improve and benefit the environment, the community, the state, and the company. Many companies specialize in site screening, characterization, and sampling of different How should a waste environmental media (i.e., air, water, soil) for management unit site potential contamination. A basic ESA (often assessment begin? referred to as the Phase I Environmental Site In considering whether to site a new waste Assessment process) typically involves management unit or laterally expand an exist- researching prior land use, deciding if sam- ing unit, certain factors will influence the sit- pling of environmental media is necessary ing process. These factors include land based on the prior activities, and determining availability, distance from waste generation contaminate fate and transport if contamina- points, ease of access, local climatic condi- tion has occurred. Liability issues can arise if tions, economics, environmental considera- the site had contamination problems prior to tions, local zoning requirements, and potential construction or expansion of the waste man- impacts on the community. As prospective agement unit. Information on the extent of sites are identified, you should become famil- contamination is needed to quantify cleanup iar with the siting considerations raised in this costs and determine the cleanup approach. chapter. Determine how to address concerns at Cleanup costs can represent an additional, each site to minimize a unit’s adverse impacts possibly significant, project cost when siting a on the environment in addition to the environ- waste management unit. ment’s adverse impacts on the unit. You should As discussed later in this chapter, you will choose the site that best balances protection of also need to consider other federal laws and human health and the environment with oper- regulations that could affect siting. For exam- ational goals. In addition to considering the ple, the Endangered Species Act (16 USC issues raised in this chapter, you should check Sections 1531 et seq.) provides for the desig- with state and local regulatory agencies early nation and protection of threatened or endan- in the siting process to identify other issues gered wildlife, fish, and plant species, and and applicable restrictions. ensures the conservation of the ecosystems on Another factor to consider is whether there which such species depend. It is the responsi- are any previous or current contamination bility of the facility manager to check with problems at the site. It is recommended that and obtain a Section 10 permit from the potential sites for new waste management Secretary of the Interior if the construction or units be free of any contamination problems. operation of a waste management unit might An environmental site assessment (ESA) may potentially impact any endangered or threat-
4-2 Getting Started—Considering the Site
ened species or its critical habitat. Thus, you water supplies, toxic and air releases, haz- might not be able to site a new waste man- ardous waste sites, water discharge permits, agement unit in an area where endangered or and Superfund sites at the national, state, and threatened species live, or expand an existing county levels. unit into such an area. As another example, EPA’s Waste Management—Facility Siting the National Historic Preservation Act (16 Application is a powerful new Web-based USC Sections 470 et seq.) protects historic tool that provides assistance in locating waste sites and archaeological resources. The facility management facilities. The tool allows the manager of a waste management unit should user to enter a ZIP code; city and state; or lat- be aware of the properties listed on the itude and longitude to identify the location of National Register of Historic Properties. The fault lines, flood planes, wetlands, and karst facility manager should consult with the state terrain in the selected area. The user also can historic preservation office to ensure that the use the tool to display other EPA regulated property to be used for a new unit or lateral facilities, monitoring sites, water bodies, and expansion of an existing unit will not impact community demographics. The Facility Siting listed historic properties, or sites with archeo- Application can be found at
1 This agency of the U.S. Department of Agriculture was formerly known as the Soil Conservation Service (SCS). 4-3 Getting Started—Considering the Site
How is it determined if a prospective site is in a 100-year floodplain? The first step in determining whether a prospective site is located in a 100-year flood- plain is to consult with the Federal Emergency Management Agency (FEMA). FEMA has pre- pared flood hazard boundary maps for most regions. If a prospective site does not appear to be located in a floodplain, further explo- Flood waters overflowed from the ration is not necessary. If uncertainty exists as Mississippi River (center) into its floodplain to whether the prospective site might be in a (foreground) at Quincy, Illinois in the 1993 floodplain, several sources of information are floods that exceeded 100-year levels in parts available to help make this determination. of the Midwest. More detailed flood insurance rate maps (FIRMs) can be obtained from FEMA. FIRMs 100-year floodplain—the area susceptible to divide floodplain areas into three zones: A, B, inundation during a large magnitude flood and C. Class A zones are the most susceptible with a 1 percent chance of recurring in any to flooding while class C zones are the least given year—is usually the floodplain of con- susceptible. FIRMs can be obtained from cern for waste management units. You should FEMA’s Web site at
2 Copies of flood maps from FEMA are available at Map Service Center, P.O. Box 1038, Jessup, MD 20794- 1038, by phone 800 358-9616, or the Internet at
4-4 Getting Started—Considering the Site
If maps cannot be obtained, and a potential site is suspected to be located in a floodplain, you can conduct a field study to delineate the floodplain and determine the floodplain’s properties. To perform a delineation, you can draw on meteorological records and physio- graphic information, such as exist- ing and planned watershed land use, topography, soils and geo- graphic mapping, and aerial photo- graphic interpretation of land forms. Additionally, you can use the U.S. Water Resources Council’s methods of determining flood potential based on stream gauge records, or you can estimate the peak discharge to approximate the probability of exceeding the 100- year flood. Contact the USGS, Office of Surface Water, for addi- tional information concerning these methods.3 What can be done if a prospective site is in a floodplain? If a new waste management unit or lateral expansion will be sited in FEMA provides flood maps like this one for most floodplains a floodplain, design the unit to pre- Source: FEMA, Q3 Flood Data Users Guide
3 Information on stream gaging and flood forecasting can be obtained from the USGS, Office of Surface Water, at 413 National Center, Reston, VA 22092, by phone 703 648-5977, or the Internet at
and duration associated with the peak (i.e., highest) flow period of the flood. While these methods can help protect your unit from flood damage and washout, be aware that they can further contribute to a decrease in the water storage and flow capac- ity of the floodplain. This, in turn, can raise the level of flood waters not only in your area but in upstream and downstream locations, increasing the danger of flood damage and adding to the cost of flood control programs. Thus, serious consideration should be given to siting a waste management unit outside a 100-year floodplain.
B. Wetlands Wetlands, which include swamps, marshes, and bogs, are vital and delicate ecosystems. They are among the most productive biologi- cal communities on earth and provide habitat for many plants and animals. The U.S. Fish Knowing the behavior of waters at their and Wildlife Service estimates that up to 43 peak flood level is important for determin- percent of all endangered or threatened ing whether waste will wash out. species rely on wetlands for their survival.5
Riprap (rock cover) reduces stream channel erosion (left) and gabions (crushed rock encased in wire mesh) help stabilize erodible slopes (right). Sources: U.S. Department of the Interior, Office of Surface Mining (left); The Construction Site—A Directory To The Construction Industry (right).
5 From EPA’s Wetlands Web site, Values and Functions of Wetlands factsheet,
tlement, action of the high water table, and For regulatory purposes under the Clean flooding. Alternatives to siting a waste man- Water Act, wetlands are defined as areas agement unit in a wetland area should be “that are inundated or saturated by sur- given serious consideration based upon face or ground water at a frequency and Section 404 requirements in the Clean Water duration sufficient to support, and that Act (CWA) as discussed below. under normal circumstances do support, a prevalence of vegetation typically adapt- If a waste management unit is to be sited in ed for life in saturated soil conditions.” a wetland area, the unit will be subject to additional regulations. In particular, Section 40 Code of Federal Regulations (CFR) 232.2(r) 404 of the Clean Water Act (CWA) authorizes the Secretary of the Army, acting through the Wetlands protect water quality by assimilating Chief of Engineers, to issue permits for the water pollutants, removing sediments contain- discharge of dredged or fill material into wet- ing heavy metals, and recharging ground- lands and other waters of the United States.6 water supplies. Wetlands also prevent Activities in waters of the United States regu- potentially extensive and costly floods by tem- lated under this permitting program include porarily storing flood waters and reducing “placement of fill material for construction or their velocity. These areas also offer numerous maintenance of any liner, berm, or other recreational opportunities. infrastructure associated with solid waste landfills,” as well as fills for development, Potential adverse impacts associated with water resource projects, infrastructure locating your unit in a wetland include dewa- improvements, and conversion of wetlands to tering the wetland (i.e., causing removal or uplands for farming and forestry (40 CFR drainage of water), contaminating the wet- Section 232.2—definition of “discharge of fill land, and causing loss of wetland acreage. material”). EPA regulations under Section 404 Damage could also be done to important wet- (33 United States Code Section 1344) stipu- land ecosystems by destroying their aesthetic lates that no discharge of dredged or fill mate- qualities and diminishing wildlife breeding rial can be permitted if a practicable and feeding opportunities. Siting in a wetland alternative exists that is less damaging to the increases the potential for damage to your aquatic environment or if the nation’s waters unit, especially your liner system and struc- would be significantly degraded. Therefore, in tural components, as a result of ground set-
Different types of wetlands: spruce bog (left) and eco pond in the Florida Everglades (right).
6 For the full text of the Clean Water Act, including Section 404, visit the U.S. House of Representatives Internet Law Library Web site at
compliance with the guidelines established state, or local permits would be a violation of under Section 404, all permit applicants must: many laws. It might be possible to learn the extent of wetlands without performing a new • Take steps to avoid wetland impacts delineation, since many wetlands have previ- where practicable. ously been mapped. The first step, therefore, • Minimize impacts to wetlands where should be to determine whether wetlands they are unavoidable. information is available for your area. • Compensate for any remaining, At the federal level, four agencies are prin- unavoidable impacts by restoring or cipally involved with wetlands identification creating wetlands. and delineation: USACE, EPA, the U.S. Fish The EPA and USACE jointly administer a and Wildlife Service (FWS), and National review process to issue permits for regulated Resource Conservation Service (NRCS). EPA activities. For projects with potentially signifi- also has a Wetlands Information Hotline (800 cant impacts, an individual permit is usually 832-7828) and a wetlands Web site at
7 To contact NWI, write to National Wetlands Inventory Center, 9720 Executive Center Drive, Suite 101, Monroe Building, St. Petersburg, FL 33702, call 727 570-5400, or fax 727 570-5420. For additional 4-8 information online or to search for maps of your area, visit:
This procedure should be performed only by ing the presence and location of hydrophytic an individual with experience in performing a vegetation (i.e., plants that are adapted for life wetlands delineation8 using standard delin- in saturated soils), wetland hydrology, and eation procedures or applicable state or local hydric soils is discussed. delineation standards. The delineation proce- dure, with which you should become familiar What can be done if a before hiring a delineator, involves collecting prospective site is in a wetland? maps, aerial photographs, plant data, soil sur- Before constructing a waste management veys, stream gauge data, land use data, and unit in a wetland area, consider whether you other information. Note that it is mandatory can locate the unit elsewhere. If an alternative that wetlands delineation for CWA Section location can be identified, strongly consider 404 permitting purposes be conducted in pursuing such an option, as required by accordance with the 1987 U.S. Army Corps of Section 404 of the CWA. Because wetlands Engineers Wetlands Delineation Manual9 are important ecosystems that should be pro- (USACE, 1991). The manual provides guide- tected, identification of practicable location lines and methods for determining whether alternatives is a necessary first step in the sit- an area is a wetland for purposes of Section ing process. Even if no viable alternative loca- 404. A three-parameter approach for assess-
NWI wetland resource maps like this one show the locations of various different types of wetlands and are available for many areas. Source: NWI web site, sample GIS Think Tank maps page,
8 Currently, there is no federal certification program. In March 1995, USACE proposed standards for a Wetlands Delineator Certification Program (WDCP), but the standards have not been finalized. If the WDCP standards are finalized and implemented, you should use WDCP-certified wetland consultants. 9 The 1987 manual can be ordered from the National Technical Information Service (NTIS) at 703 605- 6000 or obtained online at
tions are identified, it might be beneficial to the grains are saturated, the saturated granu- keep a record of the alternatives investigated, lar material turns into a viscous fluid, a noting why they were not acceptable. Such process referred to as liquefaction. This records might be useful during the interac- diminishes the bearing capacity of the soils tion between facilities, states, and members of and can lead to foundation and slope failures. the community. To avoid these hazards, do not build or If no alternatives are available, you should expand a unit within 200 feet of an active consult with state and local regulatory agen- fault. If it is not possible to site a unit more cies concerning wetland permits. Most states than 200 feet from an active fault, you should operate permitting programs under the CWA, design the unit to withstand the potential and state authorities can guide you through ground movement associated with the fault the permitting process. To obtain a permit, area. A fault is considered active if there has the state might require that the unit facility been movement along it within the last 10,000 manager assess wetland impacts and then: to 12,000 years. • Prevent contamination from leachate How is it determined if a and runoff. prospective site is in a fault area? • Minimize dewatering effects. A series of USGS maps, Preliminary Young • Reduce the loss of wetland acreage. Fault Maps, Miscellaneous Field Investigation 916, identifies active faults.10 These maps, • Protect the waste management unit however, might not be completely accurate against settling. due to recent shifts in fault lines. If a prospec- tive site is well outside the 200 foot area of C. Active Fault Areas concern, no fault area considerations exist. If it is unclear how close a prospective site is to Faults occur when stresses in a geologic an active fault, further evaluation will be nec- material exceed its ability to withstand these essary. A geologic reconnaissance of the site forces. Areas surrounding faults are subject to and surrounding areas can be useful in verify- earthquakes and ground failures, such as ing that active faults do not exist at the site. landslides or soil liquefaction. Fault move- ment can directly weaken or destroy struc- If a prospective site is in an area known or tures, or seismic activity associated with suspected to be prone to faulting, you should faulting can cause damage to structures conduct a fault characterization to determine through vibrations. Structural damage to the if the site is near a fault. A characterization waste management unit could result in the includes identifying linear features that sug- release of contaminants. In addition, fault gest the presence of faults within a 3,000-foot movement might create avenues to ground- radius of the site. Such features might be water supplies, increasing the risk of ground- shown or described on maps, aerial pho- water contamination. tographs,11 logs, reports, scientific literature, or insurance claim reports, or identified by a Liquefaction is another common problem detailed field reconnaissance of the area. encountered in areas of seismic activity. The vibrating motions caused by an earthquake If the characterization study reveals faults tend to rearrange the sand grains in soils. If within 3,000 feet of the proposed unit or lat-
10 Information about ordering these maps is available by calling 888 ASK-USGS or 703 648-6045. 11 The National Aerial Photographic Program (NAPP) and the National High Altitude Program (NHAP), both administered by USGS, are sources of aerial photographs. To order from USGS, call 605 594- 4-10 6151. For more information, see
the unit’s structural integrity would result. A setback of less than 200 feet might be ade- quate if ground movement would not damage the unit. If a lateral expansion or a new unit will be located in an area susceptible to seismic activ- ity, there are two particularly important issues to consider: horizontal acceleration and movement affecting side slopes. Horizontal acceleration becomes a concern when a loca- tion analysis reveals that the site is in a zone with a risk of horizontal acceleration in the range of 0.1 g to 0.75 g (g = acceleration of gravity). In these zones, the unit design should incorporate measures to protect the unit from potential ground shifts. To address side slope concerns, you should conduct a seismic stability analysis to determine the most effective materials and gradients for pro- tecting the unit’s slopes from any seismic instabilities. Also, design the unit to with- In this aerial view, the infamous San Andreas stand the impact of vertical accelerations. fault slices through the Carrizo Plain east of San Luis Obispo, California. If the unit is in an area susceptible to liq- uefaction, you should consider ground Source: USGS. improvement measures. These measures eral expansion, you should conduct further include grouting, dewatering, heavy tamping, investigations to determine whether any of and excavation. See Table 1 for examples of the faults are active within 200 feet of the techniques that are currently used. unit. These investigations can involve drilling and trenching the subsurface to locate fault Additional engineering options for fault zones and evidence of faulting. Perpendicular areas include the use of flexible pipes for trenching should be used on any fault within runoff and leachate collection, and redundant 200 feet of the proposed unit to examine the containment systems. In the event of founda- seismic epicenter for indications of recent tion soil collapse or heavy shifting, flexible movement. runoff and leachate collection pipes—along with a bedding of gravel or permeable materi- What can be done if a prospective al—can absorb some of the shifting-related site is in a fault area? stress to which the pipes are subjected. Also consider a secondary containment measure, If an active fault exists on the site where such as an additional liner system. In earth- the unit is planned, consider placing the unit quake-like conditions, a redundancy of this 200 feet back from the fault area. Even with nature might be necessary to prevent contam- such setbacks, only place a unit in a fault area ination of the surrounding area if the primary if it is possible to ensure that no damage to liner system fails.
4-11 Getting Started—Considering the Site
Table 1 Examples of Improvement Techniques for Liquefiable Soil Foundation Conditions Method Principle Most Suitable Soil Applications Conditions/Types
Blasting Shock waves and vibrations cause Saturated, clean sands; partly Induce liquefaction in controlled and limited liquefaction, displacement, saturated sands and silts after limited stages and increase relative density remolding, and settlement to higher flooding. to potentially nonliquefiable range. density.
Vibrocompaction Densification by vibration and Cohesionless soils with less Induce liquefaction in controlled and compaction of backfill material of sand than 20 percent fines. limited stages and increase relative density or gravel. to nonliquefiable condition. The dense column of backfill provides (a) vertical support, (b) drainage to relieve pore water pressure, and (c) shear resistance in hori- zontal and inclined directions. Used to stabilize slopes and strengthen potential failure surfaces.
Compaction piles Densification by displacement of pile Loose sandy soils; partly Useful in soils with fines. Increases relative volume and by vibration during driving; saturated clayey soils; loess. density to nonliquefiable condition. increase in lateral effective earth Provides shear resistance in horizontal and pressure. inclined directions. Used to stabilize slopes and strengthen potential failure surfaces.
Displacement and Highly viscous grout acts as radial All soils. Increase in soil relative density and compaction grout hydraulic jack when pumped in under horizontal effective stress. Reduce high pressure. liquefaction potential. Stabilize the ground against movement.
Mix-in-place piles Lime, cement, or asphalt introduced Sand, silts, and clays; all soft Slope stabilization by providing shear and walls through rotating auger or special in- or loose inorganic soils. resistance in horizontal and inclined place mixer. directions, which strengthens potential failure surfaces or slip circles. A wall could be used to confine an area of liquefiable soil.
Heavy tamping Repeated application of high- intensity Cohesionless soils best; other Suitable for some soils with fines; usable (dynamic impacts at surface. types can also be improved. above and below water. In cohesionless compaction) soils, induces liquefaction in controlled and limited stages and increases relative density to potentially nonliquefiable range.
Source: RCRA Subtitle D (258) Seismic Design Guidance for Municipal Solid Waste Landfill Facilities. (EPA, 1995c).
D. Seismic Impact Zones in a seismic impact zone. If a unit must be sited in a seismic impact zone, the unit A seismic impact zone is an area having a should be designed to withstand earthquake- 2 percent or greater probability that the maxi- related hazards, such as landslides, slope fail- mum horizontal acceleration caused by an ures, soil compaction, ground subsidence, earthquake at the site will exceed 0.1 g in 50 and soil liquefaction. years. This seismic activity can damage leachate collection and removal systems, leak Additionally, if you build a unit in a seis- detection systems, or other unit structures mic impact zone, avoid rock and soil types through excessive bending, shearing, tension, that are especially vulnerable to earthquake and compression. If a unit’s structural compo- shocks. These include very steep slopes of nents fail, leachate can contaminate sur- weak, fractured, and brittle rock or unsaturat- rounding areas. Therefore, for safety reasons, ed loess,12 which are vulnerable to transient it is recommended that a unit not be located shocks caused by tensional faulting. Avoid
12 Loess is a wind-deposited, moisture-deficient silt that tends to compact when wet. 4-12 Getting Started—Considering the Site
loess and saturated sand as well, because seis- of ground motion at your site. This can help mic shocks can liquefy them, causing sudden you determine if the structural integrity of the collapse of structures. Similar effects are possi- unit is susceptible to damage from ground ble in sensitive cohesive soils when natural motion. moisture exceeds the soil’s liquid limit. For a For waste management unit siting purpos- discussion of liquid limits, refer to the “Soil es, use USGS’ recently revised Peak Properties” discussion in Chapter 7, Section B Acceleration (%g) with 2 % Probability of – Designing and Installing Liners. Earthquake- Exceedance in 50 Years maps available at induced ground vibrations can also compact
13 For information on ordering these maps, call 888 ASK-USGS, write to USGS Information Services, Box 25286, Denver, CO 80225, or fax 303 202-4693. Online information is available at
design to ensure that your unit is designed the foundation components. Placing too appropriately. To determine the potential much waste in one area of the unit can lead effects of seismic activity on a structure, the to catastrophic shifting during an earthquake seismic design specialist should evaluate soil or heavy seismic activity. Shifting of this behavior with respect to earthquake intensity. nature can cause failure of crucial system This evaluation should account for soil components or of the unit in general. strength, degree of compaction, sorting (orga- In addition, seismic impact zones have nization of the soil particles), saturation, and design issues in common with fault areas, peak acceleration of the potential earthquake. especially concerning soil liquefaction and After conducting an evaluation of soil earthquake-related stresses. To address lique- behavior, choose appropriate earthquake pro- faction, consider employing the soil improve- tection measures. These might include shal- ment techniques described in Table 1. lower slopes, dike and runoff control designs Treating liquefiable soils in the vicinity of the using conservative safety factors, and contin- unit will improve foundation stability and gency plans or backup systems for leachate help prevent uneven settling or possible col- collection if primary systems are disrupted. lapse of heavily saturated soils underneath or Unit components should be able to withstand near the unit. the additional forces imposed by an earth- To protect against earthquake-related quake within acceptable margins of safety. stresses, consider installing redundant liners Additionally, well-compacted, cohesionless and special leachate collection and removal embankments or reasonably flat slopes in system components, such as secondary liner insensitive clay (clay that maintains its com- systems, composite liners, and leak detection pression strength when remolded) are less systems combined with a low permeability likely to fail under moderate seismic shocks soil layer. These measures function as back- (up to 0.15 g - 0.20 g). Embankments made ups to the primary containment and collec- of insensitive, cohesive soils founded on tion systems and provide a greater margin of cohesive soils or rock can withstand even safety for units during possible seismic stress- greater seismic shocks. For earthen embank- es. Examples of special leachate systems ments in seismic regions, consider designing include high-strength, flexible materials for the unit with internal drainage and core leachate containment systems; geomembrane materials resistant to fracturing. Also, prior to liner systems underlying leachate contain- or during unit construction in a seismic ment systems; and perforated polyvinyl chlo- impact zone, you should evaluate excavation ride or high-density polyethylene piping in a slope stability to determine the appropriate bed of gravel or other permeable material. grade of slopes to minimize potential slip. For landfills and waste piles, using shal- E. Unstable Areas lower waste side slopes is recommended, as steep slopes are more vulnerable to slides Siting in unstable areas should be avoided and collapse during earthquakes. Use fill because these locations are susceptible to nat- sequencing techniques that avoid concentrat- urally occurring or human-induced events or ing waste in one area of the unit for an forces capable of impairing the integrity of a extended period of time. This prevents waste waste management unit. Naturally occurring pile side slopes from becoming too steep and unstable areas include regions with poor soil unstable and alleviates differential loading of foundations, regions susceptible to mass movement, or regions containing karst ter-
4-14 Getting Started—Considering the Site
rain, which can include hidden sinkholes. overlying caverns can collapse suddenly, Unstable areas caused by human activity can resulting in sinkholes that can be more than include areas near cut or fill slopes, areas 100 feet deep and 300 feet wide. with excessive drawdown of ground water, and areas where significant quantities of oil How is it determined if a or natural gas have been extracted. If it is prospective site is in an necessary to site a waste management unit in unstable area? an unstable area, technical and construction If a stability assessment has not been per- techniques should be considered to mitigate formed on a potential site, you should have a against potential damage. qualified professional conduct one before The three primary types of failure that can designing a waste management unit on the occur in an unstable area are settlement, loss prospective site. The qualified professional of bearing strength, and sinkhole collapse. should assess natural conditions, such as soil Settlement can result from soil compression if geology and geomorphology, as well as your unit is, or will be located in, an unstable human-induced surface and subsurface fea- area over a thick, extensive clay layer. The tures or events that could cause differential unit’s weight can force water from the com- ground settlement. Naturally unstable condi- pressible clay, compacting it and allowing the tions can become more unpredictable and unit to settle. Settlement can increase as destructive if amplified by human-induced waste volume increases and can result in changes to the environment. If a unit is to be structural failure of the unit if it was not built at an assessed site that exhibits stability properly engineered. Settlement beneath a problems, tailor the design to account for any waste management unit should be assessed instability detected. A stability assessment and compared to the elongation strength and typically includes the following steps: flexibility properties of the liner and leachate Screen for expansive soils. Expansive collection pipe system. Even small amounts soils can lose their ability to support a foun- of settlement can seriously damage leachate dation when subjected to certain natural or collection piping and sumps. A unit should human-induced events, such as heavy rain or be engineered to minimize the impacts of set- explosions. Expansive soils usually are clay- tlement if it is, or will be in an unstable area. rich and, because of their molecular struc- Loss of bearing strength is a failure mode ture, tend to swell and shrink by taking up that occurs in soils that tend to expand and and releasing water. Such soils include smec- rapidly settle or liquefy. Soil contractions and tite (montmorillonite group) and vermiculite expansions can increase the risk of leachate or clays. In addition, soils rich in white alkali waste release. Another example of loss of bear- (sodium sulfate), anhydrite (calcium sulfate), ing strength occurs when excavation near the or pyrite (iron sulfide) can also swell as water unit reduces the mass of soil at the toe of the content increases. These soils are more com- slope, thereby reducing the overall strength mon in the arid western states. (resisting force) of the foundation soil. Check for soil subsidence. Soils subject Catastrophic collapse in the form of sink- to rapid subsidence include loesses, uncon- holes can occur in karst terrain. As water, solidated clays, and wetland soils. Unconsol- especially acidic water, percolates through idated clays can undergo considerable limestone, the soluble carbonate material dis- compaction when oil or water is removed. solves, leaving cavities and caverns. Land Similarly, wetland soils, which by their
4-15 Getting Started—Considering the Site
Sinkholes, like this one that occurred just north of Orlando, Florida in 1981, are a risk of development in Karst terrain. Left: aerial view (note baseball diamond for scale); right: ground-level view. Photos courtesy of City of Winter Park, Florida public relations office.
nature are water-bearing, are also subject to the USGS15 and state specific geological maps subsidence when water is withdrawn. can be reviewed to identify karst areas. Look for areas subject to mass move- Scan for evidence of excessive ground- ment or slippage. Such areas are often situ- water drawdown or oil and gas extraction. ated on slopes and tend to have rock or soil Removing underground water can increase conditions conducive to downhill sliding. the effective overburden on the foundation Examples of mass movements include soils underneath the unit. Excessive draw- avalanches, landslides, and rock slides. Some down of water might cause settlement or sites might require cutting or filling slopes bearing capacity during construction. Such activities can cause failure on the existing soil or rock to slip. foundation soils. Extraction of oil Search for karst terrain. Karst features or natural gas are areas containing soluble bedrock, such as can have similar limestone or dolomite, that have been dis- effects. solved and eroded by water, leaving charac- teristic physiographic features including Investigate sinkholes, sinking streams, caves, large the geotechnical springs, and blind valleys. The principal con- and geological cern with karst terrains is progressive or cata- characteristics strophic subsurface failure due to the of the site. It is presence of sinkholes, solution cavities, and important to subterranean caverns. Karst features can also establish soil hamper detection and control of leachate, strengths and which can move rapidly through hidden con- other engineer- Subsidence, slippage, and duits beneath the unit. Karst maps, such as ing properties. A other kinds of slope failure Engineering Aspects of Karst, Scale 1:7,500,000, geotechnical can damage structures. Map No. 38077-AW-NA-07M-00, produced by engineering con-
15 For information on ordering this map, call 888 ASK-USGS, write USGS Information Services, Box 25286, Denver, CO 80255, or fax 303 202-4693. Online information is available at 4-16
sultant can accomplish this by performing subterranean caverns. Extensive subsurface standard penetration tests, field vane shear characterization studies should be completed tests, and laboratory tests. This information before designing and building in these areas. will determine how large a unit you can safely Subsurface drilling, sinkhole monitoring, and place on the site. Other soil properties to geophysical testing are direct means that can examine include water content, shear be used to characterize a site. Geophysical strength, plasticity, and grain size distribution. techniques include electromagnetic conduc- tivity, seismic refraction, ground-penetrating Examine the liquefaction potential. It is radar, and electrical resistivity (see the box extremely important to ascertain the liquefaction below for more information). More than one potential of embankments, slopes, and founda- technique should be used to confirm and cor- tion soils. Refer to Section C of this chapter for relate findings and anomalies, and a qualified more information about liquefiable soils. geophysicist should interpret the results of What can be done if a these investigations. prospective site is in an Remote sensing techniques, such as aerial unstable area? photograph interpretation, can also provide It is advisable not to locate or expand your additional information on karst terrains. waste management unit in an unstable area. If Surface mapping can help provide an under- your unit is or will be located in such an area, standing of structural patterns and relation- you should safeguard the structural integrity ships in karst terrains. An understanding of of the unit by incorporating appropriate mea- local carbonate geology and stratigraphy can sures into the design. The integrity of the unit help with the interpretation of both remote might be jeopardized if this is not done. sensing and geophysical data. For example, to safeguard the structural You should incorporate adequate engineer- integrity of side slopes in an unstable area, ing controls into any waste management unit reduce slope height, flatten slope angle, exca- located in a karst terrain. In areas where karst vate a bench in the upper portion of the slope, development is minor, loose soils overlying or buttress slopes with compacted earth or rock the limestone can be excavated or heavily fill. Alternatively, build retaining structures, compacted to achieve the needed stability. such as retaining walls or slabs and piles. Other Similarly, in areas where the karst voids are approaches include the use of geotextiles and relatively small, the voids can be filled with geogrids to provide additional strength, wick slurry cement grout or other material. and toe drains to relieve excess pore pressures, Engineering solutions can compensate for grouting, and vacuum and wellpoint pumping the weak geologic structures by providing to lower ground- water levels. In addition, sur- ground supports. For example, ground modi- face drainage can be controlled to decrease fications, such as grouting or reinforced raft infiltration, thereby reducing the potential for foundations, could compensate for a lack of mud and debris slides. ground strength in some karst areas. Raft Additional engineering concerns arise in constructions, which are floating foundations the case of waste management units in areas consisting of a concrete footing extending containing karst terrain. The principal con- over a very large area, reduce and evenly dis- cern with karst terrains is progressive or cata- tribute waste loads where soils have a low strophic subsurface failure due to the bearing capacity or where soil conditions are presence of sinkholes, solution cavities, and variable and erratic. Note, however, that raft foundations might not always prevent the
4-17 Getting Started—Considering the Site
extreme collapse and settlement that can Geophysical Techniques occur in karst areas. In addition, due to the unpredictable and catastrophic nature of Electromagnetic Conductivity or ground failure in unstable areas, the con- Electromagnetic Induction (EMI). A transmitter struction of raft foundations and other coil generates an electromagnetic field which ground modifications tends to be complex induces eddy currents in the earth located below and can be costly, depending on the size of the transmitter. These eddy currents create sec- the area. ondary electromagnetic fields which are measured by a receiver coil. The receiver coil produces an out- put voltage that can be related to subsurface con- F. Airport Vicinities ductivity variations. Analysis of these variations The vicinity of an airport includes not only allows users to map subsurface features, stratigraph- the facility itself, but also large reserved open ic profiles, and the existence of buried objects. areas beyond the ends of runways. If a unit is Seismic Refraction. An artificial seismic source intended to be sited near an airport, there are (e.g., hammer, explosives) creates compression particular issues that take on added impor- waves that are refracted as they travel along geologic tance in such areas. You should familiarize boundaries. These refracted waves are detected by yourself with Federal Aviation Administration electromechanical transducers (geophones) which (FAA) regulations and guidelines. The prima- are attached to a seismograph that records the time ry concern associated with waste management of arrival of all waves (refracted and non-refracted). units near airports is the hazard posed to air- These travel times are compared and analyzed to craft by birds, which often feed at units man- identify the number of stratigraphic layers and the aging putrescible waste. Planes can lose depth of each layer. propulsion when birds are sucked into jet engines, and can sustain other damage in col- Ground-Penetrating Radar. A transmitting lisions with birds. Industrial waste manage- antenna dragged along the surface of the ground ment units that do not receive putrescible radiates short pulses of high-frequency radio wastes should not have a problem with birds. waves into the ground. Subsurface structures Another area of concern for landfills and reflect these waves which are recorded by a waste piles near airports is the height of the receiving antenna. The variations in reflected accumulated waste. If you own or operate return signals are used to generate an image or such a unit, you should exercise caution map of the subsurface structure. when managing waste above ground level. Electrical Resistivity. An electrical current is How is it determined if a injected into the ground by a pair of surface elec- trodes (called the current electrodes). By measuring prospective site will be located the resulting voltage (potential field) between a sec- too close to an airport? ond pair of electrodes (called the potential elec- If the prospective site is not located near trodes), the resistivity of subsurface materials is any airports, additional evaluation is not nec- measured. The measured resistivity is then com- essary. If there is uncertainty whether the pared to known values for different soil and rock prospective site is located near an airport, types. Increasing the distance between the two pairs obtain local maps of the area using the various of electrodes increases the depth of measurement. Internet resources previously discussed or from state and local regulatory agencies to identify any nearby public-use airports.
4-18 Getting Started—Considering the Site
Topographic maps available from USGS are the disposal and storage areas when practical also suitable for determining airport locations. or technically feasible. If necessary, FAA can provide information on the location of all public-use airports. In accor- dance with FAA guidance, if a new unit or an G. Wellhead Protection expansion of an existing unit will be within 5 Areas miles of the end of a public-use airport run- Wellhead protection involves protecting way, the affected airport and the regional FAA the ground-water resources that supply pub- office should be notified to provide them an lic drinking water systems. A wellhead pro- opportunity for review and comment. tection area (WHPA) is the area most What can be done if a susceptible to contamination surrounding a wellhead. WHPAs are designated and often prospective site is in an regulated to prevent public drinking water airport vicinity? sources from becoming contaminated. The If a proposed waste management unit or a technical definition, delineation, and regula- lateral expansion is to be located within tion of WHPAs vary from state to state. You 10,000 feet of an airport used by jet aircraft should contact your state or local regulatory or within 5,000 feet of an airport used only agency to determine what wellhead protec- by piston-type aircraft, design and operate tion measures are in place near prospective your unit so it does not pose a bird hazard to sites. Section II of this chapter provides aircraft. For above-ground units, design and examples of how some states specify mini- operate your unit so it does not interfere mum allowable distances between waste with flight patterns. If it appears that height management units and public water supplies, is a potential concern, consider entrenching as well as drinking water wells. Locating a the unit or choosing a site outside the air- waste management unit in a WHPA can cre- port’s flight patterns. Most nonhazardous ate a potential avenue for drinking water con- industrial waste management units do not tamination through accidental release of usually manage wastes that are attractive leachate, contaminated runoff, or waste. In food sources for birds, but if your unit han- addition, some states might have additional dles waste that potentially attracts birds, take restrictions for areas in designated “sole precautions to prevent birds from becoming source aquifier” systems. an aircraft hazard. Discourage congregation How is it determined if a of birds near your unit by preventing water from collecting on site; eliminating or cover- prospective site is in a wellhead ing wastes that might serve as a source of protection area? food; using visual deterrents, including real- A list of state wellhead protection program istic models of the expected scavenger birds’ contacts is available on EPA’s Web site at natural predators; employing sound deter-
4-19 Getting Started—Considering the Site
What can be done if a II. Buffer Zone prospective site is in a wellhead protection area? Considerations If a new waste management unit or lateral Many states require buffer zones between expansion will be located in a WHPA or sus- waste management units and other nearby pected WHPA, consider design modifications land uses, such as schools. The size of a to help prevent any ground-water contami- buffer zone often depends on the type of nation. For waste management units placed waste management unit and the land use of in these areas, work with state regulatory the surrounding areas. You should consult agencies to ensure that appropriate ground- with state regulatory agencies and local advi- water barriers are installed between the unit sory boards about buffer zone requirements and the ground-water table. These barriers before constructing a new unit or expanding should be designed using materials of an existing unit. A summary of state buffer extremely low permeability, such as zone requirements is included in the appen- geomembrane liners or low permeability soil dix at the end of this chapter. liners. The purpose of such barriers is to Buffer zones provide you with time and prevent any waste, or leachate that has per- space to mitigate situations where accidental colated through the waste, from reaching the releases might cause adverse human health or ground water and possibly affecting the pub- environmental impacts. The size of the buffer lic drinking water source. zone will be directly related to the intended In addition to ground-water barriers, the benefit. These zones provide four primary use of leachate collection, leak detection, and benefits: runoff control systems should also be consid- • Maintenance of quality of the sur- ered. Leachate contamination is possibly the rounding ground water. greatest threat to a public ground-water sup- • Prevention of contaminant migration ply posed by a waste management unit. off site. Incorporation of leachate collection, leak detection, and runoff control systems should • Protection of drinking water sup- further prevent any leachate from escaping plies. into the ground water. Further discussion • Minimization of nuisance conditions concerning liner systems, leachate collection perceived in surrounding areas. and removal systems, and leak detection sys- tems is included in Chapter 7, Section Protection of ground water will likely be B–Designing and Installing Liners. the primary concern for all involved parties. You should ensure that materials processed Control systems that separate storm-water and disposed at your unit are isolated from run-on from any water that has contacted ground-water resources. Placing your unit waste should also be considered. Proper con- further from the water table and potential trol measures that redirect storm water to the receptors, and increasing the number of supply source area should help alleviate this physical barriers between your unit and the tendency. For additional information con- water table and potential receptors, provides cerning storm water run-on and runoff con- for ground-water protection. It is therefore trol systems, refer to Chapter 6–Protecting advised that, in addition to incorporating a Surface Water. liner system, where necessary, into a waste
4-20 Getting Started—Considering the Site
protecting surrounding areas from any noise, particulate emissions, and odor associated with your unit. Buffer zones also help to pre- vent access by unauthorized people. For units located near property boundaries, houses, or historic areas, trees or earthen berms can pro- vide a buffer to reduce noise and odors. Planting trees around a unit can also improve the aesthetics of a unit, obstruct any view of unsightly waste, and help protect property values in the surrounding community. When planting trees as a buffer, place them so that their roots will not damage the unit’s liner or final cover.
A. Recommended Buffer Zones You should check with state and local offi- cials to determine what buffer zones might apply to your waste management unit. Areas Many nearby areas and land uses, such as for which buffer zones are recommended schools, call for consideration of buffer zones. include property boundaries, drinking water wells, other sources of water, and adjacent management unit’s design, you select a site houses or buildings. where an adequate distance separates the bot- Property boundaries. To minimize tom of a unit from the ground-water table. adverse effects on adjacent properties, consid- (See the appendix for a summary of these er incorporating a buffer zone or separation 16 minimum separation distances.) In the event distance into unit design. You should consid- of a release, this separation distance will er planting trees or bushes to provide a nat- allow for corrective action and natural attenu- ural buffer between your unit and adjacent 17 ation to protect ground water. properties. Additionally, in the event of an unplanned Drinking water wells, surface-water release, an adequate buffer zone will allow bodies, and public water supplies. Locating time for remediation activities to control con- a unit near or within the recharge area for taminants before they reach sensitive areas. sole source aquifers and major aquifers, Buffer zones also provide additional protec- coastal areas, surface-water bodies, or public tion for drinking water supplies. Drinking water supplies, such as a community well or water supplies include ground water, individ- water treatment facility, also raises concerns. ual and community wells, lakes, reservoirs, Releases from a waste management unit can and municipal water treatment facilities. pose serious threats to human health not only Finally, buffer zones help maintain good where water is used for drinking, but also relations with the surrounding community by where surface waters are used for recreation.
16 A detailed discussion of technical considerations concerning the design and installation of liner sys- tems, both in situ soil liners and synthetic liners, is included in Chapter 7, Section B – Designing and Installing Liners. 17 Natural attenuation can be defined as chemical and biological processes that reduce contaminant con- 4-21 centrations. Getting Started—Considering the Site
Houses or buildings. Waste management Park lands. A buffer between your unit units can present noise, odor, and dust prob- and park boundaries helps maintain the aes- lems for residents or businesses located on thetics of the park land. Park lands provide adjacent property, thereby diminishing prop- recreational opportunities and a natural erty values. Additionally, proximity to proper- refuge for wildlife. Locating a unit too close ty boundaries can invite increased to these areas can disrupt recreational quali- trespassing, vandalism, and scavenging. ties and natural wildlife patterns. Public roads. A buffer zone will help B. Additional Buffer Zones reduce unauthorized access to the unit, reduce potential odor concerns, and improve There are several other areas for which to aesthetics for travelers on the nearby road. consider establishing buffer zones, including critical habitats, park lands, public roads, and Historic or archaeological sites. A waste historic or archaeological sites. management unit located in close proximity to one of these sites can adversely impact the Critical habitats. These are geographical aesthetic quality of the site. These areas areas occupied by endangered or threatened include historic settlements, battlegrounds, species. These areas contain physical or bio- cemeteries, and Indian burial grounds. Also logical features essential to the proliferation of check whether a prospective site itself has the species. When designing a unit near a historical or archaeological significance. critical habitat, it is imperative that the criti- cal habitat be conserved. A buffer zone can help prevent the destruction or adverse modi- fication of a critical habitat and minimize harm to endangered or threatened species.18
Historic sites call for careful consideration of buffer zones. In summary, it is important to check with local authorities to ensure that placement of a new waste management unit or lateral Buffer zones can help protect endangered expansion of an existing unit will not conflict species and their habitats. with any local buffer zone criteria. You should also review any relevant state or tribal
18 For the full text of the Endangered Species Act, visit the U.S. House of Representatives Internet Law Library Web site at
regulations that specify buffer zones for your be brought by local authorities or nearby unit. For units located near any sensitive property owners. areas as described in this section, consider In situations where land use and zoning measures to minimize any possible health, restrictions might cause difficulties in expand- environmental, and nuisance impacts. ing or siting a unit, work closely with local authorities to learn about local land use and zoning restrictions and minimize potential III. Local Land Use problems. Misinterpreting or ignoring such restrictions can cause complications with and Zoning intended development schedules or designs. In many cases, the use of vegetation, fences, Considerations or walls to screen your activities can reduce In addition to location and buffer zone impacts on nearby properties. In addition, it considerations, become familiar with any might be possible to request amendments, local land use and zoning requirements. Local rezonings, special exceptions, or variances to governments often classify the land within restrictions. These administrative mechanisms their communities into areas, districts, or allow for flexibility in use and development of zones. These zones can represent different land. Learning about local requirements as use categories, such as residential, commer- early as possible in the process will maximize cial, industrial, or agricultural. You should the time available to apply for variances or consider the compatibility of a planned new rezoning permits, or to incorporate screening unit or a planned lateral expansion with near- into the plans for your unit. by existing and future land use, and contact local authorities early in the siting process. Local planning, zoning, or public works offi- cials can discuss with you the development of IV. Environmental a unit, compliance with local regulations, and available options. Local authorities might Justice impose conditions for protecting adjacent Considerations properties from potential adverse impacts In the past several years, there has been from the unit. growing recognition from communities and Addressing local land use and zoning federal and state governments that some issues during the siting process can prevent socioeconomic and racial groups might bear a these issues from becoming prominent con- disproportionate burden of adverse environ- cerns later. Land use and zoning restrictions mental effects from waste management activi- often address impacts on community and ties. President Clinton issued Executive Order recreational areas, historical areas, and other 12898, Federal Actions to Address critical areas. You should consider the prox- Environmental Justice in Minority imity of a new unit or lateral expansion to Populations and Low-Income Populations, on such areas and evaluate any potential adverse February 11, 1994.19 To be consistent with effects it might have on these areas. For the definition of environmental justice in this example, noise, dust, fumes, and odors from executive order, you should identify and construction and operation of a unit could be address, as appropriate, disproportionately considered a nuisance and legal action could high and adverse human health or environ- mental effects of waste management pro-
19 For the full text of Presidential Executive Order No. 12898 and additional information concerning environmental justice issues go to EPA’s Web site at
grams, policies, and activities on minority Tailor the public involvement activities and low-income populations. to the specific needs. Good public involve- ment programs are site-specific—they take One of the criticisms made by advocates of into account the needs of the facility, neigh- environmental justice is that local communi- borhood, and state. There is no such thing ties endure the potential health and safety as a “one-size-fits-all” public involvement risks associated with waste management program. Listening to each other carefully units without enjoying any of the economic will identify the specific environmental jus- benefits. During unit siting or expansion, tice concerns and determine the involve- address environmental justice concerns in a ment activities most appropriate to address manner that is most appropriate for the oper- those needs. ations, the community, and the state or tribal government. Provide interpreters for public meetings. Interpreters can be used to ensure the infor- You should look for opportunities to mini- mation is exchanged. Provide interpreters, as mize environmental impacts, improve the needed, for the hearing impaired and for any surrounding environment, and pursue languages, other than English, spoken by a opportunities to make the waste management significant percentage of the audience. Provide multilingual fact sheets and other information. Public notices and fact sheets should be distributed in as many lan- guages as necessary to ensure that all inter- ested parties receive necessary information. Fact sheets should be available for the visual- ly impaired in the community on tape, in large print, or braille. Promote the formation of a community/ state advisory panel to serve as the voice of the community. The Louisiana Department of Environmental Quality, for example, facility an asset to the community. When encourages the creation of environmental jus- planning these opportunities, it is beneficial tice panels comprised of community mem- to maintain a relationship with all involved bers, industry, and state representatives. The parties based on honesty and integrity, utilize panels meet monthly to discuss environmen- cross-cultural formats and exchanges, and tal justice issues and find solutions to any recognize industry, state, and local knowl- concerns identified by the group. edge of the issues. It is also important to take advantage of all potential opportunities for developing partnerships. Examples of activities that incorporate environmental justice issues include tailoring activities to specific needs; providing inter- preters, if appropriate; providing multilingual materials; and promoting the formation of a community/state advisory panel.
4-24 Getting Started—Considering the Site
Considering the Site Activity List General Siting Considerations ■ Check to see if the proposed unit site is: — In a 100-year floodplain. — In or near a wetland area. — Within 200 feet of an active fault. — In a seismic impact zone. — In an unstable area. — Close to an airport. — Within a wellhead protection area. ■ If the proposed unit site is in any of these areas: — Design the unit to account for the area’s characteristics and minimize the unit’s impacts on such areas. — Consider siting the unit elsewhere. Buffer Zone Considerations (Note that many states require buffer zones between waste management units and other nearby land uses.) ■ Check to see if the proposed unit site is near: — The ground-water table. — A property boundary. — A drinking water well. — A public water supply, such as a community well, reservoir, or water treatment facility. — A surface-water body, such as a lake, stream, river, or pond. — Houses or other buildings. — Critical habitats for endangered or threatened species. — Park lands. — A public road. — Historic or archaeological sites. ■ If the proposed unit site is near any of these areas or land uses, determine how large a buffer zone, if any, is appropriate between the unit and the area or land use.
4-25 Getting Started—Considering the Site
Considering the Site Activity List (cont.) Local Land Use and Zoning Considerations ■ Contact local planning, zoning, and public works agencies to discuss restrictions that apply to the unit. ■ Comply with any applicable restrictions, or obtain the necessary variances or special exceptions. Environmental Justice Considerations ■ Determine whether minority or low-income populations would bear a disproportionate burden of any environmental effects of the unit’s waste management activities. ■ Work with the local community to devise strategies to minimize any potentially disproportionate burdens.
4-26 Getting Started—Considering the Site
Resources
Bagchi, A. 1994. Design, Construction, and Monitoring of Landfills. John Wiley & Sons Inc.
Das, B. M. 1990. Principles of Geotechnical Engineering. 2nd ed. Boston: PWS-Kent Publishing Co.
Federal Emergency Management Agency. How to Read a Flood Insurance Map. Web Site:
Federal Emergency Management Agency. The National Flood Insurance Program Community Status Book. Web Site:
Federal Emergency Management Agency. 1995. The Zone A Manual: Managing Floodplain Development in Approximate Zone A Areas. FEMA 265.
Illinois Department of Energy and Natural Resources. 1990. Municipal Solid Waste Management Options: Volume II: Landfills.
Law, J., C. Leung, P. Mandeville, and A. H. Wu. 1996. A Case Study of Determining Liquefaction Potential of a New Landfill Site in Virginia by Using Computer Modeling. Presented at WasteTech ’95, New Orleans, LA (January).
Noble, George. 1992. Siting Landfills and Other LULUs. Technomic Publications.
Oregon Department of Environmental Quality. 1996. Wellhead Protection Facts. Web Site:
Terrene Institute.1996. American Wetlands: A Reason to Celebrate.
Texas Natural Resource Conservation Commission. 1983. Industrial Solid Waste Landfill Site Selection.
U.S. Army Corps of Engineers. 1995. Engineering and Design: Design and Construction of Conventionally Reinforced Ribbed Mat Slabs (RRMS). ETL 1110-3-471.
U.S. Army Corps of Engineers. 1995. Engineering and Design: Geomembranes for Waste Containment Applications. ETL 1110-1-172.
U.S. Army Corps of Engineers. 1992. Engineering and Design: Bearing Capacity of Soils. EM 1110-1-1905.
U.S. Army Corps of Engineers. 1992. Engineering and Design: Design and Construction of Grouted Riprap. ETL 1110-2-334.
4-27 Getting Started—Considering the Site
Resources (cont.)
U.S. Army Corps of Engineers. 1991. 1987 U.S. Army Corps of Engineers Wetlands Delineation Manual. HQUSACE.
U.S. Army Corps of Engineers. 1984. Engineering and Design: Use of Geotextiles Under Riprap. ETL 1110-2-286.
U.S. EPA. 2000a. Social Aspects of Siting RCRA Hazardous Waste Facilities. EPA530-K-00-005.
U.S. EPA. 2000b. Siting of Hazardous Waste Management Facilities and Public Opposition. EPAOSW-0-00-809.
U.S. EPA. 1997. Sensitive Environments and the Siting of Hazardous Waste Management Facilities. EPA530-K-97-003.
U.S. EPA. 1995a. OSWER Environmental Justice Action Agenda. EPA540-R-95-023.
U.S. EPA. 1995b. Decision-Maker’s Guide to Solid Waste Management, 2nd Ed. EPA530-R-95-023.
U.S. EPA. 1995c. RCRA Subtitle D (258) Seismic Design Guidance for Municipal Solid Waste Landfill Facilities. EPA600-R-95-051.
U.S. EPA. 1995d. Why Do Wellhead Protection? Issues and Answers in Protecting Public Drinking Water Supply Systems. EPA813-K-95-001.
U. S. EPA. 1994. Handbook: Ground Water and Wellhead Protection. EPA625-R-94-001.
U. S. EPA. 1993a. Guidelines for Delineation of Wellhead Protection Areas. EPA440-5-93-001.
U.S. EPA. 1993b. Solid Waste Disposal Facility Criteria: Technical Manual. EPA530-R-93-017.
U. S. EPA. 1992. Final Comprehensive State Ground-Water Protection Program Guidance. EPA100-R-93-001.
U. S. EPA. 1991. Protecting Local Ground-Water Supplies Through Wellhead Protection. EPA570-09-91-007.
U. S. EPA. 1988. Developing a State Wellhead Protection Program: A User’s Guide to Assist State Agencies Under the Safe Drinking Water Act. EPA440-6-88-003.
U.S. Geological Survey. Preliminary Young Fault Maps, Miscellaneous Field Investigation 916.
4-28 Getting Started—Considering the Site
Resources (cont.)
U.S. Geological Survey. Probabilistic Acceleration and Velocity Maps for the United States and Puerto Rico. Map Series MF-2120.
U.S. House of Representatives. 1996. Endangered Species Act. Internet Law Library. Web Site:
University of Illinois Center for Solid Waste Management and Research, Office of Technology Transfer. 1990. Municipal solid waste landfills: Volume II: Technical issues.
University of Illinois Center for Solid Waste Management and Research, Office of Technology Transfer. 1989. Municipal Solid Waste Landfills: Vol. I: General Issues.
White House. Executive Order 12898 Federal Actions to Address Environmental Justice in Minority Populations and Low-Income Populations.
4-29 Getting Started—Considering the Site
Appendix: State Buffer Zone Considerations The universe of industrial wastes and unit types is broad and diverse. States have established various approaches to address location considerations for the variety of wastes and units in their states. The tables below summarize the range of buffer zone restrictions and most com- mon buffer zone values specified for each unit type by some states to address their local con- cerns. The numbers in the tables are not meant to advocate the adoption of a buffer zone of any particular distance; rather, they serve only as examples of restrictions states have individu- ally developed. • Surface impoundments. Restrictions with respect to buffer zones vary among states. In addition, states allow exemptions or variances to these buffer zone restrictions on a case-by-case basis. Table 1 presents the range of values and the most common value used by states for each buffer zone category.
Table 1 State Buffer Zone Restrictions for Surface Impoundments Buffer Zone Category Range of Values—minimum Most Common Value (number of distance (number of states states with this common value) with this common value)
Groundwater Table 1 to 15 feet (4) 5 feet (2)
Property Boundaries 100 to 200 feet (4) 100 feet (2)
Drinking Water Wells 1,200 to 1,320 feet (2) 1,200 feet (1) 1,320 feet (1)
Public Water Supply 500 to 1,320 feet (4) 1,320 feet (2)
Surface Water Body 100 to 1,320 feet (4) 100 feet (2)
Houses or Buildings 300 to 1,320 feet (4) 1,320 feet (2)
Roads 1,000 feet (1) 1,000 feet (1)
4-30 Getting Started—Considering the Site
• Landfills. Table 2 presents the range of values and the most common state buffer zone restrictions for landfills.
Table 2 State Buffer Zone Restrictions for Landfills Buffer Zone Category Range of Values—minimum Most Common Value (number of distance (number of states with states with this common value) this common value)
Groundwater Table 1 to 15 feet (12) 5 feet (4)
Property Boundaries 20 to 600 feet (14) 100 feet (7)
Drinking Water Wells 500 to 1,320 feet (9) 500 feet (2) 600 feet (2) 1,200 feet (2)
Public Water Supply 400 to 5,280 feet (13) 1,200 feet (3)
Surface Water Body 100 to 2,000 feet (20) 100 feet (5) 1,000 feet (5)
Houses or Buildings 200 to 1,320 feet (14) 500 feet (7)
Roads 50 to 1,000 feet (8) 1,000 feet (5)
Park Land 1,000 to 5,280 feet (7) 1,000 feet (4)
Fault Areas 200 feet (2) 200 feet (2)
4-31 Getting Started—Considering the Site
• Waste Piles. Table 3 presents the state buffer zone restrictions for waste piles. Of the four states with buffer zone restrictions, only two states specified minimum distances.
Table 3 State Buffer Zone Restrictions for Waste Piles Buffer Zone Category Range of Values-minimum Most Common Value (number of distance (number of states states with this common value) with this common value)
Groundwater Table 4 feet* (1) 4 feet* (1)
Property Boundaries 50 feet (1) 50 feet (1)
Surface Water Body 50 feet (1) 50 feet (1)
Houses or Buildings or 200 feet (1) 200 feet (1) Recreational Area
Historic Archeological Site Minimum distance (1) Minimum distance (1) or Critical Habitat not specified not specified
* If no liner or storage pad is used, then this state requires four feet between the waste and the seasonal high water table.
4-32 Getting Started—Considering the Site
• Land Application.20 Table 4 presents the range of values and the most common state buffer zone restrictions for land application.
Table 4 State Buffer Zone Restrictions for Land Application Buffer Zone Category Range of Values-minimum Most Common Value (number of distance (number of states with states with this common value) this common value)
Groundwater Table 4 to 5 feet (3) 4 feet (1) 5 feet (1)
Property Boundaries 50 to 200 feet (4) 50 feet (2)
Drinking Water Wells 200 to 500 feet (2) 200 feet (1) 500 feet (1)
Public Water Supply 300 to 5,280 feet (3) 300 feet (1) 1,000 feet (1) 5,280 feet (1)
Surface Water Body 100 to 1,000 feet (5) 100 feet (2)
Houses or Buildings 200 to 3,000 feet (6) 300 feet (2) 500 feet (2)
Park Land 2,640 feet (1) 2,640 feet (1)
Fault Areas 200 feet (1) 200 feet (1)
Max. Depth of Treatment 5 feet (1) 5 feet (1)
Pipelines 25 feet (1) 25 feet (1)
Critical Habitat No minimum distance set (2) No minimum distance set (2)
Soil Conditions Not on frozen, ice or snow (1) Not on frozen, ice or snow (1) covered, or water saturated soils covered, or water saturated soils
20 In the review of state regulations performed to develop Table 5, it was not possible to distinguish between units used for treatment and units where wastes are added as a soil amendment. It is recom- mended that you consult applicable state agencies to determine which buffer zone restrictions are rele- vant to your land application unit. 4-33 Getting Started—Considering the Site
Based on the review of state requirements, Table 5 presents the most common buffer zones restrictions across all four unit types.
Table 5 Common Buffer Zone Restrictions Across All Four Unit Types Buffer Zone Category Most Common Values (total number of states for all unit types) (number of states with this common value)
Groundwater Table (20) 4 feet (4) 5 feet (4)
Property Boundaries (23) 50 feet (8) 100 feet (5)
Drinking Water Wells (13) 500 feet (3)
Public Water Supply (20) 1,000 feet (3) 1,200 feet (3) 5,280 feet (3)
Surface Water Body (30) 100 feet (5) 200 feet (5) 1,000 feet (7)
Houses or Buildings (25) 500 feet (9)
4-34 Part II Protecting Air Quality
Chapter 5 Protecting Air Quality Contents
I. Federal Airborne Emission Control Programs ...... 5-3 A. National Ambient Air Quality Standards...... 5-3 B. New Source Performance Standards ...... 5-3 C. National Emission Standards for Hazardous Air Pollutants ...... 5-4 D. Title V Operating Permits ...... 5-10 E. Federal Airborne Emission Regulations for Solid Waste Management Activities ...... 5-10 1. Hazardous Waste Management Unit Airborne Emission Regulations ...... 5-10 2. Municipal Solid Waste Landfill Airborne Emission Regulations ...... 5-10 3. Offsite Waste and Recovery Operations NESHAP ...... 5-11 F. A Decision Guide to Applicable CAA Requirements ...... 5-12 1. Determine Emissions from the Unit ...... 5-12 2. Is the Waste Management Unit Part of an Industrial Facility Which Is Subject to a CAA Title V Opening Permit? ...... 5-14 3. Conduct a Risk Evaluation Using One of the Following Options:...... 5-17
II. Assessing Risk ...... 5-17 A. Assessing Risks Associated with Inhalation of Ambient Air ...... 5-17 B. IWAIR Model ...... 5-21 1. Emissions Model...... 5-21 2. Dispersion Model ...... 5-21 3. Risk Model ...... 5-23 4. Estimation Process ...... 5-23 5. Capabilities and Limitations of the Model...... 5-27 C. Site-specific Risk Analysis ...... 5-28
III. Emission Control Techniques...... 5-32 A. Controlling Particulate Matter ...... 5-32 1. Vehicular Operations ...... 5-32 2. Waste Placement and Handling ...... 5-33 3. Wind Erosion ...... 5-35 B. VOC Emission Control Techniques...... 5-36 1. Choosing a Site to Minimize Airborne Emission Problems ...... 5-36 2. Pretreatment of Waste...... 5-36 3. Enclosure of Units ...... 5-36 4. Treatment of Captured VOCs ...... 5-37 5. Special Considerations for Land Application Units ...... 5-38
Protecting Air Activity List ...... 5-39 Contents
Resources ...... 5-40
Figures: Figure 1. Evaluating VOC Emission Risk ...... 5-13 Figure 2. Conceptual Site Diagram ...... 5-18 Figure 3. Emissions from WMU ...... 5-19 Figure 4. Forces That Affect Contaminant Plumes...... 5-20 Figure 5. IWAIR Approach for Developing Risk or Protective Waste Concentrations ...... 5-24 Figure 6. Screen 1, Method, Met Station, WMU ...... 5-25 Figure 7. Screen 2, Wastes Managed ...... 5-25
Tables: Table 1. Industries for Which NSPSs Have Been Established ...... 5-5 Table 2. HAPs Defined in Section 112 of the CAA Amendments of 1990 ...... 5-6 Table 3. Source Categories With MACT Standards ...... 5-8 Table 4. Major Source Determination in Nonattainment Areas ...... 5-15 Table 5. Constituents Included in IWAIR ...... 5-22 Table 6. Source Characterization Models...... 5-29 Table 7. Example List of Chemical Suppressants...... 5-34 Protecting Air Quality—Protecting Air Quality
Protecting Air Quality This chapter will help you address: • Airborne particulates and air emissions that can cause human health risks and damage the environment by adopting controls to minimize particulate emissions. • Assessing risks associated with air emissions and implementing pol- lution prevention, treatment, or controls as needed to reduce risks for a facility’s waste management units not addressed by require- ments under the Clean Air Act. • Using a Clean Air Act Title V permit, at facilities that must obtain one, as a vehicle for addressing air emissions from certain waste management units. Air releases from waste management units ealth effects from airborne pol- include particulates or wind-blown dust and lutants can be minor and gaseous emissions from volatile compounds reversible (such as eye irrita- tion), debilitating (such as It is recommended that every facility asthma), or chronic and poten- implement controls to address emissions of Htially fatal (such as cancer). Potential health airborne particulates. Particulates have imme- impacts depend on many factors, including diate and highly visible impacts on surround- the quantity of air pollution to which people ing neighborhoods. They can affect human are exposed, the duration of exposures, and health and can carry constituents off site as the toxicity associated with specific pollu- well. Generally, controls are achieved through tants. An air risk assessment takes these fac- good operating practices. tors into account to predict the risk or For air releases from industrial waste man- hazards posed at a particular site or facility. agement units, you need to know what regula- tory requirements under the Clean Air Act This chapter will help you address the fol- (CAA) apply to your facility, and whether those lowing questions. requirements address waste management units. • Is a particular facility subject to CAA The followup question for facilities whose requirements? waste management units are not addressed by CAA requirements, is “are there risks from air • What is an air risk assessment? releases that should be controlled?” • Do waste management units pose risks This Guide provides two tools to help you from volatile air emissions? answer these questions. First, this chapter • What controls will reduce particulate includes an overview of the major emission and volatile emissions from a facility? control requirements under the CAA and a decision guide to evaluate which of these
5-1 Protecting Air Quality—Protecting Air Quality
might apply to a facility. The steps of the deci- two-tiered approach to this assessment is rec- sion guide are summarized in Figure 1. Each ommended, depending on the complexity and facility subject to any of these requirements amount of site specific data you have. will most likely be required to obtain a CAA Limited Site-Specific Air Assessment: Title V operating permit. The decision guide The CD-ROM version of the Guide contains will help you clarify some of the key facility the Industrial Waste Air Model (IWAIR). If a information you need to identify applicable waste contains any of the 95 constituents CAA requirements. included in the model, you can use this risk If your answers in the decision guide indi- model to assess whether VOC emissions pose cate that the facility is or might be subject to a risk that warrants additional emission con- specific regulatory obligations, the next step is trols or that could be addressed more effec- to consult with EPA, state, or local air quality tively with pollution prevention or waste program staff. Some CAA regulations are treatment before placement in the waste man- industry-specific and operation-specific within agement unit. The IWAIR model allows users an industry, while others are pollutant specific to supply inputs for an emission estimate and or specific to a geographic area. EPA, state, or for a dispersion factor for the unit. local air quality managers can help you pre- Comprehensive Risk Assessment: This cisely determine applicable requirements and assessment relies on a comprehensive analysis whether waste management units are of waste and site-specific data and use of mod- addressed by those requirements. els designed to assess multi-pathway exposures You might find that waste management to airborne contaminants. There are a number units are not addressed or that a specific facili- of modeling tools available for this analysis. ty clearly does not fit into any regulatory cate- You should consult closely with your air quali- gory under the CAA. It is then prudent to ty management agency as you proceed. look beyond immediate permit requirements to assess risks associated with volatile organic compounds (VOCs) released from the unit. A
Airborne emissions are responsible for the loss of visibility between the left and right pho- tographs of the Grand Canyon. Source: National Park Service, Air Resources Division.
5-2 Protecting Air Quality—Protecting Air Quality
be rarely exceeded in a predetermined geo- I. Federal Airborne graphical area (National Ambient Air Quality Emission Control District). NAAQS are not enforced directly by EPA. Instead, each state must submit a State Programs Implementation Plan (SIP) describing how it Four major federal programs address air- will achieve or maintain NAAQS. Many SIPs borne emissions that can degrade air quality. call for airborne emission limits on industrial For more information about the CAA and facilities. EPA’s implementation of it, visit the If a waste emits VOCs, some of which are Technology Transfer Network, EPA’s premier precursors to ozone, the waste management technical Web site for information transfer unit could be affected by EPA’s NAAQS for and sharing related to air pollution topics, at ground-level ozone. Currently, states are
1 42 U.S.C. § 7409 2 For a discussion of the history of the litigation over the revised ozone standard and EPA’s plan for implementing it, including possible revisions to 40 CFR 50.9(b), see 67 FR 48896 (July 26, 2002). 5-3 Protecting Air Quality—Protecting Air Quality
tion that can reasonably be anticipated to least 10 tons per year (tpy) of any single HAP endanger public health or welfare. For indus- or at least 25 tpy of any combination of HAPs. try categories, NSPSs establish national tech- All fugitive emissions of HAPs, including emis- nology-based emission limits for air pollutants, sions from waste management units, are to be such as particulate matter (PM) or VOCs. taken into account in determining whether a States have primary responsibility for assuring stationary source is a major source. Each that the NSPSs are followed. These standards MACT standard might limit specific opera- are distinct from NAAQS because they estab- tions, processes, or wastes that are covered. lish direct national emission limits for speci- Some MACT standards specifically cover waste fied sources, while NAAQS establish air management units, while others do not. If a quality targets that states meet using a variety facility is covered by a MACT standard, it of measures that include emission limits. Table must be permitted under Title V (see below). 1 lists industries for which NSPSs have been EPA has identified approximately 170 indus- established and locations of the NSPSs in the trial categories and subcategories that are or will Code of Federal Regulations. You should be subject to MACT standards. Table 3 lists the check to see if any of the 74 New Source categories for which standards have been final- Performance Standards (NSPSs)3 apply to the ized, proposed, or are expected. The CAA calls facility.4 Any facility subject to a NSPS must for EPA to promulgate the standards in four obtain a Title V permit (see Section D below.). phases. EPA is currently in the fourth and final phase of developing proposed regulations. C. National Emission CAA also requires EPA to assess the risk to Standards for Hazardous public health remaining after the implementa- Air Pollutants tion of NESHAPs and MACT standards. EPA must determine if more stringent standards are Section 112 of the CAA Amendments of necessary to protect public health with an 5 1990 requires EPA to establish national stan- ample margin of safety or to prevent an dards to reduce emissions from a set of certain adverse environmental effect. As a first step in pollutants called hazardous air pollutants this process the CAA requires EPA to submit a (HAPs). Section 112(b) contains a list of 188 Report to Congress on its methods for making HAPs (see Table 2) to be regulated by National the health risks from residual emissions deter- Emission Standards for Hazardous Air mination. The final report, Residual Risk Pollutants (NESHAPs) referred to as Maximum Report to Congress (U.S. EPA, 1997b), was Achievable Control Technology (MACT) stan- signed on March 3, 1999 and is available from dards, that are generally set on an industry-by- EPA’s Web site at
3 40 CFR Part 60. 4 While NSPSs apply to new facilities, EPA also established emission guidelines for existing facilities. 5-4 5 42 U.S.C. § 7412. Protecting Air Quality—Protecting Air Quality
Table 1. Industries for Which NSPSs Have Been Established For electronic versions of the 40 CFR Part 60 subparts referenced below, visit
Facility 40 CFR Part Facility 40 CFR Part 60 subpart 60 subpart
Ammonium Sulfate Manufacture PP Petroleum Dry Cleaners, Rated Capacity 84 Lb JJJ Asphalt Processing & Asphalt Roofing Manufacture UU Petroleum Refineries J Auto/ld Truck Surface Coating Operations MM Petroleum Refinery Wastewater Systems QQQ Basic Oxygen Process Furnaces after 6/11/73 N Phosphate Fertilizer-Wet Process Phosphoric Acid T Beverage Can Surface Coating Industry WW Phosphate Fertilizer-Superphosphoric Acid U Bulk Gasoline Terminals XX Phosphate Fertilizer-Diammonium Phosphate V Calciners and Dryers in Mineral Industry UUU Phosphate Fertilizer-Triple Superphosphate W Coal Preparation Plants Y Phosphate Fertilizers: GTSP Storage Facilities X Commercial & Industrial SW Incinerator Units CCCC Phosphate Rock Plants NN Electric Utility Steam Generating Units after 9/18/78 DA Polymer Manufacturing Industry DDD Equipment Leaks of VOC in Petroleum Refineries GGG Polymeric Coating of Supporting Substrates Fac. VVV Equipment Leaks of VOC in SOCMI VV Portland Cement Plants F Ferroalloy Production Facilities Z Pressure Sensitive Tape & Label Surface Coating RR Flexible Vinyl & Urethane Coating & Printing FFF Primary Aluminum Reduction Plants S Fossil-fuel Fired Steam Generators after 8/17/71 D Primary Copper Smelters P Glass Manufacturing Plants CC Primary Lead Smelters R Grain Elevators DD Primary Zinc Smelters Q Graphic Arts: Publication Rotogravure Printing QQ Rubber Tire Manufacturing Industry BBB Hot Mix Asphalt Facilities I Secondary Brass and Bronze Production Plants M Incinerators E Secondary Lead Smelters L Industrial Surface Coating, Plastic Parts TTT Sewage Treatment Plants O Industrial Surface Coating-Large Appliances SS Small Indust./Comm./Institut. Steam Generating Units DC Industrial-Commercial-Institutional Steam Generation Unit DB Small Municipal Waste Combustion Units AAAA Kraft Pulp Mills BB SOCMI - Air Oxidation Processes III Large Municipal Waste Combustors after 9/20/94 EB SOCMI - Distillation Operations NNN Lead-Acid Battery Manufacturing Plants KK SOCMI Reactors RRR Lime Manufacturing HH SOCMI Wastewater YYY Magnetic Tape Coating Facilities SSS Stationary Gas Turbines GG Medical Waste Incinerators (MWI) after 6/20/96 EC Steel Plants: Elec. Arc Furnaces after 08/17/83 AAA Metal Coil Surface Coating TT Steel Plants: Electric Arc Furnaces AA Metallic Mineral Processing Plants LL Storage Vessels for Petroleum Liquids (6/73–5/78) K Municipal Solid Waste Landfills after 5/30/91 WWW Storage Vessels for Petroleum Liquids (5/78–6/84) KA Municipal Waste Combustors (MWC) EA Sulfuric Acid Plants H New Residential Wood Heaters AAA Surface Coating of Metal Furniture EE Nitric Acid Plants G Synthetic Fiber Production Facilities HHH Nonmetallic Mineral Processing Plants OOO Volatile Storage Vessel (Incl. Petroleum) after 7/23/84 KB Onshore Natural Gas Processing Plants, VOC Leaks KKK Wool Fiberglass Insulation Manufacturing Plants PPP
Onshore Natural Gas Processing: SO2 Emissions LLL
5-5 Protecting Air Quality—Protecting Air Quality
Table 2 HAPs Defined in Section 112 of the CAA Amendments of 1990
CAS# CHEMICAL NAME CAS# CHEMICAL NAME CAS# CHEMICAL NAME
75-07-0 Acetaldehyde 72-55-9 DDE 67-72-1 Hexachloroethane 60-35-5 Acetamide 334-88-3 Diazomethane 822-06-0 Hexamethylene-1,6-diisocyanate 75-05-8 Acetonitrile 132-64-9 Dibenzofurans 680-31-9 Hexamethylphosphor-amide 98-86-2 Acetophenone 96-12-8 1,2-Dibromo-3-chloropropane 110-54-3 Hexane 53-96-3 2-Acetylaminofluorene 84-74-2 Dibutylphthalate 302-01-2 Hydrazine 107-02-8 Acrolein 106-46-7 1,4-Dichlorobenzene(p) 7647-01-0 Hydrochloric acid 79-06-1 Acrylamide 91-94-1 3,3-Dichlorobenzidene 7664-39-3 Hydrogen fluoride (Hydrofluoric acid) 79-10-7 Acrylic acid 111-44-4 Dichloroethyl ether (Bis(2- chloroethyl)ether) 123-31-9 Hydroquinone 107-13-1 Acrylonitrile 542-75-6 1,3-Dichloropropene 78-59-1 Isophorone 107-05-1 Allyl chloride 62-73-7 Dichlorvos 58-89-9 Lindane (all isomers) 92-67-1 4-Aminobiphenyl 111-42-2 Diethanolamine 108-31-6 Maleic anhydride 62-53-3 Aniline 121-69-7 N,N-Diethyl aniline (N,N- 67-56-1 Methanol 90-04-0 o-Anisidine Dimethylaniline) 72-43-5 Methoxychlor 1332-21-4 Asbestos 64-67-5 Diethyl sulfate 74-83-9 Methyl bromide 71-43-2 Benzene (including benzene 119-90-4 3,3-Dimethoxybenzidine (Bromomethane) from gasoline) 60-11-7 Dimethyl aminoazobenzene 74-87-3 Methyl chloride 92-87-5 Benzidine (Chloromethane) 119-93-7 3,3’-Dimethyl benzidine 98-07-7 Benzotrichloride 71-55-6 Methyl chloroform (1,1,1- 79-44-7 Dimethyl carbamoyl chloride 100-44-7 Benzyl chloride Trichloroethane) 68-12-2 Dimethyl formamide 92-52-4 Biphenyl 78-93-3 Methyl ethyl ketone (2- 57-14-7 1,1-Dimethyl hydrazine Butanone) 117-81-7 Bis(2-ethylhexyl) phthalate (DEHP) 131-11-3 Dimethyl phthalate 60-34-4 Methyl hydrazine 542-88-1 Bis(chloromethyl)ether 77-78-1 Dimethyl sulfate 74-88-4 Methyl iodide (Iodomethane) 75-25-2 Bromoform 534-52-1 4,6-Dinitro-o-cresol, and salts 108-10-1 Methyl isobutyl ketone (Hexone) 106-99-0 1,3-Butadiene 51-28-5 2,4-Dinitrophenol 624-83-9 Methyl isocyanate 156-62-7 Calcium cyanamide 121-14-2 2,4-Dinitrotoluene 80-62-6 Methyl methacrylate 133-06-2 Captan 123-91-1 1,4-Dioxane (1,4- Diethyleneoxide) 1634-04-4 Methyl tert butyl ether 63-25-2 Carbaryl 122-66-7 1,2-Diphenylhydrazine 101-14-4 4,4-Methylene bis(2-chloroani- 75-15-0 Carbon disulfide line) 106-89-8 Epichlorohydrin (l-Chloro- 2,3- 56-23-5 Carbon tetrachloride epoxypropane) 75-09-2 Methylene chloride (Dichloromethane) 463-58-1 Carbonyl sulfide 106-88-7 1,2-Epoxybutane 120-80-9 Catechol 101-68-8 Methylene diphenyl diiso- 140-88-5 Ethyl acrylate cyanate (MDI) 133-90-4 Chloramben 100-41-4 Ethyl benzene 101779 4,4’-Methylenedianiline 57-74-9 Chlordane 51-79-6 Ethyl carbamate (Urethane) 91-20-3 Naphthalene 7782-50-5 Chlorine 75-00-3 Ethyl chloride (Chloroethane) 98-95-3 Nitrobenzene 79-11-8 Chloroacetic acid 106-93-4 Ethylene dibromide 92-93-3 4-Nitrobiphenyl 532-27-4 2-Chloroacetophenone (Dibromoethane) 100-02-7 4-Nitrophenol 108-90-7 Chlorobenzene 107-06-2 Ethylene dichloride (1,2- Dichloroethane) 79-46-9 2-Nitropropane 510-15-6 Chlorobenzilate 107-21-1 Ethylene glycol 684-93-5 N-Nitroso-N-methylurea 67-66-3 Chloroform 151-56-4 Ethylene imine (Aziridine) 62-75-9 N-Nitrosodimethylamine 107-30-2 Chloromethyl methyl ether 75-21-8 Ethylene oxide 59-89-2 N-Nitrosomorpholine 126-99-8 Chloroprene 96-45-7 Ethylene thiourea 56-38-2 Parathion 1319-77-3 Cresols/Cresylic acid (isomers and mixture) 75-34-3 Ethylidene dichloride (1,1- 82-68-8 Pentachloronitrobenzene Dichloroethane) (Quintobenzene) 95-48-7 o-Cresol 50-00-0 Formaldehyde 87-86-5 Pentachlorophenol 108-39-4 m-Cresol 76-44-8 Heptachlor 108-95-2 Phenol 106-44-5 p-Cresol 118-74-1 Hexachlorobenzene 106-50-3 p-Phenylenediamine 98-82-8 Cumene 87-68-3 Hexachlorobutadiene 75-44-5 Phosgene 94-75-7 2,4-D, salts and esters 77-47-4 Hexachlorocyclopenta-diene 7803-51-2 Phosphine
5-6 Protecting Air Quality—Protecting Air Quality
Table 2 HAPs Defined in Section 112 of the CAA Amendments of 1990 (cont)
CAS# CHEMICAL NAME CAS# CHEMICAL NAME CAS# CHEMICAL NAME
7723-14-0 Phosphorus 108-88-3 Toluene 108-38-3 m-Xylenes 85-44-9 Phthalic anhydride 95-80-7 2,4-Toluene diamine 106-42-3 p-Xylenes 1336-36-3 Polychlorinated biphenyls 584-84-9 2,4-Toluene diisocyanate [none] Antimony Compounds (Aroclors) 95-53-4 o-Toluidine [none] Arsenic Compounds (inorganic 1120-71-4 1,3-Propane sultone including arsine) 8001-35-2 Toxaphene (chlorinated cam- 57-57-8 beta-Propiolactone phene) [none] Beryllium Compounds 123-38-6 Propionaldehyde 120-82-1 1,2,4-Trichlorobenzene [none] Cadmium Compounds 114-26-1 Propoxur (Baygon) 79-00-5 1,1,2-Trichloroethane [none] Chromium Compounds 78-87-5 Propylene dichloride (1,2- 79-01-6 Trichloroethylene [none] Cobalt Compounds Dichloropropane) 95-95-4 2,4,5-Trichlorophenol [none] Coke Oven Emissions 75-56-9 Propylene oxide 88-06-2 2,4,6-Trichlorophenol [none] Cyanide Compoundsa
75-55-8 1,2-Propylenimine (2-Methyl b aziridine) 121-44-8 Triethylamine [none] Glycol ethers 91-22-5 Quinoline 1582-09-8 Trifluralin [none] Lead Compounds 106-51-4 Quinone (p-Benzoquinone) 540-84-1 2,2,4-Trimethylpentane [none] Manganese Compounds 100-42-5 Styrene 108-05-4 Vinyl acetate [none] Mercury Compounds c 96-09-3 Styrene oxide 593-60-2 Vinyl bromide [none] Fine mineral fibers 1746-01-6 2,3,7,8-Tetrachlorodi-benzo-p- 75-01-4 Vinyl chloride [none] Nickel Compounds dioxin 75-35-4 Vinylidene chloride (1,1- [none] Polycylic Organic Matterd Dichloroethylene) 79-34-5 1,1,2,2-Tetrachloroethane [none] Radionuclides (including e 127-18-4 Tetrachloroethylene 1330-20-7 Xylenes (mixed isomers) radon) (Perchloroethylene) 95-47-6 o-Xylenes [none] Selenium Compounds 7550-45-0 Titanium tetrachloride
NOTE: For all listings above which contain the word “compounds” and for glycol ethers, the following applies: Unless otherwise specified, these listings are defined as including any unique chemical substance that contains the named chemical (i.e., antimony, arsenic, etc.) as part of that chemical’s infrastructure. a X’CN where X = H’ or any other group where a formal dissociation can occur. For example KCN or Ca(CN)2. b On January 12, 1999 (64 FR 1780), EPA proposed to modify the definition of glycol ethers to exclude surfactant alcohol ethoxylates and their derivatives (SAED). On August 2, 2000 (65 FR 47342), EPA published the final action. This action deletes each individual com- pound in a group called the surfactant alcohol ethoxylates and their derivatives (SAED) from the glycol ethers category in the list of haz- ardous air pollutants (HAP) established by section 112(b)(1) of the Clean Air Act (CAA). EPA also made conforming changes in the definition of glycol ethers with respect to the designation of hazardous substances under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). “The following definition of the glycol ethers category of hazardous air pollutants applies instead of the definition set forth in 42 U.S.C. 7412(b)(1), footnote 2: Glycol ethers include mono- and di-ethers of ethylene glycol, diethylene glycol, and triethylene glycol R- (OCH2CH2)n-OR’ Where: n= 1, 2, or 3 R= alkyl C7 or less, or phenyl or alkyl substituted phenyl R’= H, or alkyl C7 or less, or carboxylic acid ester, sulfate, phosphate, nitrate, or sulfonate. c Includes mineral fiber emissions from facilities manufacturing or processing glass, rock, or slag fibers (or other mineral derived fibers) of average diameter 1 micrometer or less. (Currently under review.) d Includes organic compounds with more than one benzene ring, and which have a boiling point greater than or equal to 100°C. (Currently under review.) e A type of atom which spontaneously undergoes radioactive decay.
5-7 Protecting Air Quality—Protecting Air Quality
Table 3 Source Categories With MACT Standards
Source Category Federal Register Citation Source Category Federal Register Citation
Fuel Combustion Marine Vessel Loading Operations 60 FR 48399(F) 9/19/95 Coal- and Oil-fired Electric Utility Steam Organic Liquids Distribution Generating Units 65 FR 79825(N) 12/20/00 (Non-Gasoline) * Combustion Turbines * Surface Coating Processes Engine Test Facilities * Aerospace Industries 60 FR 45956(F) 9/1/15 Industrial Boilers * Auto and Light Duty Truck * Institutional/Commercial Boilers * Flat Wood Paneling 64 FR 63025(N) 11/18/99 Process Heaters * Large Appliance 65 FR 81134(P) 12/22/00 Reciprocating Internal Combustion Engines* Magnetic Tapes 59 FR 64580(F) 12/15/94 Rocket Testing Facilities * Manufacture of Paints, Coatings, and Non-Ferrous Metals Processing Adhesives * Primary Aluminum Production 62 FR 52383(F) 10/7/97 Metal Can * Primary Copper Smelting 63 FR 19582(P) 4/20/98 Metal Coil 65 FR 44616(P) 7/18/00 Primary Lead Smelting 64 FR 30194(F) 6/4/99 Metal Furniture * Primary Magnesium Refining * Miscellaneous Metal Parts and Products * Secondary Aluminum Production 65 FR 15689(F) 3/23/00 Paper and Other Webs 65 FR 55332(P) 9/13/00 Secondary Lead Smelting 60 FR 32587(F) 6/23/95 Plastic Parts and Products * Printing, Coating, and Dyeing of Fabrics * Ferrous Metals Processing Printing/Publishing 61 FR 27132(F) 5/30/96 Coke Ovens: Charging, Top Side, and Shipbuilding and Ship Repair 60 FR 64330(F) 12/16/96 Door Leaks 58 FR 57898(F) 10/27/93 Wood Building Products * Coke Ovens: Pushing, Quenching and Battery Stacks 66 FR 35327(P) 7/3/01 Wood Furniture 60 FR 62930(F) 12/7/95
Ferroalloys Production Waste Treatment and Disposal Silicomanganese and Ferromanganese 64 FR 27450(F) 5/20/00 Hazardous Waste Incineration 64 FR 52828(F) 9/30/99 Integrated Iron and Steel Manufacturing 66 FR 36835(P) 7/13/01 Municipal Solid Waste Landfills 65 FR 66672(P) 11/7/00 Iron Foundries * Off-Site Waste and Recovery Operations 61 FR 34140(F) 7/1/96 Steel Foundries * Publicly Owned Treatment Works 64 FR 57572(F) 10/26/99 Steel Pickling–HCl Process Facilities and Site Remediation * Hydrochloric Acid Regeneration Plants 64 FR 33202(F) 6/22/99 Agricultural Chemicals Production Mineral Products Processing Pesticide Active Ingredient Production 64 FR 33549(F) 6/23/99 Asphalt Processing * Fibers Production Processes Asphalt Roofing Manufacturing * Acrylic Fibers/Modacrylic Fibers 64 FR 34853(F) 6/30/99 Asphalt/Coal Tar Application–Metal Pipes * Spandex Production 65 FR 76408(P) 12/6/00 Clay Products Manufacturing * Lime Manufacturing * Food and Agriculture Processes Mineral Wool Production. 64 FR 29490(F) 6/1/99 Manufacturing of Nutritional Yeast 66 FR 27876(F) 5/21/01 Portland Cement Manufacturing 64 FR 31897(F) 6/14/99 Solvent Extraction for Vegetable Oil Refractories Manufacturing * Production 66 FR 19006(F) 4/12/01 Taconite Iron Ore Processing * Vegetable Oil Production 66 FR 8220(N) 1/30/01 Wool Fiberglass Manufacturing 64 FR 31695(F) 6/14/99 Pharmaceutical Production Processes Petroleum and Natural Gas Production and Refining Pharmaceuticals Production 66 FR 40121(F) 6/1/99 Oil and Natural Gas Production 64 FR 32610(F) 6/17/99 Polymers and Resins Production Natural Gas Transmission and Storage 64 FR 32610(F) 6/17/99 Acetal Resins Production 64 FR 34853(F) 6/30/99 Petroleum Refineries–Catalytic Cracking Units, Catalytic Reforming Units, and Acrylonitrile-Butadiene-Styrene Production 61 FR 48208(F) 9/12/96 Sulfur Recovery Units 63 FR 48890(P) 9/11/98 Alkyd Resins Production * Petroleum Refineries–Other Sources Not Amino Resins Production 65 FR 3275(F) 1/20/00 Distinctly Listed 60 FR 43244(F) 8/18/95 Boat Manufacturing 66 FR 44218(F) 8/22/01 Liquids Distribution Butyl Rubber Production 61 FR 46906(F) 9/5/96 Gasoline Distribution (Stage 1) 59 FR 64303(F) 12/14/94 Cellulose Ethers Production 65 FR 52166(P) 8/28/00 Epichlorohydrin Elastomers Production 61 FR 46906(F) 9/5/96
5-8 Protecting Air Quality—Protecting Air Quality
Table 3 Source Categories With MACT Standards (cont.)
Source Category Federal Register Citation Source Category Federal Register Citation
Epoxy Resins Production 60 FR 12670(F) 3/8/95 Quaternary Ammonium Compounds Ethylene-Propylene Rubber Production 61 FR 46906(F) 9/5/96 Production * Flexible Polyurethane Foam Production 63 FR 53980(F) 10/7/98 Synthetic Organic Chemical Manufacturing 59 FR 19402(F) 4/22/94 Hypalon (tm) Production 61 FR 46906(F) 9/5/96 Maleic Anhydride Copolymers Production * Miscellaneous Processes Methyl Methacrylate-Acrylonitrile Benzyltrimethylammonium Chloride Butadiene-Styrene Production 61 FR 48208(F) 9/12/96 Production * Methyl Methacrylate-Butadiene-Styrene Carbonyl Sulfide Production * Terpolymers Production 61 FR 48208(F) 9/12/96 Chelating Agents Production * Neoprene Production 61 FR 46906(F) 9/5/96 Chlorinated Paraffins Production * Nitrile Butadiene Rubber Production 61 FR 46906(F) 9/5/96 Chromic Acid Anodizing 60 FR 04948(F) 1/25/95 Nitrile Resins Production 61 FR 48208(F) 9/12/96 Combustion Sources at Kraft, Soda, and Non-Nylon Polyamides Production 60 FR 12670(F) 3/8/95 Sulfite Pulp and Paper Mills 66 FR 3180(F) 1/12/01 Phenolic Resins Production 65 FR 3275(F) 1/20/00 Commercial Dry Cleaning Polybutadiene Rubber Production 61 FR 46906(F) 9/5/96 (Perchloroethylene)–Transfer Machines 58 FR 49354(F) 9/22/93 Polycarbonates Production 64 FR 34853(F) 6/30/99 Commercial Sterilization Facilities 59 FR 62585(F) 12/6/94 Polyester Resins Production * Decorative Chromium Electroplating 60 FR 04948(F) 1/25/95 Polyether Polyols Production 64 FR 29420(F) 6/1/99 Ethylidene Norbornene Production * Polyethylene Terephthalate Production 61 FR 48208(F) 9/12/96 Explosives Production * Polymerized Vinylidene Chloride Flexible Polyurethane Foam Fabrication Production * Operations 66 FR 41718(P) 8/8/01 Polymethyl Methacrylate Resins Production* Halogenated Solvent Cleaners 59 FR 61801(F) 12/2/94 Polystyrene Production 61 FR 48208(F) 9/12/96 Hard Chromium Electroplating 60 FR 04948(F) 1/25/95 Polysulfide Rubber Production 61 FR 46906(F) 9/5/96 Hydrazine Production * Polyvinyl Acetate Emulsions Production * Industrial Cleaning (Perchloroethylene)– Dry-to-Dry machines 58 FR 49354(F) 9/22/93 Polyvinyl Alcohol Production * Industrial Dry Cleaning Polyvinyl Butyral Production * (Perchloroethylene)–Transfer Machines 58 FR 49354(F) 9/22/93 Polyvinyl Chloride and Copolymers Industrial Process Cooling Towers 59 FR 46339(F) 9/8/94 Production 65 FR 76958(P) 12/8/00 Leather Finishing Operations 67 FR 9155(F) 2/27/02 Reinforced Plastic Composites Production 66 FR 40324(P) 8/2/01 Miscellaneous Viscose Processes 65 FR 52166(F) 8/28/00 Styrene-Acrylonitrile Production 61 FR 48208(F) 9/12/96 OBPA/1,3-Diisocyanate Production * Styrene-Butadiene Rubber and Latex Production 61 FR 46906(F) 9/5/96 Paint Stripping Operations * Photographic Chemicals Production * Production of Inorganic Chemicals Phthalate Plasticizers Production * Ammonium Sulfate Production– Plywood and Composite Wood Products * Caprolactam By-Product Plants * Pulp and Paper Production 65 FR 80755(F) 12/22/00 Carbon Black Production 65 FR 76408(P) 12/6/00 Rubber Chemicals Manufacturing * Chlorine Production * Rubber Tire Manufacturing 63 FR 62414(P) 10/18/00 Cyanide Chemicals Manufacturing 65 FR 76408(P) 12/6/00 Semiconductor Manufacturing * Fumed Silica Production 64 FR 63025(N) 11/18/99 Symmetrical Tetrachloropyridine Hydrochloric Acid Production * Production * Hydrogen Fluoride Production 64 FR 34853(F) 6/30/99 Tetrahydrobenzaldehyde Manufacture 63 FR 26078(F) 5/21/98 Phosphate Fertilizers Production 64 FR 31358(F) 6/10/99 Wet-Formed Fiberglass Mat Production 65 FR 34277(P) 5/26/00 Phosphoric Acid Manufacturing 64 FR 31358(F) 6/10/99
Production of Organic Chemicals Ethylene Processes 65 FR 76408(P) 12/6/00
This table contains final rules (F), proposed rules (P), and notices (N) promulgated as of February 2002. It does not identify corrections or clarifications to rules. An * denotes sources required by Section 112 of the CAA to have MACT standards by 11/15/00 for which proposed rules are being prepared but have not yet been published.
5-9 Protecting Air Quality—Protecting Air Quality
D. Title V Operating & Association of Local Air Pollution Control Permits Officials (ALAPCO). STAPPA/ALAPCO’s Web site is
6 Federal Operating Permit Regulations were promulgated as 40 CFR Part 71 on July 1, 1996 and amended on February 19, 1999 to cover permits in Indian Country and states without fully approved Title V programs. 7 Under CAA Section 302(g), “air pollutant” is defined as any pollutant agent or combination of agents, including any physical, chemical, biological, or radioactive substance or matter which is emitted into or otherwise enters the ambient air. 8 61 FR 9905; March 12, 1996, codified at 40 CFR Subpart WWW and CC (amended 63 FR 32750, 5-10 June 16, 1998). Protecting Air Quality—Protecting Air Quality
or after May 30, 1991, and to existing landfills that have Summary of Airborne Emission accepted waste on or after Regulations for Hazardous Waste November 8, 1987. In addition to methane, MSWLFs potentially Management Units emit non-methane organic com- Subpart AA regulates organic emissions from pounds (NMOCs) in the gases process vents associated with distillation, fractionation, generated during waste decom- thin film evaporation, solvent extraction, and air or position, as well as in combus- stream stripping operations (40 CFR §§264.1030- tion of the gases in control 1036). Subpart AA only applies to these types of units devices, and from other sources, managing hazardous waste streams with organic con- such as dust from vehicle traffic centration levels of at least 10 parts per million by and emissions from leachate weight (ppmw). Subpart AA regulations require facili- treatment facilities or mainte- ties with covered process vents to either reduce total nance shops. Under the regula- organic emissions from all affected process vents at the tions, any affected MSWLF that facility to below 3 lb/h and 3.1 tons/yr, or reduce emis- emits more than 50 Mg/yr (55 sions from all process vents by 95 percent through the tpy) of NMOCs is required to use of a control device, such as a closed-vent system, install controls. vapor recovery unit, flare, or other combustion unit. Best demonstrated technology Subpart BB sets inspection and maintenance requirements for both new and requirements for equipment, such as valves, pumps, existing municipal landfills pre- compressors, pressure relief devices, sampling connec- scribe installation of a well- tion systems, open-ended valves or lines, flanges, or designed and well-operated gas control devices that contain or contact hazardous collection system and a control wastes with organic concentrations of at least 10 per- device. The collection system cent by weight (40 CFR §§264.1050-1065). Subpart should be designed to allow BB does not establish numeric criteria for reducing expansion for new cells that emissions, it simply establishes monitoring, leak detec- require controls. The control tion, and repair requirements. device (presumed to be a com- Subpart CC establishes controls on tanks, surface bustor) must demonstrate either impoundments, and containers in which hazardous an NMOC reduction of 98 per- waste has been placed ( 40 CFR §§264.1080-1091). It cent by weight in the collected applies only to units containing hazardous waste with gas or an outlet NMOC concen- an average organic concentration greater than 500 tration of no more than 20 parts ppmw. Units managing hazardous waste that has been per million by volume (ppmv). treated to reduce the concentrations of organics by 95 percent are exempt. Non-exempt surface impound- 3. Offsite Waste and ments must have either a rigid cover or, if wastes are Recovery not agitated or heated, a floating membrane cover. Closed vent systems are required to control the emis- Operations NESHAP sions from covered surface impoundments. These con- On July 1, 1996, EPA estab- trol systems must achieve the same 95 percent emission lished standards for offsite waste reductions described above under Subpart AA. and recovery operations
5-11 Protecting Air Quality—Protecting Air Quality
(OSWRO) that emit HAPs.9 To be covered by F. A Decision Guide to OSWRO, a facility must emit or have the Applicable CAA potential to emit at least 10 tpy of any single HAP or at least 25 tpy of any combination of Requirements HAPs. It must receive waste, used oil, or used The following series of questions, summa- solvents from off site that contain one or rized in Figure 1, is designed to help you iden- more HAPs.10 In addition, the facility must tify CAA requirements that might apply to a operate one of the following: a hazardous facility. This will not give you definitive waste treatment, storage, or disposal facility; answers, but can provide a useful starting point RCRA-exempt hazardous wastewater treat- for consultation with federal, state, or local per- ment operation; nonhazardous wastewater mitting authorities to determine which require- treatment facility other than a publicly owned ments apply to a specific facility and whether treatment facility; or a RCRA-exempt haz- such requirements address waste management ardous waste recycling or reprocessing opera- units at the facility. If a facility is clearly not tion, used solvent recovery operation, or used subject to CAA requirements, assessing poten- oil recovery operation. tial risks from VOC emissions at a waste man- agement unit using the IWAIR or a site-specific OSWRO contains MACT standards to risk assessment is recommended. reduce HAP emissions from tanks, surface impoundments, containers, oil-water separa- The following steps provide a walk tors, individual drain systems, other material through of this evaluation process: conveyance systems, process vents, and equipment leaks. For example, OSWRO 1. Determining Emissions From establishes two levels of air emission controls for tanks depending on tank design capacity the Unit and the maximum organic HAP vapor pres- a) Determining VOC’s present in the sure of the offsite material in the tank. For waste (waste characterization). Then process vents, control devices must achieve a assume all the VOC’s are emitted minimum of 95 percent organic HAP emis- from the unit, or sion control. To control HAP emissions from b) Estimating emissions using an emis- equipment leaks, the facility must implement sions model. This also requires waste leak detection and repair work practices and characterization. The CHEMDAT8 equipment modifications for those equipment model is a logical model for these components containing or contacting offsite types of waste units. You can use the waste having a total organic HAP concentra- EPA version on the Internet or the tion greater than 10 percent by weight (see one contained in the IWAIR model- 40 CFR 63.683(d) cross ref. to 40 CFR ing tool for the Guide, or 63.680 (c) (3)). c) Measuring emissions from the unit. While this is the most resource inten- sive alternative, measured data will provide the most accurate information.
9 61 FR 34139; July 1, 1996, as amended, 64 FR 38970 (July 20, 1999) and 66 FR 1266 (January 8, 2001). 10 OSWRO identified approximately 100 HAPs to be covered. This HAP list is a subset of the CAA 5-12 Section 112 list. Protecting Air Quality—Protecting Air Quality
Figure 1. Evaluating VOC Emission Risk
Characterize waste for potential air emissions
Is the unit part of an industrial facility which is subject to a CAA Title V operating permit by virtue of being: Facility is subject a. considered a major source; or to an air permit. b. subject to NSPSs; or YES Consult with c. considered a major source of HAPs and subject to state/local NESHAP or MACT standards; or permitting d. subject to the acid rain program; or authority e. a unit subject to the OSWRO NESHAP?
NO
Does No further the waste evaluation is NO contain any of the 95 indicated listed contaminants in IWAIR?
YES Conduct a risk evaluation using either:
a. Industrial Waste Air b. Site-specific risk Model (IWAIR) assessment
You should conduct a more site- Is specific risk assessment the total NO risk for the unit OR acceptable? You should reduce risk to accept- able levels using treatment, con- YES trols, or waste minimization
You should operate the unit in accordance with the recommendations of this guidance.
5-13 Protecting Air Quality—Protecting Air Quality
2. Is the Waste Management Unit Part of an Industrial Stationary source is defined as any building, structure, facility, or installation Facility That Is Subject to a that emits or may emit any regulated air CAA Title V Operating pollutant or any hazardous air pollutant Permit? listed under Section 112 (b) of the Act. A facility is subject to a Title V operating An air pollutant is defined as any air pol- permit if it is considered a major source of air lution agent or combination of agents, pollutants, or is subject to a NSPS, NESHAP, including a physical, chemical, biological, 11 or Title IV acid rain provision. As part of the radioactive substance or matter which is permitting process, the facility should develop emitted into or otherwise enters the ambi- an emissions inventory. Some states have ent air. additional permitting requirements. If a facili- ty is subject to a Title V operating permit, all airborne emission requirements that apply to a. Is the facility considered a major an industrial facility, including emission limi- source? tations as well as operational, monitoring, and If the facility meets any of the following reporting requirements, will be incorporated three definitions, it is considered a major in its operating permit. You should consult source (under 40 CFR § 70.2) and subject to with appropriate federal, state, and local air Title V operating permit requirements. program staff to determine whether your waste management unit is subject to air emis- i. Any stationary source or group of sion limits and controls.12 stationary sources that emits or has the potential to emit at least 100 tpy If you answer yes to any of the questions of any air pollutant. in items a. through e. below, the facility is subject to a Title V operating permit. Consult ii. Any stationary source or group of with the appropriate federal, state, and/or stationary sources that emits or has local permitting authority. the potential to emit at least 10 tpy of any single HAP or at least 25 tpy Whether or not emissions from waste of any combination of HAPs. management unit(s) will be specifically addressed through the permit process iii. A stationary source or group of sta- depends on a number of factors, including tionary sources subject to the nonat- the type of facility and CAA requirements tainment area provisions of CAA Title and state permitting resources and priorities. I that emits, or has the potential to It is prudent, when there are no applicable emit, above the threshold values for air permit requirements, to assess whether its nonattainment area category. The there might be risks associated with waste nonattainment area category and the management units and to address these source’s emission levels for VOCs and potential risks. NOx, particulate matter (PM-10), and carbon monoxide (CO) determine If you answer no to all the questions whether the stationary source meets below, continue to Step 3. the definition of a “major source.” For nonattainment areas, stationary sources are considered “major
11 EPA can designate additional source categories subject to Title V operating permit requirements. 12 Implementation of air emission controls can generate new residual waste. Ensure that these wastes are 5-14 managed appropriately, in compliance with state requirements and consistent with the Guide. Protecting Air Quality—Protecting Air Quality
sources” if they emit or have the c. Is the facility a major source of potential to emit at least the levels HAPs as defined by Section 112 of found in Table 4 below. CAA and subject to a NESHAP or If yes, the facility is subject to a Title V MACT standard? operating permit. Consult with the appropri- Under Title V of CAA, an operating permit ate federal, state, and/or local permitting is required for all facilities subject to a MACT authority. standard. NESHAPs or MACT standards are national standards to reduce HAP emissions. If no, continue to determine whether the Each MACT standard specifies particular facility is subject to a Title V operating permit. operations, processes, and/or wastes that are covered. EPA has identified approximately b. Is the facility subject to NSPSs? 170 source categories and subcategories that Any stationary source subject to a standard are or will be subject to MACT standards. of performance under 40 CFR Part 60 is sub- (Table 3 above lists the source categories for ject to NSPS. (A list of NSPSs can be found in which EPA is required to promulgate MACT Table 1 above.) standards.) MACT standards have been or will be promulgated for all major source cate- If yes, the facility is subject to a Title V gories of HAPs and for certain area sources. operating permit. Consult with the appropri- ate federal, state, and/or local permitting If yes, the facility should be permitted authority. under CAA Title V. Consult with the appro- priate federal, state, and/or local permitting If no, continue to determine if the facility authority. is subject to a Title V operating permit. If no, continue to determine if the facility must obtain a Title V operating permit.
d. Is the facility subject to the acid rain program under Title IV of CAA? If a facility, such as a Table 4. fossil-fuel fired power Major Source Determination in Nonattainment Areas plant, is subject to emission reduction Nonattainment VOCs or NOx PM-10 CO requirements or limita- Area Category13 tions under the acid rain program, it must Marginal or 100 tpy 100 tpy 100 tpy obtain a Title V operat- Moderate ing permit (40 CFR § Serious 50 tpy 70 tpy 50 tpy 72.6). The acid rain program focuses on the Severe 25 tpy — — reduction of annual sul- Extreme 10 tpy — — fur dioxide and nitro- gen oxides emissions.
13 The nonattainment categories are based upon the severity of the area’s pollution problems. The four cate-
gories for VOCs and NOx range from Moderate to Extreme. Moderate areas are the closest to meeting the attainment standard, and require the least amount of action. Nonattainment areas with more serious air quality problems must implement various control measures. The worse the air quality, the more controls areas will have to implement. PM-10 and CO have only two categories, Moderate and Serious. 5-15 Protecting Air Quality—Protecting Air Quality
e. Is the waste management unit A major source under Title III is subject to the OSWRO NESHAP? defined as any stationary source or This is just an example of the types group of stationary sources that emits or of questions you will need to has the potential to emit at least 10 tpy answer to determine whether a of any single hazardous air pollutant NESHAP or MACT standard covers (HAP) or at least 25 tpy of any combina- your facility. tion of HAPs. To be covered by the OSWRO standards, An area source is any stationary your facility must meet all these conditions: source which is not a major source but i. Be identified as a major source of which might be subject to controls. Area HAP emissions. sources represent a collection of facilities and emission points for a specific geo- ii. Receive waste, used oil, or used sol- graphic area. Most area sources are vents (subject to certain exclusions, small, but the collective volume of large 40 CFR 63.680 (b) (2)) from off site numbers of facilities can be a concern in that contain one or more HAPs.14 densely developed areas, such as urban iii. Operate one of the following six neighborhoods and industrial areas. types of waste management or recov- Examples of areas sources subject to ery operations (see 40 CFR 63.680 MACT standards include chromic acid (a) (2)): anodizing, commercial sterilization facil- ities, decorative chromium electroplat- • Hazardous waste treatment, storage, ing, hard chromium electroplating, or disposal facility. secondary lead smelting, and halogenat- • RCRA-exempt hazardous wastewater ed solvent cleaners. treatment operation. HAPs are any of the 188 pollutants • Nonhazardous wastewater treatment listed in Section 112(b) of CAA. (Table 2 facility other than a publicly owned above identifies the 188 HAPs.) treatment facility. • RCRA-exempt hazardous waste recy- If yes, the facility must obtain a Title V cling or reprocessing operation. permit. Consult with the appropriate federal, • Used solvent recovery operations. state, and/or local permitting authority. • Used oil recovery operations. When you consult with the appropriate permitting authority, it is important to clarify If yes, the unit should be covered by the whether waste management units at the facil- OSWRO standards and Title V permitting. ity are addressed by the requirements. If Consult with the appropriate federal, state, waste management units will not be and/or local permitting authority. addressed through the permit process, you If no, it is highly recommended that you should evaluate VOC emission risks. conduct an air risk evaluation as set out in If no, continue to determine if the facility step 3. must obtain a Title V operating permit.
14 OSWRO identified approximately 100 HAPs to be covered. This HAP list is a subset of the CAA Section 112 list. 5-16 Protecting Air Quality—Protecting Air Quality
3. Conducting a Risk Evaluation human health can be compromised. The con- Using One of the Following centration of chemicals in a localized area and Options: the resulting air pollution that can occur in the atmosphere is dependent upon the quantity a. Using IWAIR included with the and the rate of the emissions from a source Guide if your unit contains any of the and the ability of the atmosphere to disperse 95 contaminants that are covered in the chemicals. Both meteorological and geo- the model. graphic conditions in a local area will influ- b. Initiating a site-specific risk assess- ence the emission rate and subsequent ment for individual units. Total all dispersion of a chemical. For example, the target constituents from all applicable meteorologic stability of the atmosphere, a fac- units and consider emissions from tor dependent on air temperature, influences other sources at the facility as well. whether the emission stream will rise and mix with a larger volume of air (resulting in the dilution of pollutants) or if the emissions stream will remain close to the ground. Figure II. Assessing Risk 2 is a conceptual diagram of a waste site illus- Air acts as a medium for the transport of trating potential paths of human exposure airborne contamination and, therefore, con- through air. stitutes an exposure pathway of potential concern. Models that can predict the fate and transport of chemical emissions in the atmos- A. Assessing Risks Associated phere can provide an important tool for eval- with Inhalation of uating and protecting air quality. The Ambient Air Industrial Waste Air Model (IWAIR) included In any type of risk assessment, there are in the Guide was developed to assist facility basic steps that are necessary for gathering managers, regulatory agency staff, and the and evaluating data. An overview of some of public in evaluating inhalation risks from these steps is presented in this section to waste management unit emissions. Although assist you in understanding conceptually the IWAIR is simple to use, it is still essential to information discussed in the IWAIR section understand the basic concepts of atmospheric (Section B). The components of a risk assess- modeling to be able to interpret the results ment that are discussed in this section are: and understand the nature of any uncertain- identification of chemicals of concern, source ties. The purpose of this section is to provide characterization, exposure assessment, and general information on the atmosphere, risk characterization. Each of these steps is chemical transport in the atmosphere, and described below as it applies specifically to the risks associated with inhalation of chemi- risk resulting from the inhalation of organic cals so you can understand important factors chemicals emitted from waste management to consider when performing a risk assess- units to the ambient air. ment for the air pathway.
From a risk perspective, because humans Identification of Chemicals of Concern are continuously exposed to air, the presence A preliminary step in any risk assessment of chemicals in air is important to consider in is the identification of chemicals of concern. any type of assessment. If chemicals build up These are the chemicals present that are to high concentrations in a localized area, anticipated to have potential health effects as
5-17 Protecting Air Quality—Protecting Air Quality
Figure 2. Conceptual Site Diagram
a result of their concentrations or toxicity WMU is also needed to estimate chemical factors. An assessment is performed for a volatilization. Depending on its chemical given source, to evaluate chemical concentra- characteristics, a chemical can bind with the tions and toxicity of different chemicals. other constituents in a waste, decreasing its Based on these factors along with potential emissions to the ambient air. Source charac- mechanisms of transport and exposure path- terization involves defining each of these key ways, the decision is made to include or parameters for the WMU being modeled. The exclude chemicals in the risk assessment. accuracy of projections concerning volatiliza- tion of chemicals from WMUs into ambient Source Characterization air is improved if more site-specific informa- tion is used in characterizing the source. In this step, the critical aspects of the source (e.g., type of WMU, size, chemical concentrations, location) are necessary to Exposure Assessment obtain. When modeling an area source, such The goal of an exposure assessment is to as those included in the Guide, the amount estimate the amount of a chemical that is of a given chemical that volatilizes and dis- available and is taken in by an individual, perses from a source is critically dependent typically referred to as a receptor. An expo- on the total surface area exposed. The source sure assessment is performed in two steps: 1) characterization should include information the first step uses fate and transport model- on the surface area and elevation of the unit. ing to determine the chemical concentration The volatilization is also dependent on other in air at a specified receptor location and, 2) specific attributes related to the waste man- the second step estimates the amount of the agement practices. Waste management prac- chemical the receptor will intake by identify- tices of importance include application ing life-style activity patterns. The first step, frequency in land application units and the the fate and transport modeling, uses a com- degree of aeration that occurs in a surface bination of an emission and dispersion model impoundment. Knowledge of the overall con- to estimate the amount of chemical that indi- tent of the waste being deposited in the viduals residing or working within the vicini-
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Figure 3. Emissions from a WMU
ty of the source are exposed to through consequently, little or no movement inhalation of ambient air. When a chemical and mixing of contaminants. In such volatilizes from a WMU into the ambient air, a stable air environment, chemicals it is subjected to a number of forces that become “trapped” and unable to result in its diffusion and transport away from move. Conversely, in an unstable the point of release. environment there is significant mix- ing and therefore greater dispersion In modeling the movement of the volatile and dilution of the plume.15 chemical away from the WMU, it is often assumed that the chemical behaves as a • Prevailing wind patterns and their plume (i.e., the chemical is continuously interaction with land features: The emitted into the environment) whose move- nature of the wind patterns immedi- ment is modeled to produce estimated air ately surrounding the WMU can sig- concentrations at points of interest. This nificantly impact the local air process is illustrated in Figure 3. concentrations of airborne chemicals. Prevailing wind patterns combine The pattern of diffusion and movement of with topographic features such as chemicals that volatilize from WMUs depends hills and buildings to affect the on a number of interrelated factors. The ulti- movement of the plume. Upon mate concentration and fate of emissions to release, the initial direction that emis- the air are most significantly impacted by sions will travel is the direction of the three meteorologic conditions: atmospheric wind. The strength of the wind will stability, wind speed, and wind direction. determine how dilute the concentra- These meteorologic factors interact to deter- tion of the pollutant will be in that mine the ultimate concentration of a pollu- direction. For example, if a strong tant in a localized area. wind is present at the time the pollu- • Atmospheric stability: The stability tants are released, it is likely the pol- of the atmosphere is influenced by lutants will rapidly leave the source the vertical temperature structure of and become dispersed quickly into a the air above the emission source. In large volume of air. a stable environment, there is little or no movement of air parcels, and,
15 An example of an unstable air environment is one in which the sun shining on the earth’s surface has resulted in warmer air at the earth’s surface. This warmer air will tend to rise, displacing any cooler air that is on top of it. As these air parcels essentially switch places, significant mixing occurs. 5-19 Protecting Air Quality—Protecting Air Quality
Figure 4. Forces That Affect Contaminant Plumes.
In addition to these factors affecting the distances of transport being considered are diffusion and transport of a plume away from relatively short, the removal mechanisms its point of release, the concentration of spe- shown in the figure are likely to have a rela- cific chemicals in a plume can also be affect- tively minor effect on plume concentration ed by depletion. As volatile chemicals are (both wet and dry deposition have significant- transported away from the WMU, they can ly greater effects on airborne particulates). be removed from the ambient air through a Once the constituent’s ambient outdoor number of depletion mechanisms including concentration is determined, the receptor’s wet deposition (the removal of chemicals due extent of contact with the pollutant must be to precipitation) and dry deposition (the characterized. This step involves determining removal of chemicals due to the forces of the location and activity patterns relevant to gravity and impacts of the plume on features the receptor being considered. In IWAIR, the such as vegetation). Chemicals can also be receptors are defined as residents and work- transformed chemically as they come in con- ers located at fixed distances from the WMU, tact with the sun’s rays (i.e., photochemical and the only route of exposure considered degradation). Figure 4 illustrates the forces for these receptors is the inhalation of acting to transport and deplete the contami- volatiles. Typical activity patterns and body nant plume. physiology of workers and residents are used Because the chemicals being considered in to determine the intake of the constituent. IWAIR are volatiles and semi-volatiles and the Intake estimates quantify the extent to which
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the individual is exposed to the contaminant 1. Emissions Model and are a function of the breathing rate, The emissions model uses waste character- exposure concentration, exposure duration, ization, WMU, and facility information to exposure frequency, exposure averaging time estimate emissions for 95 constituents that (for carcinogens), and body weight. are identified in Table 5. The emission model Estimated exposures are presented in terms of selected for incorporation into IWAIR is EPA’s the mass of the chemical per kilogram of CHEMDAT8 model. The entire CHEMDAT8 receptor body weight per day. model is run as the emission component of the IWAIR model. CHEMDAT8 has under- Risk Characterization gone extensive review by both EPA and The concentrations that an individual takes industry representatives and is publicly avail- into his or her body that were determined dur- able from EPA’s Web page,
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Table 5. Constituents Included in IWAIR Chemical Compound Name Chemical Compound Name Abstracts Abstracts (CAS) (CAS) Number Number
75-07-0 Acetaldehyde 77-47-4 Hexachlorocyclopentadine 67-64-1 Acetone 67-72-1 Hexachloroethane 75-05-8 Acetonitrile 78-59-1 Isophorone 107-02-8 Acrolein 7439-97-6 Mercury 79-06-1 Acrylamide 67-56-1 Methanol 79-10-7 Acrylic acid 110-49-6 Methoxyethanol acetate, 2- 107-13-1 Acrylonitrile 109-86-4 Methoxyethanol, 2- 107-05-1 Allyl chloide 74-83-9 Methyl bromide 62-53-3 Aniline 74-87-3 Methyl chloride 71-43-2 Benzene 78-93-3 Methyl ethyl ketone 92-87-5 Benzidine 108-10-1 Methyl isobutyl ketone 50-32-8 Benzo(a)pyrene 80-62-6 Methyl methacrylate 75-27-4 Bromodichloromethane 1634-04-4 Methyl tert-butyl ether 106-99-0 Butadine, 1,3- 56-49-5 Methylcholanthrene, 3- 75-15-0 Carbon disulfide 75-09-2 Methylene chloride 56-23-5 Carbon tetrachloride 68-12-2 N-N-Dimethyl formamide 108-90-7 Chlorobenzene 91-20-3 Naphthalene 124-48-1 Chlorodibromomethane 110-54-3 n-Hexane 67-66-3 Chloroform 98-95-3 Nitrobenzene 95-57-8 Chloropphenol, 2- 79-46-9 Nitropropane, 2- 126-99-8 Chloroprene 55-18-5 NiNitrosodiethylamine 1006-10-15 cis-1,3-Dichloropropylene 924-16-3 N-Nitrosodi-n-butylamine 1319-77-3 Cresols (total) 930-55-2 N-Nitrosoyrrolidine 98-82-8 Cumene 95-50-1 o-Dichlorobenzene 108-93-0 Cyclohexanol 95-53-4 o-Toluidine 96-12-8 Dibromo-3-chloropropane, 1,2- 106-46-7 p-Dichlorobenzene 75-71-8 Dichlorodifluoromethane 108-95-2 Phenol 107-06-2 Dichloroethane, 1,2- 85-44-9 Phthalic anhydride 75-35-4 Dichloroethylene, 1,1- 75-56-9 Propylene oxide 78-87-5 Dichloropropane, 1,2- 110-86-1 Pyridine 57-97-6 Dimethylbenz[a]anthracene , 7,12- 100-42-5 Stryene 95-65-8 Dimethylphenol, 3,4- 1746-01-6 TCDD-2,3,7,8- 121-14-2 Dinitrotoluene, 2,4- 630-20-6 Tetrachloroethane, 1,1,1,2- 123-91-1 Dioxane, 1,4- 79-34-5 Tetrachloroethane, 1,1,2,2- 122-66-7 Diphenylhydrazine, 1,2- 127-18-4 Tetrachloroethylene 106-89-8 Epichlorohydrin 108-88-3 Toluene 106-88-7 Epoxybutane, 1,2- 10061-02-6 trans-1,3-Dichloropropylene 11-11-59 Ethoxyethanol acetate, 2- 75-25-2 Tribromomethane 110-80-5 Ethoxyethanol, 2- 76-13-1 Freon 113 (Trichloro-1,2,2- 1,1,2- trifluoroethane) 100-41-4 Ethylbenzene 120-82-1 Trichlorobenzene, 1,2,4- 106-93-4 Ethylene dibromide 71-55-6 Trichloroethane, 1,1,1- 107-21-1 Ethylene glycol 79-00-5 Trichloroethane, 1,1,2- 75-21-8 Ethylene oxide 79-01-6 Trichloroethylene 50-00-0 Formaldehyde 75-69-4 Trichlorofluoromethane 98-01-1 Furfural 121-44-8 Triethylamine 87-68-3 Hexachloro-1,3-butadiene 108-05-4 Vinyl acetate 118-74-1 Hexchlorobenzene 75-01-4 Vinyl chloride 1330-20-7 Xylenes
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developed by ISCST3 for many separate sce- centrations managed in the unit or the waste narios designed to cover a broad range of concentration (Cw) in the unit that should unit characteristics, including: not be exceeded to protect human health. In calculating either estimate, the model applies • 60 meteorological stations, chosen to default values for exposure factors, including represent the 9 general climate inhalation rate, body weight, exposure dura- regions of the continental U.S. tion, and exposure frequency. These default • 4 unit types. values are based on data presented in the • 17 surface area sizes for landfills, Exposure Factors Handbook (U.S. EPA, 1995a) land application units and surface and represent average exposure conditions. impoundments, and 11 surface area IWAIR maintains standard health benchmarks sizes and 7 heights for waste piles. (CSFs for carcinogens and RfCs for noncar- cinogens) for 95 constituents. These health • 6 receptor distances from the unit benchmarks are from the Integrated Risk (25, 50, 75, 150, 500, 1000 meters). Information System (IRIS) and the Health • 16 directions in relation to the edge Effects Assessment Summary Tables (HEAST). of the unit. IWAIR uses these data to perform either a for- ward calculation to obtain risk estimates or a The default dispersion factors were derived backward calculation to obtain protective by modeling many scenarios with various waste concentration estimates. combinations of parameters, then choosing as the default the maximum dispersion factor for each waste management unit/surface 4. Estimation Process area/meteorological station/receptor distance Figure 5 provides an overview of the step- combination. wise approach the user follows to calculate Based on the size and location of a unit, as risk or protective waste concentration esti- specified by a user, IWAIR selects an appro- mates with IWAIR. The seven steps of the priate dispersion factor from the default dis- estimation process are shown down the right persion factors in the model. If the user side of the figure, and the user specified specifies a unit surface area that falls between inputs are listed to the left of each step. As two of the sizes already modeled, a linear the user provides input data, the program interpolation method will estimate dispersion proceeds to the next step. Each step of the in relation to the two closest unit sizes. estimation process is discussed below. Alternatively, a user can enter a site-specif- a. Select Calculation Method. The user ic dispersion factor developed by conducting selects one of two calculation meth- independent modeling with ISCST3 or with a ods. Use the forward calculation to different model and proceed to the next step, arrive at chemical-specific and cumu- the risk calculation. lative risk estimates if the user knows the concentrations of constituents in the waste. Use the backward calcula- 3. Risk Model tion method to estimate protective The third component to the model com- waste concentrations not to be bines the constituent’s air concentration with exceeded in new units. The screen receptor exposure factors and toxicity bench- where this step is performed is shown marks to calculate either the risk from con- in Figure 6.
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Figure 5. IWAIR Approach for Developing Risk or Protective Waste Concentrations: This figure shows the steps in the tool to assist the user in developing risk or protective waste concentration estimates.
Select Calculation Method User Specifies: Risk calculation Calculation option or Allowable waste concentration calculation
Identify WMU User Specifies: Land application unit WMU type Waste pile WMU information (e.g., Surface impoundment, aerated operating parameters) and quiescent Landfill
User Specifies: Define the Waste Managed Constituents (choose up to 6) Add/modify properties data, as Concentration for risk calculation desired
Determine Emission Rates User Specifies: Emission rate option CHEMDAT8 Facility location for meteorological input or User-specified emission rates
Determine Dispersion Factors User Specifies: Interpolated from ISCST3 default Dispersion factor option dispersion factors Receptor information (e.g., distance and type) or User-specified dispersion factors
Calculate Ambient Air Concentrations Calculates ambient air concentrations for each receptor based on emission and dispersion data
Calculate Results User Specifies: Risk Calculation Risk level for allowable concentration 1. Chemical-specific carcinogenic risk calculation 2. Chemical-specific noncarcinogenic risk 3. Total cancer risk or Allowable Waste Concentration
(Cwaste) Calculation Cwaste for wastewaters (mg/L) Cwaste for solid wastes (mg/kg)
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Figure 6. Screen 1, Method, Met Station, WMU.
A. Select B. Select calculation WMU type method
C. Select met station search option
Enter zip code and search for E. Select met station emission and dispersion option Enter latitude and longitude and search for met station
D. View selected met station
Figure 7. Screen 2, Wastes Managed.
B. Select sorting option for identifying D. View chemicals selected chemicals A. Add/ modify chemicals E. Enter waste concentrations C. Identify chemicals in waste
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b. Identify Waste Management Unit. DAT8 rates, a user can provide their Four WMU types can be modeled: own site-specific emission rates surface impoundments (SIs), land developed with a different model or application units (LAUs), active land- based on emission measurements. fills (LFs), and wastepiles (WPs). For e. Determine Dispersion. The user can each WMU, you will be asked to provide site-specific unitized disper- specify some design and operating sion factors (µg/m3 per µg/m2-s) or parameters such as surface area, have the model develop dispersion depth for surface impoundments and factors based on user-specified WMU landfills, height for wastepiles, and information and the IWAIR default tilling depth for LAUs. The amount dispersion data. Because a number of of unit specific data needed as input assumptions were made in develop- will vary depending on whether the ing the IWAIR default dispersion user elects to develop CHEMDAT8 data you can elect to provide site- emission rates. IWAIR provides specific dispersion factors which can default values for several of the oper- be developed by conducting inde- ating parameters that the user can pendent modeling with ISCST3 or choose, if appropriate. with a different model. Whether you c. Define Waste Managed. Specify use IWAIR or provide dispersion fac- constituents and concentrations in tors from another source, specify dis- the waste if you choose a forward tance to the receptor from the edge calculation to arrive at chemical spe- of the WMU and the receptor type cific risk estimates. If you choose a (i.e., resident or worker). These data backward calculation to estimate pro- are used to define points of exposure. tective waste concentrations, then f. Calculate Ambient Air specify constituents of concern. The Concentration. For each receptor, screen where this step is performed the model combines emission rates is shown in Figure 7. and dispersion data to estimate ambi- d. Determine Emission Rates. You can ent air concentrations for all waste elect to develop CHEMDAT8 emis- constituents of concern. sion rates or provide your own site- g. Calculate Results. The model calcu- specific emission rates for use in lates results by combining estimated calculations. IWAIR will also ask for ambient air concentrations at a speci- facility location information to link fied exposure point with receptor the facility’s location to one of the 60 exposure factors and toxicity bench- IWAIR meteorological stations. Data marks. Presentation of results from the meteorological stations pro- depends on whether you chose a for- vide wind speed and temperature ward or backward calculation: information needed to develop emis- sion estimates. In some circum- Forward calculation: Results are estimates of stances the user might already have cancer and non-cancer risks from inhalation emissions information from monitor- exposure to volatilized constituents in the ing or a previous modeling exercise. waste. If risks are too high, options are: 1) As an alternative to using the CHEM- implement unit controls to reduce volatile air emissions, 2) implement pollution preven-
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tion or treatment to reduce volatile organic associated with waste management compound (VOC) concentrations before the units. waste enters the unit, or 3) conduct a full • The model is easy-to-use and site-specific risk assessment to more precisely requires a minimal amount of data characterize risks from the unit. and expertise. Backward calculation: Results are estimates of • The model is flexible and provides constituent concentrations in waste that can be features to meet a variety of user protectively managed in the unit so as not to needs. exceed a defined risk level (e.g., 1 x 10-6 or hazard quotient of 1) for specified receptors. A • A user can enter emission and/or dis- target risk level for your site can be calculated persion factors derived from another based on a number of site-specific factors model (perhaps to avoid some of the including, proximity to potential receptors, limitations below) and still use waste characteristics, and waste management IWAIR to conduct a risk evaluation. practices. This information should be used to • The model can run a forward calcula- determine preferred characteristics for wastes tion from the unit or a backward cal- entering the unit. There are several options if it culation from the receptor point. appears that planned waste concentrations might be too high: 1) implement pollution • A user can modify health bench- prevention or treatment to reduce VOC con- marks (HBNs) and target risk level, centrations in the waste, 2) modify waste man- when appropriate and in consultation agement practices to better control VOCs (for with other stakeholders. example, use closed tanks rather than surface impoundments), or 3) conduct a full site-spe- Limitations cific risk assessment to more precisely charac- • Release Mechanisms and Exposure terize risks from the unit. Routes. The model considers expo- sures from breathing ambient air. It 5. Capabilities and Limitations of does not address potential risks the Model attributable to particulate releases nor does it address risks associated with In many cases, IWAIR will provide a rea- indirect routes of exposure (i.e, non- sonable alternative to conducting a full-scale inhalation routes of exposure). site-specific risk analysis to determine if a Additionally, in the absence of user- WMU poses unacceptable risk to human specified emission rates, volatile health. Because the model can accommodate emission estimates are developed only a limited amount of site-specific infor- with CHEMDAT8 based on unit- and mation, however, it is important to under- waste-specific data. The CHEMDAT8 stand its capabilities and recognize situations model was developed to address only when it might not be appropriate to use. volatile emissions from waste man- agement units. Competing mecha- Capabilities nisms that can generate additional • The model provides a reasonable rep- exposures to the constituents in the resentation of VOC inhalation risks waste such as runoff, erosion, and
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particulate emissions are not EPA, 1993) can assist users in deter- accounted for in the model. mining whether a facility is in an area of simple, intermediate, or com- • Waste Management Practices. The plex terrain. user specifies a number of unit-spe- cific parameters that significantly • Receptor Type and Location. impact the inhalation pathway (e.g., IWAIR has predetermined adult size, type, and location of WMU, worker and resident receptors, six which is important in identifying receptor locations, and predeter- meteorological conditions). However, mined exposure factors. The program the model cannot accommodate cannot be used to characterize risk information concerning control tech- for other possible exposure scenarios. nologies such as covers that might For example, the model can not eval- influence the degree of volatilization uate receptors that are closer to the (e.g., whether a wastepile is covered unit than 25 meters or those that are immediately after application of new further from the unit than 1,000 waste). In this case, it might be advis- meters. If the population of concern able to generate site-specific emission for your facility is located beyond the rates and enter those into IWAIR. limits used in IWAIR, consider using a model that is more appropriate for • Terrain and Meteorological the risks posed from your facility. Conditions. If a facility is located in an area of intermediate or complex terrain or with unusual meteorologi- C. Site-specific Risk cal conditions, it might be advisable to either 1) generate site-specific air Analysis dispersion modeling results for the IWAIR is not the only model that can be site and enter those results into the applicable to a site. In some cases, a site-spe- program, or 2) use a site-specific risk cific risk assessment might be more advanta- modeling approach different from geous. A site-specific approach can be IWAIR. The model will inform the tailored to accommodate the individual needs user which of the 60 meteorological of a particular WMU. Such an approach stations is used for a facility. If the would rely on site-specific data and on the local meteorological conditions are application of existing fate and transport very different from the site chosen by models. Table 6 summarizes available emis- the model, it would be more accurate sions and/or dispersion models that can be to choose a different model. applied in a site-specific analysis. Practical considerations include the source of the The terrain type surrounding a facili- model(s), the ease in obtaining the model(s), ty can impact air dispersion model- and the nature of the model(s) (i.e., is it pro- ing results and ultimately risk prietary), and the availability of site-specific estimates. In performing air disper- data required for use of the model. Finally, sion modeling to develop the IWAIR the model selection process should determine default dispersion factors, the model whether or not the model has been verified ISCST3 assumes the area around the against analytical solutions, other models, WMU is of simple or flat terrain. The and/or field data. Proper models can be Guideline on Air Quality Models (U.S. selected based on the physical and chemical
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Table 6 Source Characterization Models Model Name Summary
AP-42 The EPA’s Compilation of Air Pollutant Emission Factors, Volume I: Stationary Point and Area Sources (AP-42), is a compilation of emission factors for a wide variety of air emission sources, including fugitive dust sources (Section 13.2). Emission factors are included for paved roads, unpaved roads, heavy construc- tion operations, aggregate handling and storage piles, industrial wind erosion (this is the 1988 Cowherd model), and abrasive blasting. These are simple emis- sion factors or equations that relate emissions to inputs (e.g., silt loading or con- tent, moisture content, mean vehicle weight, area, activity level, and wind speed). Guidance is provided for most inputs, but the more site-specific the input data used, the more accurate the results.
The entire AP-42 documentation is available at
CHEMDAT8 The CHEMDAT8 model allows the user to conduct source and chemical specific emissions modeling. CHEMDAT8 is a Lotus 1-2-3 spreadsheet that includes ana- lytical models to estimate volatile organic compound emissions from treatment, storage, and disposal facility processes under user-specified input parameters. CHEMDAT8 calculates the fractions of waste constituents of interest that are dis- tributed among pathways (partition fractions) applicable to the facility under analysis.
Emissions modeling using CHEMDAT8 is conducted using data entered by the user for unit-specific parameters. The user can choose to override the default data and enter their estimates for these unit-specific parameters. Thus, modeling emissions using CHEMDAT8 can be done with a limited amount of site-specific information.
Available at
Cowherd The Cowherd model, Rapid Assessment of Exposure to Particulate Emissions from Surface Contamination Sites, allows the user to calculate particulate emis- sion rates for wind erosion using data on wind speed and various parameters that describe the surface being eroded. The latest (1988) version of this model is event-based (i.e., erosion is modeled as occurring in response to specific events in which the wind speed exceeds levels needed to cause wind erosion). An older (1985) version of the model is not event-based (i.e., erosion is modeled as a long-term average, without regard to specific wind speed patterns over time). The older version is less complicated and requires fewer inputs, but produces more conservative results (i.e., higher emissions). The documentation on both models provides guidance on developing all inputs. Both require data on wind speed (fastest mile for the 1988 version and annual average for the 1985 ver- sion), anemometer height, roughness height, and threshold friction velocity. The 1985 version also requires input on vegetative cover. The 1988 version requires data on number of disturbances per year and, if the source is not a flat surface, pile shape and orientation to the fastest mile.
The 1985 version of the model is presented in Rapid Assessment of Exposures to Particulate Emissions from Surface Contamination Sites (U.S. EPA, 1985). Office of Health and Environmental Assessment, Washington DC.
The 1988 version of the model is available as part of AP-42, Section 13.2.5 (see above).
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Table 6 Source Characterization Models Model Name Summary
ISCLT3 The Industrial Source Complex Model-Long Term, ISCLT3, is a steady state Gaussian plume dispersion model that can be used to model dispersion of con- tinuous emissions from point or area sources over transport distances of less than 50km. It can estimate air concentration for vapors and particles, and dry deposition rates for particles (but not vapors), and can produce these outputs averaged over seasonal, annual, or longer time frames. ISCLT3 inputs include readily available meteorological data known as STAR (STability ARray) sum- maries (these are joint frequency distributions of wind speed class by wind direction sector and stability class, and are available from the National Climate Data Center in Asheville, North Carolina), and information on source character- istics (such as height, area, emission rate), receptor locations, and a variety of modeling options (such as rural or urban). Limitations of ISCLT3 include inabili- ty to model wet deposition, deposition of vapors, complex terrain, or shorter averaging times than seasonal, all of which can be modeled by ISCST3. In addi- tion, the area source algorithm used in ISCLT3 is less accurate than the one used in ISCST3. The runtime for area sources, however, is significantly shorter for ISCLT3 than for ISCST3.
ISCLT3 is available at
ISCST3 A steady-state Gaussian plume dispersion model that can estimate concentration, dry deposition rates (particles only), and wet deposition rates. Is applicable for continuous emissions, industrial source complexes, rural or urban areas, simple or complex terrain, transport distances of less than 50 km, and averaging times from hourly to annual.
Available at
Landfill Air Emissions Estimation Used to estimate emission rates for methane, carbon dioxide, nonmethane Model (LAEEM) volatile organic compounds, and other hazardous air pollutants from municipal solid waste landfills. The mathematical model is based on a first order decay equation that can be run using site-specific data supplied by the user for the parameters needed to estimate emissions or, if data are not available, using default value sets included in the model.
Developed by the Clean Air Technology Center (CATC). Can be used to estimate emission rates for methane, carbon dioxide, nonmethane organic compounds, and individual air pollutants from landfills. Can also be used by landfill owners and operators to determine if a landfill is subject to the control requirements of the federal New Source Performance Standard (NSPS) for new municipal solid waste (MSW) landfills (40 CFR 60 Subpart WWW) or the emission guidelines for existing MSW landfills (40 CFR 60 Subpart CC).
Developed for municipal solid waste landfills; might not be appropriate for all industrial waste management units.
Available at
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Table 6 Source Characterization Models Model Name Summary
Wastewater Treatment Compound WATER9 is a Windows based computer program and consists of analytical Property Processor and Air Emissions expressions for estimating air emissions of individual waste constituents in Estimator Program (WATER9) wastewater collection, storage, treatment, and disposal facilities; a database list- ing many of the organic compounds; and procedures for obtaining reports of constituent fates, including air emissions and treatment effectiveness.
WATER9 is a significant upgrade of features previously obtained in the computer programs WATER8, Chem9, and Chemdat8. WATER9 contains a set of model units that can be used together in a project to provide a model for an entire facil- ity. WATER9 is able to evaluate a full facility that contains multiple wastewater inlet streams, multiple collection systems, and complex treatment configurations. It also provides separate emission estimates for each individual compound that is identified as a constituent of the wastes.
WATER9 has the ability to use site-specific compound property information, and the ability to estimate missing compound property values. Estimates of the total air emissions from the wastes are obtained by summing the estimates for the individ- ual compounds. The EPA document Air Emissions Models for Waste and Wastewater (U.S. EPA, 1994a) includes the equations used in the WATER9 model.
Available at
Toxic Modeling System Short Term An interactive PC-based system to analyze intermittent emissions from toxic (TOXST) sources. Estimates the dispersion of toxic air pollutants from point, area, and volume sources at a complex industrial site. This system uses a Monte Carlo sim- ulation to allow the estimation of ambient concentration impacts for single and multiple pollutants from continuous and intermittent sources. In addition, the model estimates the average annual frequency with which user-specified concen- tration thresholds are expected to be exceeded at receptor sites around the mod- eled facility. TOXST requires the use of ISCT3 model input files for physical source parameters.
Available at
Toxic Screening Model (TSCREEN) TSCREEN, a Model for Screening Toxic Air Pollutant Concentrations, should be used in conjunction with the “Workbook of Screening Techniques for Assessing Impacts of Toxic Air Pollutants.” The air toxics dispersion screening models imbedded in TSCREEN that are used for the various scenarios are SCREEN2, RVD, PUFF, and the Britter-McQuaid model. Using TSCREEN, a particular release scenario is selected via input parameters, and TSCREEN model to simu- late that scenario. The model to be used and the worst case meteorological con- ditions are automatically selected based on criteria given in the workbook. TSCREEN has a front-end control program to the models that also provides, by use of interactive menus and data entry screen, the same steps as the workbook.
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attributes of the site in question. As with all should check to see if your state also has reg- modeling, however, you should consult with ulations or guidance concerning dust or fugi- your state prior to investing significant tive emission control. resources in a site-specific analysis. The state PM emissions at waste management units might have preferred models or might be able vary with the physical and chemical charac- to help plan the analysis. teristics of waste streams; the volume of waste handled; the size of the unit, its location, and associated climate; and waste transportation III. Emission Control and placement practices. The subsections below discuss the main PM-generating opera- Techniques tions and identify emission control tech- niques. The waste management units of main A. Controlling Particulate concern for PM emissions include landfills, waste piles, land application units, and closed Matter surface impoundments. Particulate matter (PM) consists of air- borne solid and liquid particles. PM is easily inhaled and can cause various health prob- 1. Vehicular Operations lems. PM also impacts the environment by Waste and cover material are often trans- decreasing visibility and harming plants as ported to units using trucks. If the waste has well as transporting constituents off site. the potential for PM to escape to the atmos- Constituents can sorb to particulate matter phere during transport, you should cover the and, therefore, wind blown dust is a potential waste with tarps or place wastes in containers pathway for constituents to leave the site. It is such as double bags or drums.17 recommended that facilities adopt controls to A unit can also use vehicles to construct address emissions of airborne particulates. lifts in landfills, apply liquids to land applica- Solid PM that becomes airborne directly or tion units, or dredge surface impoundments. indirectly as a result of human activity, is Consider using “dedicated” equipment—vehi- referred to as fugitive dust16 and it can be cles that operate only within the unit and are generated from a number of different sources. not routinely removed from the unit to per- The most common sources of fugitive dust at form other activities. This practice reduces waste management units include vehicular the likelihood that equipment movement will traffic on unpaved roads and land-based spread contaminated PM outside the unit. To units, wind erosion from land-based units, control PM emissions when equipment must and waste handling procedures. Developing a be removed from the landfill unit, such as for fugitive dust control plan is an efficient way maintenance, a wash station can remove any to tackle these problems. The plan should contaminated material from the equipment include a description of all operations con- before it leaves the unit. You should ensure ducted at the unit, a map, a list of all fugitive that this is done in a curbed wash area where dust sources at the unit, and a description of wash water is captured and properly handled. the control measures that will be used to To minimize PM emissions from all vehi- minimize fugitive dust emissions. OSHA has cles, it is recommended that you construct established standards for occupational expo- temporary roadways with gravel or other sure to dust (see 29 CFR § 1910.1000). You
16 Fugitive emissions are defined as emissions not caught by a capture system and therefore exclude PM emitted from exhaust stacks with control devices. 17 Containerizing wastes provides highly effective control of PM emissions, but, due to the large volume of 5-32 many industrial waste streams, containerizing waste might not always be feasible. Protecting Air Quality—Protecting Air Quality
coarse aggregate material to reduce silt con- tent and thus, dust generation. In addition, consider regularly cleaning paved roads and other travel surfaces of dust, mud, and conta- minated material. In land application units, the entire appli- cation surface is often covered with a soil- waste mix. The most critical preventive control measure, therefore, involves minimiz- ing contact between the application surface and waste delivery vehicles. If possible, allow only dedicated application vehicles on the increases with application intensity and fre- surface, restricting delivery vehicles to a stag- quency but also depends on activity levels, ing or loading area where they deposit waste climate, and initial surface conditions. into application vehicles or holding tanks. If Infrequent or low-intensity water application delivery vehicles must enter the application typically will not provide effective control, area, ensure that mud and waste are not while too frequent or high-intensity applica- tracked out and deposited on roadways, tion can increase leachate volume, which can where they can dry and then be dispersed by strain leachate collection systems and threat- wind or passing vehicles. en ground water and surface water. Addition of excess water to bulk waste material or to unit surfaces also can reduce the structural 2. Waste Placement and integrity of the landfill lifts, increase tracking Handling of contaminated mud off site, and increase PM emissions from waste placement and odor. These undesirable possibilities can have handling activities are less likely if exposed long-term implications for the proper man- material has a high moisture content. agement of a unit. Before instituting a water- Therefore, consider wetting the waste prior to ing program, therefore, ensure that addition loadout. Increasing the moisture content, of water does not produce undesirable however, might not be suitable for all waste impacts on ground- and surface-water quality. streams and can result in an unacceptable You should consult with your state agency increase in leachate production. To reduce with respect to these problems. the need for water or suppressants, cover or Chemical dust suppressants are an alterna- confine freshly exposed material. In addition, tive to water application. The suppressants are consider increasing the moisture content of detergent-like surfactants that increase the the cover material. total number of droplets and allow particles to It can also be useful to apply water to unit more easily penetrate the droplets, increasing surfaces after waste placement. Water is gen- the total surface area and contact potential. erally applied using a truck with a gravity or Adding a surfactant to a relatively small quan- pressure feed. Watering might or might not tity of water and mixing vigorously produces be advisable depending on application inten- small-bubble, high-energy foam in the 100 to sity and frequency, the potential for tracking 200 µm size range. The foam occupies very of contaminated material off site, and climac- little liquid volume, and when applied to the tic conditions. PM control efficiency generally surface of the bulk material, wets the fines
5-33 Protecting Air Quality—Protecting Air Quality
Table 7. Example List of Chemical Suppressants* Type Product Manufacturer
Bitumens AMS 2200, 2300® Arco Mine Sciences Coherex® Witco Chemical Docal 1002® Douglas Oil Company Peneprime® Utah Emulsions Petro Tac P® Syntech Products Corporation Resinex® Neyra Industries, Inc. Retain® Dubois Chemical Company Salts Calcium chloride Allied Chemical Corporation Dowflake, Liquid Dow® Dow Chemical DP-10® Wen-Don Corporation Dust Ban 8806® Nalco Chemical Company Dustgard® G.S.L. Minerals and Chemical Corporation Sodium silicate The PQ Corporation Adhesives Acrylic DLR-MS® Rohm and Haas Company Bio Cat 300-1® Applied Natural Systems, Inc. CPB-12® Wen-Don Corporation Curasol AK® American Hoechst Corporation DCL-40A, 1801, 1803® Calgon Corporation DC-859, 875® Betz Laboratories, Inc. Dust Ban® Nalco Chemical Company Flambinder® Flambeau Paper Company Lignosite® Georgia Pacific Corporation Norlig A, 12® Reed Lignin, Inc. Orzan Series® Crown Zellerbach Corporation Soil Gard® Walsh Chemical
* Mention of trade names or commercial products is not intended to constitute endorsement or recom- mendation for use. Source: U.S. EPA, 1989.
more effectively than water. When applied to efficiency varies, depending on the same fac- a unit, suppressants cement loose material tors as water application, as well as spray into a more impervious surface or form a sur- nozzle parameters, but generally falls face which attracts and retains moisture. between 60 and 90 percent reduction in fugi- Examples of chemical dust suppressants are tive dust emissions. Suppressant costs, how- provided in Table 7. The degree of control ever, can be high. achieved is a function of the application At land application units, if wastes contain intensity and frequency and the dilution ratio. considerable moisture, PM can be suppressed Chemical dust suppressants tend to require through application of more waste rather less frequent application than water, reducing than water or chemical suppressants. This the potential for leachate generation. Their method, however, is only viable if it would
5-34 Protecting Air Quality—Protecting Air Quality
not cause an exceedence of a design waste the exposed surface. It can also shelter mate- application rate or exceed the capacity of soil rials handling operations to reduce entrain- and plants to assimilate waste. ment during load-in and loadout. Wind fences or barriers can be portable and either At surface impoundments, the liquid man-made structures or vegetative barriers, nature of the waste means PM is not a major such as trees. A number of studies have concern while the unit is operational. Inactive attempted to determine the effectiveness of or closed surface impoundments, however, wind fences or barriers for the control of can emit PM during scraping or bulldozing windblown dust under field conditions. operations to remove residual materials. The Several of these studies have shown a uppermost layer of the low permeability soils, decrease in wind velocity, however, the such as compacted clay, which can be used to degree of emissions reduction varies signifi- line a surface impoundment, contains the cantly from study to study depending on test highest contaminant concentrations. conditions. Particulate emissions from this uppermost layer, therefore, are the chief contributor to Other wind erosion control measures contaminant emissions. When removing include passive enclosures such as three- residuals from active units, you should ensure sided bunkers for the storage of bulk materi- that equipment scrapes only the residuals, als, storage silos for various types of aggregate avoiding the liner below. material, and open-ended buildings. Such enclosures are most easily used with small, 3. Wind Erosion temporary waste piles. At land application units that use spray application, further wind Wind erosion occurs when a dry surface is erosion control can be achieved simply by exposed to the atmosphere. The effect is most not spraying waste on windy days. pronounced with bare surfaces of small parti- cles, such as silty soil; heavier or better Windblown PM emissions from a waste anchored material, such as stones or clumps pile depend on how frequently the pile is dis- of vegetation, has limited erosion potential turbed, the moisture content of the waste, the and requires higher wind speeds before ero- proportion of aggregate fines, and the height sion can begin. of the pile. When small-particle wastes are loaded onto a waste pile, the potential for Compacted clay and in-situ soil liners tend dust emissions is at a maximum, as small to form crusts as their surfaces dry. Crusted particles are easily disaggregated and picked surfaces usually have little or no erosion up by wind. This tends to occur when mater- potential. Examine the crust thickness and ial is either added to or removed from the strength during site inspections. If the crust pile or when the pile is otherwise reshaped. does not crumble easily the erosion potential On the other hand, when the waste remains might be minimal. undisturbed for long periods and is weath- Wind fences or barriers are effective means ered, its potential for dust emissions can be by which to control fugitive dust emissions greatly reduced. This occurs when moisture from open dust sources. The wind fence or from precipitation and condensation causes barrier reduces wind velocity and turbulence aggregation and cementation of fine particles in an area whose length is many times the to the surface of larger particles, and when height of the fence. This allows settling of vegetation grows on the pile, shielding the large particles and reduces emissions from surface and strengthening it with roots.
5-35 Protecting Air Quality—Protecting Air Quality
Finally, limiting the height of the pile can Removal of the volatiles near the point of reduce PM emissions, as wind velocities gen- generation can obviate the need for controls erally increase with distance from the on your subsequent process units and can ground. facilitate recycling the recovered organics back to the process. B. VOC Emission Control The control efficiency of organic removal depends on many factors, such as emissions Techniques from the removal system, and the uncon- If air modeling indicates that VOC emis- trolled emissions from management units sions are a concern, you should consider pol- before the removal device was installed. lution prevention and treatment options to Generally, overall organic removal efficiencies reduce risk. There are several control tech- of 98 to over 99 percent can be achieved. niques you can use. Some are applied before the waste is placed in the unit, reducing emissions; others contain emissions that 3. Enclosure of Units occur after waste placement; still others You might be able to control VOC emis- process the captured emissions. sions from your landfill or waste pile by installing a flexible membrane cover, enclos- 1. Choosing a Site to Minimize ing the unit in a rigid structure, or using an air-supported structure. Fans maintain posi- Airborne Emission Problems tive pressure to inflate an air-supported struc- Careful site choice can reduce VOC emis- ture. Some of the air-supported covers that sions. Locations that are sheltered from wind have been used consist of PVC-coated poly- by trees or other natural features are prefer- ester with a polyvinyl fluoride film backing. able. Knowing the direction of prevailing The efficiency of air-supported structures winds and determining whether the unit depends primarily on how well the structure would be upwind from existing and expected prevents leaks and how quickly any leaks future residences, businesses, or other popu- that do occur are detected. For effective con- lation centers can result in better siting of trol, the air vented from the structure should units. After a unit is sited, observe wind be sent to a control device, such as a carbon direction during waste placement, and plan adsorber. Worker safety issues related to or move work areas accordingly to reduce access to the interior of any flexible mem- airborne emission impacts on neighbors. brane cover or other pollutant concentration system should also be considered. 2. Pretreatment of Waste Wind fences or barriers can also aid in Pretreating waste can remove organic com- reducing organic emissions by reducing air pounds and possibly eliminate the need for mixing on the leeward side of the screen. In further air emission controls. Organic addition, wind fences reduce soil moisture removal or pretreatment is feasible for a vari- loss due to wind, which can in turn result in ety of wastes. These processes, which include decreased VOC emissions. steam or air stripping, thin-film evaporation, Floating membrane covers provide control solvent extraction, and distillation, can some- on various types of surface impoundments, times remove essentially all of the highly including water reservoirs in the western volatile compounds from your waste. United States. For successful control of
5-36 Protecting Air Quality—Protecting Air Quality
organic compounds, the membrane must be controlled. Control efficiencies of 97 to 99 provide a seal at the edge of the impound- percent have been demonstrated for carbon ment and rainwater must be removed. If gas adsorbers in many applications. is generated under the cover, vents and a Biofiltration. While covering odorous control device might also be needed. materials with soil is a longstanding odor Emission control depends primarily on the control practice, the commercial use of biofil- type of membrane, its thickness, and the tration is a relatively recent development. nature of the organic compounds in the Biofilters reproduce and improve upon the waste. Again, we recommend that you con- soil cover concept used in landfills. In a sult with your state or local air quality agency biofilter, gas emissions containing biodegrad- to identify the most appropriate emission able VOCs pass through a bed packed with control for your impoundment. damp, porous organic particles. The biologi- cally active filter bed then adsorbs the VOCs. 4. Treatment of Captured VOCs Microorganisms attached to the wetted filter In some cases, waste will still emit some material aerobically degrade the adsorbed VOCs despite waste reduction or pretreat- chemical compounds. Biofiltration can be a ment efforts. Enclosing the unit serves to pre- highly effective and low-cost alternative to vent the immediate escape of these VOCs to other, more conventional, air pollution con- the atmosphere. To avoid eventually releasing trol technologies such as thermal oxidation, VOCs through an enclosure’s ventilation sys- catalytic incineration, condensation, carbon tem, a treatment system is necessary. Some of adsorption, and absorption. Successful com- the better-known treatment methods are dis- mercial biofilter applications include treat- cussed below; others also are be available. ment of gas emissions from composting operations, rendering plants, food and tobac- co processing, chemical manufacturing, a. Adsorption foundries, and other industrial facilities.18 Adsorption is the adherence of particles of one substance, in this case VOCs, to the sur- b. Condensation face of another substance, in this case a filtra- tion or treatment matrix. The matrix can be Condensers work by cooling the vented replaced or flushed when its surface becomes vapors to their dew point and removing the saturated with the collected VOCs. organics as liquids. The efficiency of a con- denser is determined by the vapor phase con- Carbon Adsorption. In carbon adsorp- centration of the specific organics and the tion, organics are selectively collected on the condenser temperature. Two common types surface of a porous solid. Activated carbon is of condensers are contact condensers and a common adsorbent because of its high surface condensers. internal surface area: 1 gram of carbon can have a surface area equal to that of a football field and can typically adsorb up to half its c. Absorption weight in organics. For adsorption to be In absorption, the organics in the vent gas effective, replace, regenerate, or recharge the dissolve in a liquid. The contact between the carbon when treatment efficiency begins to absorbing liquid and the vent gas is accom- decline. In addition, any emissions from the plished in spray towers, scrubbers, or packed disposal or regeneration of the carbon should or plate columns. Some common solvents that might be useful for volatile organics
18 Mycock, J.C., J.D. McKenna, and L. Theodore. 1995. Handbook of Air Pollution Control Engineering and Technology. 5-37 Protecting Air Quality—Protecting Air Quality
include water, mineral oils, or other non- incinerators provide oxidation at tempera- volatile petroleum oils. Absorption efficien- tures lower than those required by thermal cies of 60 to 96 percent have been reported incinerators. Design considerations are for organics. The material removed from the important because the catalyst can be absorber can present a disposal or separation adversely affected by high temperatures, high problem. For example, organics must be concentrations of organics, fouling from par- removed from the water or nonvolatile oil ticulate matter or polymers, and deactivation without losing them as emissions during the by halogens or certain metals. solvent recovery or treatment process. 5. Special Considerations for d. Vapor Combustion Land Application Units Vapor combustion is another control tech- Since spraying wastes increases contact nique for vented vapors. The destruction of between waste and air and promotes VOC organics can be accomplished in flares; ther- emissions, if the waste contains volatile mal oxidizers, such as incinerators, boilers, organics you might want to choose another or process heaters; and in catalytic oxidizers. application method, such as subsurface injec- Flares are an open combustion process in tion. During subsurface injection, waste is which oxygen is supplied by the air sur- supplied to the injection unit directly from a rounding the flame. Flares are either operated remote holding tank and injected approxi- at ground level or elevated. Properly operated mately 6 inches into the soil; hence, the flares can achieve destruction efficiencies of waste is not exposed to the atmosphere. In at least 98 percent. Thermal vapor incinera- addition, you should consider pretreating the tors can also achieve destruction efficiencies waste to remove the organics before placing of at least 98 percent with adequately high it in the land application unit. temperature, good mixing, sufficient oxygen, and an adequate residence time. Catalytic
5-38 Protecting Air Quality—Protecting Air Quality
Protecting Air Activity List
We recommend that you consider the following issues when evaluating and controlling air emissions from industrial waste management units: ■ Understand air pollution laws and regulations, and determine whether and how they apply to a unit. ■ Evaluate waste management units to identify possible sources of volatile organic emissions. ■ Work with your state agency to evaluate and implement appropriate emission control techniques, as necessary.
5-39 Protecting Air Quality—Protecting Air Quality
Resources
American Conference of Governmental Industrial Hygienists. 1997. Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices.
Christensen, T.H., R. Cossu, and R. Stegmann. 1995. Siting, Lining Drainage & Landfill Mechanics, Proceeding from Sardinia 95 Fifth International Landfill Symposium, Volume II.
Finn, L., and R. Spencer. 1987. Managing Biofilters for Consistent Odor and VOC Treatment. BioCycle. January.
Hazardous Waste Treatment, Storage and Disposal Facilities and Hazardous Waste Generators; Organic Air Emission Standards for Tanks, Surface Impoundments, and Containers; Final Rule. Federal Register. Volume 59, Number 233, December 6, 1994. pp. 62896 - 62953.
Mycock, J.C., J.D. McKenna, and L. Theodore. 1995. Handbook of Air Pollution Control Engineering and Technology.
National Ambient Air Quality Standards for Particulate Matter. Federal Register. Volume 62, Number 138, July 18, 1997. pp. 38651 - 38701.
Orlemann, J.A., T.J. Kalman, J.A. Cummings, E.Y. Lin. 1983. Fugitive Dust Control Technology.
Robinson, W. 1986. The Solid Waste Handbook: A Practical Guide.
Texas Center for Policy Studies. 1995. Texas Environmental Almanac, Chapter 6, Air Quality.
U.S. EPA. 2002a. Industrial Waste Air Model Technical Background Document. EPA530-R-02-010.
U.S. EPA. 2002b. Industrial Waste Air Model (IWAIR) User’s Guide. EPA530-R-02-011.
U.S. EPA. 1998. Taking Toxics out of the Air: Progress in Setting “Maximum Achievable Control Technology” Standards Under the Clean Air Act. EPA451-K-98-001.
U.S. EPA. 1997a. Best Management Practices (BMPs) for Soil Treatment Technologies: Suggested Operational Guidelines to Prevent Cross-Media Transfer of Contaminants During Clean-Up Activities. EPA530-R-97-007.
U.S. EPA. 1997b. Residual Risk Report to Congress. EPA453-R-97-001.
U.S. EPA. 1996. Test Methods for Evaluating Solid Waste Physical/Chemical Methods—SW846. Third Edition.
5-40 Protecting Air Quality—Protecting Air Quality
Resources (cont.)
U.S. EPA. 1995a. Exposure Factors Handbook: Volumes 1-3. EPA600-P-95-002FA-C.
U.S. EPA. 1995b. Survey of Control Technologies for Low Concentration Organic Vapor Gas Streams. EPA456-R-95-003.
U.S. EPA. 1995c. User’s Guide for the Industrial Source Complex (ISC3) Dispersion Models: Volume I. EPA454-B-95-003a.
U.S. EPA. 1995d. User’s Guide for the Industrial Source Complex (ISC3) Dispersion Models: Volume II- Description of Model Algorithms. EPA454-B-95-003b.
U.S. EPA. 1994a. Air Emissions Models for Waste and Wastewater. EPA453-R-94-080A.
U.S. EPA. 1994b. Handbook: Control Techniques for Fugitive VOC Emissions from Chemical Process Facilities. EPA625-R-93-005.
U.S. EPA. 1994c. Toxic Modeling System Short-Term (TOXST) User’s Guide: Volume I. EPA454-R-94-058A.
U.S. EPA. 1993. Guideline on Air Quality Models. EPA450-2-78-027R-C
U.S. EPA. 1992a. Control of Air Emissions from Superfund Sites. EPA625-R-92-012.
U.S. EPA. 1992b. Protocol for Determining the Best Performing Model. EPA454-R-92-025.
U.S. EPA. 1992c. Seminar Publication: Organic Air Emissions from Waste Management Facilities. EPA625- R-92-003.
U.S. EPA. 1991. Control Technologies for Hazardous Air Pollutants. EPA625-6-91-014.
U.S. EPA. 1989. Hazardous Waste TSDF—Fugitive Particulate Matter Air Emissions Guidance Document. EPA450-3-89-019.
U.S. EPA. 1988. Compilation of Air Pollution Emission Factors. AP-42.
U.S. EPA. 1985. Rapid Assessment of Exposures to Particulate Emissions form Surface Contamination Sites.
Viessman, W., and M. Hammer. 1985. Water Supply and Pollution Control.
5-41 Part III Protecting Surface Water
Chapter 6 Protecting Surface Water Contents
I. Determining the Quality and Health of Surface Waters ...... 6 - 1 A. Water Quality Criteria...... 6 - 2 B. Water Quality Standards ...... 6 - 2 C. Total Maximum Daily Load (TMDL) Program...... 6 - 3
II. Surface-Water Protection Programs Applicable to Waste Management Units ...... 6 - 4 A. National Pollutant Discharge Elimination System (NPDES) Permit Program...... 6 - 4 1. Storm-Water Discharges ...... 6 - 5 2. Discharges to Surface Waters ...... 6 - 6 B. National Pretreatment Program...... 6 - 6 1. Description of the National Pretreatment Program ...... 6 - 6 2. Treatment of Waste at POTW Plants...... 6 - 8
III. Understanding Fate and Transport of Pollutants ...... 6 - 10 A. How Do Pollutants Move From Waste Management Units To Surface Water?...... 6 - 10 1. Overland Flow ...... 6 - 10 2. Ground Water to Surface Water ...... 6 - 11 3. Air to Surface Water ...... 6 - 11 B. What Happens When Pollutants Enter Surface Water? ...... 6 - 12 C. Pollutants Of Concern ...... 6 - 13
IV. Protecting Surface Waters ...... 6 - 13 A. Controls to Address Surface-Water Contamination from Overland Flow ...... 6 - 13 1. Baseline BMPs...... 6 - 18 2. Activity-Specific BMPs ...... 6 - 18 3. Site-Specific BMPs ...... 6 - 19 B. Controls to Address Surface-water Contamination from Ground Water to Surface Water...... 6 - 29 C. Controls to Address Surface-water Contamination from Air to Surface Water...... 6 - 29
V. Methods of Calculating Run-on and Runoff Rates ...... 6 - 30
Protecting Surface Water Activity List...... 6 - 33
Resources ...... 6 - 34
Figures: Figure 1. BMP Identification and Selection Flow Chart...... 6 - 17 Figure 2. Coverings...... 6 - 22 Figure 3. Silt Fence ...... 6 - 24 Contents (cont.)
Figure 4. Straw Bale ...... 6 - 24 Figure 5. Storm Drain Inlet Protection ...... 6 - 25 Figure 6. Collection and Sedimentation Basin...... 6 - 26 Figure 7. Outlet Protection ...... 6 - 27 Figure 8. Infiltration Trench ...... 6 - 28 Figure 9. Typical Intensity-Duration-Frequency Curves ...... 6 - 31
Tables: Table 1. Biological and Chemical Processes Occurring in Surface Water Bodies ...... 6 - 14 Table 2. Priority Pollutants ...... 6 - 15 Protecting Surface Water—Protecting Surface Water
Protecting Surface Water
This chapter will help you: • Protect surface waters by limiting the discharge of pollutants into the waters of the United States. • Guard against inappropriate discharges of pollutants associated with process wastewaters and storm water to ensure the safety of the nation’s surface waters. • Reduce storm-water discharges by complying with applicable regula- tions, implementing available storm-water controls, and identifying best management practices (BMPs) to control storm water.
water is such a valuable commodity, the pro- ver 70 percent of the Earth’s tection of our surface waters should be every- surface is water. Of all the one’s goal. Pollutants1 associated with waste Earth’s water, 97 percent is management units and storm-water dis- found in the oceans and seas, charges must be controlled. while 3 percent is fresh water. OThis fresh water is found in glaciers, lakes, This chapter summarizes how EPA and ground water, wetlands, and rivers. Because states determine the quality of surface waters and subsequently describes the existing sur- This chapter will help you address the face-water protection programs for ensuring following questions: the health and integrity of waterbodies. The fate and transport of pollutants in the surface- • What surface-water protection pro- water environment is also discussed. Finally, grams are applicable to my waste various methods that are used to control pollu- management unit? tant discharges to surface waters are described. • What are the objectives of run-on and runoff control systems? • What should be considered in design- I. Determining the ing surface-water protection systems? Quality and • What BMPs should be implemented to protect surface waters from pollu- Health of tants associated with waste manage- Surface Waters ment units? The protection of aquatic resources is gov- • What are some of the engineering and erned by the Clean Water Act (CWA). The physical mechanisms available to con- objective of the CWA is to “restore and main- trol storm water? tain the chemical, physical, and biological
1 To be consistent with the terminology used in the Clean Water Act, the term pollutant is used in this chapter in place of the term constituent. In this chapter, pollutant means an effluent or condition intro- duced to surface waters that results in degradation. Water pollutants include human and animal wastes, 6-1 nutrients, soil and sediments, toxics, sewage, garbage, chemical wastes, and heat. Protecting Surface Water—Protecting Surface Water
logical criteria (i.e., biointegrity values). These What is water quality? criteria are used by the states for developing Water quality reflects the composition of enforceable water quality standards and iden- water as affected by natural causes and tifying problem areas. human activities, expressed in terms of Water quality criteria are developed from measurable quantities and related to toxicity studies conducted on different organ- intended water use. Water quality is deter- isms and from studies of the effects of toxic mined by comparing physical, chemical, compounds on humans. Federal water quality biological, microbiological, and radiologi- criteria specify the maximum exposure con- cal quantities and parameters to a set of centrations that will provide protection of standards and criteria. Water quality is aquatic life and human health. Generally, perceived differently by different people. however, the water quality criteria describe For example, a public health official might the quality of water that will support a partic- be concerned with the bacterial and viral ular use of the water body. For the protection safety of water used for drinking and of aquatic life a two-value criterion has been bathing, while fishermen might be con- established to account for acute and chronic cerned that the quality of water be suffi- toxicity of pollutants. The human health crite- cient to provide the best habitat for fish. rion specifies the risk incurred with exposure For each intended use and water quality to the toxic compounds at a specified concen- benefit, different parameters can be used tration. The human health criterion is associ- to express water quality. ated with the increased risk of contracting a debilitating disease, such as cancer. integrity of the nation’s waters” (Section 101(a)). Section 304(a) of the CWA authorizes B. Water Quality Standards EPA to publish recommended water quality Water quality standards are laws or regula- criteria that provide guidance for states to use tions that states (and authorized tribes) adopt in adopting water quality standards under to enhance and maintain the quality of water Section 303(c). Section 303 of the CWA also and protect public health. States have the pri- establishes the Total Maximum Daily Load mary responsibility for developing and imple- (TMDL) Program which requires EPA and the menting these standards. Water quality states to identify waters not meeting water standards consist of three elements: 1) the quality standards and to establish TMDLs for “designated beneficial use” or “uses” of a those waters. waterbody or segment of a waterbody, 2) the water quality “criteria” necessary to protect A. Water Quality Criteria the uses of that particular waterbody, and 3) an antidegradation policy. “Designated use” is Under authority of Section 304 of the a term that is specified in water quality stan- CWA, EPA publishes water quality “criteria” dards for a body of water or a segment of a that reflect available scientific information on body of water (e.g., a particular branch of a the maximum acceptable concentration levels river). Typical uses include public water sup- of specific chemicals in water that will protect ply, propagation of fish and wildlife, and aquatic life, human health, and drinking recreational, agricultural, industrial, and navi- water. EPA has also established nutrient crite- gational purposes. Each state develops its own ria (e.g., phosphorus and nitrogen) and bio- use classification system based on the generic
6-2 Protecting Surface Water—Protecting Surface Water
U.S. EPA Selected Water Quality Criteria in Micrograms per Liter Aquatic Life Human Health 10-6 Risk Freshwater Marine Water and Fish Fish Ingestion Chemical Acute Chronic Acute Chronic Ingestion Only Benzene 5300 — 5100 700 0.66 40 Cadmium — — 43 9.3 10 — DDT 1.1 0.001 0.13 0.001 0.000024 0.000024 PCBs 2 0.014 10 0.03 0.000079 0.000079 uses cited in the CWA. The states may differ- the total maximum daily load (TMDL) pro- entiate and subcategorize the types of uses gram, under which the states establish the that are to be protected, such as cold-water or allowable pollutant loadings for impaired warm-water fisheries, or specific species that waterbodies (i.e., waterbodies not meeting are to be protected (e.g., trout, salmon, bass). state water quality standards) based on their States may also designate special uses to pro- “waste assimilative capacity.” EPA must tect sensitive or valuable aquatic life or habi- approve or disapprove TMDLs established by tat. In addition, the water quality criteria the states. If EPA disapproves a state TMDL, adopted into a state water quality standard EPA must establish a federal TMDL. may or may not be the same number pub- A TMDL is a calculation of the maximum lished by EPA under section 304. States have amount of a pollutant that a waterbody can the discretion to adjust the EPA’s criteria to receive and still meet water quality standards. reflect local environmental conditions and The calculation must include a margin of human exposure patterns. safety to ensure that the waterbody can be The CWA requires that the states review used for the purposes the state has designat- their standards at least once every three years ed. The calculation must also account for sea- and submit the results to EPA for review. EPA sonal variation in water quality. is required to either approve or disapprove The quantity of pollutants that can be dis- the standards, depending on whether they charged into a surface-water body without meet the requirements of the CWA. When use impairment (also taking into account nat- EPA disapproves a standard, and the state ural inputs such as erosion) is known as the does not revise the standard to meet EPA’s “assimilative capacity.” The assimilative capac- objection, the CWA requires the Agency to ity is the range of concentrations of a sub- propose substitute federal standards. stance or a mixture of substances that will not impair attainment of water quality stan- C. Total Maximum Daily dards. Typically, the assimilative capacity of surface-water bodies might be higher for Load (TMDL) Program biodegradable organic matter, but it can be Lasting solutions to water quality problems very low for some toxic chemicals that accu- and pollution control can be best achieved by mulative in the tissues of aquatic organisms looking at the fate of all pollutants in a water- and become injurious to animals and people shed. The CWA requires EPA to administer using them as food.
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A. National Pollutant What is a watershed? Discharge Elimination Watersheds are areas of land that drain to System (NPDES) Permit surface-waterbodies. A watershed general- Program ly includes lakes, rivers, estuaries, wet- lands, streams, and the surrounding The CWA requires most “point sources” landscape. Ground-water recharge areas (i.e., entities that discharge pollutants of any are also considered part of a watershed. kind into waters of the United States) to have Because watersheds are defined by natur- a permit establishing pollution limits, and al hydrology, they represent the most log- specifying monitoring and reporting require- ical basis for managing surface-water ments. This permitting process is known as resources. Managing the watershed as a the National Pollutant Discharge Elimination whole allows state and local authorities to System (NPDES). Permits are issued for three gain a more complete understanding of types of wastes that are collected in sewers overall conditions in an area and the and treated at municipal wastewater treat- cumulative stressors which affect the sur- ment plants or that discharge directly into face-water body. Information on EPA’s receiving waters: process wastewater, non- strategy to protect and restore water qual- process wastewater, and storm water. Most ity and aquatic ecosystems at the water- discharges of municipal and industrial storm shed level can be found at
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determine if they are in compliance with the conditions imposed under their permits. When is an NPDES permit NPDES permits typically establish specific needed? “effluent limitations” relating to the type of To answer questions about whether or discharge. For process wastewaters, the per- not a facility needs to seek NPDES per- mit incorporates the more stringent of tech- mit coverage, or to determine whether a nology-based limitations (either at 40 CFR particular program is administered by Parts 405 through 471 or developed on a EPA or a state agency, contact your state case-by-case basis according to the permit or EPA regional storm-water office. writer’s best professional judgement) or water Currently, 44 states and the U.S. Virgin quality-based effluent limits (WQBELs). Islands have federally-approved state Some waste management units, such as sur- NPDES permit programs. The following face impoundments, might have an NPDES 6 states do not have final EPA approval: permit to discharge wastewaters directly to Alaska, Arizona, Idaho, Massachusetts, surface waters. Other units might need an New Hampshire, and New Mexico. NPDES permit for storm-water discharges. (As of March 2001) NPDES permits are issued by EPA or states with NPDES permitting authority. If you are located in a state with NPDES authority, you “heavy” manufacturing facilities, 3) mining should contact the state directly to determine and oil and gas operations with “contaminat- the requirements for your discharges. EPA’s ed” storm-water discharges, 4) hazardous Office of Wastewater Management’s Web page waste treatment, storage, or disposal facilities, contains a complete, updated list of the states 5) landfills, land application sites, and open with approved NPDES permit programs, as dumps, 6) recycling facilities, 7) steam elec- well as a fact sheet and frequently asked tric generating facilities, 8) transportation questions about the NPDES permit program facilities, 9) sewage treatment plants, 10) at
2 Initially, a group application option was available for facilities with similar activities to jointly submit a single application for permit coverage. A multi-sector general permit was then issued based upon infor- mation provided in the group applications. The group application option was only used during the ini- tial stages of the program and is no longer available. 6-5 Protecting Surface Water—Protecting Surface Water
sector basis, information concerning industri- What types of pollutants al activities, BMPs, materials stored outdoors, are regulated by NPDES? and end-of-pipe storm-water sampling data. Based on this review, EPA identified pollu- Conventional pollutants are contained tants of concern in each industry sector, the in the sanitary wastes of households, sources of these pollutants, and the BMPs businesses, and industries. These pollu- used to control them. The Multi-Sector tants include human wastes, ground-up General Permit requires the submission of an food from sink disposals, and laundry NOI, as well as development and implemen- and bath waters. Conventional pollutants tation of a site-specific pollution prevention include fecal coliform, oil and grease, plan, as the basic storm-water control strategy total suspended solids (TSS), biochemical for each industry sector. oxygen demand (BOD), and pH. Toxic pollutants are particularly harm- 2. Discharges to Surface Waters ful to animal or plant life. They are pri- marily grouped into organics (including Most surface impoundments that are pesticides, solvents, polychlorinated addressed by the Guide are part of a facility’s biphenyls (PCBs), and dioxins) and metals wastewater treatment process that results in (including lead, silver, mercury, copper, an NPDES-permitted discharge to surface chromium, zinc, nickel, and cadmium). waters. The NPDES permit only sets pollu- tion limits for the final discharge of treated Nonconventional pollutants are any wastewater. Generally, the NPDES permit additional substances that are not con- would not establish any regulatory require- sidered conventional or toxic that may ments regarding the design or operation of require regulation. These include nutri- the surface impoundments that are part of ents such as nitrogen and phosphorus. the treatment process except that, once designed and constructed, a provision vidual permits require the submission of a requires use of those treatment processes site drainage map, a narrative description of except in limited circumstances. Individual the site that identifies potential pollutant state environmental agencies, under their sources, and quantitative testing data for spe- own statutory authorities, can impose cific parameters. General permits usually requirements on surface impoundment involve the submission of a Notice of Intent design and operation. (NOI) that includes only general information, which is neither industry-specific or pollu- B. National Pretreatment tant-specific and typically do not require the collection of monitoring data. NPDES general Program storm-water permits typically require the development and implementation of storm- 1. Description of the National water pollution prevention plans and BMPs Pretreatment Program to limit pollutants in storm-water discharges. For industrial facilities that discharge The EPA has also issued the Multi-Sector wastewaters to publicly owned treatment General Permit (60 FR 50803; September 29, works (POTW) through domestic sewer lines, 1995) which covers 29 different industry sec- pretreatment of the wastewater may be tors. The Agency reviewed, on a sector-by- required (40 CFR Part 403). Under the
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National Pretreatment Program, EPA, states, interference with the disposal of and local regulatory agencies establish dis- municipal sludge. charge limits to reduce the level of pollutants • Prevent the introduction of pollutants discharged by industry into municipal sewer into POTWs which will pass through systems. These limits control the pollutant the treatment works or otherwise be levels reaching a POTW, improve the quality incompatible with such works. of the effluent and sludges produced by the POTW, and increase the opportunity for ben- • Improve opportunities to recycle and eficial use of the end products (e.g., effluents, reclaim municipal and industrial sludges, etc). Further information about wastewaters and sludges. industrial pretreatment and the National To help accomplish these objectives, the Pretreatment Program is available on the National Pretreatment Program is charged Office of Wastewater Management’s Web page with controlling 126 priority pollutants from at
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ment requirements, are subject to the general established both mass- and concentration- and specific prohibitions identified in 40 CFR based standards. Generally, both a daily maxi- Part 403.5 (a) and (b), respectively. General mum limitation and a long-term average prohibitions forbid the discharge of any pol- limitation (e.g., average daily values in a cal- lutant to a POTW that can pass through or endar month) are established for each regu- cause interference. Specific prohibitions for- lated pollutant. bid the discharge of pollutants that pose fire Local Limits. Federal regulations located or explosion hazards; corrosives; solid or vis- at 40 CFR Parts 403.8 (f) (4) and 122.21 (j) cous pollutants in amounts that will obstruct (4) require authorities to evaluate the need system flows; quantities of pollutants that will for local limits and, if necessary, implement interfere with POTW operations; heat that and enforce specific limits protective of that inhibits biological activity; specific oils; pollu- POTW. Local limits might be developed for tants that can cause the release of toxic gases; pollutants such as metals, cyanide, BOD, TSS, and pollutants that are hauled to the POTW oil & grease, and organics that can interfere (except as authorized by the POTW). with or pass through the treatment works, Categorical Standards. Categorical pre- cause sludge contamination, or cause worker treatment standards are national, uniform, health and safety problems if discharged at technology-based standards that apply to dis- excess levels. charges to POTWs from specific industrial All POTWs designed to accommodate categories (e.g., battery manufacturing, coil flows of more than 5 million gallons per day coating, grain mills, metal finishing, petrole- and smaller POTWs with significant industri- um refining, rubber manufacturing) and limit al discharges are required to establish pre- the discharge of specific pollutants. These treatment programs. The EPA Regions and standards are described in 40 CFR Parts 405 states with approved pretreatment programs through 471. serve as approval authorities for the National Categorical pretreatment standards can be Pretreatment Program. In that capacity, they concentration-based or mass-based. review and approve requests for POTW pre- Concentration- based standards are expressed treatment program approval or modification, as milligrams of pollutant allowed per liter of oversee POTW program implementation, wastewater discharged (mg/l) and are issued review requested modifications to categorical where production rates for the particular pretreatment standards, provide technical industrial category do not necessarily corre- guidance to POTWs and IUs, and initiate late with pollutant discharges. Mass-based enforcement actions against noncompliant standards are generally expressed as a mass POTWs and IUs. per unit of production (e.g., milligrams of pollutant per kilogram of product produced) 2. Treatment of Waste at POTW and are issued where production rates do correlate with pollutant discharges. Thus, Plants limiting the amount of water discharge (i.e., A waste treatment works’ basic function is water conservation) is important to reducing to speed up the natural processes by which the pollutant load to the POTW. For a few water is purified and returned to receiving categories where reducing a facility’s flow vol- lakes and streams. There are two basic stages ume does not provide a significant difference in the treatment of wastes, primary and sec- in the pollutant load discharged, EPA has ondary. In the primary stage, solids are
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allowed to settle and are removed from which the sewage passes. More recently, inter- wastewater. The secondary stage uses biologi- locking pieces of corrugated plastic or other cal processes to further purify wastewater. synthetic media have also been used in trick- Sometimes, these stages are combined into ling beds. Bacteria gather and multiply on one operation. POTWs can also perform these stones until they can consume most of other “advanced treatment” operations to the organic matter in the sewage. The cleaner remove ammonia, phosphorus, pathogens water trickles out through pipes for further and other pollutants in order to meet effluent treatment. From a trickling filter, the sewage discharge requirements. flows to another sedimentation tank to remove excess bacteria. Disinfection of the Primary treatment. As sewage enters a effluent with chlorine is generally used to plant for treatment, it flows through a screen, complete the secondary stage. Ultraviolet which removes large floating objects such as light or ozone are also sometimes used in sit- rags and sticks that can clog pipes or damage uations where residual chlorine would be equipment. After sewage has been screened, it harmful to fish and other aquatic life. passes into a grit chamber, where cinders, sand, and small stones settle to the bottom. At Activated sludge. The activated sludge treat- this point, the sewage still contains organic ment process speeds up the work of the bac- and inorganic matter along with other sus- teria by bringing air and sludge, heavily laden pended solids. These solids are minute parti- with bacteria, into close contact with sewage. cles that can be removed from sewage by After the sewage leaves the settling tank in treatment in a sedimentation tank. When the the primary stage, it is pumped into an aera- speed of the flow of sewage through one of tion tank, where it is mixed with air and these tanks is reduced, the suspended solids sludge loaded with bacteria and allowed to will gradually sink to the bottom, where they remain for several hours. During this time, form a mass of solids called raw primary the bacteria break down the organic matter sludge. Sludge is usually removed from tanks into harmless by-products. The sludge, now by pumping, after which it can be further activated with additional millions of bacteria treated for use as fertilizer, or disposed of and other tiny organisms, can be used again through incineration if necessary. To complete by returning it to the aeration tank for mixing primary treatment, effluent from the sedimen- with new sewage and ample amounts of air. tation tank is usually disinfected with chlorine From the aeration tank, the sewage flows to before being discharged into receiving waters. another sedimentation tank to remove excess Sometimes chlorine is fed into the water to bacteria. The final step is generally the addi- kill pathogenic bacteria and to reduce tion of chlorine to the effluent. unpleasant odors. Advanced treatment. New pollution Secondary treatment. The secondary stage problems have created additional treatment of treatment removes about 85 percent of the needs on wastewater treatment systems. Some organic matter in sewage by making use of the pollutants can be more difficult to remove bacteria in it. The two principal techniques from water. Increased demands on the water used in secondary treatment are trickling fil- supply only aggravate the problem. These ters and the activated sludge process. challenges are being met through better and more complete methods of removing pollu- Trickling filters. A trickling filter is a bed of tants at treatment plants, or through preven- stones from three to six feet deep through tion of pollution at the source (refer to
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Chapter 3 – Integrating Pollution Prevention There is a correlation between the pollu- for more information). Advanced waste treat- tant loadings to surface water and the amount ment techniques in use or under develop- of precipitation (rainfall, snow, etc.) that falls ment range from biological treatment capable on the watershed in which a waste manage- of removing nitrogen and phosphorus to ment unit is located. In addition, the charac- physical-chemical separation techniques such teristics of the soil at a facility also influence as filtration, carbon adsorption, distillation, pollutant loading to surface water. If, for and reverse osmosis. These wastewater treat- example, the overland flow is diminished due ment processes, alone or in combination, can to high soil infiltration, so is the transport of achieve almost any degree of pollution con- particulate pollutants to surface water. Also, if trol desired. As waste effluents are purified to wastes are land applied and surface overland higher degrees by such treatment, the effluent flow is generated by a rainfall event, a signifi- water can be used for industrial, agricultural, cant portion of pollutants can be moved over or recreational purposes, or even as drinking land into adjacent surface water. water supplies. A diagram representing rainfall transforma- tion into runoff and other components of the hydrologic cycle is shown in Chapter 7: III. Understanding Section A–Assessing Risk. The first stage of runoff formation is condensation of atmos- Fate and pheric moisture into rain droplets or snowflakes. During this process, water comes Transport of in contact with atmospheric pollutants. The Pollutants pollution content of rainwater can therefore reach high levels. In addition, rain water dis- A. How Do Pollutants Move From Waste What is “runoff?” Management Units To Runoff is water or leachate that drains Surface Water? or flows over the land from any part of a waste management unit. 1. Overland Flow The primary means by which pollutants What is “run-on?” are transported to surface-water bodies is via Run-on is water from outside a waste overland flow or “runoff.” Runoff to surface management unit that flows into the water is the amount of precipitation after all unit. Run-on includes storm water from “losses” have been subtracted. Losses include rainfall or the melting of snow or ice infiltration into soils, interception by vegeta- that falls directly on the unit, as well as tion, depression storage and ponding, and the water that drains from adjoining evapotranspiration (i.e., evaporation from the areas. soil and transpiration by plants).
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solves atmospheric carbon dioxide and sulfur reaches the land surface at a spring or and nitrogen oxides, and acts as a weak acid through a seep in the side or bottom of a after it hits the ground, reacting with soil and river bed, lake, wetland, or other surface- limestone formations. Overland flow begins water body. Ground water can also leave the after rain particles reach the earth’s surface aquifer via the pumping of a well. The (note that during winter months runoff for- process of ground water outflowing into a mation can be delayed by snowpack forma- surface-water body or leaving the aquifer tion and subsequent melting). Rain hitting an through pumping is called discharge. exposed waste management unit will liberate Discharge from confined aquifers occurs in and pick up particulates and pollutants from much the same way except that pressure, the unit and can also dissolve other chemicals rather than gravity, is the driving force in it comes in contact with. Precipitation that moving ground water to the surface. When flows into a waste management unit, called the intersection between the aquifer and the “run-on,” can also free-up and subsequently land’s surface is natural, the pathway is called transport pollutants out of the unit. Runoff a spring. If discharge occurs through a well, carries the pollutants from the waste manage- that well is a “flowing artesian well.” ment unit as it flows downgradient following the natural contours of the watershed to nearby lakes, rivers, or wetland areas. 3. Air to Surface Water Pollutants released into the air are carried 2. Ground Water to Surface by wind patterns away from their place of Water origin. Depending on weather conditions and the chemical and physical properties of the Ground water and surface water are funda- pollutants, pollutants can be carried signifi- mentally interconnected. In fact, it is often cant distances from their source and can difficult to separate the two because they undergo physical and chemical changes as “feed” each other. As a result, pollutants can they travel. Some of these chemical changes move from one media to another. Shallow include the formation of new pollutants such water table aquifers interact closely with as ozone, which is formed from nitrogen streams, sometimes discharging water into a oxides (NOx) and hydrocarbons. stream or lake and sometimes receiving water from the stream or lake. Many rivers, lakes, Atmospheric deposition occurs when pol- and wetlands rely heavily on ground-water lutants in the air fall on the land or surface discharge as a source of water. During times waters. When pollutants are deposited in of low precipitation, some bodies of water snow, fog, or rain, the process is called wet would not contain any water at all if it were deposition, while the deposition of pollutants not for ground-water discharge. as dry particles or gases is called dry deposi- tion. Pollutants can be deposited into water An unconfined aquifer that feeds a stream bodies either directly from the air onto the is said to provide the stream’s “baseflow.” surface of the water, or through indirect Gravity is the dominant driving force in deposition, where the pollutants settle on the ground-water movement in unconfined land and are then carried into a water body aquifers. As such, under natural conditions, by runoff. ground water moves “downhill” until it
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Any pollutant that is emitted into the air can become a surface-water problem due to The Dissolved Oxygen deposition. Some of the common pollutants Problem that can be transported to surface-water bod- ies via air include different forms of nitrogen, The dissolved oxygen balance is an mercury, copper, polychlorinated biphenols important water quality consideration (PCBs), polycyclic aromatic hydrocarbons for streams and estuaries. Dissolved oxy- (PAHs), chlordane, dieldrin, lead, lindane, gen is the most important parameter for polycyclic organic matter (POM), dioxins, protecting fish and other aquatic organ- and furans. isms. Runoff with a high concentration of biodegradable organics (organic mat- ter) can have a serious effect on the B. What Happens When amount of dissolved oxygen in the Pollutants Enter Surface water. Low dissolved oxygen levels can be very detrimental to fish. The content Water? of organic matter in waste discharges is All pollutants entering surface water via commonly expressed as the biochemical runoff, ground-water infiltration, or air trans- oxygen demand (BOD) load. Organic port have an effect on the aquatic ecosystem. matter can come from a variety of Additive and synergistic effects are also fac- sources, including waste management tors because many different pollutants can units. When runoff containing organic enter a surface-water body from diverse matter is introduced into receiving sources and activities. As such, solutions to waters, decomposers immediately begin water quality problems are best achieved by to breakdown the organic matter using looking at all activities and inputs to surface dissolved oxygen to do so. Further, if water in a watershed. there are numerous inputs of organic Surface-water ecosystems (i.e., rivers, matter into a single water body, for lakes, wetlands, estuaries) are considered to example a stream, the effects will be be in a dynamic equilibrium with their inputs additive (i.e., more and more dissolved and surroundings. These ecosystems can be oxygen will be removed from the stream divided into two components, the biotic (liv- as organic matter is added along the ing) and abiotic (nonliving). Pollutants are stream reach and decomposes). This is continually moving between the two. For also an example of how an input that example, pollutants can move from the abiot- might not be considered a pollutant ic environment (i.e., the water column) into (i.e., organic matter) can lead to harmful aquatic organisms, such as fish. The intake of effects due to the naturally occurring the pollutant can occur as water moves across process within a surface-water body. the gills or directly through the skin. Toxic pollutants can accumulate in fish (known as back into the abiotic environment as the bioaccumulation), as the fish uptakes more of organism decays. the pollutant than it can metabolize or excrete. Pollutants can eventually concentrate Pollutants can also move within the abiotic in an organism to a level where death results. environment, as for example, between water At that point, the pollutants will be released and its bottom sediments. Pollutants that are attached to soil particles being carried down-
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stream will be deposited on the bottom of the human population or to aquatic organisms, streambed as the particles fall out of the such as fish). Priority pollutants of particular water column. In this manner, pollutants can concern for surface-water bodies include: accumulate in areas of low flow. Thus, it is • Metals, such as cadmium, copper, obvious that the hydrodynamical, biological, chromium, lead, mercury, nickel, and and chemical processes in aquatic systems zinc, that arise from industrial opera- cannot be separated and must be addressed tions, mining, transportation, and simultaneously when considering pollutant agricultural use. loads and impacts to surface water. Table 1 presents some additional information on the • Organic compounds, such as pesti- biological and chemical processes that occur cides, PCBs, solvents, petroleum in water bodies. hydrocarbons, organometallic com- pounds, phenols, formaldehyde, and biochemical methylation of metals in C. Pollutants Of Concern aquatic sediments. As you assess the different types of best • Dissolved gases, such as chlorine and management practices (BMPs) that can be ammonium. used at waste management units to protect surface waters (discussed in Section IV of this • Anions, such as cyanides, fluorides, chapter), you should also identify the pollu- sulfides, and sulphates. tants in the unit that pose the greatest threats • Acids and alkalis. to surface water. Factors to consider include the solubility of the constituents in the waste management unit, how easily these potential pollutants can be mobilized, degradation IV. Protecting rates, vapor pressures, and biochemical decay Surface Waters coefficients of the pollutants and any other factors that could encourage their release into the environment. A. Controls to Address While all pollutants can become toxic at Surface-Water high enough levels, there are a number of Contamination from compounds that are toxic at relatively low Overland Flow levels. These pollutants have been designated Protecting surface water entails preventing by the EPA as priority pollutants. The list of storm-water contamination during both the priority pollutants is included in Table 2. The construction of a waste management unit and list of priority pollutants is continuously the operational life of the unit. During con- under review by EPA and is periodically struction the primary concern is sediment updated. The majority of pollutants on the eroding from exposed soil surfaces. list are classified as organic chemicals. Others Temporary sediment and erosion control are heavy metals which are being mobilized measures, such as silt fences around con- into the environment by human activities at struction perimeters, straw bales around rates greatly exceeding those of natural geo- storm-water inlets, and seeding or straw cov- logical processes. Several of the priority pol- ering of exposed slopes, are typically used to lutants are also considered carcinogenic (i.e., limit and manage erosion. States or local they can increase the risk of cancer to the
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Table 1. Biological and Chemical Processes Occurring in Surface-Water Bodies After pollutants are transported to lakes, rivers, and other water bodies, they can be subject to a variety of biological and chemical processes that affect how they will interact and impact the aquat- ic ecosystem. These processes determine how pollutants are mobilized, degraded, or released into the biotic and abiotic environments. Metabolism of a toxicant consists of a series of chemical transformations that take place within an organism. A wide range of enzymes act on toxicants, that can increase water solubility, and facil- itate elimination from the organism. In some cases, however, metabolites can be more toxic than their parent compound. Sullivan. 1993. Environmental Regulatory Glossary, 6th Ed. Government Institutes. Bioaccumulation is the uptake and sequestration of pollutants by organisms from their ambient environment. Typically, the concentration of the substance in the organism exceeds the concentra- tion in the environment since the organism will store the substance and not excrete it. Phillips. 1993. In: Calow (ed), Handbook of Ecotoxicology, Volume One. Blackwell Scientific Publications. Biomagnification is the concentration of certain substances up a food chain. It is a very impor- tant mechanism in concentrating pesticides and heavy metals in organisms such as fish. Certain substances such as pesticides and heavy metals move up the food chain, work their way into a river or lake and are eaten by large birds, other animals, or humans. The substances become concentrat- ed in tissues or internal organs as they move up the chain. Sullivan. 1993. Environmental Regulatory Glossary, 6th Ed. Government Institutes. Biological degradation is the decomposition of a substance into more elementary compounds by action of microorganisms such as bacteria. Sullivan. 1993. Environmental Regulatory Glossary, 6th Ed. Government Institutes. Hydrolysis is a chemical process of decomposition in which the elements of water react with another substance to yield one or more new substances. This transformation process changes the chemical structure of the substance. Sullivan. 1993. Environmental Regulatory Glossary, 6th Ed. Government Institutes. Precipitation is a chemical or physical change whereby a pollutant moves from a dissolved form in a solution to a solid or insoluble form and subsequently drops out of the solution. Precipitation reduces the mobility of constituents, such as metals and is not generally reversible. Boulding. 1995. Soil, Vadose Zone, and Ground-Water Contamination: Assessment, Prevention, and Remediation. Oxidation/Reduction (Redox) process is a complex of biochemical reactions in sediment that influences the valence state of elements (and their ions) found in sediments. Under anaerobic con- ditions the overall process shifts to a reducing condition. The chemical properties for elements can change substantially with changes in the oxidation state. Sullivan. 1993. Environmental Regulatory Glossary, 6th Ed. Government Institutes. Photochemical process is the chemical changes brought about by the radiant energy of the sun acting upon various polluting substances. Sullivan. 1993. Environmental Regulatory Glossary, 6th Ed. Government Institutes.
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Table 2. Priority Pollutants3 001 Acenaphthene 043 Methylene chloride 085 Vinyl chloride 002 Acrolein 044 Methyl chloride 086 Aldrin 003 Acrylonitrile 045 Methyl bromide 087 Dieldrin 004 Benzene 046 Bromoform 088 Chlordane 005 Benzidine 047 Dichlorobromomethane 089 4,4-DDT 006 Carbon tetrachloride 048 Chlorodibromomethane 090 4,4-DDE 007 Chlorobenzene 049 Hexachlorobutadiene 091 4,4-DDD 008 1,2,4-trichlorobenzene 050 Hexachlorocyclopentadiene 092 Alpha-endosulfan 009 Hexachlorobenzene 051 Isophorone 093 Beta-endosulfan 010 1,2-dichloroethane 052 Naphthalene 094 Endosulfan sulfate 011 1,1,1-trichloreothane 053 Nitrobenzene 095 Endrin 012 Hexachloroethane 054 2-nitrophenol 096 Endrin aldehyde 013 1,1-dichloroethane 055 4-nitrophenol 097 Heptachlor 014 1,1,2-trichloroethane 056 2,4-dinitrophenol 098 Heptachlor epoxide 015 1,1,2,2-tetrachloroethane 057 4,6-dinitro-o-cresol 099 Alpha-BHC 016 Chloroethane 058 N-nitrosodimethylamine 100 Beta-BHC 017 Bis(2-chloroethyl) ether 059 N-nitrosodiphenylamine 101 Gamma-BHC 018 2-chloroethyl vinyl ethers 060 N-nitrosodi-n-propylamine 102 Delta-BHC 019 2-chloronaphthalene 061 Pentachlorophenol 103 PCB–1242 020 2,4,6-trichlorophenol 062 Phenol 104 PCB–1254 021 Parachlorometa cresol 063 Bis(2-ethylhexyl) phthalate 105 PCB–1221 022 Chloroform 064 Butyl benzyl phthalate 106 PCB–1232 023 2-chlorophenol 065 Di-N-Butyl Phthalate 107 PCB–1248 024 1,2-dichlorobenzene 066 Di-n-octyl phthalate 108 PCB–1260 025 1,3-dichlorobenzene 067 Diethyl Phthalate 109 PCB–1016 026 1,4-dichlorobenzene 068 Dimethyl phthalate 110 Toxaphene 027 3,3-dichlorobenzidine 069 Benzo(a) anthracene 111 Antimony 028 1,1-dichloroethylene 070 Benzo(a)pyrene 112 Arsenic 029 1,2-trans-dichloroethylene 071 Benzo(b) fluoranthene 113 Asbestos 030 2,4-dichlorophenol 072 Benzo(b) fluoranthene 114 Beryllium 031 1,2-dichloropropane 073 Chrysene 115 Cadmium 032 1,2-dichloropropylene 074 Acenaphthylene 116 Chromium 033 2,4-dimethylphenol 075 Anthracene 117 Copper 034 2,4-dinitrotoluene 076 Benzo(ghi) perylene 118 Cyanide, Total 035 2,6-dinitrotoluene 077 Fluorene 119 Lead 036 1,2-diphenylhydrazine 078 Phenanthrene 120 Mercury 037 Ethylbenzene 079 Dibenzo(,h) anthracene 121 Nickel 038 Fluoranthene 080 Indeno (1,2,3-cd) pyrene 122 Selenium 039 4-chlorophenyl phenyl ether 081 Pyrene 123 Silver 040 4-bromophenyl phenyl ether 082 Tetrachloroethylene 124 Thallium 041 Bis(2-chloroisopropyl) ether 083 Toluene 125 Zinc 042 Bis(2-chloroethoxy) methane 084 Trichloroethylene 126 2,3,7,8-TCDD
3 The list of pollutants is current as of the Federal Register dated April 2, 2001.
6-15 Protecting Surface Water—Protecting Surface Water
municipalities often require the use of sedi- from active areas of a landfill or waste pile ment and erosion controls at any construc- should be managed as leachate. You should tion site disturbing greater than a certain design a leachate collection and removal sys- number of acres, and can have additional tem to handle the potentially contaminated requirements in especially sensitive water- runoff, in addition to the leachate that might sheds. You should consult with the state and be generated by the unit. You should segre- local regulatory agencies to determine the gate noncontact runoff to reduce the volume sediment and erosion control requirements that will need to be treated as leachate. The for construction. Multi-Sector General Permit does not autho- rize discharges of leachate which includes Once a waste management unit has been storm water that comes in contact with constructed, permanent run-on and runoff waste. The discharge of leachate would be controls are necessary to protect surface regulated under either an individually drafted water. Run-on controls are designed to pre- NPDES permit with site- specific discharge vent storm water from entering the active limitations, or an alternative NPDES general areas of units. If run-on is not prevented permit if one is available. Note that for land from entering active areas, it can seep into application sites, runoff from the site can also the waste and increase the amount of adversely affect nearby surface water if pollu- leachate that must be managed. It can also tants are picked up and carried overland. deposit pollutants from nearby sites, such as pesticides from adjoining farms, further bur- BMPs are measures used to reduce or dening treatment systems. Excessive run-on eliminate pollutant releases to surface waters can also damage earthen containment sys- via overland flow. They fall into three cate- tems, such as dikes and berms. Run-on that gories, baseline, activity-specific, and site- contacts the waste can carry pollutants into specific, and can take the form of a process, receiving waters through overland runoff or activity, or physical structure. The use of into ground water through infiltration. You can divert run-on to the waste management unit by taking advantage of natural contours Why are “run-on” controls necessary? in the land or by constructing ditches or Run-on controls are designed to pre- berms designed to intercept and drain storm vent: 1) contamination of storm water, water away from the unit. Run-on diversion 2) erosion that can damage the physical systems should be designed to handle the structure of units, 3) surface discharge peak discharge of a design storm event (e.g., of waste constituents, 4) creation of a 24-hour, 25-year storm4). Also note that leachate, and 5) already contaminated surface impoundments should be designed surface water from entering the unit. with sufficient freeboard and adequate capac- ity to accommodate not only waste, but also What is the purpose of a “runoff” precipitation and run-on. control system? Runoff controls can channel, divert, and Runoff control systems are designed convey storm water to treatment facilities or, to collect and control at a minimum the if appropriate, to other intended discharge water flow resulting from a storm event points. Runoff from landfills, land treatment of a specified duration, such as a 24- units, or waste piles should be managed as a hour, 25-year storm event. potentially contaminated material. The runoff
4 This discharge is the amount of water resulting from a 24-hour rainfall event of a magnitude with a 4 percent statistical likelihood of occurring in any given year (i.e, once every 25 years). Such an event 6-16 might not occur in a given 25-year period, or might occur more than once during a single year. Protecting Surface Water—Protecting Surface Water
BMPs to protect surface water should be con- while designing and constructing a new waste sidered in both the design and operation of a management unit to ensure that the proper waste management unit. Before identifying baseline, activity-specific, and site-specific and implementing BMPs, you should assess BMPs are implemented and installed from the the potential sources of storm-water contami- start of operations. After assessing the poten- nation including possible erosion and sedi- tial and existing sources of storm-water conta- ment discharges caused by storm events. A mination, the next step is to select appropriate thorough assessment of a waste management BMPs to address these contamination sources. unit involves several steps including creating a map of the waste management unit area; considering the design Figure 1. BMP Identification and Selection Flow Chart of the unit; identifying areas Recommended Steps where spills, leaks, or discharges could or do occur; inventorying the types of wastes contained in Assessment Phase the unit; and reviewing current Develop a site map operating practices (refer to Inventory and describe exposed materials List significant spills and leaks Chapter 8–Operating the Waste Identify areas associated with industrial activity Management System for more Test for nonstorm-water discharges information). Figure 1 illustrates Evaluate monitoring/sampling data if appropriate the process of identifying and (see Chapter 9–Monitoring Performance) selecting the most appropriate BMPs. Designing a storm-water BMP Identification Phase management system to protect Operational BMPs surface water involves knowl- Source control BMPs edge of local precipitation pat- Erosion and sediment control BMPs terns, surrounding topographic Treatment BMPs features, and geologic condi- Innovative BMPs tions. You should consider sam- pling runoff to ascertain the quantity and concentration of Implementation Phase pollutants being discharged. Implement BMPs (Refer to the Chapter 9– Train employees Monitoring Performance for more information). Collecting and evaluating this type of infor- Evaluation/Monitoring Phase mation can help you to select Conduct semiannual inspection/BMP evaluation (see the most appropriate BMPs to Chapter 8–Operating the Waste Management System) prevent or control pollutant dis- Conduct recordkeeping charges. The same considera- Monitor surface water if appropriate tions (e.g., types of wastes to be Review and revise plan contained in the unit, precipita- tion patterns, local topography Adapted from U.S. EPA, 1992e. and geology) should be made
6-17 Protecting Surface Water—Protecting Surface Water
1. Baseline BMPs should be developed to prevent any acciden- These practices are, for the most part, tal releases from reaching surface water. inexpensive and relatively simple. They focus Mitigation practices. These practices con- on preventing circumstances that could lead tain, clean-up, or recover spilled, leaked, or to surface-water contamination before it can loose material before it can reach surface occur. Many industrial facilities already have water and cause contamination. Other BMPs these measures in place for product loss pre- should be considered and implemented to vention, accident and fire prevention, worker avoid releases, but procedures for mitigation health and safety, or compliance with other should be devised so that unit personnel can regulations (refer to Chapter 8–Operating the react quickly and effectively to any releases Waste Management System for more informa- that do occur. Mitigation practices include tion). Baseline BMPs include the measures sweeping or shoveling loose waste into summarized below. appropriate areas of the unit; vacuuming or Good housekeeping. A clean and orderly pumping spilled materials into appropriate work environment is an effective first step treatment or handling systems; cleaning up toward preventing contamination of run-on liquid waste or leachate using sorbents such and runoff. You should conduct an inventory as sawdust; and applying gelling agents to of all materials and store them so as to pre- prevent spilled liquid from flowing towards vent leaks and spills and, if appropriate, surface water. maintain them in areas protected from pre- Training employees to operate, inspect, cipitation and other elements. and maintain surface-water protection mea- Preventive maintenance. A maintenance sures is itself considered a BMP, as is keeping program should be in place and should records of installation, inspection, mainte- include inspection, upkeep, and repair of the nance, and performance of surface-water pro- waste management unit and any measures tection measures. For more information on specifically designed to protect surface water. employee training and record keeping, refer to Chapter 8–Operating the Waste Visual inspections. Inspections of sur- Management System. face-water protection measures and waste management unit areas should be conducted to uncover potential problems and identify 2. Activity-Specific BMPs necessary changes. Areas deserving close After assessment and implementation of attention include previous spill locations; baseline BMPs, you should also consider material storage, handling, and transfer areas; planning for activity-specific BMPs. Like and waste storage, treatment, and disposal baseline BMPs, they are often procedural areas. Any problems such as leaks or spills rather than structural or physical measures, that could lead to surface-water contamina- and they are often inexpensive and easy to tion should be corrected as soon as practical. implement. In the BMP manual for industrial facilities, Storm Water Management for Spill prevention and response. General Industrial Activities: Developing Pollution operating practices for safety and spill pre- Prevention Plans and Best Management Practices vention should be established to reduce acci- (U.S. EPA, 1992f), EPA developed activity- dental releases that could contaminate specific BMPs for nine industrial activities, run-on and runoff. Spill response plans including waste management. The BMPs that
6-18 Protecting Surface Water—Protecting Surface Water
are relevant to waste management are sum- sion, exposure minimization, erosion and marized below. sedimentation prevention, infiltration, and Preventing waste leaks and dust emis- other prevention practices. For many of the surface-water protection measures described sions due to vehicular travel. To prevent in this section, it is important to design for an leaks, you should ensure that trucks moving appropriate storm event (i.e., structures that waste into and around a waste management control run-on and runoff should be designed unit have baffles (if they carry liquid waste) for the discharge of a 24-hour, 25-year storm or sealed gates, spill guards, or tarpaulin cov- event). ers (if the waste is solid or semisolid). To minimize tracking dust off site where it can When selecting and designing surface- be picked up by storm water, wash trucks in water protection measures or systems, you a curbed truck wash area where wash water should consult state, regional, and local is captured and properly handled. For more watershed management organizations. Some information on these topics, consult Chapter of these organizations maintain management 8–Operating the Waste Management System . plans devised at the overall watershed level You should be aware that washwater from that address storm-water control. Thus, these vehicle and equipment cleaning is considered agencies might be able to offer guidance in to be “process wastewater,” and is not eligible developing surface-water protection systems for discharge under the Multi-Sector General for optimal coordination with other dis- Permit program for industrial storm-water charges in the watershed. Again, after site- discharges. Such discharges would require specific BMPs have been installed, you should coverage under either a site-specific individ- evaluate the effectiveness of the selected ual NPDES permit or an NPDES general BMPs on a regular basis to ensure that they storm-water permit. are functioning properly . For land application, choosing appropri- ate slopes. You should minimize runoff by designing a waste management unit site with slopes less than six percent. Moderate slopes help reduce storm-water runoff velocity which encourages infiltration and reduces BMP Maintenance erosion and sedimentation. Note that storm- BMPs must be maintained on a regu- water discharges from land application units lar basis to ensure adequate surface- are regulated under the Multi-Sector General water protection. Maintenance is Permit program. important because storms can damage surface-water protection measures such 3. Site-Specific BMPs as storage basin embankments or spill- In addition to baseline and activity-specific ways. Runoff can also cause sediments BMPs, you should also consider site-specific to settle in storage basins or ditches and BMPs, which are more advanced measures can carry floatables (i.e., tree branches, tailored to specific pollutant sources at a par- lumber, leaves, litter) to the basin. ticular waste management unit and usually Facilities might need to repair storm- consist of the installation of structural or water controls and periodically remove physical measures. These site-specific BMPs sediment and floatables. can be grouped into five areas: flow diver-
6-19 Protecting Surface Water—Protecting Surface Water
a. Flow Diversion What are some advantages of Flow diversion can be used to protect sur- conveyances? face water in two ways. First, it can channel storm water away from waste management Conveyances direct storm-water flows units to minimize contact of storm water around industrial areas, waste manage- with waste. Second, it can carry polluted or ment units, or other waste containment potentially polluted materials to treatment areas to prevent temporary flooding; facilities. Flow diversion mechanisms include require little maintenance; and provide storm-water conveyances and diversion long-term control of storm-water flows. dikes. What are some disadvantages of Storm-Water Conveyances (Channels, Gutters, conveyances? Drains, and Sewers) Conveyances require routing through Storm-water conveyances, such as chan- stabilized structures to minimize erosion. nels, gutters, drains, and sewers, can prevent They also can increase flow rates, might storm-water run-on from entering a waste be impractical if there are space limita- management unit or runoff from leaving a tions, and might not be economical. unit untreated. Some conveyances collect storm water and route it around waste man- agement units or other waste containment veyances should be designed with a capacity areas to prevent contact with the waste, to accept the estimated storm-water flow which might otherwise contaminate storm associated with the selected design storm water with pollutants. Other conveyances event. Section V of this chapter discusses collect water that potentially came into con- methods for determining storm water flow. tact with the waste management unit and carry it to a treatment plant (or possibly back Diversion Dikes to the unit for reapplication in the case of Diversion dikes, often made with compact- land application units, some surface ed soil, direct run-on away from a waste man- impoundments, and leachate-recirculating agement unit. Dikes are built uphill from a landfills). Conveyances should not mix the unit and usually work with storm-water con- stream of storm water diverted around the veyances to divert storm water from the unit. unit with that of water that might have con- To minimize the potential for erosion, diver- tacted waste. Remember, storm water that sion dikes are often constructed to redirect contacts waste is considered leachate and can runoff at a shallow slope to minimize its only be discharged in accordance with an velocity. A similar means of flow diversion is NPDES permit other than the Multi-Sector grading the area around the waste manage- General Permit. ment unit to keep storm water away from the Storm-water conveyances can be con- area, instead of or in addition to using diver- structed of or lined with materials such as sion dikes to redirect water that would other- concrete, clay tile, asphalt, plastic, metal, wise flow into these areas. In planning for the riprap, compacted soil, and vegetation. The installation of dikes, you should consider the material used will vary depending on the use slope of the drainage area, the height of the of the conveyance and the expected intensity dike, the size of the flow it will need to divert, of storm-water flow. Storm-water con-
6-20 Protecting Surface Water—Protecting Surface Water
and the type of conveyance that will be used with the dike. What are some advantages of diversion dikes? b. Exposure Minimization Diversion dikes limit storm-water flows over industrial site areas; can be Like flow diversion, exposure minimiza- economical, temporary structures when tion practices, such as curbing, diking, and built from soil onsite; and can be con- covering can reduce contact of storm water verted from temporary to permanent at with waste. They often are small structures any time. immediately covering or surrounding a high- er risk area, while flow diversion practices operate on the scale of an entire waste man- What are some disadvantages of agement unit. diversion dikes? Diversion dikes are not suitable for Curbing and Diking large drainage areas unless there is a These are raised borders enclosing areas gentle slope and might require mainte- where liquid spills can occur. Such areas nance after heavy rains. could include waste transfer points in land application, truck washes, and leachate man- iment. Erosion and sedimentation can threaten agement areas at landfills and waste piles. aquatic life, increase treatment costs for down- The raised dikes or curbs prevent spilled liq- stream water treatment plants, and impede uids from flowing to surface waters, enabling recreational and navigational uses of water- prompt cleanup of only a small area. ways. Erosion and sedimentation are of particu- lar concern at waste management units because Covering the sediment can be contaminated with waste Erecting a roof, tarpaulin, or other perma- constituents and because erosion can undercut nent or temporary covering (see Figure 2) or otherwise weaken waste containment struc- over the active area of a landfill or waste tures. Practices such as vegetation, interceptor transfer location can keep precipitation from dikes, pipe slope drains, silt fences, storm drain falling directly on waste materials and pre- inlet protection, collection and sedimentation vent run-on from occurring. If temporary basins, check dams, terraces and benches, and coverings are used, you should ensure that outlet protection can help limit erosion and sufficient weight is attached to prevent wind sedimentation. from moving the cover, and to repair or replace the cover material if holes or leaks Vegetation develop. Erosion and sedimentation can be reduced by ensuring that areas where storm water is c. Erosion and Sedimentation likely to flow are vegetated. Vegetation slows Prevention erosion and sedimentation by shielding soil surfaces from rainfall, improving the soil’s Erosion and sedimentation practices serve to water storage capacity, holding soil in place, limit erosion (the weathering of soil or rock slowing runoff, and filtering out sediment. particles from the ground by wind, water, or One method of providing vegetation is to pre- human activity) and to prevent particles that serve natural growth. This is achieved by are eroded from reaching surface waters as sed-
6-21 Protecting Surface Water—Protecting Surface Water
Figure 2. Coverings mentation in areas that are exposed but will not be disturbed again for a considerable time. These areas include soil stockpiles, temporary roadbanks, and dikes. Local regu- lations might require temporary seeding of areas that would otherwise remain exposed beyond a certain period of time. You should consult local officials to determine whether such requirements apply. Seeding might not be feasible for quickly establishing cover in Roof, overhang, or other arid climates or during nongrowing seasons permanent structure in other climates. Sod, although more expen- sive, can be more tolerant of these conditions than seed and establish a denser grass cover more quickly. Compost used in combination with seeding can also be used effectively to establish vegetation on slopes. Physical and chemical stabilization, and various methods of providing cover are also often considered in conjunction with vegeta- Tarp or other covering tive measures or when vegetative measures cannot be used. Physical stabilization is From U.S. EPA, 1992e. appropriate where stream flow might be increased due to construction or other activi- managing the construction of the waste man- ties associated with the waste management agement unit to minimize disturbance of sur- unit and where vegetative measures are not rounding grass and plants. If it is not possible practical. Stream-bank stabilization might to leave all areas surrounding a unit undis- involve the reinforcement of stream banks turbed, preserve strips of existing vegetation with stones, concrete or asphalt, logs, or as buffer zones in strategically chosen areas of gabions (i.e., structures formed from crushed the site where erosion and sediment control is rock encased in wire mesh). Methods of pro- most needed, such as on steep slopes uphill viding cover such as mulching, compost, mat- of the unit and along stream banks downhill ting, and netting can be used to cover from the unit. If it is not possible to leave suf- surfaces that are steep, arid, or otherwise ficient buffer zones of existing vegetation, you unsuitable for planting. These methods also should create buffer zones by planting such can work in conjunction with planting to sta- areas with new vegetation. bilize and protect seeds. (Mattings are sheets Temporary or permanent seeding of erodi- of mulch that are more stable than loose ble areas is another means of controlling ero- mulch chips. Netting is a mesh of jute, wood sion and sedimentation using vegetation. fiber, plastic, paper, or cotton that can hold Permanent seeding, often of grass, is appro- mulch on the ground or stabilize soils. These priate for establishing long-term ground measures are sometimes used with seeding to cover after construction and other land-dis- provide insulation, protect against birds, and turbing activities are complete. Temporary hold seeds and soil in place.) Chemical stabi- seeding can help prevent erosion and sedi- lization (also known as chemical mulch, soil
6-22 Protecting Surface Water—Protecting Surface Water
binder, or soil palliative) can hold the soil in to accommodate the design storm event and place and protect against erosion by spraying are kept clear of clogs. vinyl, asphalt, or rubber onto soil surfaces. Erosion and sediment control is immediate Silt Fences, Straw Bales, and Brush Barriers upon spraying and does not depend on cli- Silt fences and straw bales (see Figures 3 mate or season. Stabilizer should be applied and 4) are temporary measures designed to according to manufacturer’s instructions to capture sediment that has already eroded and ensure that water quality is not affected. reduce the velocity of storm water. Silt fences Coating large areas with thick layers of stabi- and straw bales should not be considered lizer, however, can create an impervious sur- permanent measures unless fences are main- face and speed runoff to downgradient areas tained on a routine basis and straw bales are and should be avoided. replaced regularly. They could be used, for example, during construction of a waste man- Interceptor Dikes and Swales agement unit or on a final cover before per- Dikes (ridges of compacted soil) and manent grass growth is established. swales (excavated depressions in which storm Silt fences consist of geotextile fabric sup- water flows) work together to prevent entry ported by wooden posts. These fences slow of run-on into erodible areas. A dike is built the flow of storm water and retain sediment as across a slope upgradient of an area to be the water filters through the fabric. If properly protected, such as a waste management unit, installed, straw bales perform a similar func- with a swale just above the dike. Water flows tion. Straw bales should be placed end to end down the slope, accumulates in the swale, (with no gaps in between) in a shallow, exca- and is blocked from exiting it by the dike. vated trench and staked into place. Silt fences The swale is graded to direct water slowly and straw bales limit sediment from entering downhill across the slope to a stabilized out- receiving waters if properly maintained. Both let structure. Since flows are concentrated in measures require frequent inspection and the swale, it is important to vegetate the maintenance, including checking for channels swale to prevent erosion of its channel and to eroded beneath the fence or bales, removing grade it so that predicted flows will not dam- age the vegetation.
Pipe Slope Drains What are some advantages of silt fences, straw bales, and brush barriers? Pipe slope drains are flexible pipes or hoses used to traverse a slope that is already They prevent eroded materials from damaged or at high risk of erosion. They are reaching surface waters and prevent often used in conjunction with some means downstream damage from sediment of blocking water flow on the slope, such as a deposits at minimal cost. dike. Water collects against the dike and is then channeled to one point along the dike What are some disadvantages of silt where it enters the pipe, which conveys it fences, straw bales, and brush barriers? downhill to a stabilized (usually riprap-lined) These measures are not appropriate outlet area at the bottom of the slope. You for streams or large swales and pose a should ensure that pipes are of adequate size risk of washouts if improperly installed.
6-23 Protecting Surface Water—Protecting Surface Water
accumulated sediment, and replacing dam- Figure 3. Silt Fence aged or deteriorated sections. Brush barriers work like silt fences and straw bales but are constructed of readily available materials. They consist of brush and other vegetative debris piled in a row and are often covered with filter fabric to hold them in place and increase sediment interception. Brush barriers are inexpensive due to their reuse of material that is likely available from clearing the site. New vegetation often grows in the organic material of a brush barrier, helping anchor the barrier with roots. Depending on the material used, it might be possible to leave a former brush barrier in place and allow it to biodegrade, rather than remove it.
Storm Drain Inlet Protection Bottom: Perspective of silt fence. Top: Cross- Filtering measures placed around inlets or section detail of base of silt fence. drains to trap sediment are known as inlet From U.S. EPA, 1992e. protection (see Figure 5). These measures prevent sediment from entering inlets or Figure 4. Straw Bale drains and possibly making their way to the receiving waters into which the storm drainage system discharges. Keeping sediment out of storm-water drainage systems also serves to prevent clogging, loss of capacity, and other problems associated with siltation of drainage structures. Inlet protection meth- ods include sod, excavated areas for settle- ment of sediment, straw bales or filter fences, and gravel or stone with wire mesh. These measures are appropriate for inlets draining From U.S. EPA, 1992e. small areas where soil will be disturbed. Some state or local jurisdictions require installation enough to allow most of the sediment to set- of these measures before disturbance of more tle out and accumulate on the bottom of the than a certain acreage of land begins. Regular basin. Since many pollutants are attached to maintenance to remove accumulated sedi- suspended solids, they will also settle out in ment is important for proper operation. the basin with the sediment. The quantity of sediment removed will depend on basin vol- Collection and Sedimentation Basins ume, inlet and outlet configuration, basin A collection or sedimentation basin (see depth and shape, and retention time. Regular Figure 6) is an area that retains runoff long maintenance and dredging to remove accu-
6-24 Protecting Surface Water—Protecting Surface Water
mulated sediment and to minimize growth of aquatic plants that can reduce effectiveness is What are some advantages of critical to the operation of basins. All dredged sedimentation basins? materials, whether they are disposed or They protect downstream areas against reused, should be managed appropriately. clogging or damage and contain smaller Basins can also present a safety hazard. sediment particles than sediment traps Fences or other measures to prevent unwant- can due to their longer retention time. ed public access to the basins and their associ- ated inlet and outlet structures are prudent What are some disadvantages? safety precautions. In designing collection or Sedimentation basins are generally sedimentation basins (a form of surface not suitable for large areas, require regu- impoundment), consider storm- water flow, lar maintenance and cleaning, and will sediment and pollutant loadings, and the not remove very fine silts and clays characteristics of expected pollutants. In the unless used with other measures. case of certain pollutants, it might be appro- priate to line the basins to protect the ground water below. Lining a basin with concrete also dredging of settled materials. For this reason, facilitates maintenance by allowing dredging when operating sedimentation basins, it is vehicles to drive into a drained basin and important that baseline and activity-specific remove accumulated sediment. Poor imple- BMPs are being implemented properly. We mentation of baseline and activity-specific recommend that construction of these basins BMPs can result in high sediment and pollu- be supervised by a qualified engineer familiar tant loads, leading to unusually frequent with state and local storm-water requirements.
Figure 5. Storm Drain Inlet Protection Check Dams Small rock or log dams erected across a ditch, swale, or channel can reduce the speed of water flow in the con- veyance. This reduces erosion and also allows sediment to settle out along the channel. Check dams are especially use- ful in steep, fast-flowing swales where vegetation cannot be established. For best results, it is rec- ommended that you place check dams along the swale so that the crest From U.S. EPA, 1992e. of each check dam is at the same elevation as the toe (lowest point) of the
6-25 Protecting Surface Water—Protecting Surface Water
previous (upstream) check dam. Check dams Outlet Protection work best in conveyances draining small Stone, riprap, pavement, or other stabi- areas and should be installed only in man- lized surfaces placed at a storm-water con- made conveyances. Placement of check dams veyance outlet are known as outlet protection in streams is not recommended and might (see Figure 7). Outlet protection reduces the require a permit. speed of concentrated storm-water flows exit- ing the outlet, lessening erosion and scouring Terraces and Benches of channels downstream. It also removes sed- Terraces and benches are earthen embank- iment by acting as a filter medium. It is rec- ments with flat tops or ridge-and-channels. ommended that you consider installing outlet Terraces and benches hold moisture and protection wherever predicted outflow veloci- minimize sediment loading in runoff. They ties might cause erosion. can be used on land with no vegetation or where it is anticipated that erosion will be a d. Infiltration problem. Terraces and benches reduce ero- Infiltration measures such as vegetated fil- sion damage by capturing storm-water runoff ter strips, grassed swales, and infiltration and directing it to an area where the runoff trenches encourage quick infiltration of will not cause erosion or damage. For best storm water into the ground rather than results, this area should be a grassy waterway, allowing it to remain as overland flow. vegetated area, or tiled outlet. Terraces and Infiltration not only reduces runoff velocity, benches might not be appropriate for use on but can also provide some treatment of sandy or rocky slopes. runoff, preserve natural stream flow, and recharge ground water. Infiltration measures can be inappropriate on unstable slopes or in Figure 6. cases where runoff might be contaminated, Collection and Sedimentation Basin
What are some advantages of terraces and benches? Terraces and benches reduce runoff speed and increase the distance of over- land runoff flow. In addition, they hold moisture better than do smooth slopes and minimize sediment loading in runoff.
What are some disadvantages of terraces and benches? Terraces and benches can significantly increase cut and fill costs and cause sloughing if excess water infiltrates the soil. They are not practical for sandy, steep, or shallow soils. From U.S. EPA, 1992e.
6-26 Protecting Surface Water—Protecting Surface Water
or where wells, foundations, or septic fields feet deep. It is filled with stone to allow for are nearby. temporary storage of storm water in the open spaces between the stones. The water eventu- Vegetated Filter Strips and Grassed Swales ally infiltrates the surrounding soil or is col- lected by perforated pipes in the bottom of Vegetated filter strips are gently sloped the trench and conveyed to an outflow point. areas of natural or planted vegetation. They Such trenches can remove fine sediments and allow water to pass over them in sheetflow (runoff that flows in a thin, even layer), infil- Figure 7. Outlet Protection trate the soil, and drop sediment. Vegetated filter strips are appropriate where soils are well draining and the ground-water table is deep below the surface. They will not work effectively on slopes of 15 percent or more due to high runoff velocity. Strips should be at least 20 feet wide and 50 to 75 feet long in general, and longer on steeper slopes. If pos- sible, it is best to leave existing natural vege- tation in place as filter strips, rather than planting new vegetation, which will not func- tion to capture eroded particles until it becomes established. Grassed swales function similarly to non- vegetated swales (discussed earlier in this chapter) except that grass planted along the swale bottom and sides will slow water flow and filter out sediment. Permeable soil in which the swale is cut encourages reduction of water volume through infiltration. Check dams (discussed earlier in this chapter) are sometimes provided in grassed swales to fur- ther slow runoff velocity, increasing the rate of infiltration. To optimize swale performance, it is best to use a soil which is permeable but not excessively so; very sandy soils will not hold vegetation well and will not form a stable channel structure. It is also recommended that you grade the swale to a very gentle slope to maximize infiltration.
Infiltration Trenches An infiltration trench (see Figure 8) is a From U.S. EPA, 1992e. long, narrow excavation ranging from 3 to 12
6-27 Protecting Surface Water—Protecting Surface Water
soluble pollutants. They should not be built Figure 8. Infiltration Trench in relatively impervious soils, such as clay, that would prevent water from draining from the bottom of the trench; less than 3 feet above the water table; in soil that is subject to deep frost penetration; or at the foot of slopes steeper than 5 percent. Infiltration trenches should not be used to handle conta- minated runoff. Runoff can be pretreated using a grass buffer/filter strip or treated in the trench with filter fabric.
e. Other Practices From U.S. EPA, 1992e.
Additional practices exist that can help distribution and storage systems at land prevent contamination of surface water such application units, and contaminated runoff as preventive monitoring, dust control, vehi- conveyances. cle washing, and discharge to wetlands. Many of these practices are simple and inex- pensive to implement while others, such as Dust Control monitoring, can require more resources. In addition to being an airborne pollutant, dust can settle in areas where it can be Preventive Monitoring picked up by runoff or can be transported by air and deposited directly into surface waters. Preventive monitoring includes automatic Dust particles can carry pollutants and can and control systems, monitoring of opera- also result in sedimentation of waterbodies. tions by waste management unit personnel, Several methods of dust control are available and testing of equipment. These processes to prevent this. These include irrigation, can help to ensure that equipment functions chemical treatments, minimization of as designed and is in good repair so that exposed soil areas, wind breaks, tillage, and spills and leaks, which could contaminate sweeping. For further information on dust adjacent surface waters, are minimized and control, consult Chapter 8–Operating the do not go undetected when they do occur. Waste Management System. Some automatic monitoring equipment, such as pressure gauges coupled with pressure relief devices, can correct problems without Vehicle Washing human intervention, preventing leaks or Materials that accumulate on tires and other spills that could contaminate surface water if vehicle surfaces and then disperse across a allowed to occur. Other monitoring equip- facility are an important source of surface- ment can provide early warning of problems water contamination. Vehicle washing removes so that personnel can intervene before leaks materials such as dust and waste. Washing sta- or spills occur. Systems that could contami- tions can be located near waste transfer areas nate surface water if they failed and that or near the waste management site exit. could benefit from automatic monitoring or Pressurized water spray is usually sufficient to early warning devices include leachate remove dust. Waste water from vehicle wash- pumping and treatment systems, liquid waste ing operations should be contained and han-
6-28 Protecting Surface Water—Protecting Surface Water
dled appropriately. Discharge of such waste provisions for a dry-weather flow to maintain water requires an NPDES permit other than the wetlands, 3) measures to limit mosquito the Multi-Sector General Permit. breeding, 4) structures to prevent escape of floating wetland plants (such as water Discharges to Wetlands hyacinths) into downstream areas where they are undesirable, and 5) a program of harvest- Discharge to constructed wetlands is a ing and replacing plants. method less frequently used and can involve complicated designs. The discharge of storm water into natural wetlands, or the modifica- B. Controls to Address tion of wetlands to improve their treatment Surface-water capacity, can damage a wetland ecosystem and, therefore, is subject to federal, state, and Contamination from local regulations. Ground Water to Constructed wetlands provide an alterna- Surface Water tive to natural wetlands. A specially designed Generally, the use of liners and ground- pond or basin, which is lined in some cases, water monitoring systems will reduce poten- is stocked with wetland plants that can con- tial contamination from ground water to trol sedimentation and manage pollutants surface water. For more information on pro- through biological uptake, microbial action, tecting ground water, refer to Chapter 7: and other mechanisms. Together, these Sections A–Assessing Risk, Section processes often result in better pollutant B–Designing and Installing Liners, and removal than would be expected from sedi- Section C–Designing a Land Application mentation alone. When designing construct- Program. ed wetlands, you should consider 1) that maintenance might include dredging, similar to that required for sedimentation basins, 2) C. Controls to Address Surface-water Contamination from Air What are some advantages of constructed wetlands? to Surface Water Provide aesthetic as well as water qual- Emission control techniques for volatile ity benefits and areas for wildlife habitat. organic compounds (VOC) and particulates can assist in reducing potential contamination of surface water from air. Refer to Chapter What are some disadvantages of 5–Protecting Air Quality, for more informa- constructed wetlands? tion on air emission control techniques. Discharges to wetlands might be sub- ject to multiple federal, state, and local regulations. In addition, constructed wetlands might not be feasible if land is not available and might not be effective as a storm-water control measure until time has been allowed for substantial plant growth.
6-29 Protecting Surface Water—Protecting Surface Water
V. Methods of Rational Method for Calculating Calculating Storm-Water Run-on and Runoff Flow Q = cia Runoff Rates where, The design and operation of surface-water protection systems will be driven by antici- Q = peak flow rate (runoff), expressed in pated storm-water flow. Run-on and runoff cubic feet per second (cfs)* flow rates for the chosen design storm event c = runoff coefficient, unitless. The coeffi- should be calculated in order to: 1) choose cient c is not directly calculable, so the proper type of storm-water controls to average values based on experience install, and 2) properly design the controls are used. Values of c range from 0 (all and size the chosen control measures to min- infiltration, no runoff) to 1 (all imize impacts to surface water. Controls runoff, no infiltration). For example, based on too small a design storm event, or flat lawns with sandy soil have a c sized without calculating flows will not func- value of 0.05 to 0.10, while concrete tion properly and can result in releases of streets have a c value of 0.80 to 0.95. contaminated storm water. Similarly, systems can also be designed for too large a flow, i = average rainfall intensity, expressed resulting in unnecessary control and exces- in inches per hour, for the time of sive costs. concentration, tc, which is a calcula- ble flow time from the most distant The usual approach for sizing surface- point in the drainage area to the water protection systems relies on the use of point at which Q is being calculated. standardized “design storms.” A design storm Once tc is calculated and a design is, in theory, representative of many recorded storm event frequency is selected, i storms and reflects the intensity, volume, and can be obtained from rainfall inten- duration of a storm predicted to occur once sity-duration-frequency graphs (see in a given number of years. In general, sur- Figure 9). face-water protection structures should be designed to handle the discharge from a 24- a = drainage area, expressed in acres. hour, 25-year storm event (i.e., a rainfall The drainage area is the expanse in event of 24 hours duration and of such a which all runoff flows to the point magnitude that it has a 4 percent statistical at which Q is being calculated. likelihood of occurring in any given year). * Examining the units of i and a would Figure 9 presents a typical intensity-duration- indicate that Q should be in units of frequency curve for rainfall events. ac-in/hr. However, since 1 ac-in/hr = The Hydrometeorological Design Studies 1.008 cfs, the units are interchangeable Center (HDSC) at the National Weather with a negligible loss of accuracy. Units Service has prepared Technical Paper 40, of cfs are usually desired for subse- Rainfall Frequency Atlas of the United States for quent calculations. Durations From 30 Minutes to 24 Hours and Return Periods From 1 to 100 Years (published
6-30 Protecting Surface Water—Protecting Surface Water
in 1961). This document contains rainfall Figure 9. Typical Intensity-Duration- intensity information for the entire United Frequency Curves States. Another HDSC document, NOAA Atlas 2, Precipitation Frequency Atlas of the Western United States (published in 1973) comes in 11 volumes, one for each of the 11 westernmost of the contiguous 48 states. Precipitation fre- quency maps for the eleven western most states are available on the Western Regional Climate Center’s Web page at
5 TR-55, Urban Hydrology for Small Watersheds Technical Release 55, presents simplified procedures to calculate storm runoff volume, peak rate of discharge, hydrographs, and storage volumes required for floodwater reservoirs. This software is suited for use in small and especially urbanizing watersheds. TR- 55 can be downloaded from the National Resource Conservation Service at
Storm Water Management Model (SWMM). Simulates the movement of precipitation and pollutants from the ground surface through pipe and channel networks, storage treat- ment units, and receiving waters. BASINS: A Powerful Tool for Managing Watersheds. A multi-purpose environmen- tal analysis system that integrates a geographical information system (GIS), national water- shed data, and state-of-the-art environmental assessment and modeling tools into one package. Source Loading and Management Model (SLAMM). Explores relationships between sources of urban runoff pollutants and runoff quality. It includes a wide variety of source area and outfall control practices. SLAMM is strongly based on actual field observations, with minimal reliance on theoretical processes that have not been adequately documented or confirmed in the field. SLAMM is mostly used as a planning tool, to better understand sources of urban runoff pollutants and their control. Simulation for Water Resources in Rural Basins (SWRRB). Simulates hydrologic, sedimentation, and nutrient and pesticide transport in large, complex rural watersheds. It can predict the effect of management decisions on water, sediment, and pesticide yield with seasonable accuracy for ungauged rural basins throughout the United States. Pollutant Routing Model (P-ROUTE). Estimates aqueous pollutant concentrations on a stream reach by stream reach flow basis, using 7Q10 or mean flow. Enhanced Stream Water Quality Model (QUAL2E). Simulates the major reactions of nutrient cycles, algal production, benthic and carbonaceous demand, atmospheric reaera- tion and their effects on the dissolved oxygen balance. It is intended as a water quality planning tool for developing total maximum daily loads (TMDLs) and can also be used in conjunction with field sampling for identifying the magnitude and quality characteristics of nonpoint sources.
6-32 Protecting Surface Water—Protecting Surface Water
Protecting Surface Water Activity List
You should conduct the following activities when designing or operating surface-water protection measures or systems in conjunction with waste management units. ■ Comply with applicable National Pollutant Discharge Elimination System (NPDES), state, and local permitting requirements. ■ Assess operating practices, identify potential pollutant sources, determine what con- stituents in the unit pose the greatest threats to surface water, and calculate storm- water runoff flows to determine the need for and type of storm-water controls. ■ Choose a design storm event (e.g., a 24-hour, 25-year event) and obtain precipita- tion intensity data for that event to determine the most appropriate storm-water con- trol devices. ■ Select and implement baseline and activity-specific BMPs, such as good housekeep- ing practices and spill prevention and response plans as appropriate for your waste management unit. ■ Select and establish site-specific BMPs, such as diversion dikes, collection and sedi- mentation basins, and infiltration trenches as appropriate for your waste manage- ment unit. ■ Develop a plan for inspecting and maintaining the chosen storm-water controls; if possible, include these measures as part of the operating plan for the waste manage- ment unit.
6-33 Protecting Surface Water—Protecting Surface Water
Resources
Dingman, S. 1994. Physical Hydrology. Prentice Hall.
Florida Department of Environmental Regulation. Storm Water Management: A Guide for Floridians.
Novotny, V., and H. Olem. 1994. Water Quality: Prevention, Identification, and Management of Diffuse Pollution. Van Nostrand Reinhold.
Pitt, R. 1988. Source Loading and Management Model: An Urban Nonpoint Source Water Quality Model (SLAMM). University of Alabama at Birmingham.
McGhee, T. 1991. McGraw-Hill Series in Water Resources and Environmental Engineering. 6th Ed.
Urbonas, B., and P. Stahre. 1993. Storm Water: Best Management Practices and Detention for Water Quality, Drainage, and CSO Management. PTR Prentice Hall.
U.S. EPA. 1999. Introduction to the National Pretreatment Program. EPA833-B-98-002.
U.S. EPA. 1998. Water Quality Criteria and Standards Plan–Priorities for the Future. EPA822-R-98-003.
U.S. EPA. 1995a. Process Design Manual: Land Application of Sewage Sludge and Domestic Septage. EPA625- R-95-001.
U.S. EPA. 1995b. Process Design Manual: Surface Disposal of Sewage Sludge and Domestic Septage. EPA625- R-95-002.
U.S. EPA. 1995c. NPDES Storm Water Multi-Sector General Permit Information Package.
U.S. EPA. 1995d. Storm Water Discharges Potentially Addressed by Phase II of the National Pollutant Discharge Elimination System Storm Water Program. Report to Congress. EPA833-K-94-002.
U.S. EPA. 1994a. Introduction to Water Quality Standards. EPA823-B-95-004.
U.S. EPA. 1994b. Project Summary: Potential Groundwater Contamination from Intentional and Non- Intentional Storm Water Infiltration. EPA600-SR-94-061.
U.S. EPA. 1994c. Storm Water Pollution Abatement Technologies. EPA 600-R-94-129.
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Resources (cont.)
U.S. EPA. 1993a. Overview of the Storm Water Program. EPA833-F-93-001.
U.S. EPA. 1993b. NPDES Storm Water Program: Question and Answer Document, Volume 2. EPA833- F093-002B.
U.S. EPA. 1992a. An Approach to Improving Decision Making in Wetland Restoration and Creation. EPA600-R-92-150.
U.S. EPA. 1992b. NPDES Storm Water Program: Question and Answer Document, Volume 1. EPA833-F- 93-002.
U.S. EPA. 1992c. NPDES Storm Water Sampling Guidance Document. EPA833-B-92-001.
U.S. EPA. 1992d. Storm Water General Permits Briefing. EPA833-E-93-001.
U.S. EPA. 1992e. Storm Water Management for Industrial Activities: Developing Pollution Prevention Plans and Best Management Practices. EPA832-R-92-006.
U.S. EPA. 1992f. Storm Water Management for Industrial Activities: Developing Pollution Prevention Plans and Best Management Practices. Summary Guidance. EPA833-R-92-002.
Viessman Jr., W., and M.J. Hammer. 1985. Water Supply and Pollution Control. 4th Ed.
Washington State Department of Ecology. 1993. Storm Water Pollution Prevention Planning for Industrial Facilities: Guidance for Developing Pollution Prevention Plans and Best Management Practices. Water Quality Report. WQ-R-93-015. September.
6-35 Part IV Protecting Ground-Water Quality
Chapter 7: Section A Assessing Risk Contents
I. Assessing Risk ...... 7A-3 A. General Overview of the Risk Assessment Process ...... 7A-3 1. Problem Formulation ...... 7A-3 2. Exposure Assessment ...... 7A-4 3. Toxicity Assessment ...... 7A-5 4. Risk Characterization ...... 7A-5 B. Ground-Water Risk...... 7A-6 1. Problem Formulation ...... 7A-6 2. Exposure Assessment ...... 7A-7 3. Toxicity Assessment ...... 7A-11 4.Risk Characterization...... 7A-12
II. The IWEM Ground-Water Risk Evaluation ...... 7A-14 A. The Industrial Waste Management Evaluation Model (IWEM) ...... 7A-15 1. Leachate Concentrations...... 7A-16 2. Models Associated with IWEM...... 7A-16 3. Important Concepts for Use of IWEM ...... 7A-18 B. Tier 1 Evaluations...... 7A-22 1. How Are the Tier 1 Lookup Tables Used? ...... 7A-23 2. What Do the Results Mean and How Do I Interpret Them? ...... 7A-25 C. Tier 2 Evaluations...... 7A-27 1. How is a Tier 2 Analysis Performed? ...... 7A-27 2. What Do the Results Mean and How Do I Interpret Them? ...... 7A-32 D. Strengths and Limitations ...... 7A-34 1. Strengths ...... 7A-34 2. Limitations ...... 7A-34 E. Tier 3: A Comprehensive Site-Specific Evaluation ...... 7A-35 1. How is a Tier 3 Evaluation Performed?...... 7A-35
Assessing Risk Activity List ...... 7A-40
Resources ...... 7A-41
Tables: Table 1. Earth’s Water Resources ...... 7A-1 Table 2. Examples of Attenuation Processes ...... 7A-10 Table 3. List of Constituents in IWEM with Maximum Contaminant Levels (MCLs) ...... 7A-13 Contents
Table 4. Example of Tier 1 Summary Table for MCL-based LCTVs for Landfill - No Liner/In situ Soils ..7A-24 Table 5. Example of Tier 1 Summary Table for HBN-based LCTVs for Landfill - No Liner/In situ Soils 7A-25 Table 6. Example of Tier 1 Summary Table for MCL-based LCTVs for Landfill - Single Clay Liner ...... 7A-25 Table 7. Example of Tier 1 Summary Table for MCL-based LCTVs for Landfill - Composite Liner ...... 7A-25 Table 8. Input Parameters for Tier 2 ...... 7A-29 Table 9. A Sample Set of Site-Specific Data for Input to Tier 2 ...... 7A-31 Table 10. Example of Tier 2 Detailed Summary Table - No Liner/In situ Soils ...... 7A-31 Table 11. Example of Tier 2 Detailed Summary Table - Single Clay Liner...... 7A-32 Table 12. Example Site-Specific Ground-water Fate and Transport Models...... 7A-38 Table 13. ASTM Ground-Water Modeling Standards ...... 7A-39
Figures: Figure 1: Representation of Contaminant Plume Movement ...... 7A-5 Figure 2: Three Liner Scenarios Considered in the Tiered Modeling Approach for Industrial Waste Guidelines ...... 7A-22 Figure 3: Using Tier 1 Lookup Tables...... 7A-27 Protecting Ground Water—Assessing Risk
Assessing Risk This chapter will help you: • Protect ground water by assessing risks associated with new waste management units and tailoring management controls accordingly. • Understand the three-tiered evaluation discussed in this chapter that can be used to determine whether a liner system is necessary, and if so, which liner system is recommended, or whether land application is appropriate. • Follow guidance on liner design and land application practices.
round water is Table 1. the water found Earth’s Water Resources in the soil and rock that make Resource Percent of Percent of up the Earth’s Total Nonoceanic Gsurface. Although it com- Oceans 97.25 — prises only about 0.69 per- cent of the Earth’s water Ice caps and glaciers 2.05 74.65 resources, ground water is of Ground water and soil moisture 0.685 24.94 great importance. It repre- Lakes and rivers 0.0101 0.37 sents about 25 percent of fresh water resources, and Atmosphere 0.001 0.036 when the largely inaccessible Biosphere 0.00004 0.0015 fresh water in ice caps and glaciers is discounted, Adapted from Berner, E.K. and R. Berner. 1987. The Global ground water is the Earth’s Water Cycle: Geochemistry and Environment largest fresh water resource—easily surpassing percent of the total water used by industry.2 lakes and rivers, as shown in Table 1. Ground water also has other important environ- Statistics about the use of ground water as a mental functions, such as providing recharge to drinking water source underscore the impor- lakes, rivers, wetlands, and estuaries. tance of this resource. Ground water is a source of drinking water for more than half of Water beneath the ground surface occurs in the people in the United States.1 In rural an upper unsaturated (vadose) zone and a areas, 97 percent of households rely on deeper saturated zone. The unsaturated zone ground water as their primary source of is the area above the water table where the drinking water. soil pores are not filled with water, although some water might be present. The subsurface In addition to its importance as a domestic area below the water table where the pores water supply, ground water is heavily used by and cracks are filled with water is called the industry and agriculture. It provides approxi- saturated zone. This chapter focuses on mately 37 percent of the irrigation water and 18
1 Surface water, in the form of lakes and rivers, is the other major drinking water source. Speidel, D., L. Ruedisili, and A. Agnew. 1988. Perspectives on Water: Uses and Abuses. 2 Excludes cooling water for steam-electric power plants. U.S. Geological Survey. 1998. Estimated Use of 7A-1 Water in the United States in 1995. Protecting Ground Water—Assessing Risk
ground water in the saturat- ed zone, where most ground-water withdrawals are made. Because ground water is a major source of water for Precipitation
Infiltration drinking, irrigation, and Evaporation
process water, many different Transpiration Percolation parties are concerned about Runoff ground-water contamination, Unsaturated including the public; indus- Well Zone Water Table try; and federal, state, and local governments. Many Groundwater Runoff potential threats to the quali- Saturated ty of ground water exist, Zone Groundwater Lake Flow such as the leaching of fertil- Groundwater flow izers and pesticides, contam- to lakes and streams ination from faulty or overloaded septic fields, and Ground Water in the Hydrologic Cycle releases from industrial facil- The hydrologic cycle involves the continuous movement of ities, including waste man- water between the atmosphere, surface water, and the agement units. ground. Ground water must be understood in relation to If a source of ground both surface water and atmospheric moisture. Most addi- water becomes contaminat- tions (recharge) to ground water come from the atmosphere ed, remedial action and in the form of precipitation, but surface water in streams, monitoring can be costly. rivers, and lakes will move into the ground-water system Remediation can require wherever the hydraulic head of the water surface is higher years of effort, or in some than the water table. Most water entering the ground as pre- circumstances, might be cipitation returns to the atmosphere by evapotranspiration. technically infeasible. For Most water that reaches the saturated zone eventually these reasons, preventing returns to the surface by flowing to points of discharge, ground-water contamination such as rivers, lakes, or springs. Soil, geology, and climate is important, or at least min- will determine the amounts and rates of flow among the imizing impacts to ground atmospheric, surface, and ground-water systems. water by implementing con- trols tailored to the risks associated with the waste. Industrial Waste Management Evaluation Model (IWEM), which was developed as part This chapter addresses how ground-water of this Guide. Additionally, the chapter dis- resources can be protected through the use of cusses the use of this tool and how to apply a systematic approach of assessing potential its results and recommendations. It is highly risk to ground water from a proposed waste recommended that you also consult with your management unit (WMU). It discusses assess- state regulatory agency, as appropriate. More ing risk and the three-tiered ground-water risk specific information on the issues described in assessment approach implemented in the
7A-2 Protecting Ground Water—Assessing Risk
this chapter is available in the companion in the future, and the likelihood that such documents to the IWEM software: User’s contact will harm these people. This process Guide for the Industrial Waste Management shows how great (or small) the risks might Evaluation Model (U.S. EPA, 2002b), and be. It also points to who is at risk, what is Industrial Waste Management Evaluation Model causing the risk, and how certain one can be (IWEM) Technical Background Document (U.S. about the risks. A general overview of these EPA, 2002a). steps is presented below to help explain how the process is used in performing the assess- ments associated with IWEM. The compo- nents of a risk assessment that are discussed I. Assessing Risk in this section are: problem formulation, exposure assessment, toxicity assessment, and A. General Overview of the risk characterization. Each of these steps is Risk Assessment Process described as it specifically applies to risk resulting from the release of chemical con- Our ground-water resources are essential stituents from WMUs to ground water. for biotic life on the planet. They also act as a medium for the transport of contaminants and, therefore, constitute an exposure path- 1. Problem Formulation way of concern. Leachate from WMUs can be The first step in the risk assessment a source of ground-water contamination. process is problem formulation. The purpose Residents who live close to a WMU and who of this step is to clearly define the risk ques- use wells for water supply can be directly tion to be answered and identify the objec- exposed to waste constituents by drinking or tives, scope, and boundaries of the bathing in contaminated ground water. assessment. This phase can be viewed as Residents also can be exposed by inhaling developing the overall risk assessment study volatile organic compounds (VOCs) and design for a specific problem. Activities that semi-volatile organic compounds (SVOCs) might occur during this phase include: that are released indoors while using ground • Articulating a clear understanding of water for showering or via soil gas migration the purpose and intended use of the from subsurface plumes. risk assessment. The purpose of this section is to provide • Identifying the constituents of concern. general information on the risk assessment process and a specific description of how • Identifying potential release scenarios. each of the areas of risk assessment is applied • Identifying potential exposure path- in performing ground-water risk analyses. ways. Greater detail on each of the steps in the process as they relate to assessing ground- • Collecting and reviewing available water risk is provided in later sections of this data. chapter. • Identifying data gaps. In any risk assessment, there are basic • Recommending data collection steps that are necessary for gathering and efforts. evaluating data. This Guide uses a four-part process to estimate the likelihood of chemi- • Developing a conceptual model of cals coming into contact with people now or what is occurring at the site.
7A-3 Protecting Ground Water—Assessing Risk
Although this step can be formal or infor- of data will be useful in determining the mal, it is critical to the development of a suc- potential for exposure to and intake of con- cessful assessment that fully addresses the stituents. problem at hand. In addition, the develop- The next step in this process includes ment of a conceptual model helps direct the identifying exposure pathways through next phases of the assessment and provides a ground water and estimating exposure con- clear understanding of the scope and design centrations at the well3. In modeling the of the assessment. movement of the constituents away from the WMU, the Guide generally assumes that the 2. Exposure Assessment constituents behave as a plume (see Figure The goals of an exposure assessment are 1), and the plume’s movement is modeled to to: 1) characterize the source, 2) characterize produce estimated concentrations of con- the physical setting of the area that contains stituents at points of interest. As shown in the WMU, 3) identify potential exposure Figure 1, the unsaturated zone receives pathways, 4) understand the fate and trans- leachate from the WMU. In general, the flow port of constituents of concern, and 5) calcu- in the unsaturated zone tends to be gravity- late constituent doses. driven, although other factors (e.g., soil porosity, capillarity, moisture potential) can Source characterization involves defining also influence downward flow. certain key parameters for the WMU. The accuracy of predicting risks improves as more Transport through the unsaturated zone site-specific information is used in the char- delivers constituents to the saturated zone, or acterization. In general, critical aspects of the aquifer. Once the contaminant arrives at the source (e.g., type of WMU, size, location, water table, it will be transported downgradi- potential for leachate generation, and expect- ent toward wells by the predominant flow ed constituent concentrations in leachate) field in the saturated zone. The flow field is should be obtained. Knowledge of the overall governed by a number of hydrogeologic and composition of the waste deposited in the climate-driven factors, including regional WMU and of any treatment processes occur- hydraulic gradient, hydraulic conductivity of ring in the WMU is important to determine the saturated zone, saturated zone thickness, the overall characteristics of the leachate that local recharge rate (which might already be will be generated. accounted for in the regional hydraulic gradi- ent), and infiltration rate through the WMU. The second step in evaluating exposure is to characterize the site with respect to its The next step in the process is to estimate physical characteristics, as well as those of the exposure concentrations at a well. Many the human populations near the site. processes can occur in the unsaturated zone Important site characteristics include climate, and in the saturated zone that can influence meteorology, geologic setting, and hydrogeol- the concentrations of constituents in leachate ogy. Consultation with appropriate technical in a downgradient well. These processes experts (e.g., hydrogeologists, modelers) include dilution and attenuation, partitioning might be needed to characterize the site. to solid, hydrolysis, and degradation. Characterizing the populations near the site Typically, these factors should be considered with respect to proximity to the site, activity when estimating the expected constituent patterns, and the presence of sensitive sub- concentrations at a receptor. groups might also be appropriate. This group
3 In this discussion and in IWEM, the term “well” is used to represent an actual or hypothetical ground- 7A-4 water monitoring well or drinking water well, located downgradient from a WMU. Protecting Ground Water—Assessing Risk
Figure 1: Representation of Contaminant Plume Movement
Waste Management Unit
Well C Land Surface
Leachate Unsaturated Zone
Water Table DAF
Saturated Zone Leachate Plume
The final step in this process is estimating exposed individuals. It is also meant to pro- the dose. The dose is determined based on vide, where possible, an estimate of the rela- the concentration of a constituent in a medi- tionship between the extent of exposure to a um and the intake rate of that medium for constituent and the increased likelihood the receptor. For example, the dose is depen- and/or severity of adverse effects. The intent dent on the concentration of a constituent in is to establish a dose-response relationship a well and the ingestion rate of ground water between a constituent concentration and the from that well by the receptor. The intake incidence of an adverse effect. It is usually a rate is dependent on many behavior patterns, five-step process that includes: 1) gathering including ingestion rate, exposure duration, toxicity information for the substances being and exposure frequency. In addition, a risk evaluated, 2) identifying the exposure periods assessor should consider the various routes of for which toxicity values are necessary, 3) exposure (e.g., ingestion, inhalation) to deter- determining the toxicity values for noncar- mine a dose. cinogenic effects, 4) determining the toxicity values for carcinogenic effects, and 5) sum- After all of this information has been col- marizing the toxicity information. The deriva- lected, the exposure pathways at the site can tion and interpretation of toxicity values be characterized by identifying the potentially requires toxicological expertise and should exposed populations, exposure media, expo- not be undertaken by those without training sure points, and relevant exposure routes and and experience. It is recommended that you then calculating potential doses. contact your state regulatory agency for more specific guidance. 3. Toxicity Assessment The purpose of a toxicity assessment is to 4. Risk Characterization weigh available evidence regarding the poten- This step involves summarizing and inte- tial for constituents to cause adverse effects in grating the toxicity and exposure assessments
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and developing qualitative and quantitative a. Waste Characterization expressions of risk. To characterize noncar- A critical component in a ground-water cinogenic effects, comparisons are made risk assessment is the characterization of the between projected intakes of substances and leachate released from a WMU. Leachate is toxicity values to predict the likelihood that the liquid formed when rain or other water exposure would result in a non-cancer health comes into contact with waste. The character- problem, such as neurological effects. To char- istics of the leachate are a function of the acterize potential carcinogenic effects, the composition of the waste and other factors probability that an individual will develop (e.g., volume of infiltration, exposure to dif- cancer over a lifetime of exposure is estimated fering redox conditions, management of the from projected intake and chemical-specific WMU). Waste characterization includes both dose-response information. The dose of a par- identification of the potential constituents in ticular contaminant to which an individual the leachate and understanding the physical was exposed—determined during the expo- and chemical properties of the waste. sure assessment phase—is combined with the toxicity value to generate a risk estimate. Identification of the potential constituents Major assumptions, scientific judgements, in leachate requires a thorough understanding and, to the extent possible, estimates of the of the waste that will be placed in a WMU. uncertainties embodied in the assessment are Potential constituents include those used in also presented. Risk characterization is a key typical facility processes, as well as degrada- step in the ultimate decision-making process. tion products from these constituents. For ground-water risk analyses, it is important to not only identify the potential constituents of B. Ground-Water Risk concern in the leachate, but also the likely The previous section provided an overview concentration of these constituents in leachate. of risk assessment; this section provides more To assist in the identification of constituents detailed information on conducting a risk present in leachate, EPA has developed several assessment specific to ground water. In partic- leachate tests including the Toxicity ular, this section characterizes the phases of a Characteristic Leaching Procedure (TCLP), the risk assessment—problem formulation, expo- Synthetic Precipitation Leaching Procedure sure assessment, toxicity assessment, and risk (SPLP), and the Multiple Extraction Procedure characterization—in the context of a ground- (MEP). These and other tests that can be used water risk assessment. to characterize leachate are discussed more fully in Chapter 2—Characterizing Waste and are described in EPA’s SW-846 Test Methods for 1. Problem Formulation Evaluating Solid Wastes (U.S. EPA, 1996 and as The intent of the problem formulation updated). phase is to define the risk question to be In addition to identifying the constituents answered. For ground-water risk assessments, present, waste characterization includes the question often relates to whether releases understanding the physical, biological, and of constituents to the ground water are pro- chemical properties of the waste. The physical tective of human health, surface water, or and chemical properties of the waste stream ground-water resources. This section discuss- affect the likelihood and rate that constituents es characterizing the waste and developing a will move through the WMU. For example, conceptual model of a site. the waste properties influence the partitioning
7A-6 Protecting Ground Water—Assessing Risk
of constituents among the aqueous, vapor, Information about constituent toxicity can be and solid phases. Temperature, pH, pressure, collected from publicly available resources chemical composition,4 and the presence of such as the Integrated Risk Information microorganisms within WMUs may have sig- System (IRIS)
4 Generally, the model considers a high ratio of solids to leachate, and therefore, the user should consider this before applying a 20 to 1 solids to leachate ratio. 7A-7 Protecting Ground Water—Assessing Risk
allow the user to remove the source of conta- b. Site Characterization minated leachate at a future date. Surface Site characterization addresses the physical impoundments, which are generally managed characteristics of the site as well as the popu- with standing water, provide a constant lations at or near the site. Important physical source of liquid for leachate generation and characteristics include the climate, geology, potentially result in greater volumes of hydrology, and hydrogeology. These physical leachate. characteristics help define the likelihood that The size of the unit is important because water might enter the unit and the likelihood units with larger areas have the potential to that leachate might travel from the bottom of generate greater volumes of contaminated the unit to the ground water. For example, leachate than units with smaller areas. Also, areas of high rainfall are more likely to gener- units such as landfills that are designed with a ate leachate than arid regions. The geology of greater depth below the ground’s surface can the site also can affect the rate of infiltration result in decreased travel time from the bot- through the unsaturated zone. For example, tom of the unit to the water table, resulting in areas with fractured bedrock can allow less sorption of constituents. In some cases, a leachate through more quickly than a packed unit might be hydraulically connected with clay material with a low hydraulic conductivi- the water table resulting in no attenuation in ty. Hydrology should also be considered the unsaturated zone. because ground water typically discharges to surface water. The presence of surface waters The design of the unit is important because can restrict flow to wells or might require it might include an engineered liner system analysis of the impact of contaminated ground that can reduce the amount of infiltration water on receptors present in the surface through the WMU, or a cover that can reduce water. Finally, factors related to the hydrogeol- the amount of water entering the WMU. ogy, such as the depth to the water table, also Typical designs might include compacted clay influence the rate at which leachate reaches liners or geosynthetic liners. For surface the water table. impoundments, sludge layers from compacted sediments might also help reduce the amount The characterization of the site also includes of leachate released. The compacted sedi- identifying and characterizing populations at ments can have a lower hydraulic conductivi- or near the site. When characterizing popula- ty than the natural soils resulting in slower tions, it is important to identify the relative movement of leachate from the bottom of the location of the populations to the site. For unit. Covers also affect the rate of leachate example, it is important to determine whether generation by limiting the amount of liquid receptors are downgradient from the unit and that reaches the waste, thereby limiting the the likely distance from the unit to wells. It is amount of liquid available to form leachate. also important to determine typical activity Co-disposal of different wastes can result in patterns, such as whether ground water is increased or decreased rates of leachate gener- used for drinking water or agricultural purpos- ation. Generally, WMUs with appropriate es. The presence of potential receptors is criti- design specifications can result in reduced cal for determining a complete exposure leachate generation. pathway. People might not live there now, but they might live there in 50 years, based on future use assumptions. State or local agencies have relevant information to help you identify
7A-8 Protecting Ground Water—Assessing Risk
areas that are designated as potential sources movement of waste constituents can be of underground drinking water. expected through coarse-textured materials, such as sand and gravel, than through fine- c. Understanding Fate and Transport textured materials, such as silt and clay. Other key flow and transport parameters include In general, the flow in the unsaturated zone dispersivity (which determines how far a tends to be gravity-driven. As shown in Figure plume will spread horizontally and vertically 1, the unsaturated zone receives leachate infil- as it moves away from the source) and porosi- tration from the WMU. Therefore, the vertical ty (which determines the amount of pore flow component accounts for most of the fluid space in the geologic materials in the unsatu- flux between the base of the WMU and the rated and saturated zone used for flow and water table. Water-borne constituents are car- transport and can affect transport velocity). ried vertically downward toward the water table by the advection process. Mixing and As waste constituents migrate through the spreading occur as a result of hydrodynamic unsaturated and saturated zones, they can dispersion and diffusion. Transport processes undergo a number of biochemical and in the saturated zone include advection, physicochemical processes that can lead to a hydrodynamic dispersion, and sorption. reduction in concentration of potential Advection is the process by which con- ground-water contaminants. These processes stituents are transported by the motion of the are collectively referred to as attenuation flowing ground water. Hydrodynamic disper- processes. Attenuation processes can remove sion is the tendency for some constituents to or degrade waste constituents through filtra- spread out from the path that they would be tion, sorption, precipitation, hydrolysis, bio- expected to flow. Sorption is the process by logical degradation, bio-uptake, and redox which leachate molecules adhere to the sur- reactions. Some of these processes (e.g., face of individual clay, soil, or sediment parti- hydrolysis, biological degradation) can actual- cles. Attenuation of some chemicals in the ly result in the formation of different chemi- unsaturated zone is attributable to various cals and greater toxicity. Attenuation biochemical or physicochemical processes, processes are dependent upon several factors, such as degradation and sorption. including ground-water pH, ground-water temperature, and the presence of other com- The type of geological material below the pounds in the subsurface environment. Table unit affects the rate of movement because of 2 provides additional information on attenua- differences in hydraulic and transport proper- tion processes. ties. One of the key parameters controlling contaminant migration rates is hydraulic con- ductivity. The larger the hydraulic conductivi- d. Exposure Pathways ty, the greater the potential migration rate due A complete exposure pathway usually con- to lower hydraulic resistance of the formation. sists of four elements: 1) a source and mecha- Hydraulic conductivity values of some hydro- nism of chemical release, 2) a retention or geologic environments, such as bedded sedi- transport medium (in this case, ground mentary rock aquifers, might not be as large water), 3) a point of potential human contact as those of other hydrogeologic environments, with the contaminated medium (often referred such as sand and gravel or fractured lime- to as the exposure point), and 4) an exposure stone. As a general principle, more rapid route (e.g., ingestion). Residents who live near
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Table 2: Examples of Attenuation Processes Biological degradation: Decomposition of a substance into more elementary compounds by action of microorganisms such as bacteria. Sullivan. 1993. Environmental Regulatory Glossary, 6th Ed. Government Institutes. Bio-uptake: The uptake and (at least temporary) storage of a chemical by an exposed organism. The chemical can be retained in its original form and/or modified by enzymatic and non-enzymatic reac- tions in the body. Typically, the concentrations of the substance in the organism exceed the concentra- tions in the environment since the organism will store the substance and not excrete it. Sullivan. 1993. Environmental Regulatory Glossary, 6th Ed. Government Institutes. Filtration: Physical process whereby solid particles and large dissolved molecules suspended in a fluid are entrapped or removed by the pore spaces of the soil and aquifer media. Boulding, R. 1995. Soil, Vadose Zone, and Ground-Water Contamination: Assessment, Prevention, and Remediation. Hydrolysis: A chemical process of decomposition in which the elements of water react with another substance to yield one or more entirely new substances. This transformation process changes the chem- ical structure of the substance. Sullivan. 1993. Environmental Regulatory Glossary, 6th Ed. Government Institutes. Oxidation/Reduction (Redox) reactions: Involve a transfer of electrons and, therefore, a change in the oxidation state of elements. The chemical properties for elements can change substantially with changes in the oxidation state. U.S. EPA. 1991. Site Characterization for Subsurface Remediation. Precipitation: Chemical or physical change whereby a contaminant moves from a dissolved form in a solution to a solid or insoluble form. It reduces the mobility of constituents, such as metals. Unlike sorption, precipitation is not generally reversible. Boulding, R. 1995. Soil, Vadose Zone, and Ground- Water Contamination: Assessment, Prevention, and Remediation. Sorption: The ability of a chemical to partition between the liquid and solid phase by determining its affinity for adhering to other solids in the system such as soils or sediments. The amount of chemi- cal that "sorbs" to solids is dependent upon the characteristics of the chemical, the characteristics of the surrounding soils and sediments, and the quantity of the chemical. Sorption generally is reversible. Sorption often includes both adsorption and ion exchange.
a site might use ground water for their water beneath houses. This pathway is character- supply, and thus, the exposure point would be ized by the vapors seeping into households a well. Exposure routes typical of residential through the cracks and holes in basements use of contaminated ground water include and concrete slabs. In some cases, concentra- direct ingestion through drinking water, der- tions of constituents can reach levels that pre- mal contact while bathing, and inhalation of sent chronic health hazards. Factors that can VOCs during showering or from other house- contribute to the potential for vapor intrusion hold water uses (e.g., dishwashers). include the types of constituents present in the ground water, the presence of pavement Another potential pathway of concern is or frozen surface soils (which result in higher exposure to ground-water constituents from subsurface pressure gradients and greater the intrusion of vapors of VOCs and SVOCs transport), and the presence of subsurface through the basements and concrete slabs
7A-10 Protecting Ground Water—Assessing Risk
gases such as methane that affect the rate of contaminants to cause adverse effects in transport of other constituents. Because of the exposed individuals, and where possible, pro- complexity of this pathway and the evolving vides an estimate of the increased likelihood science regarding this pathway, IWEM focuses and severity of adverse effects as a result of on the risks and pathways associated with exposure to a contaminant. IWEM uses two residential exposures to contaminated ground different toxicity measures—maximum conta- water. If exposure through this route is likely, minant levels (MCLs) and health-based num- the user might consider Tier 3 modeling to bers (HBNs). Each of these measures is based assess this pathway. EPA is planning to issue a on toxicity values reflecting a cancer or non- reference document regarding the vapor cancer effect. Toxicity data are based on intrusion pathway in the near future. human epidemiologic data, animal data, or other supporting studies (e.g., laboratory e. Dose Calculation studies). In general, data can be used to char- acterize the potential adverse effect of a con- The final element of the exposure assess- stituent as either carcinogenic or ment is the dose calculation. The dose to a non-carcinogenic. For the carcinogenic effect, receptor is a function of the concentration at EPA generally assumes there is a non-thresh- the exposure point (i.e, the well) and the old effect and estimates a risk per unit dose. intake rate by the receptor. The concentration For the noncarcinogenic effect, EPA generally at the exposure point is based on the release assumes there is a threshold below which no from the source and the fate and transport of adverse effects occur. The toxicity values used the constituent. The intake rate is dependent in IWEM include: on the exposure route, the frequency of expo- sure, and the duration of exposure. • Oral cancer slope factors (CSFo) for oral exposure to carcinogenic conta- EPA produced the Exposure Factors minants. Handbook (U.S. EPA, 1997a) as a reference for providing a consistent set of exposure factors • Reference doses (RfD) for oral expo- to calculate the dose. This reference is avail- sure to contaminants that cause non- able from EPA’s National Center for cancer health effects. Environmental Assessment Web site • Inhalation cancer slope factors (CSFi)
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predicted. CSFs are expressed in units of pro- million individuals exposed to the contami- portion (of a population) affected per mil- nant. Lower concentrations of the contami- ligram/kilogram-day (mg/kg-day). For nant are not likely to cause adverse health noncancer health effects, the RfD and the RfC effects. Exceptions might occur, however, in are used as health benchmarks for ingestion individuals exposed to multiple contaminants and inhalation exposures, respectively. RfDs that produce the same health effect. Similarly, and RfCs are estimates of daily oral exposure a higher incidence of cancer among sensitive or of continuous inhalation exposure, respec- subgroups, highly exposed subpopulations, or tively, that are likely to be without an appre- populations exposed to more than one cancer- ciable risk of adverse effects in the general causing contaminant might be expected. As population, including sensitive individuals, noted previously, the exposure factors used to over a lifetime. The methodology used to calculate HBNs are described in the Exposure develop RfDs and RfCs is expected to have an Factors Handbook (U.S. EPA, 1997a). uncertainty spanning an order of magnitude. 4. Risk Characterization a. Maximum Contaminant Levels Risk characterization is the integration of (MCLs) the exposure assessment and the toxicity MCLs are maximum permissible contami- assessment to generate qualitative and quan- nant concentrations allowed in public drink- titative expressions of risk. For carcinogens, ing water and are established under the Safe the target risk level used in IWEM to calcu- Drinking Water Act. For each constituent to late the HBNs is 1 x 10-6. A risk of 1 x 10-6 be regulated, EPA first sets a Maximum describes an increased chance of one in a Contaminant Level Goal (MCLG) as a level million of a person developing cancer over a that protects against health risks. The MCL lifetime, due to chronic exposure to a specific for each contaminant is then set as close to chemical. The target hazard quotient used to its MCLG as possible. In developing MCLs, calculate the HBNs for noncarcinogens is 1. EPA considers not only the health effects of A hazard quotient of 1 indicates that the esti- the constituents, but also additional factors, mated dose is equal to the RfD (the level such as the cost of treatment, available ana- below which no adverse effect is expected). lytical and treatment technologies. Table 3 An HQ of 1, therefore, is frequently EPA’s lists the 57 constituents that have MCLs that threshold of concern for noncancer effects. are incorporated in IWEM. These targets are used to calculate unique HBNs for each constituent of concern and b. Health-based Numbers (HBNs). each exposure route of concern (i.e., inges- tion or inhalation). The parameters that describe a chemical’s toxicity and a receptor’s exposure to the chem- Usually, doses less than the RfD (HQ = 1) ical are considered in calculation of the are not likely to be associated with adverse HBN(s) of that chemical. HBNs are the maxi- health effects and, therefore, are less likely to mum contaminant concentrations in ground be of regulatory concern. As the frequency or water that are not expected to cause adverse magnitude of the exposures exceeding the noncancer health effects in the general popula- RfD increase (HQ > 1), the probability of tion (including sensitive subgroups) or that adverse effects in a human population will not result in an additional incidence of increases. However, it should not be categori- cancer in more than approximately one in one cally concluded that all doses below the RfD
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Table 3. List of Constituents in IWEM with Maximum Contaminant Levels (MCLs) (States can have more stringent standards than federal MCLs.)
Organics with an MCL mg/l mg/l
Benzene 0.005 HCH (Lindane) gamma- 0.0002 Benzo[a]pyrene 0.0002 Heptachlor 0.0004 Bis(2-ethylhexyl)phthalate 0.006 Heptachlor epoxide 0.0002 Bromodichloromethane* 0.10 Hexachlorobenzene 0.001 Butyl-4,6-dinitrophenol,2-sec-(Dinoseb) 0.007 Hexachlorocyclopentadiene 0.05 Carbon tetrachloride 0.005 Methoxychlor 0.04 Chlordane 0.002 Methylene chloride (Dichloromethane) 0.005 Chlorobenzene 0.1 Pentachlorophenol 0.001 Chlorodibromomethane* 0.10 Polychlorinated biphenyls (PCBs) 0.0005 Chloroform* 0.10 Styrene 0.1 Dibromo-3-chloropropane 1,2-(DBCP) 0.0002 TCD Dioxin 2,3,7,8- 0.00000003 Dichlorobenzene 1,2- 0.6 Tetrachloroethylene 0.005 Dichlorobenzene 1,4- 0.075 Toluene 1 Dichloroethane 1,2- 0.005 Toxaphene (chlorinated camphenes) 0.003 Dichloroethylene cis-1,2- 0.07 Tribromomethane (Bromoform)* 0.10 Dichloroethylene trans-1,2- 0.1 Trichlorobenzene 1,2,4- 0.07 Dichloroethylene 1,1-(Vinylidene chloride) 0.007 Trichloroethane 1,1,1- 0.2 Dichlorophenoxyacetic acid 2,4- (2,4-D) 0.07 Trichloroethane 1,1,2- 0.005 Dichloropropane 1,2- 0.005 Trichloroethylene (1,1,2- Trichloroethylene) 0.005 Endrin 0.002 2,4,5-TP (Silvex) 0.05 Ethylbenzene 0.7 Vinyl chloride 0.002 Ethylene dibromide (1,2- Dibromoethane) 0.00005 Xylenes 10
Inorganics with an MCL
Antimony 0.006 Copper*** 1.3 Arsenic** 0.05 Fluoride 4.0 Barium 2.0 Lead*** 0.015 Beryllium 0.004 Mercury (inorganic) 0.002 Cadmium 0.005 Selenium 0.05 Chromium 0.1 Thallium 0.002 (total used for Cr III and Cr VI)
For list of current MCLs, visit:
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are “acceptable’’ (or will be risk-free) and that screening. If the use of Tier 1 provides an all doses in excess of the RfD are “unaccept- agreeable assessment, the conservative nature able’’ (or will result in adverse effects). For of the model can be relied upon, and the IWEM, the output from the risk characteriza- additional resources required for further tion helps determine with 90 percent proba- analysis can be avoided. Of course, where bility (i.e., with a confidence that for 90 there is concern with the results from Tier 1, percent of the realizations) whether or not a a more precise assessment of risk at the design system is protective (i.e., has a cancer planned unit location should be conducted. risk of < 1 x 10-6, non-cancer hazard quotient The second approach is to try and accommo- of < 1.0). IWEM does not address the cumu- date many of the most important site-specific lative risk due to simultaneous exposure to factors in a simplified form, useable by indus- multiple constituents. The results of the risk try, state, and environmental representatives. assessment might encourage the user to con- This model, labeled Tier 2, is available as part duct a more site-specific analysis, or consider of this Guide, and is a major new step in opportunities for waste minimization or pol- moving EPA guidance away from national, lution prevention. “one size fits all” approaches. Third, a site- specific risk analysis can be conducted. This approach should provide the most precise assessment of the risks posed by the planned II. The IWEM unit. Such an analysis, labeled Tier 3, should Ground-Water be conducted by experts in ground-water modeling, and can require significant Risk Evaluation resources. This Guide identifies the benefits This section takes the principles of risk and sources for selecting site-specific models, assessment described in Part I and applies but does not provide such models as part of them to evaluating industrial waste manage- this Guide. In many cases, corporations will ment unit liner designs. This is accomplished go directly to conducting the more exacting using IWEM and a three-tiered ground-water Tier 3 analysis, which EPA believes is accept- modeling approach to make recommenda- able under the Guide. There is, however, still tions regarding the liner design systems that a need for the Tier 2 tool. State and environ- should be considered for a potential unit, if a mental representatives might have limited liner design system is considered necessary. resources to conduct or examine a Tier 3 The tiered approach was chosen to provide assessment; Tier 2 can provide a point of facility managers, the public, and state regu- comparison with the results of the Tier 3 lators flexibility in assessing the appropriate- analysis, narrow the technical discussion to ness of particular WMU designs as the user those factors which are different in the mod- moves from a national assessment to an els, and form a basis for a more informed dia- assessment using site-specific parameters. logue on the reasonableness of the differences. The three tiers allow for three possible IWEM is designed to address Tier 1 and approaches. The first approach is a quick Tier 2 evaluations. Both tiers of the tool con- screening tool, a set of lookup tables, which sider all portions of the risk assessment provides conservative national criteria. While process (i.e., problem formulation, exposure this approach, labeled Tier 1, does not take assessment, toxicity assessment, and risk into account site- (or even state-) specific con- characterization) to generate results that vary ditions, it does provide a rapid and easy from a national-level screening evaluation to
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a site-specific assessment. The Tier 3 evalua- of the Tier 2 evaluation with the appropriate tion is a complex, site-specific hydrogeologic state regulatory agency before selecting a liner investigation that would be performed with design for a new WMU. other models such as those listed at the end If the Tier 1 and Tier 2 modeling do not of this chapter. Those models could be used adequately simulate conditions at a proposed to evaluate hydrogeological complexities that site because the hydrogeology of the site is are not addressed by IWEM. Brief outlines of complex, or because the user believes Tier 2 the three tiers follow. does not adequately address a particular site- A Tier 1 evaluation involves comparing the specific parameter, the user is advised to con- expected leachate concentrations of wastes sider a more in-depth, site-specific risk being assessed against a set of pre-calculated assessment. This Tier 3 assessment involves a maximum recommended leachate concentra- more detailed, site-specific ground-water fate tions (or Leachate Concentration Threshold and transport analysis. The user should con- Values—LCTVs). The Tier 1 LCTVs are sult with state officials and appropriate trade nationwide, ground-water fate and transport associations to solicit recommendations for modeling results from EPA’s Composite Model approaches for the analysis. for Leachate Migration with Transformation The remainder of this section discusses in Products (EPACMTP). EPACMTP simulates greater detail how to use IWEM to perform a the fate and transport of leachate infiltrating Tier 1 or Tier 2 evaluation. In addition, this from the bottom of a WMU and predicts con- section presents information concerning the centrations of those contaminants in a well. In use of Tier 3 models. making these predictions, the model quantita- tively accounts for many complex processes that dilute and attenuate the concentrations of A. The Industrial Waste waste constituents as they move through the Management Evaluation subsurface to the well. The results that are generated show whether a liner system is con- Model (IWEM) sidered necessary, and if so which liner sys- The IWEM is the ground-water modeling tems will be protective for the constituents of component of the Guide for Industrial Waste concern. Tier 1 results are designed to be pro- Management, used for recommending appro- tective with 90 percent certainty at a 1x10-6 priate liner system designs, where they are risk level for carcinogens or a noncancer haz- considered necessary, for the management of ard quotient of < 1.0. RCRA Subtitle D industrial waste. IWEM compares the expected leachate concentration The Tier 2 evaluation incorporates a limit- (entered by the user) for each waste con- ed number of site-specific parameters to help stituent with a protective level calculated by a provide recommendations about which liner ground-water fate and transport model to system (if any is considered necessary) is pro- determine whether a liner system is needed. tective for constituents of concern in settings When IWEM determines a liner system is that are more reflective of your site. IWEM is necessary, it then evaluates two standard liner designed to facilitate site-specific simulations types (i.e., single clay-liner and composite without requiring the user to have any previ- liner). This section discusses components of ous ground-water modeling experience. As the tool and important concepts whose under- with any ground-water risk evaluation, how- standing is necessary for its effective use. The ever, the user is advised to discuss the results user can refer to the User’s Guide for the
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Industrial Waste Management Evaluation Model processes that occur as waste constituents (U.S. EPA, 2002b) for information necessary and their transformation products move to to perform Tier 1 and Tier 2 analyses, and the and through ground water. As leachate carry- Industrial Waste Management Evaluation Model ing waste constituents migrates through the Technical Background Document (U.S. EPA, unsaturated zone to the water table, attenua- 2002a), for more information on the use and tion processes, such as adsorption and degra- development of IWEM. dation, reduce constituent concentrations. Ground-water transport in the saturated zone 1. Leachate Concentrations further reduces leachate concentrations through dilution and attenuation. The con- The first step in determining a protective centration of constituents arriving at a well, waste management unit design is to identify therefore, is lower than that in the leachate the expected constituents in the waste and released from a WMU. expected leachate concentrations from the waste. In order to assess ground-water risks In the unsaturated zone, the model simu- using either the Tier 1 or Tier 2 evaluations lates one-dimensional vertical migration with provided in IWEM, the expected leachate steady infiltration of constituents from the concentration for each individual constituent WMU. In the saturated zone, EPACMTP sim- of interest must be entered into the model. ulates three-dimensional plume-movement See Chapter 2—Characterizing Wastes, for a (i.e., horizontal as well as transverse and ver- detailed discussion of the various approaches tical spreading of a contaminant plume). The available to use in evaluating expected model considers not only the subsurface fate leachate concentrations. and transport of constituents, but also the formation and the fate and transport of trans- formation (daughter and granddaughter) 2. Models Associated with IWEM products. The model also can simulate the One of the highlights of IWEM is its abili- fate and transport of metals, taking into ty to simulate the fate and transport of waste account geochemical influences on the constituents at a WMU with a small number mobility of metals. of site-specific inputs. To accomplish this task, IWEM incorporates the outputs of three b. MINTEQA2 other models, specifically EPACMTP, MINTE- QA2, and HELP. This section discusses these In the subsurface, metal contaminants can three models. undergo reactions with other substances in the ground water and with the solid aquifer or soil matrix material. Reactions in which a. EPACMTP the metal is bound to the solid matrix are EPA’s Composite Model for Leachate referred to as sorption reactions, and the Migration with Transformation Products metal bound to the solid is said to be sorbed. (EPACMTP) is the backbone of IWEM. During contaminant transport, sorption to EPACMTP is designed to simulate subsurface the solid matrix results in retardation (slower fate and transport of contaminants leaching movement) of the contaminant front. from the bottom of a WMU and predict con- Transport models such as EPACMTP incorpo- centrations of those contaminants in a down- rate a retardation factor to account for sorp- gradient well. In making these predictions, tion processes. the model accounts for many complex
7A-16 Protecting Ground Water—Assessing Risk
The actual geochemical processes that con- For the application of HELP to IWEM, an trol the sorption of metals can be quite com- existing database of infiltration and recharge plex, and are influenced by factors such as rates was used for 97 climate stations in the pH, the type and concentration of the metal lower 48 contiguous states. Five climate sta- in the leachate plume, the presence and con- tions (located in Alaska, Hawaii, and Puerto centrations of other constituents in the Rico) were added to ensure coverage leachate plume, and other factors. The throughout all of the United States. These cli- EPACMTP model is not capable of simulating matic data were then used along with data on all these processes in detail. Another model, the soil type and WMU design characteristics, MINTEQA25, is used to determine a sorption to calculate a water balance for each applica- coefficient for each of the metals species. For ble liner design as a function of the amount IWEM, distributions of variables (e.g., leach- of precipitation that reaches the surface of the able organic matter, pH) were used to gener- unit, minus the amount of runoff and evapo- ate a distribution of isotherms for each metal transpiration. The HELP model then comput- species. EPACMTP, in turn, samples from ed the net amount of water that infiltrates these calculated sorption coefficients and uses through the surface of the unit (accounting the selected isotherm as a modeling input to for recharge), the waste, and the unit’s bottom account for the effects of nationwide or layer (for unsaturated soil and clay liner sce- aquifer-specific ground-water and leachate narios only), based on the initial moisture geochemistry on the sorption and mobility of content and the hydraulic conductivity of metals constituents. each layer. Although data were collected for all 102 c. HELP sites, these data were only used for the The Hydrologic Evaluation of Landfill unlined landfills, waste piles, and land appli- Performance (HELP) model is a quasi-two- cation units. For the clay liner scenarios dimensional hydrologic model for computing (landfills and waste piles only), EPA grouped water balances of landfills, cover systems, and sites and ran the HELP model only for a sub- other solid waste management facilities. The set of the facilities that were representative of primary purpose of the model is to assist in the ranges of precipitation, evaporation, and the comparison of design alternatives. HELP soil type. The grouping is discussed further in uses weather, soil, and design data to com- the IWEM Technical Background Document pute a water balance for landfill systems (U.S. EPA, 2002a). accounting for the effects of surface storage; In addition to climate factors and the par- snowmelt; runoff; infiltration; evapotranspira- ticular unit design, the infiltration rates calcu- tion; vegetative growth; soil moisture storage; lated by HELP are affected by the landfill lateral subsurface drainage; leachate recircula- cover design, the permeability of the waste tion; unsaturated vertical drainage; and leak- material in waste piles, and the soil type of age through soil, geomembrane, or composite the land application unit. For every climate liners. The HELP model can simulate landfill station and WMU design, multiple HELP systems consisting of various combinations of infiltration rates are calculated. In Tier 1, for vegetation, cover soils, waste cells, lateral a selected WMU type and design, the drain layers, low permeability barrier soils, EPACMTP Monte Carlo modeling process and synthetic geomembrane liners. For fur- was used to randomly select from among the ther information on the HELP model, visit: HELP-derived infiltration and recharge data.
5 MINTEQA2 is a geochemical equilibrium speciation model for computing equilibria among the dis- solved, absorbed, solid, and gas phases in dilute aqueous solution. 7A-17 Protecting Ground Water—Assessing Risk
This process captured both the nationwide depending on the exposure duration of the variation in climate conditions and variations reference ground-water concentration (RGC) in soil type. In Tier 2, the WMU location is a of interest. For example, IWEM assumes a required user input, and the climate factors 30-year exposure duration for carcinogens, used in HELP are fixed. However, in Tier 2, and therefore, the maximum average concen- the Monte Carlo process is still used to tration is the highest 30-year average across account for local variability in the soil type, the modeling horizon. After calculating the landfill cover design, and permeability of maximum average concentrations across the waste placed in waste piles. 10,000 realizations, the concentrations are arrayed from lowest to highest and the 90th 3. Important Concepts for Use percentile of this distribution is selected as the constituent concentration for IWEM. of IWEM Once the 90th percentile exposure con- Several important concepts are critical to centration is determined, it is used in one of understanding how IWEM functions. These two ways. For both the Tier 1 analysis and concepts include 90th percentile exposure the Tier 2 analysis, the 90th percentile expo- concentration, dilution and attenuations fac- sure concentration is compared with the tors (DAFs), reference ground-water concen- expected waste leachate concentration to trations (RGCs), leachate concentration generate a DAF. This calculation is discussed threshold values (LCTVs), and units designs. further in the following section. For Tier 2, the 90th percentile exposure concentration is a. 90th Percentile Exposure the concentration of interest for the analysis. Concentration The 90th percentile exposure concentration The 90th percentile exposure concentra- can be directly compared with the reference tion was chosen to represent the estimated ground-water concentration to assist in waste constituent concentration at a well for a management decision-making. given leachate concentration. The 90th per- centile exposure concentration was selected b. Dilution and Attenuation Factors because this concentration is protective for DAFs represent the expected reduction in 90 percent of the model simulations con- waste constituent concentration resulting ducted for a Tier 1 or Tier 2 analysis. In Tier from fate and transport in the subsurface. A 1, the 90th percentile concentration is used DAF is defined as the ratio of the constituent to calculate a DAF, which is then used to gen- concentration in the waste leachate to the erate a leachate concentration threshold value concentration at the well, or: (LCTV). In Tier 2, the 90th percentile con- centration is directly compared with a refer- CL ence ground-water concentration to DAF = ——— determine whether a liner system is neces- C sary, and if so whether the particular liner W design is protective for a site. where: DAF is the dilution and attenua- tion factor; The 90th percentile exposure concentra- tion is determined by running EPACMTP in a CL is the leachate concentration Monte Carlo mode for 10,000 realizations. (mg/L); and For each realization, EPACMTP calculates a CW is the ground-water well con- maximum average concentration at a well, centration (mg/L).
7A-18 Protecting Ground Water—Assessing Risk
The magnitude of a DAF reflects the com- because the site-specific leachate concentra- bined effect of all dilution and attenuation tion is used in the EPACMTP model runs, the processes that occur in the unsaturated and 90th percentile exposure concentration can saturated zones. The lowest possible value of be compared directly to the RGC. a DAF is one. A DAF of 1 means that there is no dilution or attenuation at all; the concen- c. Reference Ground-Water tration at a well is the same as that in the Concentration (RGC) waste leachate. High DAF values, on the other hand, correspond to a high degree of As used in this Guide and by IWEM, a ref- dilution and attenuation. This means that the erence ground-water concentration (RGC) is expected concentration at the well will be defined as a constituent concentration thresh- much lower than the concentration in the old in a well that is protective of human leachate. For any specific site, the DAF health. RGCs have been developed based on depends on the interaction of waste con- maximum contaminant levels (MCLs) and stituent characteristics (e.g., whether or not health-based-numbers (HBN). Each con- the constituent degrades or sorbs), site-specif- stituent can have up to five RGCs: 1) based ic factors (e.g., depth to ground water, hydro- on an MCL, 2) based on carcinogenic effects geology), and physical and chemical from ingestion, 3) based on carcinogenic processes in the subsurface environment. In effects from inhalation while showering, 4) addition, the DAF calculation does not take based on non-carcinogenic effects from inges- into account when the exposure occurs, as tion, and 5) based on non-carcinogenic long as it is within a 10,000-year time-frame effects from inhalation while showering. following the initial release of leachate. Thus, The IWEM’s database includes 226 con- if two constituents have different mobility, the stituents with at least one RGC. Of the 226 first might reach the well in 10 years, while constituents, 57 have MCLs (see Table 3), the second constituent might not reach the 212 have ground-water ingestion HBNs, 139 well for several hundred years. EPACMTP, have inhalation HBNs, and 57 have both an however, can calculate the same or very simi- MCL and HBN. The HBNs were developed lar DAF values for both constituents. using standard EPA exposure assumptions for For the Tier 1 analysis in IWEM, DAFs are residential receptors. For carcinogens, IWEM based on the 90th percentile exposure con- used a target risk level equal to the probabili- centration. EPACMTP was implemented by ty that there might be one increased cancer randomly selecting one of the settings from case per one million exposed people (com- -6 the WMU database and assigning a unit monly referred to as a 1x10 cancer risk). leachate concentration to each site until The target hazard quotient used to calculate 10,000 runs had been conducted for a WMU. the HBNs for noncarcinogens was 1 (unit- The resulting 10,000 maximum well concen- less). A hazard quotient of 1 indicates that trations based on the averaging period associ- the estimated dose is equal to the oral refer- ated with the exposure duration of interest ence dose (RfD) or inhalation reference con- (i.e., 1-year, 7-years, 30-years) were then centration (RfC). These targets were used to arrayed from lowest to highest. The 90th per- calculate unique HBNs for each constituent of centile concentration of this distribution is concern and each exposure route of concern then used as the concentration in the ground- (ingestion or inhalation). For further informa- water well (Cw) for calculating the DAF. The tion on the derivation of the IWEM RGCs, DAF is similarly calculated for the Tier 2, but see the Industrial Waste Management Evaluation Model Technical Background
7A-19 Protecting Ground Water—Assessing Risk
Document (U.S. EPA, 2002a). Users also can MCL is the maximum concentra- add new constituents and RGCs can vary tion level depending on the protective goal. For exam- HBN is the health-based number ple, states can impose more stringent drink- ing water standards than federal MCLs.6 To The evaluation of whether a liner system is keep the software developed for this Guide needed and subsequent liner system design up-to-date, and to accommodate concerns at recommendations is determined by compar- levels different from the current RGCs, the ing the expected waste constituent leachate RGC values in the IWEM software tool can concentrations to the corresponding calculat- be modified by the user of the software. ed LCTVs. LCTVs are calculated for all unit types (i.e., landfills, waste piles, surface impoundments, land application units) by d. Leachate Concentration Threshold type of design (i.e., no liner/in situ soils, sin- Values (LCTVs) gle liner, or composite liner).7 The Tier 1 The purpose of the Tier 1 analysis in evaluation is generally the most protective IWEM is to determine whether a liner system and calculates LCTVs using data collected on is needed, and if so, to recommend liner sys- WMUs throughout the United States.8 LCTVs tem designs or determine the appropriateness used in Tier 1 are designed to be protective of land application with minimal site-specific to a level of 1x10-6 for carcinogens or a non- data. These recommendations are based on cancer hazard quotient of < 1.0 with a 90 LCTVs that were calculated to be protective percent certainty considering the range of for each waste constituent in a unit. These variability associated with the waste sites LCTVs are the maximum leachate concentra- across the United States. LCTVs from the Tier tions for which water in a well is not likely to 1 analysis are generally applicable to sites exceed the corresponding RGC. The LCTV across the country; users can determine for each constituent accounts for dilution and whether a specific liner design for a WMU is attenuation in the unsaturated and saturated protective by comparing expected leachate zones prior to reaching a well. An LCTV has concentrations for constituents in their waste been generated for a no liner/in situ soils sce- with the LCTVs for each liner design. nario and for two standard liner types (i.e., single clay liner and composite liner) and The Tier 2 analysis differs from the Tier 1 each RGC developed for a constituent. analysis in that IWEM calculates a site-specif- ic DAF in Tier 2. This allows the model to The LCTV for a specific constituent is the calculate a site-specific 90th percentile expo- product of the RGC and the DAF: sure concentration that can be compared LCTV = DAF * MCL with an RGC to determine if a liner system is needed and to recommend the appropriate or LCTV = DAF * HBN liner system if necessary. The additional cal- Where: LCTV is the leachate concentra- culation of an LCTV is not necessary. IWEM tion threshold value continues to perform the calculation, howev- er, to help users determine whether waste DAF is the dilution and attenua- minimization might be appropriate to meet a tion factor specific design. For example, a facility might
6 For example, a state can make secondary MCLs mandatory, which are not federally enforceable stan- dards, or a state might use different exposure assumptions, which can result in a different HBN. In addition, states can choose to use a different risk target than is used in this Guidance. 7 LCTVs are influenced by liner designs because of different infiltration rates. 7A-20 8 For additional information on the nationwide data used in the modeling, see the IWEM Technical Background Document (U.S. EPA, 2002a). Protecting Ground Water—Assessing Risk
find it more cost effective to reduce the con- a flexible membrane liner in contact with a centration of constituents in its waste and clay liner. In Tier 2, users also can evaluate design a clay-lined landfill than to dispose of other liner designs by providing a site-specific the current waste in a composite landfill. The infiltration rate based on the liner design. For LCTV calculated for the Tier 2 analysis is land applications units, only the no liner/in based on the expected leachate concentration situ soils scenario is evaluated because liners for a specific site and site-specific data for are not typically used at this type of facility. several sensitive parameters. Because the Tier To determine an appropriate design in Tier 2 analysis includes site-specific considera- 1, IWEM compares expected leachate con- tions, LCTVs from this analysis are not centrations for all of the constituents in the applicable to other sites. leachate to constituent-specific LCTVs and then reports the minimum design system that e. Determination of Liner Designs is protective for all constituents. If the expect- The primary method of controlling the ed leachate concentrations of all waste con- release of waste constituents to the subsurface stituents are lower than their respective no is to install a low permeability liner at the liner/in situ soils LCTVs, the proposed WMU base of a WMU. A liner generally consists of a does not need a liner to contain the waste. layer of clay or other material with a low On the other hand, if the Tier 1 screening hydraulic conductivity that is used to prevent evaluation indicates a liner is recommended, or mitigate the flow of liquids from a WMU. a user can verify this recommendation with a The type of liner that is appropriate for a spe- follow-up Tier 2 (or possibly Tier 3) analysis cific WMU, however, is highly dependent for at least those constituents whose expected upon a number of location-specific character- leachate concentrations exceed the Tier 1 istics, such as climate and hydrogeology. LCTV values. These characteristics are critical in determin- If the user proceeds to a Tier 2 analysis, ing the amount of liquid that migrates into IWEM will evaluate the three standard the subsurface from a WMU and in predicting designs or it can evaluate a user-supplied the release of contaminants to ground water. liner design. The user can supply a liner The IWEM software is intended to assist design by providing a site-specific infiltration the user in determining if a new industrial rate that reflects the expected infiltration rate waste management unit can rely on a no through the user’s liner system. In the Tier 2 liner/in situ soils design, or whether one of analysis, IWEM conducts a location-adjusted the two recommended liners designs, single Monte Carlo analysis based on user inputs to clay liner or composite liner, should be used. generate a 90th percentile exposure concen- The no liner/in situ soils design (Figure 2a) tration for the site. The 90th percentile expo- represents a WMU that relies upon location- sure concentration is then compared with the specific conditions, such as low permeability RGC to determine whether a liner is consid- native soils beneath the unit or low annual ered necessary, and where appropriate, rec- precipitation rates to mitigate the release of ommend the design that is protective for each contaminants to groundwater. The single clay constituent expected in the leachate. If the liner (Figure 2b) design represents a 3-foot Tier 2 analysis indicates that the no liner/in thick clay liner with a low hydraulic conduc- situ soils scenario or the user-defined liner is tivity (1x10-7 cm/sec) beneath a WMU. A not protective, the user can proceed to a full composite liner design (Figure 2c) consists of site-specific Tier 3 analysis.
7A-21 Protecting Ground Water—Assessing Risk
Figure 2. Three Liner Scenarios Considered in the Tiered Modeling Approach for Industrial Waste Guidelines
Waste Waste Waste Flexible Membrane Liner Native Soil Clay Liner Clay Liner
yyy
a) No Liner/In Situ Soils Scenario b) Single Liner Scenario c) Composite Liner Scenario
yyy B. Tier 1 Evaluations concentrations for each constituent by WMU and design. These distributions reflect the vari- In a Tier 1 evaluation, IWEM compares ability among industrial waste management the expected leachate concentration for each units across the United States. The 90th per- constituent with the LCTVs calculated for centile concentration from this distribution was these constituents and determines a mini- then used to calculate a DAF for each con- mum recommended design that is protective stituent by WMU and design. Each of these for all waste constituents. The required DAFs was then combined with constituent- inputs are: the type of WMU the user wishes specific RGCs to generate the LCTVs presented to evaluate, the constituents of concern, and the expected leachate concentrations of con- stituents of concern. The results for each constituent have been compiled for each unit About Monte Carlo Analysis type and design and are available in the Monte Carlo analysis is a computer- IWEM Technical Background Document (U.S. based method of analysis developed in EPA, 2002a) and in the model on the CD- the 1940s that uses statistical sampling ROM version of this Guide. techniques in obtaining a probabilistic The tabulated results for Tier 1 of IWEM approximation to the solution of a math- have been generated by running the ematical equation or model. The name EPACMTP for a wide range of conditions that refers to the city on the French Riviera, reflect the varying site conditions that can be which is known for its gambling and expected to occur at waste sites across the other games of chance. Monte Carlo United States. The process, which was used analysis is increasingly used in risk to simulate varying site conditions, is known assessments because it allows the risk as a Monte Carlo analysis. A Monte Carlo manager to make decisions based on a analysis determines the statistical probability statistical level of protection that reflects or certainty that the release of leachate might the variability and/or uncertainty in risk result in a ground-water concentration parameters or processes, rather than exceeding regulatory or risk-based standards. making decisions based on a single point estimate of risk. For further information For the Tier 1 analysis, 10,000 realizations on Monte Carlo analysis in risk assess- of EPACMTP were run for each constituent, ment, see EPA’s Guiding Principles for WMU, and design combination to generate Monte Carlo Analysis. (U.S. EPA, 1997b). distributions of maximum average exposure
7A-22 Protecting Ground Water—Assessing Risk
in the IWEM software and in the tables includ- As noted previously in this chapter, one of ed in the technical background document. the first steps in a ground-water risk assess- ment is to characterize the waste going into a The advantages of a Tier 1 screening evalu- unit. Characterization of the waste includes ation are that it is fast, and it does not require identifying the constituents expected in the site-specific information. The disadvantage of leachate and estimating leachate concentra- the Tier 1 screening evaluation is that the tions for each of these constituents. analysis does not use site-specific information Identification of constituents expected in and might result in a design recommendation leachate can be based on process knowledge that is more stringent than is needed for a or chemical analysis of the waste. Leachate particular site. For instance, site-specific con- concentrations can be estimated using ditions, such as low precipitation and a deep process knowledge or an analytical leaching unsaturated zone, might warrant a less strin- test appropriate to the circumstances, such as gent design. Before implementing a Tier 1 the Toxicity Characteristic Leaching recommendation, it is recommended that you Procedure (TCLP). For more information on also perform a Tier 2 assessment for at least identifying waste constituents, estimating those waste constituents for which Tier 1 waste constituent leachate concentrations, indicates that a no liner design is not protec- and selecting appropriate leaching tests, refer tive. The following sections provide addition- to Chapter 2 — Characterizing Waste. al information on how to use the Tier 1 lookup tables. The following example illustrates the Tier 1 process for evaluating a proposed design 1. How Are the Tier 1 Lookup for an industrial landfill. The example assumes the expected leachate concentration Tables Used? for toluene is 1.6 mg/L and styrene is 1.0 The Tier 1 tables provide an easy-to-use tool to assist waste management decision- making. Important benefits of the Tier 1 Information Needed to approach are that it requires minimum data Use Tier 1 Lookup Tables from the user and provides immediate guid- Waste management Landfill, surface ance on protective design scenarios. There are unit types: impoundment, only three data requirements for the Tier 1 waste pile, or land analysis: WMU type, constituents expected in application unit. the waste leachate, and the expected leachate Constituents Constituent names concentration for each constituent in the expected and/or CAS numbers. waste. The Tier 1 tables are able to provide in the leachate: immediate guidance because EPACMTP simu- lations for each constituent, WMU, and Leachate Expected leachate design combinations were run previously for concentrations: concentration of a national-scale assessment to generate appro- each constituent or priate LCTVs for each combination. Because concentration in the simulations represent a national-scale surface impound- assessment, the LCTVs in the Tier 1 tables ments or waste to be represent levels in leachate that are protective applied. at most sites.
7A-23 Protecting Ground Water—Assessing Risk
mg/L. Both toluene and styrene have three ferences are that the HBN-results present the LCTVs: one based on an MCL, one based on constituent-specific HBN rather than the non-cancer ingestion, and one based on non- MCL and include an additional column that cancer inhalation. Tables 4 and 5 provide identifies the pathway and effect that support detailed summary information for the no the development of the LCTV. For the con- liner/in situ soils scenario for MCL-based trolling pathway and effect column, IWEM LCTVs and the HBN-based LCTVs, respec- would indicate whether the most protective tively, that is similar to the information that pathway is ingestion of drinking water (indi- can be found in the actual look-up tables. cated by ingestion) or inhalation during showering (indicated by inhalation) and For the Tier 1 MCL-based analysis pre- whether the adverse effect is a cancer or non- sented in Table 4, the results provide the cancer effect. In this example, both styrene following information: constituent CAS and toluene have two HBN-based LCTVS: number, constituent name, constituent-spe- one for ingestion non-cancer and one for cific MCL, user-provided leachate concen- inhalation non-cancer. Only the results for tration, constituent-specific DAF, the the controlling HBN exposure pathway and constituent-specific LCTV, and whether the effect are shown. In Table 5, only the results specified design is protective at the target for the inhalation-during-showering pathway risk level. To provide a recommendation as for non-cancer effects are shown because this to whether a specific design is protective or is the most protective pathway (that is, the not, IWEM compares the LCTV with the LCTV for the inhalation-during-showing leachate concentration to determine pathway is lower than the LCTV for ingestion whether the design is protective. In the of drinking water) for both of these con- example presented in Table 4, the no stituents. As shown in Table 5, comparison of liner/in situ soils scenario is not protective the leachate concentration of styrene (1.0 for styrene because the leachate concentra- mg/L) and toluene (1.6 mg/L) to their respec- tion provided by the user (1.0 mg/L) is tive LCTVs (8.0 mg/L and 2.9 mg/L) indi- greater than the Tier 1 LCTV (0.22 mg/L). cates that the no liner/in situ soils design is For toluene, the no liner/in situ soils sce- protective for the Tier 1 HBN-based LCTVs. nario is protective because the leachate con- centration (1.6 mg/L) is less than the Tier 1 Based on the results for the no liner/in situ LCTV (2.2 mg/L). soils scenario, the user could proceed to the comparison of the expected leachate concen- For the health-based number (HBN)-based tration for styrene with the MCL-based LCTV results presented in Table 5, the detailed for a single clay liner to determine whether results present similar information to that the single clay liner design is protective. The presented for the MCL-based results. The dif-
Table 4: Example of Tier 1 Summary Table for MCL-based LCTVs for Landfills - No Liner/In situ Soils CAS # Constituent MCL (mg/L) Leachate Concentration (mg/L) DAF LCTV (mg/L) Protective?
100-42-5 Styrene 0.1 1.0 2.2 0.22 No 108-88-3 Toluene 1.0 1.6 2.2 2.2 Yes
7A-24 Protecting Ground Water—Assessing Risk
Table 5: Example of Tier 1 Summary Table for HBN-based LCTVs for Landfills - No Liner/In situ Soils CAS # Constituent HBN (mg/L) Leachate DAF LCTV (mg/L) Protective? Controlling Concentration Pathway & (mg/L) Effect
100-42-5 Styrene 3.6 1.0 2.2 8.0 Yes Inhalation Non-cancer 108-88-3 Toluene 1.3 1.6 2.2 2.9 Yes Inhalation Non-cancer
user also can proceed to a Tier 2 or Tier 3 Table 7 presents the results of the Tier 1 analysis to determine whether a more site- MCL-based analysis for a composite liner.9 A specific approach might indicate that the no comparison of the leachate concentration for liner/in situ soils design is protective for the styrene (1.0 mg/L) to the MCL-based LCTV site. Table 6 presents the Tier 1 results for the (1000 mg/L) indicates that the composite single clay liner. As shown, the single clay liner is the recommended liner based on a liner would not be protective for the MCL- Tier 1 analysis that will be protective for both based analysis because the expected leachate styrene and toluene. concentration for styrene (1.0 mg/L) exceeds the LCTV for styrene (0.61 mg/L). Based on 2. What Do the Results Mean these results, the user could continue on to evaluate whether a composite liner is protec- and How Do I Interpret Them? tive for styrene. For the Tier 1 analysis, IWEM evaluates the no liner/in situ soils, single clay liner, and
Table 6: Example of Tier 1 Summary Table for MCL-based LCTVs for Landfills - Single Clay Liner CAS # Constituent MCL (mg/L) Leachate Concentration (mg/L) DAF LCTV (mg/L) Protective?
100-42-5 Styrene 0.1 1.0 6.1 0.61 No 108-88-3 Toluene 1.0 1.6 6.1 6.1 Yes
Table 7: Example of Tier 1 Summary Table for MCL-based LCTVs for Landfills - Composite Liner CAS # Constituent MCL (mg/L) Leachate Concentration (mg/L) DAF LCTV (mg/L) Protective?
100-42-5 Styrene 0.1 1.0 5.4x104 1000 Yes 108-88-3 Toluene 1.0 1.6 2.9x104 1000 Yes
9 Table 7 also indicates the effect of the 1000 mg/L cap on the results. The LCTV results from multiply- ing the RGC with the DAF. In this example, the MCL for styrene (0.1 mg/L) multiplied by the unitless DAF (5.4 x 104) would result in an LCTV of 5,400 mg/L, but because LCTVs are capped, the LCTV for styrene in a composite liner is capped at 1,000 mg/L. See Chapter 6 of the Industrial Waste Management 7A-25 Evaluation Model Technical Background Document (U.S. EPA, 2002a) for further information. Protecting Ground Water—Assessing Risk
composite liner design scenarios, in that stituents whose concentrations exceed a land order. Generally, if the expected leachate con- application threshold, the recommendation is centrations for all constituents are lower than that land application might not be appropri- the no liner LCTVs, the proposed unit does ate. The model does not consider the other not need a liner to contain this waste. If any design scenarios. expected constituent concentration is higher After conducting the Tier 1 evaluation, than the no liner/in situ soils LCTV, a single users should consider the following steps: compacted clay liner or composite liner would be recommended for containment of • Perform additional evaluations. the waste using the Tier 1 analysis. If any The Tier 1 evaluation provides a con- expected concentration is higher than the servative screening assessment whose single clay liner LCTV, the recommendation values are calculated to be protective is at least a composite liner. If any expected over a range of conditions and situa- concentration is higher than the composite tions. Although a user could elect to liner LCTV, pollution prevention, treatment, install a liner based on the Tier 1 or additional controls should be considered, results, it is appropriate that a user or a Tier 2 or Tier 3 analysis can be conduct- consider Tier 2 or Tier 3 evaluations ed to consider site-specific factors before to confirm these recommendations. making a final judgment. For waste streams • Consider pollution prevention, with multiple constituents, the most protec- recycling, or treatment. If you do tive design that is recommended for any one not want to conduct a Tier 2 or Tier constituent is the overall recommendation. In 3 analysis, and the waste has one or the example illustrated in Tables 4, 5, 6, and more “problem” constituents that call 7, the recommended design is a composite for a more stringent and costly design liner because the expected leachate concen- system (or which make land applica- tration for styrene exceeds the no liner/in situ tion inappropriate), you could con- soils and clay liner LCTVs in the MCL-based sider pollution prevention, recycling, analysis, but is lower than the composite and treatment options for those con- liner LCTV. For the HBN-based analysis, a no stituents. Options that previously liner/in situ soils design would provide ade- might have appeared economically quate protection for the site because, as infeasible, might be worthwhile if shown in Table 5, the leachate concentrations they can reduce the problem con- for styrene and toluene are lower than their stituent concentration to a level that respective HBN-based LCTVs. results in a different design recom- The interpretation for land application is mendation or would make land similar to the interpretation for landfills. application appropriate. Then, after However, only the no liner/in situ soils sce- implementing these measures, repeat nario is evaluated for land application the Tier 1 evaluation. Based on the because these types of units generally do not results presented in Table 6, pollution use liner systems. Thus, if all the waste prevention, recycling, or treatment leachate concentrations are below the no measures could be used to reduce the liner/in situ soils MCL-based and HBN-based expected leachate concentration for LCTVs in the Tier 1 lookup tables, land- styrene below 0.61 mg/L so that a applying waste might be appropriate for the single liner is recommended for the site. If the waste has one or more con- unit. Consult Chapter 3—Integrating
7A-26 Protecting Ground Water—Assessing Risk
Pollution Prevention, for ideas and 1. How is a Tier 2 Analysis tools. Performed? • Implement recommendations. You Under Tier 2, the user can provide site- can design the unit based on the specific information to refine the design rec- design recommendations of the Tier ommendations. The Tier 2 analysis leads the 1 lookup tables without performing user through a series of data entry screens further analysis or considering pollu- and then runs EPACMTP to generate a design tion prevention or recycling activities. recommendation based on the site-specific In the case of land application, a land information provided by the user. The user application system might be devel- can provide data related to the WMU, the oped (after evaluating other factors) if subsurface environment, infiltration rates, the lookup tables found no liner nec- physicochemical properties, and toxicity. The essary for all constituents. In either user can evaluate the three designs discussed case, it is recommended that you above or provide data reflecting a site-specific consult the appropri- ate agency to ensure Figure 3. Using Tier 1 Lookup Tables compliance with state regulations. Identify proposed WMU type. Figure 3 illustrates the basic steps using the Tier 1 Estimate waste leachate concentration for all potential constituents expected to be lookup tables to determine present in the waste. an appropriate design for a proposed waste manage- Compare expected leachate concentrations ment unit or whether land to calculated LCTVs for all potential application is appropriate. YES constituents.
C. Tier 2 Evaluations The Tier 2 evaluation is Will pollution preven- tion, recycling, or treat- designed to provide a Do you have ment be implemented to site-specific more accurate evaluation reduce concentrations of NO data? than Tier 1 by allowing problem constituents? the user to provide site- specific data. In many YES cases, a Tier 2 evaluation might suggest a less strin- NO Consider a Tier 2 evaluation or gent and less costly design performing a comprehensive Tier than a Tier 1 evaluation Consider implement- 3 site-specific ground-water fate ing liner and/or land and transport analysis. would recommend. This application recom- section describes the mendation, or obtain- inputs for the analysis and ing additional data for the process for determin- a Tier 2 or Tier 3 analysis. ing a protective recom- mendation.
7A-27 Protecting Ground Water—Assessing Risk
liner design. As a result, a Tier 2 analysis “optional” parameters that are used unless provides a protective design recommendation the user provides site-specific data. The intended only for use at the user’s site, and is default values are derived from a number of not intended to be applied to other sites. sources, including a survey of industrial This section discusses the inputs that a user waste management units, a hydrogeologic can provide and the results from the analysis. database, water-balance modeling, and values reported in the scientific literature. The selec- a. Tier 2 Inputs tion of default values is explained in the IWEM Technical Background Document (U.S. In addition to the inputs required for the EPA, 2002a). If site-specific data are avail- Tier 1 analysis, a Tier 2 analysis allows users able, they should be used to derive the most to provide additional inputs that account for appropriate design scenario for a particular attributes that are specific to the user’s site. site.10 The Tier 2 inputs that are common to the Tier 1 evaluation are: In addition to the above parameters, users can also enter certain constituent specific • WMU type—waste pile, surface properties, as follows: impoundment, or land application unit. • Organic carbon distribution coeffi- cient (KOC). A function of the nature • Chemical constituents of concern of a sorbent (the soil and its organic present in the WMU. carbon content) and the properties of • Leachate concentration (in mg/L) of a chemical (the leachate constituent). each constituent. It is equal to the ratio of the solid and dissolved phase concentrations, If the user has already performed a Tier 1 measured in milliliters per gram analysis and continues to a Tier 2 analysis, (mL/g). The higher the value of the the Tier 1 inputs are carried forward to the distribution coefficient, the higher Tier 2 analysis. In the Tier 2 analysis, howev- the adsorbed-phase concentration, er, the user can change these data without meaning the constituent would be changing the Tier 1 data. less mobile. For metals, IWEM pro- In addition to the Tier 1 inputs, the user vides an option to enter a site-specif-
also provides values for additional parameters ic soil-water partition coefficient (Kd), including WMU area, WMU depth for land- which overrides the MINTEQA2 fills, ponding depth for surface impound- default sorption isotherms. ments, and the climate center in the IWEM • Degradation coefficient. The rate at database that is nearest to the site. These which constituents degrade or decay parameters can have a significant influence within an aquifer due to biochemical on the LCTVs generated by the model and processes, such as hydrolysis or also are relatively easy to determine. The user biodegradation (measured in units of also has the option to provide values for sev- 1/year). The default decay rate in eral more parameters. Table 8 presents the IWEM represents degradation from list of “required” and “optional” parameters. chemical hydrolysis only, since Because site-specific data for all of the biodegradation rates are strongly EPACMTP parameters might not be available, influenced by site-specific factors. In the model contains default values for the Tier 2, a user can enter an overall
10 A Tier 2 evaluation is not always less conservative than a Tier 1. For example, if a site has a very large area, a very shallow water table, and/or the aquifer thickness is well below the national average, then 7A-28 the Tier 2 evaluation results can be more stringent than the Tier 1 analysis results. Protecting Ground Water—Assessing Risk
Table 8. Input Parameters for Tier 2
Parameter Description Use in Model Units Applicable Required or WMU Optional
WMU area Area covered by the WMU To determine the area for Square meters (m2) All Required infiltration of leachate
WMU location Geographic location of WMU in terms of To determine local climatic Unitless All Required the nearest of 102 climate stations conditions that affect infiltration and aquifer recharge
Total waste Depth of the unit for landfills (average For landfills, used to determine Meters (m) LF Required for management unit thickness of waste in the landfill, not the landfill depletion rate. For SI landfills and depth counting the thickness of a liner below the surface impoundments, used surface waste or the thickness of a final cover on as the hydraulic head to derive impoundments top of the waste) and surface leakage impoundments (depth of the free-standing liquid in the impoundment, not counting the thickness of any accumulated sediment layer at the base of the impoundment)
Depth of waste Depth of the base of the unit below the Used together with depth of the Meters (m) LF Optional management unit ground surface water table to determine SI below ground distance leachate has to travel WP surface through unsaturated zone to reach ground water
Surface Thickness of sediment at the base of Limits infiltration from unit. Meters (m) SI Optional Impoundment surface impoundment (discounting sediment layer thickness of engineered liner, if present) thickness
WMU operational Period of time WMU is in operation. IWEM assumes leachate Years WP Optional life generation occurs over the same SI period of time. LAU
WMU infiltration Rate at which leachate flows from the Affected by area’s rainfall Meters per year All Optional rate bottom of a WMU (including any liner) intensity and design (m/yr) into unsaturated zone performance. Users either input infiltration rates directly or allow IWEM to estimate values based on the unit’s geographic location,11 liner design, cover design and WMU type.
Soil type Predominant soil type in the vicinity of Uses site-specific soil data to sandy loam All Optional the WMU model leachate migration silt loam through unsaturated zone and silty clay loam determine regional recharge rate
Distance to a well The distance from a WMU to a To determine the horizontal Meters (m) All Optional downgradient well. distance over which dilution and attenuation occur.
Hydrogeological Information on the hydrogeological setting Determines certain aquifer Varies All Optional setting of the WMU characteristics (depth to water table, saturated zone thickness, saturated zone hydraulic conductivity, ground-water hydraulic gradient) when complete information not available
11 For surface impoundments IWEM can use either the unit’s geographic location or impoundment characteristics (such as ponding depth, and thickness of sediment layer) to estimate the infiltration rates. 7A-29 Protecting Ground Water—Assessing Risk
Table 8. Input Parameters for Tier 2 (con’t)
Parameter Description Use in Model Units Applicable Required or WMU Optional
Depth to the water The depth of the zone between the land Used to predict travel time. Meters (m) All Optional table surface and the water table
Saturated zone Thickness of the saturated zone of the Delineates the depth over Meters (m) All Optional thickness aquifer which leachates can mix with ground waters.
Saturated zone Hydraulic conductivity of the saturated With hydraulic gradient, used Meters per year All Optional hydraulic zone, or the permeability of the saturated to calculate ground-water flow (m/yr) conductivity zone in the horizontal direction. rates.
Ground-water Regional horizontal ground-water gradient With hydraulic conductivity, Meters per meter All Optional hydraulic gradient used to calculate the ground- (m/m) water flow rate.
Distance to nearest The distance from the unit to the nearest Affects the calculation of Meters (m) SI Optional surface water body water body ground-water mounding at a site.
degradation rate which overrides the The overall result of a Tier 2 analysis is a IWEM default. A user can choose to design recommendation similar to the Tier 1 include degradation due to hydroly- analysis. However, the basis for the recom- sis and biodegradation in the overall mendation differs slightly. To illustrate the degradation rate. similarities and differences between the results from the two tiers, the remainder of b. Tier 2 Results this section continues the example Tier 1 evaluation through a Tier 2 evaluation. In the After providing site-specific inputs, the Tier 1 example, the disposal of toluene and user generates design recommendations for styrene in a proposed landfill is evaluated. each constituent by launching EPACMTP The expected leachate concentration for from within IWEM. EPACMTP will then sim- toluene is 1.6 mg/L and the expected ulate the site and determine the 90th per- leachate concentration for styrene is 1.0 centile exposure concentration for each mg/L. In Tier 2, after inputting the site-spe- design scenario. IWEM determines the mini- cific data summarized in Table 9 and using mum recommended design at a 90th per- default data for the remaining parameters, centile exposure concentration by performing the user can then launch the EPACMTP 10,000 Monte Carlo simulations of model simulations. EPACMTP for each waste constituent and design. Upon completion of the modeling After completing the EPACMTP model analyses, IWEM will display the minimum simulations, IWEM produces the results on design recommendation and the calculated, screen. Table 10 presents the detailed results location-specific LCTVs based on the 90th of a Tier 2 analysis for the no liner/in situ percentile exposure concentration. soils scenario. The data presented in this table are similar to the data presented in the Tier 1 results, but the Tier 2 analysis expands
7A-30 Protecting Ground Water—Assessing Risk
Table 9. the information provided to A Sample Set of Site-Specific Data for Input to Tier 2 the user. It includes additional information regarding the tox- Parameters Site-Specific Data icity standard, the reference ground-water concentration Infiltration rate* Local climate: Madison, WI (RGC), and the 90th per- Soil type: fine-grained soil centile exposure concentra- Waste management unit area 15,000 m2 tion. The toxicity standard is included because the user can Waste management unit depth 2 m select specific standards, pro- Depth to the water table 10 m vide a user-defined standard, Aquifer thickness 25 m or compare to all standards. In Toxicity standards Compare to all this example, all standards were selected; the user can Distance to a well 150 m identify the result for each standard from a single table. * The Tier 2 model uses an infiltration rate for the liner scenarios The LCTV continues to repre- based on local climate and soil data. sent the maximum leachate Table 10: Example of Tier 2 Detailed Summary Table - No Liner/In situ Soils CAS # Constituent Leachate DAF LCTV Toxicity Ref. 90th Percentile Protective? Concentration (mg/L) Standard Ground- Exposure (mg/L) water Concentration Conc. (mg/L) (mg/L)
100-42-5 Styrene 1.0 8.3 0.83 MCL 0.1 0.1201 No
100-42-5 Styrene 1.0 8.3 29.88 HBN - 3.6 0.1201 Yes Ingestion Non- Cancer
100-42-5 Styrene 1.0 8.3 40.67 HBN - 4.9 0.1201 Yes Inhalation Non- cancer
108-88-3 Toluene 1.6 8.3 8.3 MCL 1 0.1922 Yes
108-88-3 Toluene 1.6 8.4 10.92 HBN - 1.3 0.1894 Yes Ingestion Non- cancer
108-88-3 Toluene 1.6 8.4 41.16 HBN - 4.9 0.1894 Yes Inhalation Non- cancer
7A-31 Protecting Ground Water—Assessing Risk
concentration for a design scenario that is ence ground-water concentration (0.1 mg/L). still protective for a reference ground-water In addition, under the “Protective?” column, concentration, but the LCTV is not the basis IWEM refers the user to the appropriate liner for the design recommendation. result if a less stringent design is recom- mended. In Table 11, the user is referred to The RGC and 90th percentile exposure the no liner/in situ soils results for the HBN- concentration are provided because they are based ingestion and inhalation results the point of comparison for the Tier 2 analy- because, as shown in Table 10, the no sis. (The LCTV, however, continues to provide liner/in situ soils scenario is protective. If a information about a threshold that might be Tier 2 analysis determines that a single clay useful for pollution prevention or waste mini- liner is protective for all constituents, then mization efforts.) As shown in Table 10, the IWEM would not continue to an evaluation no liner/in situ soils scenario is protective for of a composite liner. For this example of toluene because all of the 90th percentile styrene and toluene disposed of in a landfill, exposure concentrations are less than the the recommended minimum design is a sin- three RGCs for toluene, while the no liner/in gle clay liner, because the 90th percentile situ soils scenario is not protective for styrene exposure concentration (0.0723) is less than for the MCL comparison. For that standard, the MCL-based RGC (0.1). the 90th percentile exposure concentration (0.1201 mg/L) exceeds the RGC (0.1 mg/L). In this case, IWEM would launch EPACMTP 2. What Do the Results Mean to evaluate a clay liner to determine whether and How Do I Interpret Them? that liner design would be protective. The Tier 2 analysis provides LCTVs and Table 11 provides the single clay liner recommendations for a minimum protective results for a Tier 2 analysis. As shown in the design. In the Tier 1 analysis, that recommen- table, the single clay liner is protective dation is based on a comparison of expected because the 90th percentile exposure concen- leachate concentrations to LCTVs to determine tration (0.0723 mg/L) is less than the refer- whether a design scenario is protective. In the
Table 11: Example of Tier 2 Detailed Summary Table - Single Clay Liner CAS # Constituent Leachate DAF LCTV Toxicity Ref. 90th Percentile Protective? Concentration (mg/L) Standard Ground- Exposure (mg/L) water Concentration Conc. (mg/L) (mg/L)
100-42-5 Styrene 1.0 14 1.4 MCL 0.1 0.0723 Yes
100-42-5 Styrene 1.0 14 50.4 HBN - 3.6 0.0722 See No liner Ingestion Results Non- Cancer
100-42-5 Styrene 1.0 14 68.6 HBN - 4.9 0.0722 See No liner Inhalation Results Non- cancer
7A-32 Protecting Ground Water—Assessing Risk
Tier 2 analysis, LCTVs can be used to help treatment options for those constituents. If, waste managers determine whether waste min- after conducting the Tier 2 evaluation, the imization techniques might lower leachate user is not satisfied with the resulting recom- concentrations and enable them to use less mendations, or if site-specific conditions costly unit designs, but IWEM does not need seem likely to suggest a different conclusion to calculate an LCTV to make a design recom- regarding the appropriateness of land applica- mendation. If the 90th percentile ground- tion of a waste, then the user can conduct a water concentration does not exceed the more in-depth, site-specific, ground-water specified RGC, then the evaluated design sce- risk analysis (Tier 3). nario is protective for that constituent. If the In addition to the Tier 2 evaluation, other 90th percentile ground-water concentrations fate and transport models have been devel- for all constituents under the no liner/in situ oped that incorporate location-specific consid- soils scenario are below their respective RGCs , erations, such as the American Petroleum then IWEM will recommend that no liner/in Institute’s (API’s) Graphical Approach for situ soils is needed to protect the ground Determining Site-Specific Dilution-Attenuation water. If the 90th percentile ground-water con- Factors.12 API developed its approach to calcu- centration of any constituent exceeds its RGC, late facility-specific DAFs quickly using then a single clay liner is recommended (or, in graphs rather than computer models. Graphs the case of land application units, land appli- visually indicate the sensitivity to various cation is not recommended). Similarly, if the parameters. This approach can be used for 90th percentile ground-water concentration of impacted soils located above or within an any constituent under the single clay liner sce- aquifer. This approach accounts for attenua- nario exceeds its RGC, then a composite liner tion with distance and time due to is recommended. As previously noted, howev- advective/dispersive processes. API’s approach er, you may decide to conduct a Tier 3 site- has a preliminary level of analysis that uses a specific analysis to determine which design small data set containing only measures of the scenario is most appropriate. See the ensuing constituent plume’s geometry. The user can section on Tier 3 analyses for further informa- read other necessary factors off graphs provid- tion. For waste streams with multiple con- ed as part of the approach. This approach also stituents, the most protective liner design that has a second level of analysis in which the is recommended for any one constituent is the user can expand the data set to include site- overall recommendation. As in the Tier 1 eval- specific measures, such as duration of con- uation, pollution prevention, recycling, and stituent leaching, biodegradation of treatment practices could be considered when constituents, or site-specific dispersivity val- the protective standard of a composite liner is ues. At either level of analysis, the calculation exceeded if you decide not to undertake a Tier results in a DAF. This approach is not appro- 3 assessment to reflect site-specific conditions. priate for all situations; for example, it should If the Tier 2 analysis found land applica- not be used to estimate constituent concentra- tion to be appropriate for the constituents of tions in active ground-water supply wells or concern, then a new land application system to model very complex hydrogeologic set- may be considered (after evaluating other fac- tings, such as fractured rock. It is recom- tors). Alternatively, if the waste has one or mended that you consult with the appropriate more “problem” constituents that make land state agency to discuss the applicability of the application inappropriate, the user might API approach or any other location-adjusted consider pollution prevention, recycling, and model prior to use.
12 A copy of API’s user manual, The Technical Background Document and User Manual (API Publication 4659), can be obtained from the American Petroleum Institute, 1220 L Street, NW, Washington, DC 20005, 202 682-8375. 7A-33 Protecting Ground Water—Assessing Risk
D. Strengths and ground water via ingestion of drink- Limitations ing water and inhalation while show- ering. IWEM does not consider Listed below are some of IWEM’s strengths vapor intrusion into buildings. It also and limitations that the user should be aware of: does not address potential risks through environmental pathways 1. Strengths other than ground water, such as volatile emissions from a WMU, sur- • The tool is relatively easy to use and face runoff and erosion, and indirect requires a minimal amount of data exposures through the food chain and modeling expertise. pathway. Other chapters in this • The tool can perform rapid Tier 1 Guide, however, address ways to screening evaluations. Tier 2 evalua- assess or control potential risks via tions allow for many site-specific such other pathways. adjustments. • The use of a waste concentration to • The tool is designed to be flexible leachate concentration ratio of with respect to the availability of site- 10,000 in IWEM Tier 2 may overesti- specific data for a Tier 2 evaluation. mate the amount of contaminant The user needs to provide only a mass in the WMU, allowing the small number of inputs, but if more modeling results to approach non- data are available, the tool can depleting source steady-state values accommodate their input. for WMUs without engineered liners. • Users can enter their own infiltration This may result in an underestima- rates to evaluate additional design tion of the Tier 2 LCTVs. scenarios and still use IWEM to con- • IWEM considers only human health duct a risk evaluation. risks. Exposure and risk to ecological • The user can modify RGC values, receptors are not included. when appropriate, and in consulta- • The conceptual flow model used in tion with other stakeholders. EPACMTP in conjunction with • The user can modify properties of IWEM Tier 2 data input constraints the 226 constituents (e.g., adding might produce ground-water veloci- biodegradation), and can add addi- ties that might be greater than can be tional constituents for evaluation. assumed based on the site-specific hydraulic conductivity and hydraulic • The tool provides recommendations gradient values. The maximum val- for protective design systems. It can ues that the velocities can reach are also be used to evaluate whether limited by a model constraint that waste leachate reduction measures appropriately prevents the modeled would be appropriate. water level from rising above the ground surface. Despite this con- 2. Limitations straint, modeled velocities might be greater than expected velocities based • IWEM considers only exposures on site-specific hydraulic conductivi- from contact with contaminated ty and hydraulic gradient.
7A-34 Protecting Ground Water—Assessing Risk
• The risk evaluation in IWEM is based on the ground-water concentration of Why is it important to use individual waste constituents. IWEM a qualified professional? does not address the cumulative risk due to simultaneous exposure to mul- • Fate and transport modeling can be tiple constituents (although it does very complex; appropriate training use a carcinogenic risk level at the and experience are required to cor- conservative end of EPA’s risk range). rectly use and interpret models. • IWEM is not designed for sites with • Incorrect fate and transport modeling complex hydrogeology, such as frac- can result in a liner system that is not tured (karst) aquifers. sufficiently protective or an inappro- priate land application rate. • The tool is inappropriate for sites where non-aqueous phase liquid • To avoid incorrect analyses, check to (NAPL) contaminants are present. see if the professional has sufficient training and experience at analyzing • IWEM does not account for all possi- ground-water flow and contaminant ble fate and transport processes. For fate and transport. example, colloid transport might be important at some sites but is not considered in IWEM. While the user professional experienced in ground-water can enter a constituent-specific modeling. State officials and appropriate degradation rate constant to account trade associations might be able to suggest a for biodegradation, IWEM simulates good consultant to perform the analysis. biodegradation in a relatively simple way by assuming the rate is the same 1. How is a Tier 3 Evaluation in both the unsaturated and the satu- Performed? rated zones. A Tier 3 evaluation will generally involve a more detailed site-specific analysis than Tier E. Tier 3: A Comprehensive 2. Sites for which a Tier 3 evaluation might Site-Specific Evaluation be performed typically involve complex and heterogeneous hydrogeology. Selection and If the Tier 1 and Tier 2 evaluations do not application of appropriate ground-water adequately simulate conditions at a proposed models require a thorough understanding of site, or if you decide that sufficient data are the waste and the physical, chemical, and available to skip a Tier 1 or Tier 2 analysis, a hydrogeologic characteristics of the site. site-specific risk assessment could be consid- ered.13 In situations involving a complex A Tier 3 evaluation should involve the fol- hydrogeologic setting or other site-specific lowing steps: factors that are not accounted for in IWEM, a • Developing a conceptual hydrogeo- detailed site-specific ground-water fate and logical model of the site. transport analysis might be appropriate for determining risk to ground water and evalu- • Selecting a flow and transport simu- ating alternative designs or application rates. lation model. It is recommended that you consult with the • Applying the model to the site. appropriate state agency and use a qualified
13 For example, if ground-water flow is subject to seasonal variations, use of the Tier 2 evaluation tool might not be appropriate because the model is based on steady-state flow conditions. 7A-35 Protecting Ground Water—Assessing Risk
As with all modeling, you should consult • What other contaminant sources are with the state before investing significant present? resources in a site-specific analysis. The state • What fate processes are likely to be might have a list of preferred models and significant (e.g. sorption and might be able to help plan the fate and trans- biodegradation)? port analysis. • Are plume concentrations high enough to make density effects sig- a. Developing a Conceptual nificant? Hydrogeological Model The first step in the site-specific Tier 3 b. Selecting a Fate and Transport evaluation is to develop a conceptual hydro- geological model of the site. The conceptual Simulation Model model should describe the key features and Numerous computer models exist to simu- characteristics to be captured in the fate and late ground-water fate and transport. transport modeling. A complete conceptual Relatively simple models are often based on hydrogeological model is important to ensure analytical solutions of the mathematical that the fate and transport model can simu- equations governing ground-water flow and late the important features of the site. The solute transport equations. However, such conceptual hydrogeological model should models generally cannot simulate the com- address questions such as: plexities of real world sites, and for a rigor- ous Tier 3 evaluation, numerical models • Does a confined aquifer, an uncon- based on finite-difference or finite-element fined aquifer, or both need to be sim- techniques are recommended. The primary ulated? criteria for selecting a particular model • Does the ground water flow through should be that it is consistent with the char- porous media, fractures, or a combi- acteristics of the site, as described in the con- nation of both? ceptual site hydrogeological model, and that it is able to simulate the significant processes • Is there single, or are there multiple, that control contaminant fate and transport. hydrogeologic layers to be simulated? In addition to evaluating whether a model • Is the hydrogeology constant or vari- will adequately address site characteristics, able in layer thickness? the following questions should be answered • Are there other hydraulic sources or to ensure that the model will provide accu- sinks (e.g., extraction or injection rate, verifiable results: wells, lakes, streams, ponds)? • What is the source of the model? • What is the location of natural no- How easy is it to obtain and is the flow boundaries and/or constant model well documented? head boundaries? • Are documentation and user’s manu- • How significant is temporal (season- als available for the model? If yes, are al) variation in ground-water flow they clearly written and do they pro- conditions? Does it require a tran- vide sufficient technical background sient flow model? on the mathematical formulation and solution techniques?
7A-36 Protecting Ground Water—Assessing Risk
geology and the principles of flow and trans- What are some useful resources for port, as well as experience in using models selecting a ground-water fate and and interpreting model results are essential. transport model? The American Society for Testing and Materials The following resources can help (ASTM) has developed guidance that might be select appropriate modeling software: useful for conducting modeling. A listing of guidance material can be found in Table 13. • Ground Water Modeling Compendium, Second Edition (U.S. EPA, 1994c) The first step in applying the model to a site is to calibrate it. Model calibration is the • Assessment Framework for Ground- process of matching model predictions to Water Modeling Applications (U.S. EPA, observed data by adjusting the values of 1994b) input parameters. In the case of ground-water • Technical Guide to Ground-water Model modeling, the calibration is usually done by Selection at Sites Contaminated with matching predicted and observed hydraulic Radioactive Substances (U.S. EPA, head values. Calibration is important even for 1994a) well-characterized sites, because the values of measured or estimated model parameters are • EPA’s Center for Subsurface Modeling always subject to uncertainty. Calibrating the Support (CSMoS—RSKERL; Ada, flow model is usually achieved by adjusting Oklahoma) the value(s) of hydraulic conductivity and • Anderson, Mary P. and William W. recharge rates. In addition, if plume monitor- Woessner. Applied Groundwater ing data or tracer test data are available, Modeling: Simulation of Flow and transport parameters such as dispersivity, and Advective Transport (Academic Press, sorption and degradation parameters can also 1992) be calibrated. A properly calibrated model is a powerful tool for predicting contaminant • EPA regional offices fate and transport. Conversely, if no calibra- tion is performed due to lack of suitable site • Has the model been verified against data, any Tier 3 model predictions will analytical solutions and other mod- remain subject to considerable uncertainty. els? If yes, are the test cases available At a minimum, a site-specific analysis so that a professional consultant can should provide estimated leachate concentra- test the model on his/her computer tions at specified downgradient points for a system? proposed design. For landfills, surface • Has the model been validated using impoundments and waste piles, you should field data? compare these concentrations to appropriate MCLs, health-based standards, or state stan- Table 12 provides a brief description of a dards. For land application units, if a waste number of commonly used ground-water fate leachate concentration is below the values and transport models. specified by the state, land application might be appropriate. Conversely, if a leachate con- c. Applying the Model to the Site centration is above state-specified values, For proper application of a ground-water land application might not be protective of flow and transport model, expertise in hydro- the ground water.
7A-37 Protecting Ground Water—Assessing Risk
Table 12. Example Site-Specific Ground-Water Fate and Transport Models
Model Name Description
MODFLOW MODFLOW is a 3-D, ground-water flow model for steady state and transient simulation of saturated flow problems in confined and unconfined aquifers. It calculates flow rates and water balances. The model includes flow towards wells, through riverbeds, and into drains. MODFLOW is the industry standard for ground-water modeling that was developed and still maintained by the United States Geological Survey (USGS). MODFLOW-2000 is the current version. MODFLOW is a public domain model; numerous pre- and post-processing software packages are available commercially. MODFLOW can simulate ground-water flow only. In order to simulate contaminant transport, MODFLOW must be used in conjunction with a compatible solute transport model (MT3DMS, see below).
MODFLOW and other USGS models can be obtained from the USGS Web site at
MT3DMS Modular 3-D Transport model (MT3D) is commonly used in contaminant transport model- ing and remediation assessment studies. Originally developed for EPA, the current version is known as MT3DMS. MT3DMS has a comprehensive set of options and capabilities for sim- ulating advection, dispersion/diffusion, and chemical reactions of contaminants in ground- water flow systems under general hydrogeologic conditions. MT3DMS retains the same modular structure of the original MT3D code, similar to that implemented in MODFLOW. The modular structure of the transport model makes it possible to simulate advection, dis- persion/diffusion, source/sink mixing, and chemical reactions separately without reserving computer memory space for unused options. New packages involving other transport processes and reactions can be added to the model readily without having to modify the existing code.
NOTE: The original version of this model known as MT3D, released in 1991, was based on a mathematical formulation which could result in mass-balance errors. This version should be avoided.
MT3DMS is maintained at the University of Alabama, and can be obtained at:
BIOPLUME-III BIOPLUME-III is a 2-D, finite difference model for simulating the natural attenuation of organic contaminants in ground water due to the processes of advection, dispersion, sorp- tion, and biodegradation. Biotransformation processes are potentially important in the restoration of aquifers contaminated with organic pollutants. As a result, these processes require valuation in remedial action planning studies associated with hydrocarbon contami- nants. The model is based on the USGS solute transport code MOC. It solves the solute transport equation six times to determine the fate and transport of the hydrocarbons, the 3- 3+ 2- 2+ electron acceptors (O2, NO , Fe , SO4 , and CO2), and the reaction byproducts (Fe ). A number of aerobic and anaerobic electron acceptors (e.g., oxygen, nitrate, sulfate, iron (III), and carbon dioxide) have been considered in this model to simulate the biodegradation of organic contaminants. Three different kinetic expressions can be used to simulate the aero- bic and anaerobic biodegradation reactions.
BIOPLUME-III and other EPA supported ground-water modeling software can be obtained via the EPA Center for Subsurface Modeling Support at the RS Kerr Environmental Research Lab in Ada, Oklahoma:
7A-38 Protecting Ground Water—Assessing Risk
A well-executed site-specific analysis can be expenditure of limited resources. If possible, a useful instrument to anticipate and avoid the model and the results of the final analyses, potential risks. A poorly executed site-specific including input and output parameters and analysis, however, could over- or under- key assumptions, should be shared with emphasize risks, possibly leading to adverse stakeholders. Chapter 1—Understanding Risk human health and environmental effects, or and Building Partnerships provides a more costly cleanup liability, or it could overempha- detailed description of activities to keep the size risks, possibly leading to the unnecessary public informed and involved.
Table 13. ASTM Ground-Water Modeling Standards
The American Society for Testing and Materials (ASTM), Section D-18.21.10 concerns subsurface fluid-flow (ground-water) modeling. The ASTM ground-water modeling section is one of several task groups funded under a cooperative agreement between USGS and EPA to develop consensus standards for the environmental industry and keep the modeling community informed as to the progress being made in development of modeling standards. The standards being developed by D-18.21.10 are “guides” in ASTM terminology, which means that the content is analogous to that of EPA guidance documents. The ASTM mod- eling guides are intended to document the state-of-the-science related to various topics in subsurface modeling. The following standards have been developed by D-18.21.10 and passed by ASTM. They can be purchased from ASTM by calling 610 832-9585. To order or browse for pub- lications, visit ASTM’s Web site
7A-39 Protecting Ground Water—Assessing Risk
Assessing Risk Activity List
■ Review the risk characterization tools recommended by this chapter. ■ Characterize the waste in accordance with the recommendations of Chapter 2 — Characterizing Waste. ■ Obtain expected leachate concentrations for all relevant waste constituents. ■ If a Tier 1 evaluation is conducted, understand and use the Tier 1 Evaluation to obtain recommen- dations for the design of your waste management unit (as noted previously, you can skip the Tier 1 analysis and proceed directly to a Tier 2 or Tier 3 analysis). ■ If a design system or other measures are recommended in a Tier 1 analysis, perform a Tier 2 analy- sis if you believe the recommendations are overly protective. Also, if data are available, you can conduct a Tier 2 or Tier 3 analysis without conducting a Tier 1 evaluation. ■ If your site characteristics or your waste management needs are particularly complex, or do not adequately simulate conditions reflected in a Tier 1 or Tier 2 analysis, consult with your state and a qualified professional and consider a more detailed, site-specific Tier 3 analysis.
7A-40 Protecting Ground Water—Assessing Risk
Resources
ASTM. 1996. ASTM Standards on Analysis of Hydrologic Parameters and Ground Water Modeling, Publication Number 03-418096-38.
ASTM. 1993. D-5447 Guide for Application of a Ground-Water Flow Model to a Site-Specific Problem.
ASTM. 1993. D-5490 Guide for Comparing Ground-Water Flow Model Simulations to Site-specific Information.
ASTM. 1994. D-5609 Guide for Defining Boundary Conditions in Ground-Water Flow Modeling.
ASTM. 1994. D-5610 Guide for Defining Initial Conditions in Ground-Water Flow Modeling.
ASTM. 1994. D-5611 Guide for Conducting a Sensitivity Analysis for a Ground-Water Flow Model Application.
ASTM. 1994. D-5718 Guide for Documenting a Ground-Water Flow Model Application.
ASTM. 1994. D-5719 Guide to Simulation of Subsurface Air Flow Using Ground-Water Flow Modeling Codes.
ASTM. 1995. D-5880 Guide for Subsurface Flow and Transport Modeling.
ASTM. 1996. D-5981 Guide for Calibrating a Ground-Water Flow Model Application.
Bagchi, A. 1994. Design, Construction, and Monitoring of Landfills.
Berner, E. K. and R. Berner. 1987. The Global Water Cycle: Geochemistry and Environment.
Boulding, R. 1995. Soil, Vadose Zone, and Ground-Water Contamination: Assessment, Prevention, and Remediation.
Lee, C. 1992. Environmental Engineering Dictionary, 2d. Ed.
Sharma, H., and S. Lewis. 1994. Waste Containment Systems, Waste Stabilization, and Landfills.
Speidel, D., L. Ruedisili, and A. Agnew. 1988. Perspectives on Water: Uses and Abuses.
7A-41 Protecting Ground Water—Assessing Risk
Resources (cont.)
U.S. EPA. 2002a. Industrial Waste Management Evaluation Model (IWEM) Technical Background Document. EPA530-R-02-012.
U.S. EPA. 2002b. The User’s Guide for the Industrial Waste Management Evaluation Model. EPA530-R- 02-013.
U.S. EPA. 2002c. EPACMTP Data/Parameters Background Document.
U.S. EPA. 2002d. EPACMTP Technical Background Document.
U.S. EPA. 1997a. Exposure Factors Handbook. EPA600-P-95-002F.
U.S. EPA. 1997b. Guiding Principles for Monte Carlo Analyses. EPA630-R-97-001.
U.S. EPA. 1994a. A Technical Guide to Ground-Water Model Selection at Sites Contaminated with Radioactive Substance. EPA 4-2-R-94-012.
U.S. EPA. 1994b. Assessment Framework for Ground-Water Modeling Applications. EPA500-B- 94-003.
U.S. EPA. 1994c. Ground-Water Modeling Compendium, Second Edition. EPA500-B-94-003.
U.S. EPA. 1991. Seminar Publication: Site Characterization for Subsurface Remediation. EPA625-4-91-026.
U.S. EPA. 1989. Exposure Assessment Methods Handbook.
U.S. EPA. 1988. Selection Criteria For Mathematical Models Used In Exposure Assessments: Ground-water Models. EPA600-8-88-075.
U.S. EPA. 1988. Superfund Exposure Assessment Manual.
7A-42 Part IV Protecting Ground Water
Chapter 7: Section B Designing and Installing Liners
Technical Considerations for New Surface Impoundments, Landfills, and Waste Piles Contents
I. In-Situ Soil Liners ...... 7B-1
II. Single Liners ...... 7B-2 A. Compacted Clay Liners ...... 7B-2 B. Geomembranes or Flexible Membrane Liners ...... 7B-10 C. Geosynthetic Clay Liners ...... 7B-17
III. Composite Liners...... 7B-22
IV. Double Liners (Primary and Secondary Lined Systems) ...... 7B-23
V. Leachate Collection and Leak Detection Systems ...... 7B-24 A. Leachate Collection System...... 7B-24 B. Leak Detection System ...... 7B-28 C. Leachate Treatment System ...... 7B-29
VI. Construction Quality Assurance and Quality Control ...... 7B-29 A. Compacted Clay Liner Quality Assurance and Quality Control ...... 7B-32 B. Geomembrane Liner Quality Assurance and Quality Control ...... 7B-32 C. Geosynthetic Clay Liner Quality Assurance and Quality Control ...... 7B-33 D. Leachate Collection System Quality Assurance and Quality Control...... 7B-34
Designing and Installing Liners Activity List...... 7B-36
Resources ...... 7B-37
Appendix ...... 7B-43
Figures: Figure 1. Water Content for Achieving a Specific Density ...... 7B-6 Figure 2: Two Types of Footed Rollers...... 7B-8 Figure 3: Four Variations of GCL Bonding Methods ...... 7B-19 Figure 4: Typical Leachate Collection System ...... 7B-25 Figure 5: Typical Geonet Configuration...... 7B-27 Protecting Ground Water—Designing and Installing Liners
Designing and Installing Liners—Technical Considerations for New Surface Impoundments, Landfills, and Waste Piles This chapter will help you: • Employ liner systems where needed to protect ground water from contamination. • Select from clay liners, synthetic liners, composite liners, leachate collection systems, and leak detection systems as appropriate. • Consider technical issues carefully to ensure that the liner system will function as designed.
nce risk has been characterized I. In-Situ Soil and the most appropriate design system is chosen, the Liners next step is unit design. The For the purpose of the Guide, in-situ soil Industrial Waste Management refers to simple, excavated areas or impound- OEvaluation Model (IWEM), discussed in ments, without any additional engineering Chapter 7, Section A—Assessing Risk can be controls. The ability of natural soils to hinder used to determine appropriate design system transport and reduce the concentration of recommendations. A critical part of this constituent levels through dilution and atten- design for new landfills, waste piles, and sur- uation can provide sufficient protection when face impoundments is the liner system. The the initial constituent levels in the waste liner system recommendations in the Guide stream are very low, when the wastes are do not apply to land application units, since inert, or when the hydrogeologic setting such operations generally do not include a affords sufficient protection. liner system as part of their design. (For design of land application units, refer to What are the recommendations Chapter 7, Section C—Designing a Land for in-situ soils? Application Program.) You should work with your state agency to ensure consideration of The soil below and adjacent to a waste any applicable design system requirements, management unit should be suitable for con- recommendations, or standard practices the struction. It should provide a firm foundation state might have. In this chapter, sections I for the waste. Due to the low risk associated though IV discuss four design options—no with wastes being managed in these units, a liner/in-situ soils, single liner, composite liner, liner might not be necessary; however, it is and double liner. Section V covers leachate still helpful to review the recommended loca- collection and leak detection systems, and tion considerations and operating practices for section VI discusses construction quality the unit. assurance and quality control.
7B-1 Protecting Ground Water—Designing and Installing Liners
What technical issues should be II. Single Liners considered with the use of in-situ If the risk evaluation recommended the use soils? of a single liner, the next step is to determine the type of single liner system most appropri- In units using in-situ natural soils, con- ate for the site. The discussion below address- struction and design of an engineered liner es three types of single liner systems: will not be necessary; however, there are still compacted clay liners, geomembrane liners, technical concerns to consider. These include and geosynthetic clay liners. Determining the following: which material, or combination of materials, is • The stability of foundation soils. important for protecting human health and 1 • The compatibility of the waste with the environment. native soils. • The location where the unit will be A. Compacted Clay Liners sited. A compacted clay liner can serve as a single • The potential to recompact existing liner or as part of a composite or double liner soils. system. Compacted clay liners are composed of natural mineral materials (natural soils), Potential instability can occur in the foun- bentonite-soil blends, and other materials dation soil, if its load-bearing capacity and placed and compacted in layers called lifts. If resistance to movement or consolidation are natural soils at the site contain a significant insufficient to support the waste. The ground- quantity of clay, then liner materials can be water table or a weak soil layer also can influ- excavated from onsite locations known as bor- ence the stability of the unit. You should take row pits. Alternatively, if onsite soils do not measures, such as designing maximum slopes, contain sufficient clay, clay materials can be to avoid slope failure during construction and hauled from offsite sources, often referred to operation of the waste management unit. Most as commercial pits. soil slopes are stable at a 3:1 horizontal to ver- tical inclination. There are common sense Compacted clay liners can be designed to operating practices to ensure that any wastes work effectively as hydraulic barriers. To to be managed on in-situ soils will not inap- ensure that compacted clay liners are well propriately interact with the soils. When using constructed and perform as they are designed, in-situ soils, refer to Chapter 4—Considering it is important to implement effective quality the Site. Selecting an appropriate location will control methods emphasizing soil investiga- be of increased importance, since the added tions and construction practices. Three objec- barrier of an engineered liner will not be pre- tives of quality assurance and quality control sent. Because in-situ soil can have non-homo- for compacted soil liners are to ensure that 1) geneous material, root holes, and cracks, its selected liner materials are suitable, 2) liner performance can be improved by scarifying materials are properly placed and compacted, and compacting the top portion of the in-situ and 3) the completed liner is properly protect- natural soils. ed before, during, and after construction. Quality assurance and quality control are dis- cussed in greater detail in section VI.
1 Many industry and trade periodicals, such as Waste Age, MSW Management, Solid Waste Technologies, and World Wastes, have articles on liner types and their corresponding costs, as well as advertisements 7B-2 and lists of vendors. Protecting Ground Water—Designing and Installing Liners
What are the thickness and Soil Properties hydraulic conductivity recommen- Minimizing hydraulic conductivity is the dations for compacted clay liners? primary goal in constructing a soil liner. Factors to consider are water content, plasticity Compacted clay liners should be at least 2 characteristics, percent fines, and percent grav- feet thick and have a maximum hydraulic el, as these properties affect the soil’s ability to conductivity of 1 x 10-7 cm/sec (4 x 10-8 achieve a specified hydraulic conductivity. in/sec). Hydraulic conductivity refers to the Hydraulic conductivity. It is important to degree of ease with which a fluid can flow select compacted clay liner materials so that through a material. A low hydraulic conduc- remolding and compacting of the materials tivity will help minimize leachate migration will produce a low hydraulic conductivity. out of a unit. Designing a compacted clay Factors influencing the hydraulic conductivi- liner with a thickness ranging from 2 to 5 feet ty at a particular site include: the degree of will help ensure that the liner meets desired compaction, compaction method, type of clay hydraulic conductivity standards and will material used, soil moisture content, and also minimize leachate migration as a result density of the soil during liner construction. of any cracks or imperfections present in the The hydraulic conductivity of a soil also liner. Thicker compacted clay liners provide depends on the viscosity and density of the additional time to minimize leachate migra- fluid flowing through it. Consider measuring tion prior to the clay becoming saturated. hydraulic conductivity using methods such as What issues should be considered American Society of Testing and Materials (ASTM) D-5084.2 in the design of a compacted clay Water content. Water content refers to the liner? amount of liquid, or free water, contained in a The first step in designing a compacted given amount of material. Measuring water clay liner is selecting the clay material. The content can help determine whether a clay quality and properties of the material will material needs preprocessing, such as moisture influence the performance of the liner. The adjustment or soil amendments, to yield a most common type of compacted soil is one specified density or hydraulic conductivity. that is constructed from naturally occurring Compaction curves can be used to depict soils that contain a significant quantity of moisture and density relationships, using clay. Such soils are usually classified as CL, either ASTM D-698 or ASTM D-1557, the CH, or SC in the Unified Soil Classification standard or modified Proctor test methods, System (USCS). Some of the factors to con- depending on the compaction equipment used sider in choosing a soil include soil proper- and the degree of firmness in the foundation 3 ties, interaction with wastes, and test results materials. The critical relationship between for potentially available materials. clay soil moisture content and density is explained thoroughly in Chapter 2 of EPA’s 1993 technical guidance document Quality
2 ASTM D-5084, Standard Test Method for Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall Permeameter. 3 ASTM D-698, Test Method for Laboratory Compaction Characteristics of Soil Using Standard Effort (12,400 ft-lbf/ft3 (600 kN-m/m3)). ASTM D-1557, Test Method for Laboratory Compaction Characteristics of Soil Using Modified Effort 3 3 (56,000 ft-lbf/ft (2,700 kN-m/m )). 7B-3 Protecting Ground Water—Designing and Installing Liners
Assurance and Quality Control for Waste sized particles. Soils with less than 30 percent Containment Facilities (U.S. EPA, 1993c). fines can be worked to obtain hydraulic con- ductivities below 1 x 10-7 cm/sec (4 x 10-8 Plasticity characteristics. Plasticity char- in./sec), but use of these soils requires more acteristics describe a material’s ability to careful construction practices. behave as a plastic or moldable material. Soils containing clay are generally categorized Gravel is defined as particles unable to as plastic. Soils that do not contain clay are pass through the openings of a Number 4 non-plastic and typically considered unsuit- sieve, which has an opening size equal to able materials for compacted clay liners, 4.76 mm (0.2 in.). Although gravel itself has unless soil amendments such as bentonite a high hydraulic conductivity, relatively large clay are introduced. amounts of gravel, up to 50 percent by weight, can be uniformly mixed with clay Plasticity characteristics are quantified by materials without significantly increasing the three parameters: liquid limit, plastic limit, hydraulic conductivity of the material. Clay and plasticity index. The liquid limit is materials fill voids created between gravel defined as the minimum moisture content (in particles, thereby creating a gravel-clay mix- percent of oven-dried weight) at which a soil- ture with a low hydraulic conductivity. As water mixture can flow. The plastic limit is long as the percent gravel in a compacted the minimum moisture content at which a clay mixture remains below 50 percent, cre- soil can be molded. The plasticity index is ating a uniform mixture of clay and gravel, defined as the liquid limit minus the plastic where clay can fill in gaps, is more critical limit and defines the range of moisture con- than the actual gravel content of the mixture. tent over which a soil exhibits plastic behav- ior. When soils with high plastic limits are You should pay close attention to the per- too dry during placement, they tend to form cent gravel in cases where a compacted clay clods, or hardened clumps, that are difficult liner functions as a bottom layer to a geosyn- to break down during compaction. As a thetic, as gravel can cause puncturing in result, preferential pathways can form around geosynthetic materials. Controlling the maxi- these clumps allowing leachate to flow mum particle size and angularity of the grav- through the material at a higher rate. Soil el should help prevent puncturing, as well as plasticity indices typically range from 10 per- prevent gravel from creating preferential flow cent to 30 percent. Soils with a plasticity paths. Similar to gravel, soil particles or rock index greater than 30 percent are cohesive, fragments also can create preferential flow sticky, and difficult to work with in the field. paths. To help prevent the development of Common testing methods for plasticity char- preferential pathways and an increased acteristics include the methods specified in hydraulic conductivity, it is best to use soil ASTM D-4318, also known as Atterberg lim- liner materials where the soil particles and its tests.4 rock fragments are typically small (e.g., 3/4 inch in diameter). Percent fines and percent gravel. Typical soil liner materials contain at least 30 percent fines and can contain up to 50 percent gravel, Interactions With Waste by weight. Common testing methods for per- Waste placed in a unit can interact with cent fines and percent gravel are specified in compacted clay liner materials, thereby influ- ASTM D-422, also referred to as grain size encing soil properties such as hydraulic con- distribution tests.5 Fines refer to silt and clay-
4 ASTM D-4318, Standard Test Method for Liquid Limit, Plastic Limit, and Plasticity Index of Soils. 5 ASTM D-422, Standard Test Method for Particle-Size Analysis of Soils. 7B-4 Protecting Ground Water—Designing and Installing Liners
ductivity and permeability. Two ways that next step is to test a representative sample of waste materials can influence the hydraulic soil to determine material properties such as conductivity of the liner materials are plasticity characteristics, percent gravel, and through dissolution of soil minerals and percent fines. To confirm the suitability of the changes in clay structure. Soil minerals can materials once construction begins, you be dissolved, or reduced to liquid form, as a should consider requesting that representa- result of interaction with acids and bases. For tive samples from the materials in the borrow example, aluminum and iron in the soil can or commercial pit be tested periodically after be dissolved by acids, and silica can be dis- work has started. solved by bases. While some plugging of soil Material selection steps will vary, depend- pores by dissolved minerals can lower ing on the origin of the materials for the pro- hydraulic conductivity in the short term, the ject. For example, if a commercial pit provides creation of piping and channels over time can the materials, locating an appropriate onsite lead to an increased hydraulic conductivity in borrow pit is not necessary. In addition to the the long term. The interaction of waste and tests performed on the material, it is recom- clay materials can also cause the creation of mended that a qualified inspector make visual positive ions, or cations. The presence of observations throughout the construction cations such as sodium, potassium, calcium, process to ensure that harmful materials, such and magnesium can change the clay struc- as stones or other large matter, are not present ture, thereby influencing the hydraulic con- in the liner material. ductivity of the liner. Depending on the cation type and the clay mineral, an increased What issues should be considered presence of such cations can cause the clay minerals to form clusters and increase the in the construction of a liner and permeability of the clay. Therefore, before the operation of a unit? selecting a compacted clay liner material, it is You should develop test pads to demon- important to develop a good understanding strate construction techniques and material of the composition of the waste that will be performance on a small scale. During unit con- placed in the waste management unit. EPA’s struction and operation, some additional fac- Method 9100, in publication SW-846, mea- tors influencing the performance of the liner sures the hydraulic conductivity of soil sam- include: preprocessing, subgrade preparation, ples before and after exposure to permeants.6 method of compaction, and protection against desiccation and cracking. Each of these steps, Locating and Testing Material from preprocessing through protection against Although the selection process for com- desiccation and cracking, should be repeated pacted clay liner construction materials can for each lift or layer of soil. vary from project to project, some common material selection steps include locating and Test Pads testing materials at a potential borrow or Preparing a test pad for the compacted commercial pit before construction, and clay liner helps verify that the materials and observing and testing material performance methods proposed will yield a liner that throughout construction. First, investigate a meets the desired hydraulic conductivity. A potential borrow or commercial pit to deter- test pad also provides an opportunity to mine the volume of materials available. The
6 SW-846, Test Methods for Evaluating Solid Waste: Physical/Chemical Methods.
7B-5 Protecting Ground Water—Designing and Installing Liners
demonstrate the performance of alternative mum tend to have a relatively high hydraulic materials or methods of construction. A test conductivity. Soils compacted at water con- pad should be constructed with the soil liner tents greater than optimum tend to have low materials proposed for a particular project, hydraulic conductivity and low strength. using the same preprocessing procedures, Proper soil water content revolves around compaction equipment, and construction achieving a minimum dry density, which is practices proposed for the actual liner. A expressed as a percentage of the soil’s maxi- complete discussion of test pads (covering mum dry density. The minimum dry density dimensions, materials, and construction) can typically falls in the range of 90 to 95 percent be found in Chapter 2 of EPA’s 1993 techni- of the soil’s maximum dry density value. From cal guidance document Quality Assurance and the minimum dry density range, the required Quality Control for Waste Containment Facilities water content range can be calculated, as (U.S. EPA, 1993c). A discussion of commonly shown in Figure 1. In this example the soil used methods to measure in-situ hydraulic has a maximum dry density of 115 lb/cu ft. conductivity is also contained in that chapter. Based upon a required minimum dry density value of 90 percent of maximum dry density, Preprocessing Although some liner Figure 1. materials can be ready Water Content for Achieving a Specific Density for use in construction immediately after they are excavated, many materials will require some degree of prepro- cessing. Preprocessing methods include: water content adjustment, removal of oversized particles, pulverization of any clumps, homoge- nization of the soils, and introduction of addi- tives, such as bentonite. Water content adjustment. For natural soils, the degree of satu- ration of the soil liner at the time of compaction, known as molding water content, influences the engineering properties of the compacted material. Soils compacted at water contents less than opti- Source: U.S. EPA, 1988.
7B-6 Protecting Ground Water—Designing and Installing Liners
which is equal to 103.5 lb/cu ft, the required mon practice is to blend bentonite with them water content ranges from 10 to 28 percent. to reduce the hydraulic conductivity. Bentonite is a clay mineral that expands when it comes It is less problematic to compact clay soil into contact with water. Relatively small at the lower end of the required water con- amounts of bentonite, on the order of 5 to 10 tent range because it is easier to add water to percent, can be added to sand or other nonco- the clay soil than to remove it. Thus, if pre- hesive soils to increase the cohesion of the cipitation occurs during construction of a site material and reduce hydraulic conductivity. which is being placed at the lower end of the required water content range, the additional Sodium bentonite is a common additive water might not result in a soil water content used to amend soils. However, this additive is greater than the required range. Conversely, if vulnerable to degradation as a result of con- the site is being placed at the upper end of tact with certain chemicals and waste the range, for example at 25 percent, any leachates. Calcium bentonite, a more perme- additional moisture will be excessive, result- able material than sodium bentonite, is anoth- ing in water content over 28 percent and er common additive used to amend soils. making the 90 percent maximum dry density Approximately twice as much calcium ben- unattainable. Under such conditions con- tonite is needed to achieve a hydraulic con- struction should halt while the soil is aerated ductivity comparable to that of sodium and excess moisture is allowed to evaporate. bentonite. Amended soil mixtures generally Removal of oversized particles. require mixing in a pug mill, cement mixer, or other mixing equipment that allows water to Preprocessing clay materials, to remove cob- be added during the mixing process. bles or large stones that exceed the maximum Throughout the mixing and placement allowable particle size, can improve the soil’s processes, water content, bentonite content, compactibility and protect any adjacent and particle distribution should be controlled. geomembrane from puncture. Particle size Other materials that can be used as soil addi- should be small (e.g., 3/4 inch in diameter) tives include lime cement and other clay min- for compaction purposes. If a geomembrane erals, such as atapulgite. It can be difficult to will be placed over the compacted clay, only mix additives thoroughly with cohesive soils, the upper lift of clay needs to address con- or clays; the resultant mixture might not cerns regarding puncture resistance. achieve the desired level of hydraulic conduc- Observation by quality assurance and quality tivity throughout the entire liner. control personnel is the most effective method to identify areas where oversized par- ticles need to be removed. Cobbles and Subgrade Preparation stones are not the only materials that can It is important to ensure that the subgrade interfere with compactive efforts. Chunks of on which a compacted clay liner will be con- dry, hard clay, also known as clods, often structed is properly prepared. When a com- need to be broken into smaller pieces to be pacted clay liner is the lowest component of a properly hydrated, remolded, and compact- liner system, the subgrade consists of native ed. In wet clay, clods are less of a concern soil or rock. Subgrade preparation for these since wet clods can often be remolded with a systems involves compacting the native soil reasonable compactive effort. to remove any soft spots and adding water to Soil amendments. If the soils at a unit do or removing water from the native soil to not have a sufficient percentage of clay, a com- obtain a specified firmness. Alternatively, in
7B-7 Protecting Ground Water—Designing and Installing Liners
some cases, the compacted clay liner can be ness, and the bonding between the lifts. placed on top of a geosynthetic material, such Molding water content, described earlier as a geotextile. In such cases, subgrade prepa- under preprocessing, is another factor influ- ration involves ensuring the smoothness of encing the effectiveness of compaction. the geosynthetic on which the clay liner will Type of equipment. Factors to consider be placed and the conformity of the geosyn- when selecting compaction equipment thetic material to the underlying material. include: the type and weight of the com- pactor, the characteristics of any feet on the Compaction drum, and the weight of the roller per unit The main purpose of compaction is to length of drummed surface. Heavy com- densify the clay materials by breaking and pactors, weighing more than 50,000 pounds, remolding clods of material into a uniform with feet long enough to penetrate a loose lift mass. Since amended soils usually do not of soil, are often the best types of compactor develop clumps, the primary objective of for clay liners. For bentonite-soil mixtures, a compaction for such materials is to increase footed roller might not be appropriate. For the material’s density. Proper compaction of these mixtures, where densification of the liner materials is essential to ensure that a material is more important than kneading or compacted clay liner meets specified remolding it to meet low hydraulic conduc- hydraulic conductivity standards. Factors tivity specifications, a smooth-drum roller or influencing the effectiveness of compaction a rubber- tired roller might produce better efforts include: the type of equipment select- results. Figure 2 depicts two types of footed ed, the number of passes made over the rollers, a fully penetrating footed roller and a materials by such equipment, the lift thick- partially-penetrating footed roller.
Figure 2 Two Types of Footed Rollers
Source: U.S. EPA, 1993c.
7B-8 Protecting Ground Water—Designing and Installing Liners
For placement of liners on side slopes, are usually necessary to remold and compact consider the angle and length of the slope. clay liner materials thoroughly. Placing continuous lifts on a gradually An equipment pass can be defined as one inclined slope will provide better continuity pass of the compaction equipment or as one between the bottom and sidewalls of the pass of a drum over a given area of soil. It is liner. Since continuous lifts might be impossi- important to clearly define what is meant by ble to construct on steeper slopes due to the a pass in any quality assurance or quality difficulties of operating heavy compaction control plans. It does not matter which defin- equipment on these slopes, materials might ition is agreed upon, as long as the definition need to be placed and compacted in horizon- is used consistently throughout the project. tal lifts. When sidewalls are compacted hori- zontally, it is important to avoid creating Lift thickness. You should determine the seepage planes, by securely connecting the appropriate thickness (as measured before edges of the horizontal lift with the bottom of compaction) of each of the several lifts that the liner. Because the lift needs to be wide will make up the clay liner. The initial thick- enough to accommodate compaction equip- ness of a loose lift will affect the compactive ment, the thickness of the horizontal lift is effort needed to reach the lower portions of often greater than the thickness specified in the lift. Thinner lifts allow compactive efforts the design. In such cases, you should consid- to reach the bottom of a lift and provide er trimming soil material from the construct- greater assurance that compaction will be suf- ed side slopes and sealing the trimmed ficient to allow homogenous bonding surface using a sealed drum roller. between subsequent lifts. Loose lift thickness- es typically range between 13 and 25 cm (5 It is common for contractors to use several and 10 in.). Factors influencing lift thickness different types of compaction equipment dur- are: soil characteristics, compaction equip- ing liner construction. Initial lifts might need ment, firmness of the foundation materials, the use of a footed roller to fully penetrate a and the anticipated compaction necessary to loose lift. Final lifts also might need the use meet hydraulic conductivity requirements. of a footed roller for compaction, however, they might be formed better by using a Bonding between lifts. Since it is smooth roller after the lift has been compact- inevitable that some zones of higher and ed to smooth the surface of the lift in prepa- lower hydraulic conductivity, also known as ration for placement of an overlying preferential pathways, will be present within geomembrane. each lift, lifts should be joined or bonded in a way that minimizes extending these zones or Number of passes. The number of passes pathways between lifts. If good bonding is made by a compactor over clay materials can achieved, the preferential pathways will be influence the overall hydraulic conductivity truncated by the bonded zone between the of the liner. The minimum number of passes lifts. At least two recommended methods that is reasonable depends on a variety of exist for preparing proper bonds. The first site-specific factors and cannot be general- method involves kneading, or blending the ized. In some cases, where a minimum cover- new lift with the previously compacted lift age is specified, it might be possible to using a footed roller. Using a roller with feet calculate the minimum number of passes to long enough to fully penetrate through the meet such a specification. At least 5 to 15 top lift and knead the previous lift improves passes with a compactor over a given point the quality of the bond. A second method
7B-9 Protecting Ground Water—Designing and Installing Liners
involves using a disc harrow or similar equip- increase the hydraulic conductivity of a liner. ment to scarify, or roughen, and wet the top It is important to avoid construction during inch of the recently placed lift, prior to plac- freezing weather. If freezing does occur and ing the next lift. the damage affects only a shallow depth, the liner can be repaired by rerolling the surface. Protection Against Desiccation and If deeper freezing occurs, the repairs might be more complicated. For a general guide to Cracking frost depths, see Figure 1 of Chapter 11— You should consider how to protect com- Performing Closure and Post-Closure Care. pacted clay liners against desiccation and freezing during and after construction. Protection against desiccation is important, B. Geomembranes or because clay soil shrinks as it dries. Depend- Flexible Membrane Liners ing on the extent of shrinkage, it can crack. Geomembranes or flexible membrane lin- Deep cracks, extending through more than ers are used to contain or prevent waste con- one lift, can cause problems. You should stituents and leachate from escaping a waste measure water content to determine whether management unit. Geomembranes are made desiccation is occurring. by combining one or more plastic polymers There are several ways to protect compact- with ingredients such as carbon black, pig- ed clay liners from desiccation. One preven- ments, fillers, plasticizers, processing aids, tive measure is to smooth roll the surface with crosslinking chemicals, anti-degradants, and a steel drummed roller to produce a thin, biocides. A wide range of plastic resins are dense skin of soil; this layer can help mini- used for geomembranes, including high den- mize the movement of water into or out of the sity polyethylene (HDPE), linear low density compacted material. Another option is to wet polyethylene (LLDPE), low density linear the clay periodically in a uniform manner; polyethlene (LDLPE), very low density poly- however, it is important to make sure to avoid ethlene (VLDPE), polyvinyl chloride (PVC), creating areas of excessive wetness. A third flexible polypropylene (fPP), chlorosulfonated measure involves covering compacted clay polyethylene (CSPE or Hypalon), and ethyl- liner materials with a sheet of white or clear ene propylene diene termonomer (EPDM). plastic or tarp to help prevent against desicca- Most manufacturers produce geomembranes tion and cracking. The cover should be through extrusion or calendering. In the weighted down with sandbags or other mater- extrusion process, a molten polymer is ial to minimize exposure of the underlying stretched into a nonreinforced sheet; extrud- materials to air. Using a light-colored plastic ed geomembranes are usually made of HDPE will help prevent overheating, which can dry and LLDPE. During the calendering process, out the clay materials. If the clay liner is not a heated polymeric compound is passed being covered with a geosynthetic, another through a series of rollers. In this process, a method to prevent desiccation involves cover- geomembrane can be reinforced with a ing the clay with a layer of protective cover woven fabric or fibers. Calendered geomem- soil or intentionally overbuilding the clay liner branes are usually made of PVC and CSPE. and shaving it down to liner grade. Protection against freezing is another important consideration, because freezing can
7B-10 Protecting Ground Water—Designing and Installing Liners
What are the thickness recommen- These stresses include the self-weight of the dations for geomembrane liners? geomembrane and any down drag caused by waste settlement on side slope liners. Geomembranes range in thicknesses from 20 Puncture and tear resistance. to 120 mil (1 mil = 0.001 in.). A good design Geomembrane liners can be subject to tearing should include a minimum thickness of 30 mil, during installation due to high winds or han- except for HDPE liners, which should have a dling. Puncture resistance is also important to minimum thickness of 60 mil. These recom- consider since geomembranes are often mended minimum thicknesses ensure that the placed above or below materials that might liner material will withstand the stress of con- have jagged or angular edges. For example, struction and the weight load of the waste, and geomembranes might be installed above a allow adequate seaming to bind separate granular drainage system that includes gravel. geomembrane panels. Reducing the potential for tearing or puncture, through proper con- Susceptibility to environmental stress struction and quality control, is essential for a cracks. Environmental factors can cause geomembrane to perform effectively. cracks or failures before a liner is stressed to its manufactured strength. These imperfec- What issues should be considered tions, referred to as environmental stress in the design of a geomembrane cracks, often occur in areas where a liner has been scratched or stressed by fatigue. These liner? cracks can also result in areas where excess Several factors to address in the design surface wetting agents have been applied. In include: determining appropriate material surface impoundments, where the geomem- properties and testing to ensure these proper- brane liner has greater exposure to the atmos- ties are met, understanding how the liner will phere and temperature changes, such interact with the intended waste stream, exposure can increase the potential for envi- accounting for all stresses imposed by the ronmental stress cracking. design, and ensuring adequate friction. Ultraviolet resistance. Ultraviolet resis- tance is another factor to consider in the Material Properties and Selection design of geomembrane liners, especially in cases where the liner might be exposed to When designing a geomembrane liner, you ultraviolet radiation for prolonged periods of should examine several properties of the time. In such cases, which often occur in sur- geomembrane material in addition to thick- face impoundments, ultraviolet radiation can ness, including: tensile behavior, tear resis- cause degradation and cracking in the tance, puncture resistance, susceptibility to geomembrane. Adding carbon black or other environmental stress cracks, ultraviolet resis- additives during the manufacturing process tance, and carbon black content. can increase a geomembrane’s ultraviolet Tensile behavior. Tensile behavior refers to resistance. Backfilling over the exposed the tensile strength of a material and its ability geomembrane also works to prevent degrada- to elongate under strain. Tensile strength is the tion due to ultraviolet radiation. ability of a material to resist pulling stresses without tearing. The tensile properties of a Interactions With Waste geomembrane must be sufficient to satisfy the stresses anticipated during its service life. Since the main purpose of a geomembrane is to provide a barrier and prevent contami-
7B-11 Protecting Ground Water—Designing and Installing Liners
nants from penetrating through the geomem- Designing for Adequate Friction brane, chemical resistance is a critical consid- Adequate friction between the geomem- eration. Testing for chemical resistance might brane liner and the soil subgrade, as well as be warranted depending on the type, vol- between any geosynthetic components, is umes, and characteristics of waste managed necessary to prevent extensive slippage or at a particular unit and the type of geomem- sloughing on the slopes of a unit. Design brane to be used. An established method for equations for such components should evalu- testing the chemical resistance of geomem- ate: 1) the ability of a liner to support its own branes, EPA Method 9090, can be found in weight on side slopes, 2) the ability of a liner SW-846. ASTM has also adopted standards to withstand down-dragging during and after for testing the chemical compatibility of vari- waste placement, 3) the best anchorage con- ous geosynthetics, including geomembranes, figuration for the liner, 4) the stability of soil with leachates from waste management units. cover on top of a liner, and 5) the stability of ASTM D-5747 provides a standard for testing other geosynthetic components, such as geot- the chemical compatibility of 7 extiles or geonets, on top of a liner. An evalu- geomembranes. ation of these issues can affect the choice of geomembrane material, polymer type, fabric Stresses Imposed by Liner Design reinforcement, thickness, and texture neces- A liner design should take into account the sary to achieve the design requirements. stresses imposed on the liner by the design Interface strengths can be significantly configuration. These stresses include: the dif- improved by using textured geomembranes. ferential settlement in foundation soil, strain What issues should be consid- requirements at the anchor trench, strain requirements over long, steep side slopes, ered in the construction of a stresses resulting from compaction, and seis- geomembrane liner? mic stresses. Often an anchor trench designed to secure the geomembrane during construc- When preparing to construct a geomem- tion is prepared along the perimeter of a unit brane liner, you should plan appropriate cell. This action can help prevent the shipment and handling procedures, perform geomembrane from slipping down the interi- testing prior to construction, prepare the or side slopes. Trench designs should include subgrade, consider temperature effects, and a depth of burial sufficient to hold the speci- account for wind effects. In addition, you fied length of liner. If forces larger than the should select a seaming process, determine a tensile strength of the liner are inadvertently material for and method of backfilling, and developed, then the liner could tear. For this plan for testing during construction. reason, the geomembrane liner should be allowed to slip or give in the trench after con- Shipment, Handling, and Site Storage struction to prevent such tearing. To help You should follow quality assurance and reduce unnecessary stresses in the liner de- quality control procedures to ensure proper sign, it is advisable to avoid using horizontal handling of geomembranes. Different types of seams. For more information on design stress- geomembrane liners require different types of es, consult Geosynthetic Guidance for packaging for shipment and storage. Hazardous Waste Landfill Cells and Surface Typically a geomembrane manufacturer will Impoundments (U.S. EPA, 1987). provide specific instructions outlining the
7 ASTM D-5747, Practice for Tests to Evaluate the Chemical Resistance of Geomembranes to Liquids.
7B-12 Protecting Ground Water—Designing and Installing Liners
handling, storage, and construction specifica- Guidance Document: Quality Assurance and tions for a product. In general, HDPE and Quality Control for Waste Containment Facilities LLDPE geomembrane liners are packaged in a (U.S. EPA, 1993c). roll form, while PVC and CSPE-R liners (CSPE-R refers to a CSPE geomembrane liner Testing Prior to Construction reinforced with a fabric layer) are packaged in panels, accordion-folded in two directions, Before any construction begins, is it recom- and placed onto pallets. Whether the liner is mended that you test both the geomembrane shipped in rolls or panels, you should pro- materials from the manufacturer and the vide for proper storage. The rolls and panels installation procedures. Acceptance and con- should be packaged so that fork lifts or other formance testing is used to evaluate the per- equipment can safely transport them. For formance of the manufactured geomembranes. rolls, this involves preparing the roll to have a Constructing test strips can help evaluate how sufficient inside diameter so that a fork lift well the intended construction process and with a long rod, known as a stinger, can be quality control procedures will work. used for lifting and moving. For accordion Acceptance and conformance testing. panels, proper packaging involves using a You should perform acceptance and confor- structurally-sound pallet, wrapping panels in mance testing on the geomembrane liner treated cardboard or plastic wrapping to pro- received from the manufacturer to determine tect against ultraviolet exposure, and using whether the materials meet the specifications banding straps with appropriate cushioning. requested. While the specific ASTM test Once the liners have been transported to the methods vary depending on geomembrane site, the rolls or panels can be stored until the type, recommended acceptance and confor- subgrade or subbase (either natural soils or mance testing for geomembranes includes another geosynthetic) is prepared. evaluations of thickness, tensile strength and elongation, and puncture and tear resistance Subgrade Preparation testing, as appropriate. For most geomem- brane liner types, the recommended ASTM Before a geomembrane liner is installed, method for testing thickness is ASTM D- you should prepare the subgrade or subbase. 5199.8 For measuring the thickness of tex- The subgrade material should meet specified tured geomembranes, you should use ASTM grading, moisture content, and density D-5994.9 For tensile strength and elongation, requirements. In the case of a soil subgrade, ASTM D-638 is recommended for the HDPE it is important to prevent construction equip- and LLDPE sheets, while ASTM D-882 and ment used to place the liner from deforming ASTM D-751 are recommended for PVC and the underlying materials. If the underlying CSPE geomembranes, respectively.10 Puncture materials are geosynthetics, such as geonets resistance testing is typically recommended or geotextiles, you should remove all folds for HDPE and LLDPE geomembranes using and wrinkles before the liner is placed. For ASTM D-4833.11 To evaluate tear resistance further information on geomembrane place- for HDPE, LLDPE, and PVC geomembrane ment, see Chapter 3 of EPA’s Technical
8 ASTM D-5199, Standard Test Method for Measuring Nominal Thickness of Geotextiles and Geomembranes. 9 ASTM D-5994, Measuring Core Thickness of Textured Geomembranes. 10 ASTM D-638, Standard Test Method for Tensile Properties of Plastics. ASTM D-882, Standard Test Methods for Tensile Properties of Thin Plastic Sheeting. ASTM D-751, Standard Test Methods for Coated Fabrics. 11 ASTM D-4833, Standard Test Method for Index Puncture Resistance of Geotextiles, Geomembranes, 7B-13 and Related Products. Protecting Ground Water—Designing and Installing Liners
liners, the recommended testing method is potential for tearing as a result of uplift. If ASTM D-1004, Die C.12 For CSPE-R wind uplift is a potential problem, panels can geomembranes, ply adhesion is more of a be weighted down with sand bags. concern than tear or puncture resistance and can be evaluated using ASTM D-413, Seaming Processes Machine Method, Type A.13 Once panels or rolls have been placed, Test strips. In preparation for liner place- another critical step involves field-seaming ment and field seaming, you should develop the separate panels or rolls together. The test strips and trial seams as part of the con- selected seaming process, such as thermal or struction process. Construction of such sam- chemical seaming, will depend on the chemi- ples should be performed in a manner that cal composition of the liner. To ensure the reproduces all aspects of field production. integrity of the seam, you should use the Providing an opportunity to test seaming seaming method recommended by the manu- methods and workmanship helps ensure that facturer. Thermal seaming uses heat to bond the quality of the seams remains constant together the geomembrane panels. Examples and meets specifications throughout the of thermal seaming processes include extru- entire seaming process. sion welding and thermal fusion (or melt bonding). Chemical seaming involves the use Temperature Effects of solvents, cement, or an adhesive. Chemical seaming processes include chemical fusion Liner material properties can be altered by and adhesive seaming. For more information extreme temperatures. High temperatures can on seaming methods, Technical Guidance cause geomembrane liner surfaces to stick Document: Inspection Techniques for the together, a process commonly referred to as Fabrication of Geomembrane Field Seams (U.S. blocking. On the other hand, low tempera- EPA, 1991c), contains a full chapter on each ture can cause the liner to crack when of the traditional seaming methods and addi- unrolled or unfolded. Recommended maxi- tional discussion of emerging techniques, mum and minimum allowable sheet tempera- such as ultrasonic, electrical conduction, and tures for unrolling or unfolding geomembrane magnetic energy source methods. liners are 50°C (122°F) and 0°C (32°F), respectively. In addition to sticking and crack- Consistent quality in fabricating field ing, extreme temperatures can cause geomem- seams is paramount to liner performance. branes to contract or expand. Polyethylene Conditions that could affect seaming should geomembranes expand when heated and con- be monitored and controlled during installa- tract when cooled. Other geomembranes can tion. Factors influencing seam construction contract slightly when heated. Those respon- and performance include: ambient tempera- sible for placing the liner should take temper- ture, relative humidity, wind uplift, changes ature effects into account as they place, seam, in geomembrane temperature, subsurface and backfill in the field. water content, type of supporting surface used, skill of the seaming crew, quality and Wind Effects consistency of chemical or welding materials, preparation of liner surfaces to be joined, It is recommended that you take measures moisture at the seam interface, and cleanli- to protect geomembrane liners from wind ness of the seam interface. damage. Windy conditions can increase the
12 ASTM D-1004, Standard Test Method for Initial Tear Resistance of Plastic Film and Sheeting. 13 ASTM D-413, Standard Test Methods for Rubber Property-Adhesion to Flexible Substrate. 7B-14 Protecting Ground Water—Designing and Installing Liners
To help control some of these factors, no cover layer is a geosynthetic, it will typically more than the amount of sheeting that can be be a geonet or geocomposite drain placed used during a shift or a work day should be directly over the geomembrane. Careful deployed at one time. To prevent erosion of placement of backfill materials is critical to the underlying soil surface or washout of the avoid puncturing or tearing the geomem- geomembrane, proper storm water control brane material. measures should be employed. Ambient tem- For soil covers, three considerations deter- perature can become a concern, if the mine the amount of slack to be placed in the geomembrane liner has a high percentage of underlying geomembrane. These considera- carbon black. Although the carbon black will tions include selecting the appropriate type of help to prevent damage resulting from ultra- soil, using the proper type of equipment, and violet radiation, because its dark color establishing a placement procedure for the absorbs heat, it can increase the ambient tem- soil. When selecting a soil for backfilling, perature of the geomembrane, making instal- characteristics to consider include particle lation more complicated. To avoid surface size, hardness, and angularity, as each of these moisture or high subsurface water content, can affect the potential for tearing or punctur- geomembranes should not be deployed when ing the liner. To prevent wrinkling, soil covers the subgrade is wet. should be placed over the geomembrane in Regardless of how well a geomembrane such a way that construction vehicles do not liner is designed, its ability to meet perfor- drive directly on the liner. Care should be mance standards depends on proper quality taken not to push heavy loads of soil over the assurance and quality control during installa- geomembrane in a continuous manner. tion. Geomembrane sheets and seams are Forward pushing can cause localized wrinkles subject to tearing and puncture during instal- to develop and overturn in the direction of lation; punctures or tears can result from con- movement. Overturned wrinkles create sharp tact with jagged edges or underlying materials creases and localized stress in the liner and or by applying stresses greater than the can lead to premature failure. A recommend- geomembrane sheet can handle. Proper quali- ed method for placing soil involves continual- ty assurance and quality control can help ly placing small amounts of soil or drainage minimize the occurrence of pinhole or seam material and working outward over the toe of leaks. For example, properly preparing the the previously placed material. underlying layer and ensuring that the gravel Another recommended method involves is of an acceptable size reduces the potential placing soil over the liner with a large back- for punctures. hoe and spreading it with a bulldozer or sim- ilar equipment. If a predetermined amount of Protection and Backfilling slack is to be placed in the geomembrane, the Geomembrane liners that can be damaged temperature of the liner becomes an impor- by exposure to weather or work activities tant factor, as it will effect the ability of the should be covered with a layer of soil or a liner to contract and expand. Although the geosynthetic as soon as possible after quality recommended methods for covering assurance activities associated with geomem- geomembrane liners with soil can take more brane testing are completed. If the backfill time than backfilling with larger amounts of layer is a soil material, it will typically be a soil, these methods are designed to prevent drainage material like sand or gravel. If the damage caused by covering the liner with too
7B-15 Protecting Ground Water—Designing and Installing Liners
much soil too quickly. In the long run, pre- tive testing should be performed during con- venting premature liner failure can be faster struction also. For increased quality assur- and more cost-effective than having to repair ance, it is recommended that peel and shear a damaged liner. tests on samples from the installed geomem- brane be performed by an independent labo- The types of geosynthetics that are often ratory. Testing methods for shear testing, peel used as protective covering include geotex- testing, and tensile testing vary for different tiles and geonets. Geogrids and drainage geo- geomembrane liner types. composites can be used for cover soil reinforcement on slopes. The appendix at the Determining the number of samples to end of this chapter provides additional infor- take is a difficult step. Taking too few sam- mation on geosynthetic materials. For ples results in a poor statistical representation geosynthetic protective covers, as with soil of the geomembrane quality. On the other backfilling, to prevent tearing or puncturing, hand, taking too many samples requires most construction vehicles should not be additional costs and increases the potential permitted to move directly on the geomem- for defects. Defects can result from the repair brane. Some possible exceptions include patches used to cover the areas from which small, 4-wheel, all terrain vehicles or other samples were taken. types of low ground pressure equipment. A common sampling strategy is “fixed Even with these types of vehicles, drivers increment sampling” where samples are should take extreme care to avoid move- taken at a fixed increment along the length of ments, such as sudden starts, stops, and the geomembrane. Increments range from 80 turns, which can damage the geomembrane. to 300 m (250 to 1,000 ft). The type of Seaming-related equipment should be welding, such as extrusion or fusion welding, allowed on the geomembrane liner, as long as used to connect the seams and the type of it does not damage the liner. Geosynthetic geomembrane liner can also help determine materials are placed directly on the liner and the appropriate sampling interval. For exam- are not bonded to it. ple, extrusion seams on HDPE require grind- ing prior to welding and if extensive grinding Testing During Construction occurs, the strength of the HDPE might Testing during construction enables assess- decrease. In such cases, sampling at closer ment of the integrity of the seams connecting intervals, such as 90 to 120 m (300 to 400 the geomembrane panels. Tests performed on ft), might provide a more accurate descrip- the geomembrane seams are categorized as tion of material properties. If the seam is a either destructive or nondestructive. dual hot edge seam, both the inner and outer seams might need to be sampled and tested. Destructive testing. Destructive testing refers to removing a sample from the liner If test results for the seam or sheet samples seam or sheet and performing tests on the do not meet the acceptance criteria for the sample. For liner seams, destructive testing destructive tests, you should continue testing includes shear testing and peel testing; for the area surrounding the rejected sample to liner sheets, it involves tensile testing. While determine the limits of the low quality seam. quality control procedures often require Once the area of low quality has been identi- destructive testing prior to construction, in fied, then corrective measures, such as seaming order to ensure that the installed seams and a cap over the length of the seam or reseaming sheets meet performance standards, destruc- the affected area, might be necessary.
7B-16 Protecting Ground Water—Designing and Installing Liners
Nondestructive testing. Unlike destruc- parable to that of compacted clay or tive tests, which examine samples taken from geomembrane liners. the geomembrane liner in the containment area, nondestructive tests are designed to What are the mass per unit area evaluate the integrity of larger portions of and hydraulic conductivity recom- geomembrane seams without removing pieces of the geomembrane for testing. Common mendations for geosynthetic clay nondestructive testing methods include: the liners? probe test, air lance, vacuum box, ultrasonic Geosynthetic clay liners are often designed methods (pulse echo, shadow, and impedance to perform the same function as compacted planes), electrical spark test, pressurized dual clay and geomembrane liner components. For seam, and electrical resistivity. You should geosynthetic clay liners, you should design select the test method most appropriate for for a minimum of 3.7 kg/m2 (0.75 lb/ft2) dry the material and seaming method. If sections weight (oven dried at 105°C) of bentonite of a seam fail to meet the acceptable criteria clay with a hydrated hydraulic conductivity of the appropriate nondestructive test, then of no more than 5 x 10-9 cm/sec (2 x 10-9 those sections need to be delineated and in/sec). It is important to follow manufacturer patched, reseamed, or retested. If repairing specifications for proper GCL installation. such sections results in large patches or areas of reseaming, then destructive test methods What issues should be consid- are recommended to verify the integrity of such pieces. ered in the design of a geosyn- thetic clay liner? C. Geosynthetic Clay Liners Factors to consider in GCL design are the If a risk evaluation recommended the use specific material properties needed for the of a single liner, another option to consider is liner and the chemical interaction or compat- a geosynthetic clay liner (GCL). GCLs are fac- ibility of the waste with the GCL. When con- tory-manufactured, hydraulic barriers typical- sidering material properties, it is important to ly consisting of bentonite clay (or other very keep in mind that bentonite has a low shear low permeability materials), supported by strength when it is hydrated. Manufacturers geotextiles or geomembranes held together by have developed products designed to increase needling, stitching, or chemical adhesives. shear strength. GCLs can be used to augment or replace compacted clay liners or geomembranes, or Materials Selection and Properties they can be used in a composite manner to For an effective GCL design, material augment the more traditional compacted clay properties should be clearly defined in the or geomembrane materials. GCLs are typical- specifications used during both manufacture ly used in areas where clay is not readily and construction. The properties that should available or where conserving air space is an be specified include: type of bonds, thick- important factor. As GCLs do not have the ness, moisture content, mass per unit area, level of long-term field performance data that shear strength, and tensile strength. Each of geomembranes or compacted clay liners do, these properties is described below. states might request a demonstration that performance of the GCL design will be com-
7B-17 Protecting Ground Water—Designing and Installing Liners
Type of bonds. Geosynthetic clay liners strength, bentonite clay can be placed are available with a variety of bonding between geotextiles and stitch bonded or designs, which include a combination of clay, needle- punched to provide additional stabil- adhesives, and geomembranes or geotextiles. ity. For example, a GCL with geotextiles sup- The type of adhesives, geotextiles, and ported by stitch bonding has greater internal geomembranes used as components of GCLs resistance to shear in the clay layer than a varies widely. One type of available GCL GCL without any stitching. Needle-punched design uses a bentonite clay mixed with an GCLs tend to provide greater resistance than adhesive bound on each side by geotextiles. stitch-bonded GCLs and can also provide A variation on this design involves stitching increased friction resistance against an the upper and lower geotextiles together adjoining layer, because they require the use through the clay layer. Alternatively, another of nonwoven geotextiles. Increased friction is option is to use a GCL where geotextiles on an important consideration on side slopes. each side of adhesive or nonadhesive ben- Mass per unit area. Mass per unit area tonite clay are connected by needle punch- refers to the bentonite content of a GCL. It is ing. A fourth variation uses a clay mixed with important to distribute bentonite evenly an adhesive bound to a geomembrane on one throughout the GCL in order to meet desired side; the geomembrane can be either the hydraulic conductivity specifications. All lower or the upper surface. Figure 3 displays GCL products available in North America use cross section sketches of the four variations a sodium bentonite clay with a mass per unit of GCL bonds. While these options describe area ranging from 3.2 to 6.0 kg/m2 (0.66 to GCLs available at the time of this Guide, 1.2 lb/ft2), as manufactured. emerging technologies in GCL designs should also be reviewed and considered. Interaction With Waste Thickness. The thickness of the various available GCL products ranges from 4 to 6 During the selection process for a GCL mm (160 to 320 mil). Thickness measure- liner, you should evaluate the chemical com- ments are product dependent. Some GCLs patibility of the liner materials with the types can be quality controlled for thickness while of waste that are expected to be placed in the others cannot. unit. Certain chemicals, such as calcium, can have an adverse effect on GCLs, resulting in a Moisture content. GCLs are delivered to loss of liner integrity. Specific information on the job site at moisture contents ranging from GCL compatibilities should be available from 5 to 23 percent, referred to as the “dry” state. the manufacturer. GCLs are delivered dry to prevent premature hydration, which can cause unwanted varia- What issues should be consid- tions in the thickness of the clay component ered in the construction of a as a result of uneven swelling. geosynthetic clay liner? Stability and shear strength. GCLs should be manufactured and selected to meet Prior to and during construction, it is rec- the shear strength requirements specified in ommended that a qualified professional design plans. In this context, shear strength should prepare construction specifications for is the ability of two layers to resist forces the GCL. In these specifications, procedures moving them in opposite directions. Since for shipping and storing materials, as well as hydrated bentonite clay has low shear performing acceptance testing on delivered
7B-18 Protecting Ground Water—Designing and Installing Liners
Figure 3 Four Variations of GCL Bonding Methods
Source: U.S. EPA, 1993c.
7B-19 Protecting Ground Water—Designing and Installing Liners
materials, should be identified. The specifica- aged core makes deployment more difficult tions should also address methods for sub- and can lead to other problems. For example, grade preparation, joining panels, repairing rolls are sometimes handled by a fork lift sections, and protective backfilling. with a stinger attached. The stinger is a long tapered rod that fits inside the core. If the Shipment, Handling, and Site core is crushed, the stinger can damage the liner during deployment. Storage GCLs are manufactured in widths of Acceptance and Conformance approximately 2 to 5 m (7 to 17 ft) and lengths of 30 to 60 m (100 to 200 ft). Testing Directly after manufacturing, GCLs are rolled Acceptance and conformance testing is rec- around a core and covered with a thin plastic ommended either upon delivery of the GCL protective covering. This waterproof covering rolls or at the manufacturer’s facility prior to serves to protect the material from premature delivery. Conformance test samples are used hydration. GCLs should be stored at the fac- to ensure that the GCL meets the project tory with these protective coverings. Typical plans and specifications. GCLs should be storage lengths range from a few days to 6 rewrapped and replaced in dry storage areas months. To ensure protection of the plastic immediately after test samples are removed. covering and the rolls themselves during Liner specifications should prescribe sampling loading and unloading, it is recommended frequencies based on either total area or on that qualified professionals specify the equip- number of rolls. Since variability in GCLs can ment needed at the site to lift and deploy the exist between individual rolls, it is important rolls properly. for acceptance and conformance testing to account for this. Conformance testing can To reduce the potential for accidental include the following. damage or for GCLs to absorb moisture at the site, you should try to arrange for “just- Mass per unit area test. The purpose of in-time-delivery” for GCLs transported from evaluating mass per unit area is to ensure an the factory to the field. Even with “just-in- even distribution of bentonite throughout the time-delivery,” it might be necessary to store GCL panel. Although mass per unit area GCLs for short periods of time at the site. varies from manufacturer to manufacturer, a Often the rolls can be delivered in trailers, typical minimum value for oven dry weight which can then serve as temporary storage. is 3.7 kg/m2 (0.75 lb/ft2). Mass per unit area To help protect the GCLs prior to deploy- should be tested using ASTM D-5993.14 This ment, you should use wooden pallets to keep test measures the mass of bentonite per unit the rolls off the ground, placing heavy, water- area of GCL. Sampling frequencies should be proof tarps over the GCL rolls to protect determined using ASTM D- 4354.15 them from precipitation, and using sandbags Free swell test. Free swell refers to the to help keep the tarps in place. ability of the clay to absorb liquid. Either Manufacturer specifications should also ASTM D-5890 or GRI-GCL1, a test method indicate how high rolls of GCLs can be developed by the Geosynthetic Research stacked horizontally during storage. Over- Institute, can be used to evaluate the free stacking can cause compression of the core swell of the material.16 around which the GCL is wrapped. A dam-
14 ASTM D-5993, Standard Test Method for Measuring Mass per Unit Area of Geosynthetic Clay Liners. 15 ASTM D-4354, Standard Practice for Sampling of Geosynthetics for Testing. 7B-20 16 ASTM D-5890, Test Method for Swell Index of Clay Mineral Components of Geosynthetic Clay Liners. GRI-GCL1, Swell Measurement of the Clay Component of Geosynthetic Clay Liners. Protecting Ground Water—Designing and Installing Liners
Direct shear test. Shear strength of the smooth-wheel roller and maintained in a GCLs can be evaluated using ASTM D-5321.17 smooth condition prior to deployment. The sampling frequency for this performance- oriented test is often based on area, such as Joining Panels one test per 10,000 m2 (100,000 ft2). GCLs are typically joined by overlapping Hydraulic conductivity test. Either ASTM panels, without sewing or mechanically con- D-5084 (modified) or GRI-GCL2 will mea- necting pieces together. To ensure proper sure the ease with which liquids can move joints, you should specify minimum and 18 through the GCL. maximum overlap distances. Typical overlap Other tests. Testing of any geotextiles or distances range from 150 to 300 mm (6 to 12 geomembranes should be made on the origi- in.). For some GCLs, such as needle punched nal rolls of the geotextiles or geomembranes GCLs with nonwoven geotextiles, it might be and before they are fabricated into the GCL necessary to place bentonite on the area of product. Once these materials have been overlap. If this is necessary, you should take made part of the GCL product, their proper- steps to prevent fugitive bentonite particles ties can change as a result of any needling, from coming into contact with the leachate stitching, or gluing. Additionally, any peel collection system, as they can cause physical tests performed on needle punched or stitch clogging. bonded GCLs should use the modified ASTM D-413 with a recommended sampling fre- Repair of Sections Damaged During 2 2 19 quency of one test per 2,000 m (20,000 ft ). Liner Placement During installation, GCLs might incur Subgrade Preparation some damage to either the clay component or Because the GCL layer is relatively thin, to any geotextiles or geomembranes. For the first foot of soil underlying the GCL damage to geotextile or geomembrane com- should have a hydraulic conductivity of 1 x ponents, repairs include patching using geot- 10-5 cm/sec or less. Proper subgrade prepara- extile or geomembrane materials. If the clay tion is essential to prevent damage to the component is disturbed, a patch made from GCL layer as it is installed. This includes the same GCL product should be used to per- clearing away any roots or large particles that form any repairs. could potentially puncture the GCL and its geotextile or geomembrane components. The Protective Backfilling soil subgrade should be of the specified grad- ing, moisture content, and density required As soon as possible after completion of by the installer and approved by a construc- quality assurance and quality control activi- tion quality assurance engineer for placement ties, you should cover GCLs with either a soil of the GCL. Construction equipment deploy- layer or a geosynthetic layer to prevent ing the rolls should not deform or rut the soil hydration. The soil layer can be a compacted subgrade excessively. To help ensure this, the clay liner or a layer of coarse drainage materi- soil subgrade should be smooth rolled with a al. The geosynthetic layer is typically a
17 ASTM D-5321, Standard Test Method for Determining the Coefficient of Soil and Geosynthetic or Geosynthetic and Geosynthetic Friction by the Direct Shear Method. 18 ASTM D-5084, Standard Test Method for Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall Permeameter. GRI-GCL2, Permeability of Geosynthetic Clay Liners (GCLs). 19 ASTM D-413, Standard Test Methods for Rubber Property-Adhesion to Flexible Substrate. 7B-21 Protecting Ground Water—Designing and Installing Liners
geomembrane; however, depending on site- What are the thickness and specific designs, it can be a geotextile. As hydraulic conductivity recom- noted earlier, premature hydration before covering can lead to uneven swelling, result- mendations for composite liners? ing in a GCL with varied thickness. Each component of the composite liner Therefore, a GCL should be covered with its should follow the recommendations for subsequent soil or geosynthetic layer before a geomembranes, geosynthetic clay liners, and rainfall or snowfall occurs. Premature hydra- compacted clay liners described earlier. tion is less of a concern for GCLs, where the Geomembrane liners should have a mini- geosynthetic components are needle punched mum thickness of 30 mil, except for HDPE or stitch bonded, because these types of con- liners, which should have a minimum thick- nections can better limit clay expansion. ness of 60 mil. Similarly, compacted clay lin- ers should be at least 2 feet thick and are typically 2 to 5 feet thick. For compacted III. Composite clay liners and geosynthetic clay liners, you should use materials with maximum Liners hydraulic conductivities of 1 x 10-7 cm/sec (4 A composite liner consists of both a x 10-8 in/sec) and 5 x 10-9 cm/sec (2 x 10-9 geomembrane liner and natural soil. The in/sec), respectively. geomembrane forms the upper component with the natural soil being the lower compo- What issues should be consid- nent. The ususal variations are: ered in the design of a compos- • Geomembrane over compacted clay ite liner? liner (GM/CCL). As a starting point, you should follow the • Geomembrane over geosynthetic clay design considerations discussed previously for liner (GM/GCL). single liners. In addition, to achieve the bene- • Geomembrane over geosynthetic clay fits of a combined liner system, you should liner over compacted clay liner install the geomembrane to ensure good con- (GM/GCL/CCL). tact with the compacted clay layer. The uni- formity of contact between the geomembrane A composite liner provides an effective and the compacted clay layer helps control hydraulic barrier by combining the comple- the flow of leachate. Porous material, such as mentary properties of the two different liners drainage sand or a geonet, should not be into one system. The geomembrane provides a placed between the geomembrane and the highly impermeable layer to maximize leachate clay layer. Porous materials will create a layer collection and removal. The natural soil liner of higher hydraulic conductivity, which will serves as a backup in the event of any leakage increase the amount of leakage below any from the geomembrane. With a composite geomembrane imperfection. liner design, you should construct a leachate collection and removal system above the You should consider the friction or shear geomembrane. Information on design and con- strength between a compacted clay layer and struction of leachate collection and removal a geomembrane. The friction or shear stress systems is provided in Section V below. at this surface is often low and can form a weak plane on which sliding can occur.
7B-22 Protecting Ground Water—Designing and Installing Liners
ASTM D-5321 provides a test method for To minimize desiccation of the compacted determining the friction coefficient of soil and clay layer, you should place the geomem- geomembranes.20 When using bentonite- brane over the clay layer as soon as possible. amended soils, it is important to account for Additional cover materials should also be how the percentage of bentonite added and placed over the geomembrane. Exposed the degree of saturation affect interface fric- geomembranes absorb heat, and high temper- tion. To provide for stable slopes, it is impor- atures can dry out and crack an underlying tant to control both the bentonite and compacted clay layer. Daily cyclic changes in moisture contents. A textured geomembrane temperature can draw water from the clay can increase the friction with the clay layer layer and cause this water to condense on the and improve stability. underside of the geomembrane. This with- drawal of water can lead to desiccation crack- What issues should be consid- ing and potential interface stability concerns. ered in the construction of a composite liner? IV. Double Liners To achieve good composite bonding, the geomembrane and the compacted clay layer (Primary and should have good hydraulic contact. To improve good contact, you should smooth- Secondary Lined roll the surface of the compacted clay layer using a smooth, steel-drummed roller and Systems) remove any stones. In addition, you should In a double-lined waste management unit, place and backfill the geomembrane so as to there are two distinct liners—one primary minimize wrinkles. (top) liner and one secondary (bottom) liner. Each liner might consist of compacted clay, a The placement of geomembranes onto a geomembrane, or a composite (consisting of a compacted clay layer poses a challenge, geomembrane and a compacted clay layer or because workers cannot drive heavy GCL). Above the primary liner, it is recom- machines over the clay surface without mended that you construct a leachate collec- potentially damaging the compacted clay tion and removal system to collect and convey component. Even inappropriate footwear can liquids out of the waste management unit and leave imprints in the clay layer. It might be to control the depth of liquids above the pri- possible to drive some types of low ground mary liner. In addition, you should place a pressure equipment or small, 4-wheel, all ter- leak detection, collection, and removal system rain vehicles over the clay surface, but drivers between the primary and secondary liner. should take extreme care to avoid move- This leak detection system will provide leak ments, such as sudden starts, stops, and warning, as well as collect and remove any turns, that could damage the surface. To liquid or leachate that has escaped the prima- avoid damaging the clay layer, it is recom- ry liner. See section V below for information mended that you unroll geomembranes by on the design of leachate collection and lifting the rolls onto jacks at a cell side and removal systems and leak detection, collec- pulling down on the geomembrane manually. tion, and removal systems. Also, the entire roll with its core can be unrolled onto the cell (with auxiliary support using ropes on embankments).
20 ASTM D-5321, Standard Test Method for Determining the Coefficient of Soil and Geosynthetic or Geosynthetic and Geosynthetic Friction by the Direct Shear Method. 7B-23 Protecting Ground Water—Designing and Installing Liners
What are the thickness and tion systems serve this purpose. You should hydraulic conductivity recom- consult with the state agency too determine if such systems are required. The primary func- mendations for double liners? tion of a leachate collection and removal sys- tem is to collect and convey leachate out of a Each component of the double liner unit and to control the depth of leachate should follow the recommendations for above a liner. The primary function of a leak geomembranes, compacted clay liners, or detection system is to detect leachate that has composite liners described earlier. escaped the primary liner. A leak detection Geomembrane liners should have a minimum system refers to drainage material located thickness of 30 mil, except for HDPE liners, below the primary liner and above a sec- which should have a minimum thickness of ondary liner (if there is one); it acts as a sec- 60 mil. Similarly, compacted clay liners ondary leachate collection and removal should be at least 2 feet thick and are typical- system. After the leachate has been removed ly 2 to 5 feet thick. For compacted clay liners and collected, a leachate treatment system and geosynthetic clay liners, use materials might be incorporated to process the leachate with maximum hydraulic conductivities of 1 and remove harmful constituents. x 10-7 cm/sec (4 x 10-8 in/sec) and 5 x 10-9 cm/sec (2 x 10-9 in/sec), respectively. The information in this section on leachate collection and leak detection systems is What issues should be consid- applicable if the unit is a landfill or a waste ered in the design and construc- pile. Surface impoundments, which manage liquid wastes, usually will not have leachate tion of a double liner? collection and removal systems unless they Like composite liners, double liners are will be closed in-place as landfills; they might composed of a combination of single liners. have leak detection systems to detect liquid When planning to design and construct a wastes that have escaped the primary liner. double liner, you should consult the sections Leachate collection or leak detection systems on composite and single liners first. In addi- generally are not used with land application. tion, you should consult the sections on leachate collection and removal systems and leak detection systems. A. Leachate Collection System A typical leachate collection system V. Leachate includes a drainage layer, collection pipes, a removal system, and a protective filter layer. Collection and Leachate collection systems are designed to collect leachate for treatment or alternate dis- Leak Detection posal and to reduce the buildup of leachate above the liner system. Figure 4 shows a Systems cross section of a typical leachate collection One of the most important functions of a system showing access to pipes for cleaning. waste management unit is controlling leachate and preventing contamination of the underlying ground water. Both leachate col- lection and removal systems and leak detec-
7B-24 Protecting Ground Water—Designing and Installing Liners
Figure 4 Typical Leachate Collection System
Source: U.S. EPA, 1995b
What are the recommendations potential leachate generation, you should use for leachate collection and water balance equations or models. The most commonly used method to estimate leachate removal systems? generation is EPA’s Hydrogeologic Evaluation of Landfill Performance (HELP) model.21 This You should design a leachate collection and model uses weather, soil, and waste manage- removal system to maintain less than 30 cm ment unit design data to determine leachate (12 in.) depth of leachate, or “head,” above generation rates. the liner if granular soil or a geosynthetic material is used. The reason for maintaining What issues should be consid- this level is to prevent excessive leachate from building up above the liner, which could ered in the design of a leachate jeopardize the liner’s performance. This collection and removal system? should be the underlying factor guiding the design, construction, and operation of the You should design a leachate collection leachate collection and removal system. and removal system to include the following elements: a low-permeability base, a high- You should design a leachate collection permeability drainage layer, perforated and removal system capable of controlling the leachate collection pipes, a protective filter estimated volume of leachate. To determine layer, and a leachate removal system. During
21 Available on the CD-ROM version of the Guide, as well as from the U.S. Army Corps of Engineers Web site
design, you should consider the stability of when used in conjunction with a filter layer the base, the transmissivity of the drainage or geotextile to prevent clogging. Geonets layers, and the strength of the collection consist of integrally connected parallel sets of pipes. It is also prudent to consider methods plastic ribs overlying similar sets at various to minimize physical, biological, and chemi- angles. Geonets are often used on the side cal clogging within the system. walls of waste management units because of their ease of installation. Figure 5 depicts a Low-Permeability Base typical geonet material configuration. A leachate collection system is placed over The most critical factor involved with using the unit’s liner system. The bottom liner geonets in a high-permeability drainage layer should have a minimum slope of 2 percent to is the material’s ability to transmit fluids allow the leachate collection system to gravity under load. The flow rate of a geonet can be 22 flow to a collection sump. This grade is nec- evaluated by ASTM D-4716. Several addi- essary to provide proper leachate drainage tional measures for determining the transmis- throughout the operation, closure, and post- sivity of geonets are discussed in the Solid closure of the unit. Estimates of foundation Waste Disposal Facility Criteria: Technical soil settlement should include this 2 percent Manual (U.S. EPA, 1993b). grade as a post-settlement design. Perforated Leachate Collection Pipes High-Permeability Drainage Layer Whenever the leachate collection system is A high-permeability drainage layer consists a natural soil, a perforated piping system of drainage materials placed directly over the should be located within it to rapidly trans- low-permeability base, at the same minimum mit the leachate to a sump and removal sys- 2 percent grade. The drainage materials can tem. Through the piping system, leachate be either granular soil or geosynthetic materi- flows gravitationally to a low point where the als. For soil drainage materials, a maximum of sump and removal system is located. The 12 inches of materials with a hydraulic con- design of perforated leachate collection pipes, ductivity of at least 1 x 10-2 cm/sec (4 x 10-3 therefore, should consider necessary flow in/sec) is recommended. For this reason, sand rates, pipe sizing, and pipe structural and gravel are the most common soil materi- strength. After estimating the amount of als used. If the drainage layer is going to leachate using the HELP model or a similar incorporate sand or gravel, it should be water balance model, it is possible to calcu- demonstrated that the layer will have suffi- late the appropriate pipe diameter and spac- cient bearing capacity to withstand the waste ing. For the leachate collection system load of the full unit. Additionally, if the waste design, you should select piping material that management unit is designed on grades of 15 can withstand the anticipated weight of the percent or higher, it should be demonstrated waste, construction and operating equipment that the soil drainage materials will be stable stresses, and foundation settling. Most on the steepest slope in the design. leachate collection pipes used in modern waste management units are constructed of Geosynthetic drainage materials such as HDPE. HDPE pipes provide great structural geonets can be used in addition to, or in place strength, while allowing significant chemical of, soil materials. Geonets promote rapid resistance to the many constituents found in transmission of liquids and are most effective leachate. PVC pipes are also used in waste
22 ASTM D-4716, Standard Test Method for Constant Head Hydraulic Transmissivity (In-Plane Flow) of Geotextiles and Geotextile Related Products. 7B-26 Protecting Ground Water—Designing and Installing Liners
Figure 5 but small enough to Typical Geonet Configuration retain larger soil parti- cles. The number of openings in the geotex- tile should be large enough that, even if some of the openings clog, the remaining openings will be suffi- cient to pass the design flow rate. In addition to pore size, geotextile fil- ter specifications should include durability requirements. The management units, but they are not as chemi- advantages of geotextile cally resistant as HDPE pipes. materials include vertical space savings and easy placement. Chapter 5 of Technical Guidance Document: Quality Assurance and Protective Filter Layer Quality Control for Waste Containment Facilities To protect the drainage layer and perforat- (U.S. EPA, 1993c) offers guidance on protec- ed leachate collection piping from clogging, tion of drainage layers. you should place a filter layer over the high- permeability drainage layer. To prevent waste Leachate Removal System material from moving into the drainage layer, the filter layer should consist of a material Leachate removal often involves housing a with smaller pore space than the drainage sump within the leachate collection drainage layer materials or the perforation openings in layer. A sump is a low point in the liner con- the collection pipes. Sand and geotextiles are structed to collect leachate. Modern waste the two most common materials used for fil- management unit sumps often consist of pre- tration. You should select sand that allows fabricated polyethylene structures supported adequate flow of liquids, prevents migration on a steel plate above the liner. Especially of overlying solids or soils into the drainage with geomembrane liners, the steel plate layer, and minimizes clogging during the ser- serves to support the weight of the sump and vice life. In designing the sand filter, you protect the liner from puncture. Gravel filled should consider particle size and hydraulic earthen depressions can serve as the sump. conductivity. The advantages of using sand Reinforced concrete pipe and concrete floor- materials include common usage, traditional ing also can be used in place of the polyethyl- design, and durability. ene structure but are considerably heavier. Any evaluation of geotextile materials To remove leachate that has collected in should address the same concerns but with a the sump, you should use a submersible few differences. To begin with, the average pump. Ideally, the sump should be placed at pore size of the geotextile should be large a depth of 1 to 1.5 m (3 to 5 ft) to allow enough to allow the finer soil particles to pass enough leachate collection to prevent the pump from running dry. You should consider
7B-27 Protecting Ground Water—Designing and Installing Liners
installing a level control, backup pump, and leachate collection and removal systems. To warning system to ensure proper sump oper- minimize chemical and biological clogging for ation. Also consider using a backup pump as granular drainage material, the best procedure an alternate to the primary pump and to is to keep the interstices of the granular assist it during high flow periods. A warning drainage material as open as possible. system should be used to indicate pump mal- The leachate collection pipes are also sus- function. ceptible to similar clogging. To prevent this, Standpipes, vertical pipes extending you should incorporate measures into the through the waste and cover system, offer design to allow for routine pipe cleaning, one method of removing leachate from a using either mechanical or hydraulic meth- sump without puncturing the liner. ods. The cleaning components can include Alternatively, you can remove leachate from a pipes with a 15 cm (6 in) minimum diameter sump using pipes that are designed to pene- to facilitate cleaning; access located at major trate the liner. When installing pipe penetra- pipe intersections or bends to allow for tions through the liner, you should proceed inspections and cleaning; and valves, ports, with extreme caution to prevent any liner or other appurtenances to introduce biocides damage that could result in uncontained and cleaning solutions. Also, you should leachate. Both of these options rely on gravity check that the design does not include wrap- to direct leachate to a leachate collection ping perforated leachate collection pipes pond or to an external pumping station. directly with geotextile filters. If the geotex- tile becomes clogged, it can block flow into Minimizing Clogging the pipe. Leachate collection and removal systems are susceptible to physical, biological, and B. Leak Detection System chemical clogging. Physical clogging can The leak detection system (LDS) is also occur through the migration of finer-grained known as the secondary leachate collection materials into coarser-grained materials, thus and removal system. It uses the same reducing the hydraulic conductivity of the drainage and collection components as the coarser-grained material. Biological clogging primary leachate collection and removal sys- can occur through bacterial growth in the tem and identifies, collects, and removes any system due to the organic and nutrient mate- leakage from the primary system. The LDS rials in leachate. Chemical clogging can be should be located directly below the primary caused by chemical precipitates, such as cal- liner and above the secondary liner. cium carbonates, causing blockage or cemen- tation of granular drainage material. What are the recommendations Proper selection of drainage and filter mate- for leak detection systems? rials is essential to minimize clogging in the high-permeability drainage layer. Soil and geo- The LDS should be designed to assess the textile filters can be used to minimize physical adequacy of the primary liner against clogging of both granular drainage material leachate leakage; it should cover both the and leachate collection pipes. When placed bottom and side walls of a waste manage- above granular drainage material, these filters ment unit. The LDS should be designed to can also double as an operations layer to pre- collect leakage through the primary layer and vent sharp waste from damaging the liner or transport it to a sump within 24 hours.
7B-28 Protecting Ground Water—Designing and Installing Liners
The LDS should allow for monitoring and treatment techniques, the carbon absorption collection of leachate escaping the primary process and reverse osmosis are the two most liner system. You should monitor the LDS on common methods. Carbon absorption uses a regular basis. If the volume of leachate carbon to remove dissolved organics from detected by the LDS appears to be increasing leachate and is very expensive. Reverse osmo- or is significant, you should consider a closer sis involves feeding leachate into a tubular examination to determine possible remedia- chamber whose wall acts as a synthetic mem- tion measures. A good rule of thumb is that if brane, allowing water molecules to pass the LDS indicates a seepage level greater than through but not pollutant molecules, thereby 20 gallons per acre per day, the system might separating clean water from waste constituents. need closer monitoring or remediation. What are the recommendations C. Leachate Treatment for leachate treatment systems? System You should review all applicable federal and state regulations and discharge standards Once the leachate has been removed from to determine which treatment system will the unit and collected, you should consider ensure long-term compliance and flexibility taking measures to characterize the leachate for the unit. Site-specific factors will also play in order to ensure proper management. There a fundamental role in determining the proper are several methods of disposal for leachate, leachate treatment system. For some facilities, and the treatment strategy will vary according onsite storage and treatment might not be an to the disposal method chosen. Leachate dis- option due to space constraints. For other posal options include discharging to or facilities, having a nearby, publicly owned pumping and hauling to a publicly owned treatment works might make pretreatment treatment works or to an onsite treatment and discharge to the treatment works an system; treating and discharging to the envi- attractive alternative. ronment; land application; and natural or mechanical evaporation. When discharging to or pumping and hauling leachate to a publicly owned treat- VI. Construction ment works, a typical treatment strategy Quality includes pretreatment. Pretreatment could involve equalization, aeration, sedimentation, Assurance and pH adjustment, or metals removal.23 If the plan for leachate disposal does not involve a Quality Control remote treatment facility, pretreatment alone Even the best unit design will not translate usually is not sufficient. into a structure that is protective of human health and the environment, if the unit is not There are two categories of leachate treat- properly constructed. Manufacturing quality ment, biological and physical/chemical. The assurance and manufacturing quality control most common method of biological treatment (MQA and MQC) are also important issues is activated sludge. Activated sludge is a “sus- for the overall project; however, they are dis- pended-growth process that uses aerobic cussed only briefly here since they are pri- microorganisms to biodegrade organic contam- marily the responsibility of a manufacturer. inants in leachate.”24 Among physical/chemical Nonetheless, it is best to select a manufactur-
23 Arts, Tom. “Alternative Approaches For Leachate Treatment.” World Wastes. 24 Ibid. 7B-29 Protecting Ground Water—Designing and Installing Liners
er who incorporates appropriate quality uct meets project specifications. CQA testing, assurance and quality control (QA and QC) often referred to as acceptance inspection, mechanisms as part of the manufacturing provides a measure of the final product quali- process. The remainder of this section pro- ty and its conformance with project plans vides a general description of the compo- and specifications. Performing acceptance nents of a construction quality assurance and inspections routinely, as portions of the pro- construction quality control (CQA and CQC) ject become complete, allows early detection program for a project. CQA and CQC are and correction of deficiencies, before they critical factors for waste management units. become large and costly. They are not interchangeable, and the dis- On routine construction projects, CQA is tinction between them should be kept in normally the concern of the facility manager mind when preparing plans. CQA is third and is usually performed by an independent, party verification of quality, while CQC con- third-party testing firm. The independence of sists of in-process measures taken by the con- the testing firm is important, particularly tractor or installer to maintain quality. You when a facility manager has the capacity to should establish clear protocols for identify- perform the CQA activities. Although the ing and addressing issues of concern throughout every stage of construction. MQC, MQA, CQC, and CQA What is manufacturing quality Manufacturing quality control assurance? (MQC) is measures taken by the manu- facturer to ensure compliance with the The desired characteristics of liner materi- material and workmanship specifications als should be specified in the unit’s contract of the facility manager. with the manufacturer. The manufacturer should be responsible for certifying that mate- Manufacturer quality assurance rials delivered conform to those specifications. (MQA) is measures taken by facility per- MQC implemented to ensure such confor- sonnel, or by an impartial party brought mance might take the form of process quality in expressly for the purpose, to deter- control or computer-aided quality control. If mine if the manufacturer is in compli- requested, the manufacturer should provide ance with the specifications of the facility information on the MQC measures used, manager. allow unit personnel or engineers to visit the Construction quality control (CQC) manufacturing facility, and provide liner sam- is measures taken by the installer or con- ples for testing. It is good practice for the tractor to ensure compliance with the manufacturer to have a dedicated individual installation specifications of the facility in charge of MQC who would work with unit manager. personnel in these areas. Construction quality assurance What is construction quality (CQA) is measures taken by facility per- assurance? sonnel, or by an impartial party brought in expressly for the purpose, to deter- CQA is a verification tool employed by the mine if the installer or contractor is in facility manager or regulatory agency, consist- compliance with the installation specifi- ing of a planned series of observations and cations of the facility manager. tests designed to ensure that the final prod-
7B-30 Protecting Ground Water—Designing and Installing Liners
facility’s in-house CQA personnel might be How can implementation of CQA registered professional engineers, a perception and CQC plans be ensured? of misrepresentation might arise if CQA is not performed by an independent third party. When preparing to design and construct a The independent party should designate a waste management unit, regardless of design, CQA officer and fully disclose any activities you should develop CQA and CQC plans or relationships that the officer has with the customized to the project. To help the project facility manager that might impact his or her run smoothly, the CQA plan should be easy impartiality or objectivity. If such activities or to follow. You should organize the CQA plan relationships exist, the CQA officer should to reflect the sequence of construction and describe actions that have been or can be write it in language that will be familiar to an taken to avoid, mitigate, or neutralize the average field technician. For a more detailed possibility they might affect the CQA officer’s discussion of specific CQA and CQC activi- objectivity. State regulatory representatives ties recommended for each type of waste can help evaluate whether these mechanisms management unit, you should consult are sufficient to ensure acceptable CQA. Technical Guidance Document: Quality Assurance and Quality Control for Waste What is construction quality Management Containment Facilities (U.S. EPA, 1993c). This document provides information control? to develop comprehensive QA plans and to CQC is an ongoing process of measuring carry out QC procedures at waste manage- and controlling the characteristics of the prod- ment units. uct in order to meet manufacturer’s or project CQA and CQC plans can be implemented specifications. CQC inspections are typically through a series of meetings and inspections, performed by the contractor to provide an in- which should be documented thoroughly. process measure of construction quality and Communication among all parties involved in conformance with the project plans and speci- design and construction of a waste manage- fications, thereby allowing the contractor to ment unit is essential to ensuring a quality correct the construction process if the quality product. You should define responsibility and of the product is not meeting the specifica- authority in written QA and QC plans and tions and plans. Since CQC is a production ensure that each party involved understands tool employed by the manufacturer of materi- its role. Pre-construction meetings are one als and by the contractor installing the materi- way to help clarify roles and responsibilities. als at the site, the Guide does not cover CQC During construction, meetings can continue in detail. CQC is performed independently of to be useful to help resolve misunderstandings CQA. For example, while a geomembrane and to identify solutions to unanticipated liner installer will perform CQC testing of problems that might develop. Some examples field seams, the CQA program should require of typical meetings during the course of any independent testing of those same seams by a construction project include pre-bid meetings, third-party inspector. resolution meetings, pre-construction meet- ings, and progress meetings.
7B-31 Protecting Ground Water—Designing and Installing Liners
A. Compacted Clay Liner contractor; and submitting blind samples, Quality Assurance and such as duplicates and blanks, for analysis by the contractor’s testing staff or independent Quality Control laboratories. Although manufacturing quality control You should also consider constructing a and quality assurance are often the responsi- test pad prior to full-scale construction as a bility of the materials manufacturer, in the CQA tool. As described earlier in the section case of soil components, manufacturing and on compacted clay liners, pilot construction construction quality control testing can be or test fill of a small-scale test pad can be the responsibility of the facility manager. The used to verify that the soil, equipment, and CQA and CQC plans should specify proce- construction procedures can produce a liner dures for quality assurance and quality con- that performs according to the construction trol during construction of the compacted drawings and specifications. clay liners. Specific factors to examine or test during How can implementation of QA construction of a test fill include: preparation and QC be ensured for a com- and compaction of foundation material to the required bearing strength; methods of con- pacted clay liner? trolling uniformity of the soil material; com- QC testing is typically performed by the pactive effort, such as type of equipment and contractor on materials used in construction number of passes needed to achieve required of the liner. This testing examines material soil density and hydraulic conductivity; and properties such as moisture content, soil den- lift thickness and placement procedures sity, Atterberg limits, grain size, and laborato- needed to achieve uniformity of density ry hydraulic conductivity. Additional testing throughout a lift and prevent boundary of soil moisture content, density, lift thick- effects between lifts or between placements in ness, and hydraulic conductivity helps ensure the same lift. Test pads can also provide a that the waste management unit has been means to evaluate the ability of different constructed in accordance with the plans and types of soil to meet hydraulic conductivity technical specifications. requirements in the field. In addition to allowing an opportunity to evaluate material CQA testing for soil liners includes the performance, test pads also allow evaluation same tests described for QC testing in the of the skill and competence of the construc- paragraph above. Generally, the tests are per- tion team, including equipment operators formed less frequently. CQA testing is per- and QC specialists. formed by an individual or an entity independent of the contractor. Activities of the CQA officer are essential to document B. Geomembrane Liner quality of construction. The responsibilities Quality Assurance and of the CQA officer and his or her staff might include communicating with the contractor; Quality Control interpreting and clarifying project drawings As with the construction of soil liners, and specifications with the designer, facility installation of geomembrane liners should be manager, and contractor; recommending in conformance with a CQA and CQC plan. acceptance or rejection by the facility manag- The responsibilities of the CQA personnel for er of work completed by the construction the installation of the geomembrane are gen-
7B-32 Protecting Ground Water—Designing and Installing Liners
erally the same as the responsibilities for the testing frequencies. When varying testing fre- construction of a compacted clay liner, with quency, you should establish well-defined the addition of certain activities including procedures for modifying testing frequency. It observations of the liner storage area and lin- is also important to evaluate testing methods, ers in storage, and handling of the liner as the understand the differences among testing panels are positioned in the cell. methods, and request those methods appro- Geomembrane CQA staff should also observe priate for the material and seaming method seam preparation, seam overlap, and materi- be used. Nondestructive testing methods are als underlying the liner. preferrable when possible to help reduce the number of holes cut into the geomembrane. How can implementation of QA Geomembrane CQA staff also should docu- and QC be ensured for a ment the results of their observations and pre- geomembrane liner? pare reports indicating the types of sampling conducted and sampling results, locations of Prior to installation, you should work with destructive samples, locations of patches, the geomembrane manufacturer to ensure the locations of seams constructed, and any prob- labeling system for the geomembrane rolls is lems encountered. In some cases, they might clear and logical, allowing easy tracking of the need to prepare drawings of the liner installa- placement of the rolls within the unit. It is tion. Record drawing preparation is frequently important to examine the subgrade surface assigned to the contractor, to a representative with both the subgrade contractor and the liner of the facility manager, or to the engineer. You installer to ensure it conforms to specifications. should request complete reports from any Once liner installation is underway, CQA CQA staff and the installers. To ensure com- staff might be responsible for observations of plete CQA documentation, it is important to destructive testing conducted on scrap test maintain daily CQA reports and prepare welds prior to seaming. Geomembrane CQA weekly summaries. staff might also be responsible for sending destructive seam sampling to an independent testing laboratory and reviewing the results for C. Geosynthetic Clay Liner conformance to specifications. Other observa- Quality Assurance and tions for which the CQA staff are typically Quality Control responsible include observations of all seams Construction quality assurance for geosyn- and panels for defects due to manufacturing thetic clay liners is still a developing area; the and handling, and placement and observations GCL industry is continuing to establish stan- of all pipe penetrations through a liner. dardized quality assurance and quality con- Test methods, test parameters, and testing trol procedures. The CQA recommendation frequencies should be specified in the CQA for GCLs can serve as a starting point. You plan to provide context for any data collect- should check with the GCL manufacturer and ed. It is prudent to allow for testing frequen- installer for more specific information. cy to change, based on the performance of the geomembrane installer. If test results indi- cate poor workmanship, you should increase testing. If test results indicate high quality installation work, you can consider reducing
7B-33 Protecting Ground Water—Designing and Installing Liners
How can implementation of QA facility manager. The purpose of leachate col- and QC be ensured for a geosyn- lection system CQA is to document that the system is constructed in accordance with thetic clay liner? design specifications. It is recommended that you develop a How can implementation of QA detailed CQA plan, including product speci- fications; shipping, handling, and storage and QC be ensured for a procedures; seaming methods; and placement leachate collection system? of overlying material. It is important to work with the manufacturer to verify that the Prior to construction, CQA staff should product meets specifications. Upon receipt of inspect all materials to confirm that they meet the GCL product, you should also verify that the construction plans and specifications. it has arrived in good condition. These materials include: geonets; geotextiles; pipes; granular material; mechanical, electri- During construction, CQA staff should cal, and monitoring equipment; concrete ensure that seams are overlapped properly forms and reinforcements; and prefabricated and conform to specifications. CQA staff structures such as sumps and manholes. The should also check that panels, not deployed leachate collection system foundation, either a within a short period of time, are stored geomembrane or compacted clay liner, should properly. In addition, as overlying material is also be inspected, upon its completion, to placed on the GCL, it is important to restrict ensure that it has proper grading and is free vehicle traffic directly on the GCL. You of debris and liquids. should prohibit direct vehicle traffic, with the exception of small, 4-wheel, all terrain vehi- During construction, CQA staff should cles. Even with the small all-terrain vehicles, observe and document, as appropriate, the drivers should take extreme care to avoid placement and installation of pipes, filter lay- movements, such as sudden starts, stops, and ers, drainage layers, geonets and geotextiles, turns, which can damage the GCL. sumps, and mechanical and electrical equip- ment. For pipes, observations might include As part of the CQA documentation, it is descriptions of pipe bedding material, quality important to maintain records of weather and thickness, as well as the total area cov- conditions, subgrade conditions, and GCL ered by the bedding material. Observations panel locations. Also, you should document of pipe installations should focus on the loca- any repairs that were necessary or other tion, configuration, and grading of the pipes, problems identified and addressed. as well as the quality of connections at joints. For granular filter layers, CQA activities D. Leachate Collection might include observing and documenting System Quality material thickness and quality during place- Assurance and Quality ment. For granular drainage layers, CQA might focus on the protection of underlying Control liners, material thickness, proper overlap Leachate collection system CQC should be with filter fabrics and geonets (if applicable), performed by the contractor. Similar activi- and documentation of any weather condi- ties should be performed for CQA by an tions that might affect the overall perfor- independent party acting on behalf of the mance of the drainage layer. For geonets and
7B-34 Protecting Ground Water—Designing and Installing Liners
other geosynthetics, CQA observations should focus on the area of coverage and lay- out pattern, as well as the overlap between panels. For geonets, CQA staff might want to make sure that the materials do not become clogged by granular material that can be car- ried over, as a result of either wind or runoff during construction. Upon completion of construction, each component should be inspected to identify any damage that might have occurred during its installation or during construction of another component. For example, a leachate collection pipe can be crushed during place- ment of a granular drainage layer. Any dam- age that does occur should be repaired, and the repairs should be documented in the CQA records.
7B-35 Protecting Ground Water—Designing and Installing Liners
Designing and Installing Liners Activity List
■ Review the recommended location considerations and operating practices for the unit. ■ Select appropriate liner type—single, composite, or double liner—or in-situ soils, based on risk characterization. ■ Evaluate liner material properties and select appropriate clay, geosynthetic, or combination of mate- rials; consider interactions of liner and soil material with waste. ■ Develop a construction quality assurance (CQA) plan defining staff roles and responsibilities and specifying test methods, storage procedures, and construction protocols. ■ Ensure a stable in-situ soil foundation, for nonengineered liners. ■ Prepare and inspect subgrade for engineered liners. ■ Work with manufacturer to ensure protective shipping, handling, and storage of all materials. ■ Construct a test pad for compacted clay liners. ■ Test compacted clay liner material before and during construction. ■ Preprocess clay material to ensure proper water content, remove oversized particles, and add soil amendments, as applicable. ■ Use proper lift thickness and number of equipment passes to achieve adequate compaction. ■ Protect clay material from drying and cracking. ■ Develop test strips and trial seams to evaluate geomembrane seaming method. ■ Verify integrity of factory and field seams for geomembrane materials before and during construction. ■ Backfill with soil or geosynthetics to protect geomembranes and geosynthetic clay liners during construction. ■ Place backfill materials carefully to avoid damaging the underlying materials. ■ Install geosynthetic clay liner with proper overlap. ■ Patch any damage that occurs during geomembrane or geosynthetic clay liner installation. ■ Design leachate collection and removal system to allow adequate flow and to minimize clogging; include leachate treatment and leak detection systems, as appropriate. ■ Document all CQA activities, including meetings, inspections, and repairs.
7B-36 Protecting Ground Water—Designing and Installing Liners
Resources
ASTM D-413. 1993. Standard Test Methods for Rubber Property-Adhesion to Flexible Substrate.
ASTM D-422. 1990. Standard Test Method for Particle-Size Analysis of Soils.
ASTM D-638. 1991. Standard Test Method for Tensile Properties of Plastics.
ASTM D-698. 1991. Test Method for Laboratory Compaction Characteristics of Soil Using Standard Effort (12,400 ft-lbf/ft3 (600 kN-m/m3)).
ASTM D-751. 1989. Standard Test Methods for Coated Fabrics.
ASTM D-882. 1991. Standard Test Methods for Tensile Properties of Thin Plastic Sheeting.
ASTM D-1004. 1990. Standard Test Method for Initial Tear Resistance of Plastic Film and Sheeting.
ASTM D-1557. 1991. Test Method for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft3 (2,700 kN-m/m3)).
ASTM D-4318. 1993. Standard Test Method for Liquid Limit, Plastic Limit, and Plasticity Index of Soils.
ASTM D-4354. 1989. Standard Practice for Sampling of Geosynthetics for Testing.
ASTM D-4716. 1987. Standard Test Method for Constant Head Hydraulic Transmissivity (In-Plane Flow) of Geotextiles and Geotextile Related Products.
ASTM D-5084. 1990. Standard Test Method for Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall Permeameter.
ASTM D-5199. 1991. Standard Test Method for Measuring Nominal Thickness of Geotextiles and Geomembranes.
ASTM D-5261. 1992. Standard Test Method for Measuring Mass per Unit Area of Geotextiles.
ASTM D-5321. 1992. Standard Test Method for Determining the Coefficient of Soil and Geosynthetic or Geosynthetic and Geosynthetic Friction by the Direct Shear Method.
7B-37 Protecting Ground Water—Designing and Installing Liners
Resources (cont.)
Bagchi, A. 1994. Design, Construction, and Monitoring of Landfills.
Berg, R., and L. Well. 1996. A Position Paper on: The Use of Geosynthetic Barriers in Nonhazardous Industrial Waste Containment.
Berger, E. K. and R. Berger. 1997. The Global Water Cycle.
Borrelli, J. and D. Brosz. 1986. Effects of Soil Salinity on Crop Yields.
Boulding, J.R. 1995. Practical Handbook of Soil, Vadose Zone, and Ground Water Contamination: Assessment, Prevention and Remediation. Lewis Publishers.
Brandt, R.C. and K.S. Martin. 1996. The Food Processing Residual Management Manual. September.
Daniel, D.E., and R.M. Koerner. 1991. Landfill Liners from Top to Bottom. Civil Engineering. December.
Daniel, D.E., and R.M. Koerner. 1993. Technical Guidance Document: Quality Assurance and Quality Control for Waste Containment Facilities. Prepared for U.S. EPA. EPA600-R-93-182.
Daniel, D.E., and R.M. Koerner. 1995. Waste Containment Facilities: Guidance for Construction, Quality Assurance and Quality Control of Liner and Cover Systems.
Evanylo, G.K. and W. L. Daniels. 1996. The Value and Suitability of Papermill Sludge and Sludge Compost as a Soil Amendment and Soilless Media Substitute. Final Report. The Virginia Department of Agriculture and Consumer Services, P.O. Box 1163, Room 402, Richmond, VA. April.
Federal Test Method Standard 101C. 1980. Puncture Resistance and Elongation Test (1/8 Inch Radius Probe Method).
Fipps, G. 1995. Managing Irrigation Water Salinity in the Lower Rio Grande Valley.
Geosynthetic Research Institute. 1993. GRI-GCL1, Swell Measurement of the Clay Component of GCLs.
Geosynthetic Research Institute. 1993. GRI-GCL2, Permeability of Geosynthetic Clay Liners (GCLs).
7B-38 Protecting Ground Water—Designing and Installing Liners
Resources (cont.)
Idaho Department of Health and Welfare. 1988. Guidelines for Land Application of Municipal and Industrial Wastewater. March.
Koerner, R.M. 1994. Designing with Geosynthetics, Third Edition.
McGrath, L., and P. Creamer. 1995. Geosynthetic Clay Liner Applications in Waste Disposal Facilities.
McGrath, L., and P. Creamer. 1995. Geosynthetic Clay Liner Applications. Waste Age. May.
Michigan Department of Natural Resources, Waste Characterization Unit. 1991. Guidance for Land Application of Wastewater Sludge in Michigan. March.
Michigan Department of Natural Resources, Waste Characterization Unit. 1991. Guide to Preparing a Residuals Management Plan. March.
Minnesota Pollution Control Agency. 1993. Land Treatment of Landfill Leachate. February.
Northeast Regional Agricultural Engineering Cooperative Extension. 1996. Nutrient Management Software: Proceedings from the Nutrient Management Software Workshop. NRAES-100. December.
Northeast Regional Agricultural Engineering Cooperative Extension. 1996. Animal Agriculture and the Environment: Nutrients, Pathogens, and Community Relations. NRAES-96. December.
Northeast Regional Agricultural Engineering Cooperative Extension. 1993. Utilization of Food Processing Residuals. Selected Papers Representing University, Industry, and Regulatory Applications. NRAES-69. March.
North Carolina Cooperative Extension Service. 1994. Soil facts: Careful Soil Sampling - The Key to Reliable Soil Test Information. AG-439-30.
Oklahoma Department of Environmental Quality. Title 252. Oklahoma Administrative Code, Chapter 647. Sludge and Land Application of Wastewater.
Sharma, H., and S. Lewis. 1994. Waste Containment Systems, Waste Stabilization, and Landfills: Design and Evaluation.
Smith, M.E., S. Purdy, and M. Hlinko. 1996. Some Do’s and Don’ts of Construction Quality Assurance. Geotechnical Fabrics Report. January/February.
7B-39 Protecting Ground Water—Designing and Installing Liners
Resources (cont.)
Spellman, F. R. 1997. Wastewater Biosolids to Compost.
Texas Water Commission. 1983. Industrial Solid Waste Management Technical Guideline No. 5: Land Application. December.
Tsinger, L. 1996. Chemical Compatibility Testing: The State of Practice. Geotechnical Fabrics Report. October/November.
University of Nebraska Cooperative Extension Institute of Agriculture and Natural Resources. 1991. Guidelines for Soil Sampling. G91-1000-A. February.
U.S. EPA. 2001. Technical Resource Document: Assessment and recommendations for Improving the Performance of Waste Containment Systems. Draft.
U.S. EPA. 1996a. Issue Paper on Geosynthetic Clay Liners (GCLs).
U.S. EPA. 1996b. Report of 1995 Workshop on Geosynthetic Clay Liners. EPA600-R-96-149. June.
U.S. EPA. 1995a. A Guide to the Biosolids Risk Assessments for the EPA Part 503 Rule. EPA832-B-93- 005. September.
U.S. EPA. 1995b. Decision Maker’s Guide to Solid Waste Management. Volume II. EPA530-R-95-023.
U.S. EPA. 1995c. Laboratory Methods for Soil and Foliar Analysis in Long-Term Environmental Monitoring Programs. EPA600-R-95-077.
U.S. EPA. 1995d. Process Design Manual: Land Application of Sewage Sludge and Domestic Septage. EPA625-R-95-001. September.
U.S. EPA. 1995e. Process Design Manual: Surface Disposal of Sewage Sludge and Domestic Septage. EPA625-R-95-002. September.
U.S. EPA. 1994a. A Plain English Guide to the EPA Part 503 Biosolids Rule. EPA832-R-93-003. September.
U.S. EPA. 1994b. Biosolids Recycling: Beneficial Technology for a Better Environment. EPA832-R-94- 009. June.
U.S. EPA. 1994c. Guide to Septage Treatment and Disposal. EPA625-R-94-002. September.
7B-40 Protecting Ground Water—Designing and Installing Liners
Resources (cont.)
U.S. EPA. 1994d. Land Application of Sewage Sludge: A Guide for Land Appliers on the Requirements of the Federal Standards for the Use or Disposal of Sewage Sludge, 40 CFR Part 503. EPA831-B-93- 002b. December.
U.S. EPA. 1994e. Seminar Publication: Design, Operation, and Closure of Municipal Solid Waste Landfills. EPA625-R-94-008.
U.S. EPA. 1993a. Domestic Septage Regulatory Guidance: A Guide to the EPA 503 Rule. EPA832-B-92- 005. September.
U.S. EPA. 1993b. Solid Waste Disposal Facility Criteria: Technical Manual. EPA530-R-93-017.
U.S. EPA. 1993c. Technical Guidance Document: Quality Assurance and Quality Control for Waste Containment Facilities. EPA600-R-93-182.
U.S. EPA. 1992. Control of Pathogens and Vector Attraction in Sewage Sludge. EPA625-R-92-013. December.
U.S. EPA. 1991a. Seminar Publication: Design and Construction of RCRA/CERCLA Final Covers. EPA625-4-91-025.
U.S. EPA. 1991b. Seminar Publication: Site Characterization for Subsurface Remediation. EPA625-4-91- 026.
U.S. EPA. 1991c. Technical Guidance Document: Inspection Techniques for the Fabrication of Geomembrane Field Seams. EPA530-SW-91-051.
U.S. EPA. 1990. State Sludge Management Program Guidance Manual. October.
U.S. EPA. 1989a. Seminar Publication: Requirements for Hazardous Waste Landfill Design, Construction, and Closure. EPA625-4-89-022.
U.S. EPA. 1989b. Seminar Publication: Corrective Action: Technologies and Applications. EPA625-4-89- 020.
U.S. EPA. 1988. Lining of Waste Containment and Other Impoundment Facilities. EPA600-2-88-052.
U.S. EPA. 1987. Geosynthetic Guidance for Hazardous Waste Landfill Cells and Surface Impoundments. EPA600-2-87-097.
7B-41 Protecting Ground Water—Designing and Installing Liners
Resources (cont.)
U.S. EPA. 1986a. Project Summary: Avoiding Failure of Leachate Collection and Cap Drainage Systems. EPA600-S2-86-058.
U.S. EPA. 1986b. Test Methods for Evaluating Solid Waste: Physical/Chemical Methods. EPASW-846.
U.S. EPA. 1983. Process Design Manual for Land Application of Municipal Sludge. EPA625-1-83-016. October.
U.S. EPA, U.S. Army Corps of Engineers, U.S. Department of Interior, and U.S. Department of Agriculture. 1981. Process Design Manual for Land Treatment of Municipal Wastewater. EPA625-1-81- 013. October.
U.S. EPA. 1979. Methods for Chemical Analysis of Water and Wastes. EPA600-4-79-020.
Viessman Jr., W. and M.J. Hammer. 1985. Water Supply and Pollution Control. 4th ed.
Washington State Department of Ecology. 1993. Guidelines for Preparation of Engineering Reports for Industrial Wastewater Land Application Systems. Publication #93-36. May.
Webber, M.D. and S.S. Sing. 1995. Contamination of Agricultural Soils. In Action, D.F. and L.J. Gregorich, eds. The Health of Our Soils.
Wisconsin Department of Natural Resources. 1996. Chapter NR 518: Landspreading of Solid Waste. April.
7B-42 Protecting Ground Water—Designing and Installing Liners
Appendix Geosynthetic Materials25 application areas, however, they function almost exclusively as reinforcement materials. Geotextiles Geotextiles form one of the two largest Geonets group of geosynthetics. Their rise in growth Geonets, called geospacers by some, con- during the past fifteen years has been nothing stitute another specialized segment within the short of awesome. They are indeed textiles in geosynthetic area. They are usually formed by the traditional sense, but consist of synthetic a continuous extrusion of parallel sets of fibers rather than natural ones such as cotton, polymeric ribs at acute angles to one another. wool, or silk. Thus biodegradation is not a When the ribs are opened, relatively large problem. These synthetic fibers are made into apertures are formed into a netlike configura- a flexible, porous fabric by standard weaving tion. Their design function is completely machinery or are matted together in a ran- within the drainage area where they have dom, or nonwoven, manner. Some are also been used to convey fluids of all types. knit. The major point is that they are porous to water flow across their manufactured plane Geomembranes and also within their plane, but to a widely varying degree. There are at least 80 specific Geomembranes represent the other largest application areas for geotextiles that have been group of geosynthetics and in dollar volume developed; however, the fabric always per- their sales are probably larger than that of forms at least one of five discrete functions: geotextiles. Their growth has been stimulated by governmental regulations originally enact- 1. Separation ed in 1982. The materials themselves are 2. Reinforcement “impervious” thin sheets of rubber or plastic material used primarily for linings and covers 3. Filtration of liquid- or solid-storage facilities. Thus the 4. Drainage primary function is always as a liquid or vapor barrier. The range of applications, how- 5. Moisture barrier (when impregnated) ever, is very great, and at least 30 individual applications in civil engineering have been Geogrids developed. Geogrids represent a rapidly growing seg- ment within the geosynthetics area. Rather Geosynthetic Clay Liners than being a woven, nonwoven or knit textile Geosynthetic clay liners (or GCLs) are the (or even a textile-like) fabric, geogrids are newest subset within geosynthetic materials. plastics formed into a very open, gridlike They are rolls of factory fabricated thin layers configuration (i.e., they have large apertures). of bentonite clay sandwiched between two Geogrids are either stretched in one or two geotextiles or bonded to a geomembrane. directions for improved physical properties or Structural integrity is maintained by needle made on weaving machinery by unique punching, stitching or physical bonding. methods. By themselves, there are at least 25 They are seeing use as a composite compo-
25 Created by Geosynthetic Research Institute. Accessed from the Internet on October 16, 2001 at
nent beneath a geomembrane or by them- geomembrane; or any one of these three selves as primary or secondary liners. materials with another material (e.g., deformed plastic sheets, steel cables, or steel Geopipe (aka Buried Plastic Pipe) anchors). This exciting area brings out the best creative efforts of the engineer, manufac- Perhaps the original geosynthetic material turer, and contractor. The application areas still available today is buried plastic pipe. This are numerous and growing steadily. The “orphan” of the Civil Engineering curriculum major functions encompass the entire range was included due to an awareness that plastic of functions listed for geosynthetics discussed pipe is being used in all aspects of geotechni- previously: separation, reinforcement, filtra- cal, transportation, and environmental engi- tion, drainage, and liquid barrier. neering with little design and testing awareness. This is felt to be due to a general lack of formalized training. The critical nature “Geo-Others” of leachate collection pipes coupled with high The general area of geosynthetics has compressive loads makes geopipe a bona-fide exhibited such innovation that many systems member of the geosynthetics family. The func- defy categorization. For want of a better tion is clearly drainage. phrase, geo-others, describes items such as threaded soil masses, polymeric anchors, and Geocomposites encapsulated soil cells. As with geocompos- ites their primary function is product-depen- A geocomposite consists of a combination dent and can be any of the five major of geotextile and geogrid; or geogrid and functions of geosynthetics. geomembrane; or geotextile, geogrid, and
7B-44 Part IV Protecting Ground Water
Chapter 7: Section C Designing A Land Application Program Contents
I. Identifying Waste Constituents for Land Application...... 7C-2
II. Evaluating Waste Parameters ...... 7C-4 A. Total Solids Content ...... 7C-4 B. pH ...... 7C-5 C. Biodegradable Organic Matter ...... 7C-6 D. Nutrients ...... 7C-6 E. Metals...... 7C-8 F. Carbon-to-Nitrogen Ratio...... 7C-8 G. Soluble Salts ...... 7C-9 H.Calcium Carbonate Equivalent ...... 7C-11 I. Pathogens ...... 7C-11
III. Measuring Soil Properties ...... 7C-12
IV. Studying the Interaction of Plants and Microbes with Waste ...... 7C-14 A. Greenhouse and Field Studies ...... 7C-15 B. Assessing Plant and Microbial Uptake Rates ...... 7C-16 C. Effects of Waste on Plant and Microbe Growth...... 7C-17 D. Grazing and Harvesting Restrictions...... 7C-18
V. Considering Direct Exposure, Ecosystem Impacts, & Bioaccumulation of Waste...... 7C-18
VI. Accounting for Climate ...... 7C-19
VII. Calculating An Agronomic Application Rate ...... 7C-19
VIII.Monitoring ...... 7C-21
IX. Odor Controls ...... 7C-22
Designing a Land Application Program Activity List ...... 7C-23
Resources...... 7C-24
Tables: Table 1: Summary of Important Waste Parameters ...... 7C-4 Table 2: Salinity Tolerance of Selected Crops ...... 7C-10 Table 3: EC and SAR Levels Indicative of Saline, Sodic, and Saline-Sodic Soils ...... 7C-11
Figures: Figure 1: A Recommended Framework for Evaluating Land Application ...... 7C-3 Figure 2: The Nitrogen Cycle ...... 7C-7 Protecting Ground Water—Designing A Land Application Program
Designing A Land Application Program This chapter will help you: • Assess the risks associated with waste constituents when consider- ing application directly to the land as a soil amendment, or for treatment, or disposal. • Account for the designated ground-water constituents identified in Chapter 7, Section A—Assessing Risk, as well as other waste para- meters such as soil properties and plant and microbial interactions. • Evaluate the capacity of the soil, vegetation, and microbial life to safely assimilate the waste when developing an application rate. Some of the benefits of land application and application can be a beneficial include: and practical method for treating and disposing of some wastes. Because • Biodegradation of waste. If a waste land application does not rely on lin- stream contains sufficient organic ers to contain waste, however, there material, plants and microorganisms Lare some associated risks. With proper planning can significantly biodegrade the and design, a land application program can waste, assimilating its organic compo- meet waste management and land preservation nents into the soil. After allowing suf- goals, and avoid negative impacts such as nox- ficient time for assimilation of the ious odors, long-term damage to soil, and waste, more waste can be applied to a releases of contaminants to ground water, sur- given site without significantly face water, or the air. This chapter describes and increasing the total volume of waste at recommends a framework for addressing a vari- the site. This is in contrast to landfills ety of waste parameters, in addition to the con- and waste piles, in which waste accu- stituents outlined in Chapter 7, Section mulates continually and generally A—Assessing Risk,1 and other factors such as does not biodegrade quickly enough soil properties and plant and microbial nutrient to reduce its volume significantly. use2 that can affect the ability of the land to • Inclusion of liquids. Land applica- safely assimilate directly applied waste. tion units can accept bulk, non-con- Successful land application programs address tainerized liquid waste. The water the interactions among all these factors.
1 The constituents incorporated in IWEM, including the heavy metals and synthetic organic chemicals, typically have little or no agricultural value and can threaten human health and the environment even in small quantities. The term “waste parameters” as used in this section refers to some additional con- stituents such as nitrogen and biodegradable organic matter and other site-specific properties such as pH, that can have considerable agricultural significance and that can significantly impact human health and the environment. 2 40 CFR Part 503 specifies requirements for land application of sludge from municipal sewage treatment plants. The Part 503 regulations apply to sewage sludge (now generally referred to as “biosolids”) or mixtures of sewage sludge and industrial process wastes, not to industrial wastes alone. Some of the specifications in Part 503, for example those concerning pathogens, might be helpful in evaluating land application of industrial wastes. For mixtures of sewage sludge and industrial waste, the ground-water and air risk assessments and the framework laid out in the Guide can help address constituents that are 7C-1 not covered under the Part 503 regulations. Protecting Ground Water—Designing A Land Application Program
content of some liquid wastes make covered by any permits, MOUs, or other agree- them desirable at land application ments concerning land application. The Guide sites in arid climates. When managing does not supersede or modify conditions estab- liquid waste, land application can lished in regulatory or other binding mecha- reduce the need for expensive dewa- nisms, such as MOUs or agreements.3 tering processes. Some wastes might be designated by state • Improvement of soil. Applying waste or local regulators as essentially equivalent to directly to land can improve soil qual- a manufactured product or raw material. Such ity if the waste contains appropriate designations usually are granted only when levels of biodegradable organic matter use of the designated waste would not present and nutrients. Nutrients can improve a greater environmental and health risk than the chemical composition of the soil would use of the manufactured or raw materi- to the extent that it can better support al it replaces. Equivalence designations are vegetation, while biodegradable organ- included in the category of “other agreements” ic matter can improve its physical above. If there are no designated ground-water properties and increase its water constituents other than those on which the retention capacity. This potential for designation is based, then the guidelines chemical and physical improvements described in this chapter can help you to through land application have led to determine an appropriate application rate. its use in conditioning soil for agricul- If the constituent(s) identified in the waste tural use. is not currently covered under an agreement, Figure 1 outlines a framework for evaluat- IWEM or another site-specific model can help ing land application. This framework incorpo- you determine whether land application of the rates both the ground-water risk assessment constituent(s) will be protective of ground methodology recommended in Chapter 7, water. In some cases, pollution prevention or Section A–Assessing Risk, as well as the other treatment can lower constituents levels so that waste parameters and factors important to a waste can be land applied. In other cases, land application. land application might not be feasible. In this event, you should pursue other waste manage- ment options. If your modeling results indi- cate that the constituents can be land applied, I. Identifying then the guidelines described in this chapter Waste can once again help you to determine an appropriate application rate. Constituents for Your modeling efforts should consider both Land Application the direct exposure and ecosystem pathways. These pathways are extremely important in If a waste leachate contains any of the con- land application since waste is placed on the stituents covered in the IWEM ground-water land and attenuated by the natural environ- model, you should first check with a federal, ment rather than contained by an engineered state, or other regulatory agency to see if the structure. waste constituents identified in the waste are
3 EPA has signed agreements with states, industries, and individual sites concerning land application. One example is EPA’s Memorandum of Understanding (MOU) between the American Forest and Paper Association (AFPA) and the U.S. EPA Regarding the Implementation of the Land Application Agreements Among AF&PA Member Pulp and Paper Mills and the U.S. EPA, January 1994. For more information on this MOU contact either AFPA’s Director of Industrial Waste Programs at 111 19th Street, N.W., 7C-2 Washington, D.C. 20036 or EPA’s Director of the Office of Pollution Prevention and Toxics. Protecting Ground Water—Designing A Land Application Program
Figure 1. A Recommended Framework for Evaluating Land Application
Perform waste characterization • Ground-water constituents • Other waste parameters
Identify waste constituents
Yes Follow terms of Are all IWEM constituents identified in the waste permit, MOU, covered by permit, MOU, or other agreement?* or agreement No
Yes Evaluate waste Evaluate IWEM constituents identified in parameters the waste to determine whether land appli- cation is protective of ground water using IWEM or other risk assessment tool Measure soil parameters No
Constituents should not be land applied Study interaction of and you should treat wastes and plants and microbes reassess land application potential or with waste identify other disposal options
Consider direct expo- sure, ecosystem impacts, and bioaccu- mulation of waste * All constituents should have been assessed and shown not to be a risk, or are addressed by constituents directly covered Account for climate by MOU, permit, or other agreement.
Calculate agronomic application rate
Evaluate application rate. If waste stream exceeds rate, consider additional management measures 7C-3 Protecting Ground Water—Designing A Land Application Program
tion rate and are summarized in Table 1. After II. Evaluating the initial evaluation, you should sample and Waste characterize the waste on a regular basis and after process changes that might affect waste Parameters characteristics to help determine whether you In addition to the ground-water con- should change application practices or con- stituents designated in Chapter 7, Section sider other waste management options. A–Assessing Risk, you should evaluate the waste’s total solids content, pH, biodegradable A. Total Solids Content matter, pathogens, nutrients, metals, carbon to nitrogen ratio, soluble salts, and calcium Total solids content indicates the ratio of carbonate equivalent when considering land solids to water in a waste. It includes both application. These parameters provide the suspended and dissolved solids, and is usual- basis for determining an initial waste applica- ly expressed as a percentage of the waste.
Table 1 Summary of Important Waste Parameters
Waste Parameter Significance
Total solids content Indicates ratio of solids to water in waste and influences application method.
pH Controls metals solubility (and therefore mobility of metals toward ground water) and affects biological processes.
Biodegradable organic matter Influences soil’s water holding capacity, cation exchange, and other physical and chemical properties, including odor.
Nutrients (nitrogen, phosphorus, Affect plant growth; nitrogen is a major determinant of application rate; and potassium) can contaminate ground water or cause phytotoxicity if applied in excess.
Carbon to nitrogen ratio Influences availability of nitrogen to plants.
Soluble salts Can inhibit plant growth, reduce soil permeability, and contaminate ground water.
Calcium carbonate equivalent Measures a waste’s ability to neutralize soil acidity.
Pathogens Can threaten public health by migrating to ground water or being car- ried by surface water, wind, or other vectors.
Ground-water constituents Can present public health risk through ground-water contamination, designated in Chapter 7, Section A– direct contact with waste-soil mix, transport by surface water, and Risk Assessment including metals accumulation in plants. Metals inhibit plant growth and can be and organic chemicals phytotoxic at elevated concentrations. Zinc, copper, and nickel are micronutrients essential to plant growth, but can inhibit growth at high levels.
7C-4 Protecting Ground Water—Designing A Land Application Program
Total solids content depends on the type of waste, as well as whether the waste has been treated prior to land application. If waste is dried, composted, dewatered, thickened, or conditioned prior to land application, water content is decreased, thereby increasing the total solids content (for some dry, fine, partic- ulate wastes, such as cement kiln dust, condi- 4 tioning might involve adding water). Source: Ag-Chem Equipment Co., Inc. Understanding the total solids content will Reprinted with permission help you develop appropriate storage and handling procedures and establish an applica- tion rate. Total solids content also can affect your choice of application method and equip- ment. Some methods, such as spray irriga- tion, might not work effectively if the solids content is too high. If it is low, meaning liq- uid content is correspondingly high, waste transportation costs could increase. If the total solids content of the waste is expected to vary, you can select equipment to accom- Source: Ag-Chem Equipment Co., Inc. modate materials with a range of solids con- Reprinted with permission tent. For example, selecting spreaders that will not clog if the waste is slightly drier than usual will help operations run more efficient- ly and reduce equipment problems.
B. pH A waste’s pH is a measure of its acidic or alkaline quality. Most grasses and legumes, as Source: Ag-Chem Equipment Co., Inc. well as many shrubs and deciduous trees, Reprinted with permission grow best in soils with a pH range from 5.5 microorganisms and can increase the mobility to 7.5. If a waste is sufficiently acidic or alka- of zinc, cadmium, and lead. line5 to move soil pH out of that range, it can hamper plant growth. Acidic waste promotes Aqueous waste with a pH of 2 or less or a leaching of metals, because most metals are pH of 12.5 or more meets the definition of more soluble under acidic conditions than hazardous waste under federal regulations (40 neutral or alkaline conditions. Once in solu- CFR 261.22(a)). If the pH of a waste makes it tion, the metals would be available for plant too acidic for land application, you can con- uptake or could migrate to ground water. sider adjusting waste pH before application. Alkaline conditions inhibit movement of Lime is often used to raise pH, but other most metals. Extreme alkalinity, where pH is materials are also available. The pH is also greater than 11, impairs growth of most soil important to consider when developing waste handling and storage procedures.
4 Some states consider composted materials to no longer be wastes. Consult with the regulatory agency for applicable definitions. 5 A pH of 7 is neutral. Materials with pH less than 7 are acidic, while those with pH greater than 7 are 7C-5 alkaline. Protecting Ground Water—Designing A Land Application Program
C. Biodegradable Organic waste has broken down) can induce nitrogen Matter deficiency (see section D. below) or lead to anaerobic conditions. Wastes containing a relatively high percent- age of biodegradable organic matter have greater potential as conditioners to improve D. Nutrients the physical properties of soil. The percentage Nitrogen, phosphorus, and potassium are of biodegradable organic matter in soil is often referred to as primary or macro-nutri- important to soil fertility, as organic matter ents and plants use them in large amounts. can add nutrients; serve as an absorption and Plants use secondary nutrients, including sul- retention site for nutrients; and provide chem- fur, magnesium, and calcium, in intermediate ical compounds, such as chelating agents, that quantities. They use micronutrients, includ- help change nutrients into more plant-avail- ing iron, manganese, boron, chlorine, zinc, able forms. The content of biodegradable copper, and molybdenum, in very small organic matter is typically expressed as a per- quantities. Land application is often used to centage of sample dry weight. increase the supply of these nutrients, espe- Biodegradable organic matter also influ- cially the primary nutrients, in an effort to ences soil characteristics. Soils with high improve plant growth. organic matter content often have a darker Nutrient levels are key determinants of color (ranging from brown to black), increased application rates. Excessive soil nutrient lev- cation exchange capacity—capacity to take up els, caused by high waste application rates, and give off positively charged ions—and can be phytotoxic or result in contamination greater water holding capacity. Biodegradable of ground water, soil, and surface water. organic matter also can help stabilize and Nutrient loading is dependent on nutrient improve the soil structure, decrease the density levels in both the waste and the soil, making of the material, and improve aeration in the characterization of the soil, as well as of the soil. In addition, organic nutrients are less like- waste, important. ly than inorganic nutrients to leach. Nitrogen. Nitrogen content is often the How can biodegradable organic primary factor determining whether a waste matter affect the waste applica- is agriculturally suitable for land application, and, if so, at what rate to apply it. Nitrogen tion rate? deficiency is detrimental to the most basic While organic materials provide a signifi- plant processes, as nitrogen is an essential cant source of nutrients for plant growth, element for photosynthesis. Sufficient nitro- decomposition rates can vary significantly gen promotes healthy growth and imparts a among materials. Food processing residues, for dark green color in vegetation. Lack of nitro- example, generally decompose faster than gen can be identified by stunted plant growth denser organic materials, such as wood chips. and pale green or yellowish colored vegeta- It is important to account for the decomposi- tion. Extreme nitrogen deficiency can cause tion rate when determining the volume, rate plants to turn brown and die. On the other and frequency of waste application. Loading extreme, excessive nitrogen levels can result the soil with too much decomposing organic in nitrate leaching, which can contaminate matter (such as by applying new waste before ground-water supplies. a previous application of slowly decomposing
7C-6 Protecting Ground Water—Designing A Land Application Program
Although nitrate poses the greatest threat Potassium. Potassium is an essential to ground water, nitrogen occurs in a variety nutrient for protein synthesis and plays an of forms including ammonium, nitrate, important role in plant hardiness and disease nitrite, and organic nitrogen. These forms tolerance. In its ionic form (K+), potassium taken together are measured as total nitrogen. helps to regulate the hydration of plants. It You should account for the ever-occurring also works in the ion transport system across nitrogen transformations that take place in cell membranes and activates many plant the soil before and after waste is applied. enzymes. Like other nutrients, symptoms of These transformations are commonly deficiencies include yellowing, burnt or described as the nitrogen cycle and are illus- dying leaves, as well as stunted plant growth. trated below in Figure 2. Symptoms of potassium deficiency also, in certain plants, can include Figure 2. The Nitrogen Cycle reduced disease resistance and winter hardiness. How can I take nutrient levels into account?
Gaseous You should develop a nutri- Losses (N2, NOx) ent management plan that Precipitation Organic Residues accounts for the amount of Plant Organic Matter nitrogen, phosphorus, and Denitrification Consumption (R-NH2) potassium being supplied by all Mineralization Nitrates sources at a site. The U.S. (NO ) Ammonium (NH4) 3 Nitrification Nitrification Micelle Department of Agriculture, Fixation Nitrites (NO2) Natural Resources Conservation Clay Leaching Minerals Service has developed a conser- vation practice standard “Nutrient Management” Code 590 that can Phosphorus. Phosphorus plays a role in be used as the basis for your nutrient man- the metabolic processes and reproduction of agement plan. The purpose of this standard plants. When soil contains sufficient quanti- is to budget and supply nutrients for plant ties of phosphorus, root growth and plant production, to properly utilize manure or maturation improve. Conversely, phospho- organic by-products as a plant nutrient rus-deficient soils can cause stunted plant source, to minimize agricultural nonpoint growth. Excessive phosphorus can lead to source pollution of surface and ground-water inefficient use of other nutrients and, at resources, and to maintain or improve the extreme levels, zinc deficiency. High phos- physical, chemical, and biological condition phorus usage on crops and its associated of the soil. Updated versions of this standard runoff into surface water bodies has increased can be obtained from the Internet at the biological productivity of surface waters
6 U.S. Department of Agriculture, Agricultural Research Service. Agricultural Phosphorus and Eutrophication, 1999. Washington, DC. 7C-7 Protecting Ground Water—Designing A Land Application Program
amount of any of the plant nutrients. If, how- How can I determine acceptable ever, waste application rates are based solely metal concentrations? on nitrogen levels, resulting levels of other nutrients such as phosphorus and potassium The Tier I and II ground-water models can can exceed crop needs or threaten ground help you identify acceptable metals concentra- water or surface water bodies. You should tions for land application. Also it is important avoid excessive nutrient levels by monitoring to consult with your local, state, or regional waste concentrations and soil buildup of agriculture extension center on appropriate nutrients and reducing the application rate as nutrient concentrations for plant growth. If the necessary, or by spacing applications to allow risk evaluation indicates that a waste is appro- plant uptake between applications. Your priate for land application, but subsequent soil local, state, or regional agricultural extension or plant tissue testing finds excessive levels of service might have already developed materi- metals, you can consider pretreating the waste als on or identified software for nutrient with a physical or chemical process, such as management planning. Consult with them chemical precipitation to remove some metals about the availability of such information. before application. Northeast Regional Agricultural Engineering Services (NRAES) Cooperative Extension, for example, has compiled information on nutri- F. Carbon-to-Nitrogen Ratio ent management software programs.7 The carbon-to-nitrogen ratio refers to the relative quantities of these two elements in a waste or soil. Carbon is associated with E. Metals organic matter, and the carbon-to-nitrogen A number of metals are included in IWEM ratio reflects the level of inorganic nitrogen for evaluating ground-water risk. Some metals, available. Plants cannot use organic nitrogen, such as zinc, copper, and manganese, are but they can absorb inorganic nitrogen such essential soil micronutrients for plant growth. as ammonium. For many wastes, the carbon- These are often added to inorganic commercial to-nitrogen ratio is computed as the dry fertilizers. At excessive concentrations, howev- weight content of organic carbon divided by er, some of these metals can be toxic to the total nitrogen content of waste. humans, animals, and plants. High concentra- Some wastes rich in organic materials (car- tions of copper, nickel, and zinc, for example, bon) can actually induce nitrogen deficien- can cause phytotoxicity or inhibit plant cies. This occurs when wastes provide carbon growth. Also, the uptake and accumulation of in quantities that microbes cannot process metals in plants depends on a variety of plant without depleting available nitrogen. Soil and soil factors, including pH, biodegradable microbes use carbon to build cells and nitro- organic matter content, and cation exchange gen to synthesize proteins. Any excess organ- capacity. Therefore, it is important to evaluate ic nitrogen is then converted to inorganic levels of these metals in waste, soil, and plants nitrogen, which plants can use. The carbon- from the standpoint of agricultural significance to-nitrogen ratio tells whether excess organic as well as health and environmental risk. nitrogen will be available for this conversion. When the carbon-to-nitrogen ratio is less than 20 to 1—indicating a high nitrogen con- tent—organic nitrogen is mineralized, or con-
7 Nutrient Management Software: Proceedings from the Nutrient Management Software Workshop. To order, call NRAES at 607 255-7654 and request publication number NRAES-100. 7C-8 Protecting Ground Water—Designing A Land Application Program
verted from organic nitrogen to inorganic G. Soluble Salts ammonium, and becomes available for plant The term soluble salts refers to the inorganic growth. For maximal plant growth, the litera- soil constituents (ions) that are dissolved in the ture recommends maintaining a ratio below soil water. Major soluble salt ions include calci- 20 to 1. When the carbon-to-nitrogen ratio is um (Ca2+), magnesium (Mg2+), sodium (Na+), in the range of 20 to 1 to 30 to 1—a low potassium (K+), chloride (Cl-), sulfate (SO 2-), nitrogen content—soil micro-organisms use 4 bicarbonate (HCO -), and nitrate (NO -). Total much of the organic nitrogen to synthesize 3 3 dissolved solids (TDS) refers to the total proteins, leaving only small excess amounts amount of all minerals, organic matter, and to be mineralized. This phenomenon, known nutrients that are dissolved in water. The solu- as immobilization, leaves little inorganic ble salt content of a material can be determined nitrogen available for plant uptake. When the by analyzing the concentration of the individ- carbon-to-nitrogen ratio is greater than 30 to ual constituent ions and summing them, but 1, immobilization is the dominant process, this is a lengthy procedure. TDS of soil or causing stunted plant growth. The period of waste can reasonably be estimated by measur- immobilization, also known as nitrogen or ing the electrical conductivity (EC) of a mixture nitrate depression, will vary in length of the material and water. EC can be measured depending on the decay rate of the organic directly on liquid samples. TDS is found by matter in the waste. As a result, plant growth multiplying the electrical conductivity reading within that range might not be stunted, but is in millimhos/cm (mmhos/cm) by 700 to give not likely to be maximized. TDS in parts per million (ppm) or mg/l. How can I manage changing Soluble salts are important for several rea- carbon-to-nitrogen ratios? sons. First, saline soil, or soil with excessive salt concentrations, can reduce plant growth The cycle of nitrogen conversions within and seed germination. As salt concentration the soil is a complex, continually changing in soil increases, osmotic pressure effects process (see Figure 2). As a result, if applying make it increasingly difficult for plant roots to waste based only on assumed nitrogen miner- extract water from the soil. Through a certain alization rates, it is often difficult to ensure range, this will result in reduced crop yield, that the soil contains sufficient inorganic up to a maximum beyond which crops will nitrogen for plants at appropriate times. If be unable to grow. The range and maximum you are concerned about reductions in crop for a few representative crops are shown in yield, you should monitor the soil’s carbon- Table 2. For this reason, the salt content of to-nitrogen ratio and, when it exceeds 20 to the waste, rather than its nitrogen content, 1, reduce organic waste application and/or can be the primary determinant of its agricul- supplement the naturally mineralized nitro- tural suitability for land application, especial- gen with an inorganic nitrogen fertilizer, such ly on irrigated soils in arid regions. as ammonium nitrate. Methods to measure soil carbon include EPA Method 9060 in Test The second reason soluble salts are impor- Methods for Evaluating Solid Waste, tant is that sodic soil, or soil with excessive + Physical/Chemical Methods—SW-846. Nitrogen levels of sodium ions (Na ) relative to diva- 2+ 2+ content can be measured with simple labora- lent ions (Ca , Mg ), can alter soil structure tory titrations. and reduce soil permeability. The sodium absorption rate (SAR) of a waste is an indica- tor of its sodicity. To calculate the SAR of a
7C-9 Protecting Ground Water—Designing A Land Application Program
Table 2: Salinity Tolerance of Selected Crops
Soil Salinity (mmhos/cm)a that will result in:
Crop 0% yield 50% yield 100% yield reductionb reductionb reductionb
Alfalfa 2.0 8.8 16
Bermuda grass 6.9 14.7 23
Clover 1.5 10.3 19
Perennial rye 5.6 12.1 19
Tall fescue 3.9 13.3 32
Source: Borrelli, J. and D. Brosz. 1986. Effects of Soil Salinity on Crop Yields.
a A rule of thumb from the irrigation industry holds that soil salinity will be 1½ times the salinity of applied irrigation water. The effect that waste salinity will have on soil salinity, however, is not as easily predicted and depends on the waste’s water content and other properties and on the application rate.
b Reductions are stated as a percentage of maximum expected yield.
waste or soil, determine the Na+, Ca2+, and The third reason soluble salts are impor- Mg2+ concentrations in milliequivalents per tant is that specific ions can induce plant tox- liter8 for use in the following equation:9 icities or contaminate ground water. Sodium and chloride ions, for example, can become Na+ phytotoxic at high concentrations. To assess SAR = sodic- or toxic-inducing characteristics, you ½(Ca2+ + Mg2+) should conduct an analysis of specific ions in addition to measuring EC. Soils characterized by both high salts What can I do if a waste is either (excessive TDS as indicated by EC) and excessive sodium ions (excessive Na+ as indi- saline or sodic? cated by SAR) are called saline-sodic soils, Saline waste. If a waste is saline, careful and can be expected to have the negative attention to soil texture, plant selection, and characteristics of both saline soils and sodic application rate and timing can help. Coarse soils described above. Table 3 displays EC soils often have a lower clay content and are and SAR levels indicative of saline, sodic, and less subject to sodium-induced soil structure saline-sodic soils.
8 The term milliequivalents per liter (meq/l) expresses the concentration of a dissolved substance in terms of its combining weight. Milliequivalents are calculated for elemental ions such as Na+, Ca2+, and Mg2+ by multiplying the concentration in mg/l by the valence number (1 for Na+, 2 for Ca2+ or Mg2+) and dividing by the atomic weight (22.99 for Na+, 40.08 for Ca2+, or 24.31 for Mg2+). 9 If the proper equipment to measure these concentrations is not available, consider sending soil and waste samples to a soil testing laboratory, such as that of the local extension service (visit
Table 3 EC and SAR Levels Indicative of Saline, Sodic, and Saline-Sodic Soils
Soil Characterization
Normal Saline Sodic Saline-Sodic
a EC < 4 and EC > 4 SAR> 13 EC > 4 and SARb < 13 SAR > 13
Source: Fipps, G. Managing Irrigation Water Salinity In the Lower Rio Grande Valley. aIn units of mmhos/cm bdimensionless
problems. While coarse soils help minimize sum (CaSO4) to irrigation water can also help soil structural problems associated with salin- to reduce the SAR, by increasing soil calcium ity, they also have higher infiltration and per- levels. Although this might help address sodi- meability rates, which allow for more rapid um-induced soil structure problems, if choos- percolation or flushing of the root zone. This ing to add constituents to alter the SAR, the can increase the risk of waste constituents EC should also be monitored to ensure salini- being transported to ground water. ty levels are not increased too much. Since plants vary in their tolerance to saline environments, plant selection also is H. Calcium Carbonate important. Some plant species, such as rye grass, canary grass, and bromegrass, are only Equivalent moderately tolerant and exhibit decreased Calcium carbonate equivalent (CCE) is growth and yields as salinity increases. Other used to measure a waste’s ability to neutralize plants, such as barley and bermuda grass, are soil acidity—its buffering capacity—as com- more saline-tolerant species. pared with pure calcium carbonate. Buffering capacity refers to how much the pH changes You should avoid applying high salt con- when a strong acid or base is added to a solu- tent waste as much as possible. For saline tion. A highly buffered solution will show wastes, a lower application rate, and thor- only a slight change in pH when strong acids ough tilling or plowing can help dilute the or bases are added. Conversely, if a solution overall salt content of the waste by mixing it has a low buffering capacity, its pH will with a greater soil volume. To avoid the change rapidly when a base or acid is added inhibited germination associated with saline to it. If a waste has a 50 percent CCE, it soils, it also can help to time applications of would need to be applied at twice the rate of high-salt wastes well in advance of seedings. pure calcium carbonate to achieve the same Sodic waste. SAR alone will not tell how buffering effect. sodium in a waste will affect soil permeability; it is important to investigate the EC of a waste as well. Even if a waste has a high SAR, plants I. Pathogens might be able to tolerate this level if the waste Potential disease-causing microorganisms also has an elevated EC. As with saline waste, or pathogens, such as bacteria, viruses, proto- for sodic waste select a coarser-textured soil to zoa, and the eggs of parasitic worms, might help address sodium concerns. Adding gyp- be present in certain wastes. Standardized
7C-11 Protecting Ground Water—Designing A Land Application Program
testing procedures are available to help deter- mine whether a waste contains pathogens. What are methods for stabilizing You should consider using such tests espe- waste prior to land application? cially if your process knowledge indicates The following methods, recommended that a waste might contain pathogens. Fecal for stabilizing sewage sludge, can also be coliform bacteria can be quantified, for exam- useful for reducing pathogens in waste: ple, by using a membrane filtering technique, • Aerobic digestion which involves passing liquid waste through a filter, incubating the filtrate (which contains • Air drying the bacteria) on a culture medium for 24 • Anaerobic digestion hours, and then counting the number of bac- terial colonies formed. • Composting How can I reduce pathogenic • Lime stabilization risks? More detailed information on each of these and other methods can be found Methods to reduce pathogenic risk include in EPA’s Control of Pathogens and Vector disinfecting or stabilizing a waste prior to Attraction in Sewage Sludge (U.S. EPA, land application. Examples of treatment 1992). methods recognized for sewage sludge stabilization are included in the sidebar. Pathogens present a public health hazard if ments for pathogen reductions for specific they are transferred to food or feed crops, waste types. contained in runoff to surface waters, or transported away from a land application site by vectors. If pathogen-carrying vectors are a III. Measuring Soil concern at a site, it is important to establish measures to control them. For examples of Properties methods to control vectors, refer to Chapter Physical, biological, and chemical charac- 8–Operating the Waste Management System. teristics of the soil are key factors in deter- Additional information on pathogen reduc- mining its capacity for waste attenuation. If tion and methods to control vectors can be the soil is overloaded, rapid oxygen deple- obtained from 40 CFR 503.15 and 40 CFR tion, extended anaerobic conditions, and the 503.32 (EPA’s Sewage Sludge Rule.) A dis- accumulation of odorous and phytotoxic cussion of these alternatives is available in end-products can impair soil productivity EPA’s guidance document Land Application of and negatively impact adjacent properties. Sewage Sludge: A Guide for Land Appliers on With proper design and operation, waste can the Requirements of the Federal Standards for be successfully applied to almost any soil; the Use or Disposal of Sewage Sludge, 40 CFR however, sites with highly permeable soil Part 503 (U.S. EPA, 1994a). (e.g., sand), highly impermeable soil (e.g., The services of a qualified engineer might clay), poorly drained soils, or steep slopes be necessary to design an appropriate process can present special design issues. Therefore, for reducing pathogens in a waste. You it is advisable to give such sites lower priority should consult with the state to determine during the site selection process. whether there are any state-specific require-
7C-12 Protecting Ground Water—Designing A Land Application Program
How can I evaluate the soil at a types vary considerably, further subdivision of site? soil horizons or collection of samples over a greater variety of depths might be appropriate. To help evaluate the soil properties of a For more information about how to obtain site, you should consult the U.S. Department representative soil samples and to submit of Agriculture (USDA) soil survey for the them for analysis, you can consult EPA’s prospective area. These surveys provide infor- Laboratory Methods for Soil and Foliar Analysis mation on properties such as soil type and in Long-Term Environmental Monitoring permeability. USDA has prepared soil surveys Programs (U.S. EPA, 1995d), or state guides, for most counties in each state. To obtain a such as Nebraska’s Guidelines for Soil Sampling, copy of the survey for an area, contact the G91-1000. Natural Resource Conservation Service offices, the county conservation district, the state agri- Why are chemical and biological cultural cooperative extension service, or local properties of soil important? health authorities/planning agency. These soils surveys will help during site selection; howev- Chemical and biological properties of the er, conditions they describe can differ from soil, like those of the waste, influence the the actual soil conditions. attenuation of waste constituents. These properties include pH, percentage of organic Several guidance documents on soil sur- matter, and cation exchange capacity. Affected veys are also available from USDA. These attenuation processes in the soil include documents include the National Soil Survey absorption, adsorption, microbial degrada- Handbook and the guide Soil Taxonomy: A tion, biological uptake, and chemical precipi- Basic System of Soil Classification for Making tation. For example, adsorption—the process and Interpreting Soil Surveys. The National Soil by which molecules adhere to the surface of Survey Handbook provides an abundance of other particles, such as clay—increases as the information including help on interpreting cation exchange capacity and pH of the soil soil surveys, a primer on soil properties and increase. Cation exchange capacity, in turn, is soil quality, and guides for predicting the per- dependent on soil composition, increasing as meability of your soil. Both of these docu- the clay content of the soil increases. ments are available over the Internet and can Adsorption through cation exchange is an be obtained from
7C-13 Protecting Ground Water—Designing A Land Application Program
increases. Sites with soils with permeabilities techniques, and application rates. The agen- that are too high or too low have lower land cies that regulate land application in a state application potential. Soils with high perme- can provide specific guidance concerning ability can allow wastes to move through with- slopes. Soils on concave land and broad flat out adequate attenuation. Soils with low lands, on the other hand, frequently are permeability can cause pooling or excessive poorly drained and can be waterlogged dur- surface runoff during intense rainstorms. ing part of the year. Soils in relatively flat Excessive runoff conditions can be compensat- areas can have intermediate properties with ed for somewhat by minimizing surface slope respect to drainage and runoff and could be during site selection. Soils with low perme- more suitable for land application. ability are also prone to hydraulic overloading. The amount of liquid that can be assimi- lated by a soil system is referred to as its IV. Studying the hydraulic loading capacity. In addition to a soil’s permeability, hydraulic loading capacity Interaction of is dependent on other factors such as cli- mate, vegetation, site characteristics, and Plants and other site-specific soil properties such as soil Microbes with type, depth to seasonally high water table, slope and erodibility, water intake rate, and Waste underlying geology and hydrogeology. The next step in the design of a land Exceeding the hydraulic loading capacity of a application unit is to consider the plants and site, can lead to rapid leaching of waste con- microbes at the site and how they will inter- stituents into ground water, reduction in bio- act with the waste. This interaction includes logical activity, sustained anaerobic the uptake and degradation of waste con- conditions, soil erosion, and possible conta- stituents, the effects of the wastes on plant mination of surface waters. It can also result and microbial growth, and changes that can in excessive evaporation, which can cause occur in plants or crops affecting their use as excessive odor and unwanted airborne emis- food or feed. The uptake of nutrients by sions. In order to avoid hydraulic overload- plants and microbes on plant roots or in soil ing at a site, application of liquid or affects the rate of waste assimilation and semi-liquid waste or wastewater should be biodegradation, usually increasing it. managed so uncontrolled runoff or prolonged It might be necessary to conduct green- saturation of the soil does not occur. house or field studies or other tests of plants, An important indicator of soil properties is soil, and microbes to understand and quanti- its topography, which affects the potential for fy these interactions. You should consult with soil erosion and contaminated surface-water the state agricultural department, the local runoff. Soils on ridge tops and steep slopes health department, and other appropriate are typically well drained, well aerated, and agencies if considering land application of shallow. Steep slopes, however, increase the wastes containing designated ground-water likelihood of surface runoff of waste and of constituents or other properties that are soil erosion into surface waters. State guide- potentially harmful to food or feed crops. lines, therefore, often specify the maximum Industry groups might also be able to pro- slopes allowable for land application sites for vide information about plants with which various waste characteristics, application they have land application experience.
7C-14 Protecting Ground Water—Designing A Land Application Program
A. Greenhouse and Field extension service might have previous experi- Studies ence with that specific type of waste. State agricultural extension services, depart- Greenhouse studies. Aside from their ments of environmental protection, or public smaller scale, greenhouse studies differ from universities might have previous studies about field studies primarily in that they are con- plant uptake of nutrients, especially nitrogen, ducted indoors under controlled conditions, phosphorus, and potassium, but it is impor- while field studies are conducted under nat- tant to recognize that the results of studies ural environmental conditions. A greenhouse conducted under different conditions (such as study typically involves distributing represen- different waste type, application rate, plant tative soil samples from the site into several type, or climate) are only partially relevant to a pots to test different application rates, appli- specific situation. Furthermore, most studies to cation methods, and crops. Using several date have focused on relatively few plant duplicate pots for each rate, method, or crop species, such as corn, and only a handful of allows averaging and statistical aggregating of constituents, typically metals. Greenhouse results. It is also important to establish con- studies or pilot-scale field studies attempt to trol pots, some with no waste and no plants, model site-specific conditions by growing the others with waste but no plants (to observe intended crops in soil from the prospective the extent to which waste assimilation effects application site. These studies are useful are due to soil and pre-existing microbes) and because individual parameters can be varied, still others with plants but without waste (as such as plant type and waste application rate, a baseline for comparison with waste-amend- to determine the effects of each factor. ed plant growth). Additionally, greenhouse or field studies might To the be required by some states to certify that a extent waste has agricultural benefits. Generally, the feasible, first point of contact for assistance with studies tempera- is the state agricultural extension service. Many ture, state extensions can conduct these studies; mois- others might be able to provide guidance or ture, and expertise but will recommend engaging a pri- other vate consultant to conduct the studies. parame- ters should simulate actual site conditions. How do I conduct greenhouse or There should be a series of several duplicate field studies? pots grown with each combination of plant type, application rate, and other parameters. Currently, no national guidelines exist for Pots should be arranged to avoid environ- 10 conducting greenhouse or field studies, but mental conditions disproportionately affecting check to see if the state has guidance on one series of pots. For example, you should accepted practices. Working with a state agri- avoid placing a whole series of pots in a row cultural extension service or a local university closest to a light source; instead, it is better to will provide the benefit of their expertise and place one pot from each of several series in experience with local conditions, such as that row or randomize placement of pots. which plants are suitable for local soils and climate. If a particular industry sector has a The controlled greenhouse environment large presence in a state, the state agricultural allows the study of a wide range of waste-soil
10 Based on conversations with Dr. Rufus L. Chaney and Patricia Milner, U.S. Department of Agriculture.
7C-15 Protecting Ground Water—Designing A Land Application Program
field conditions, even with good fertility and management. Both greenhouse and field studies typically include extensive sampling of waste, soil before application, plants or representative parts of plants, soil after application, growth of plants, and, to the extent feasible, water. You should sample soil at the surface and in lower horizons using core sampling. Some soil tests require mixing samples with water interactions without risking the loss of plants to form a paste or slurry. Plant tissue tests due to weather, animal hazards, and other often require dry-weight samples, made by environmental influences. At the same time, drying cut plants at about 65°C. Water can this can introduce differences from actual be collected in lysimeters (buried chambers conditions. Root confinement, elevated soil made from wide perforated pipe) and temperature, and rapidly changing moisture removed using hand pumps. levels, for example, can increase the uptake The effects of waste on organisms in the of pollutants by potted plants compared to soil can also be monitored during greenhouse 11 uptake under field conditions. and field studies. The literature suggests, that Field studies. Field studies, on the other the effects of waste on earthworms are a good hand, can test application rates and crops on indicator of effects on soil organisms in gen- plots at the actual proposed site. As with eral. It might be worthwhile, therefore, to greenhouse studies, duplicate plots are useful stock greenhouse pots or field study plots for statistical purposes, and controls are with earthworms at the beginning of a study needed. Field study data can be more useful and monitor the waste constituent levels and because it more closely reflects real-world the effects on the worms during and at the conditions, but it also can be more difficult end of the study. Although these brief studies to obtain because of uncontrollable circum- will not effectively model long-term exposure stances such as flooding or unusual pest to waste constituents, it is possible to gauge damage that can occur at the time of the short-term and acute effects. study. Field studies also can be subject to sit- ing, health and safety, and permitting requirements. B. Assessing Plant and Microbial Uptake Rates Field studies also help determine the actu- al land area required for land application and Plants. After performing studies, you the quality of runoff generated. Soil and should measure the amounts of various ground-water monitoring help to confirm nutrients, metals, and other constituents in that waste constituents are being taken up by tissue samples from plants grown in the plants and not leaching into the ground greenhouses or on test plots. This tells water. Results from field studies, however, approximately how much of these con- might not be duplicated on actual working stituents the plants extracted from the soil- plots after multiple waste applications, due to waste mix. By measuring plant-extracted long-term soil changes. Crop yields also can quantities under these various conditions, vary by as much as 15 to 25 percent under you can determine a relationship between
11 If a waste contains VOCs, ensure the possibility of VOCs accumulating within the enclosed greenhouse is addressed. 7C-16 Protecting Ground Water—Designing A Land Application Program
plant type, application rate, and nutrient stituents in the process of using other com- extraction. From this, you can choose the pounds as an energy source. Aerobic microor- conditions which result in the desired uptake ganisms require oxygen to metabolize waste rate while avoiding uptake of designated and produce carbon dioxide and water as end ground-water constituents at undesirable products. Anaerobic microbes function with- concentrations. Plant uptake is often mea- out oxygen but produce methane and hydro- sured as a ratio of the pollutant load found in gen sulfide as end products. These gases can the plants to the pollutant load applied to the present a safety risk as well as environmental land as illustrated below: threats, and hydrogen sulfide is malodorous. For these reasons, it is recommended that µg pollutant kg pollutant you maintain conditions that favor aerobic per g dry plant tissue hectare microbes. For many microorganisms, these condi- This ratio serves to place pollutant uptake tions include a pH of 6 to 8 and temperatures in the context of the original amount of pol- of 10°C to 30°C. In addition, microbes might lutant applied. be unable to transfer oxygen from soil effi- ciently if the moisture content is near satura- In choosing plants for a land application tion, or they might be unable to obtain unit, you should also consider growing seasons sufficient water if the soil is too dry. A water in relation to periods of waste application rate. content of 25 to 85 percent of the soil’s water Specific waste application rates associated with holding capacity is recommended in the liter- corresponding uptakes of nutrients by plants, ature. Oxygen generally is available through as indicated in greenhouse or field studies, are diffusion from the atmosphere, but this applicable only during the growing phases cov- mechanism might provide insufficient oxygen ered by the study. At other times, waste appli- if there is too little pore space (less than 10 cation might be infeasible because plants are percent of soil volume) or if so much organic not present to help assimilate waste, or because matter is applied that oxygen is consumed plants are too large to permit passage of appli- faster than it is replaced. cation equipment without sustaining damage. Microbes. Certain microbes can biode- grade organic chemicals and other waste con- C. Effects of Waste on stituents. Some accomplish this by directly Plant and Microbe using the constituents as a source of carbon Growth and energy, while others co-metabolize con- Greenhouse and field studies can tell what effect the waste will have on plant growth pat- terns. A typical method of quantifying plant growth is to state it in terms of biomass pro- duction, which is the dry weight of the cut plants (or representative parts of the plants). If the plants grown with waste applications show greater mass than the control plants,12 the waste might be providing useful nutrients or otherwise improving the soil. If the plants grown with waste applied at a certain rate
12 Trends detected in studies assume that results have been subjected to tests of statistical validity before finding a trend significant. 7C-17 Protecting Ground Water—Designing A Land Application Program
weigh less than the controls, some con- state to see if there are any restrictions on stituent(s) in the waste might be excessive at this practice. Growing crops for human con- the studied application rate. Comparing the sumption on soil amended with waste calls results from several different application rates for even greater caution. In some states, this can help find the rate that maximizes growth practice is prohibited or regulated, and in and avoids detrimental and phytotoxic effects. states where it is allowed, finding food processors or distributors willing to purchase Analyzing soil and water after plant growth such crops can be difficult. allows for a comparison between the planted pots or plots against the control to discern the When testing crops before feeding them differences due to plant action. If water sam- to animals, local agricultural extension ser- ples show excessive nutrient (especially nitro- vices might be able to help determine what gen) levels at a certain application rate, this levels are appropriate for animal consump- might indicate that the plants were unable to tion. If plant tissue samples or findings of a use all the nutrients in the waste applied at fate and transport model indicate waste con- that rate, suggesting that the application was stituent levels inappropriate for animal con- excessive. If soil and water tests show that sumption, it is important that you not use constituents are consumed, and if other possi- harvested plants as fodder or allow grazing ble causes can be ruled out, microbes might on the site. Additionally, plants with high be responsible. Further investigation of constituent levels will probably be inappro- microbial action might involve sampling of priate for other agricultural use, and thus microbes in soil, counting their population, would likely necessitate disposal of such and direct measurement of waste constituents crops as a waste after harvest. and degradation byproducts.
D. Grazing and Harvesting V. Considering Restrictions Direct Exposure, If a waste might contain pathogens or des- ignated ground-water constituents, and the Ecosystem established vegetative cover on the land Impacts, & application site is intended for animal con- sumption, it is important to take precautions Bioaccumulation to minimize exposure of animals to these contaminants. This is important because ani- of Waste mals can transport pathogens and ground- You should evaluate the impacts that your water constituents from one site to another, land application unit will have on direct and can be a point of entry for waste con- exposure and ecological pathways as well as stituents and pathogens into the food chain. the potential for bioaccumulation of land- applied waste. During the land application If harvesting crops from a unit for use as unit’s active life, direct human exposure to animal fodder, you should test plants for the waste or waste-amended soil is primarily a presence of undesirable levels of the desig- risk to personnel involved in the operation. nated ground-water constituents before feed- You should follow OSHA standards and ing. Grazing animals directly on a unit is ensure that personnel are properly trained discouraged by some states.13 If considering and use proper protective clothing and equip- direct grazing, you should consult with the 13 Grazing can also be unwise due to potential effects on soil physical structure. The weight of heavy ani- mals can compact soil, decreasing pore space, which can reduce the soil’s waste attenuation capacity. 7C-18 Protecting Ground Water—Designing A Land Application Program
ment when working onsite. You should limit Climate also determines which plants can direct exposure to others through steps such grow in a region and the length of the grow- as access control and vehicle washing to pre- ing season. If the local climate cannot sup- vent tracking waste and waste amended soil port the plants that might be most helpful in off site. assimilating the particular constituents in a given waste, the use of land application might Access control will also limit exposure of be limited to other crops at a lower applica- some animals. If crops will be used for animal tion rate. If the climate dictates that the part fodder or grazing, you should test harvested of the growing cycle during which land appli- fodder for the designated ground-water con- cation is appropriate is short, a larger area for stituents before use and restrict grazing times. land application might be necessary. After a site is closed, there might be long-term access risks to future land uses and the gener- There are also operating considerations al public. To minimize these risks, long-term associated with climate. Since waste should access controls or deed restrictions might be not be applied to frozen or very wet soil, the appropriate. Consult Chapter 11—Performing application times can be limited in cold or Closure and Post-Closure Care for further rainy climates. In climates where the ground information. can freeze, winter application poses particular problems even when the ground is not frozen, Direct exposure of native animals is often because if the ground freezes soon after appli- impossible to control and might be an entry cation, the waste that remained near the soil point for the ground-water constituents into surface can run off into surface waters during the food chain. Worms, for example, might subsequent thaw periods. Waste nutrients are be present in the soil and take in these con- also more likely to leach through the soil and stituents. Birds or other animals could then into the ground water following spring thaw, consume the worms, bioaccumulate, or be prior to crop growth and nutrient uptake. transported off site. Furthermore, animals can These problems can be partially solved by ingest plants grown on waste-amended soil. providing sufficient waste storage capacity for Therefore, you should also consider pathways periods of freezing or rainy weather. such as these in evaluating your plans for land application. VII. Calculating An VI. Accounting for Agronomic Climate Application Rate Local climate considerations should also The purpose of a land application unit enter into your land application planning (i.e., waste disposal versus beneficial use) process. For example, wastes that are high in helps determine the waste application rate soluble salts are less appropriate and can have best suited for that unit. When agricultural deleterious effects in arid climates due to the benefits are to be maximized, the application osmotic pressure from the salts inhibiting root rate is governed by the agronomic rate. The uptake of water. On the other hand, the down- objective for determining an agronomic appli- ward movement of water in the soil is minimal cation rate is to match, as closely as possible, in arid climates, making the migration of waste the amount of available nutrients in the waste constituents to ground water less likely. with the amount required by the crop. One
7C-19 Protecting Ground Water—Designing A Land Application Program
example of an equation for calculating agro- How do I determine the agro- nomic application rates is: nomic rate? Agronomic application rate = (Crop nutri- ent uptake × Crop yield)-Nutrient credits Computer models can help determine site- specific agronomic rates. Modeling nitrogen Where: levels in waste and soil-plant systems can help Crop nutrient uptake = Amount of nutri- provide information about physical and ents absorbed by a particular crop. These hydrologic conditions and about climatic requirements are readily available from influences on nitrogen transformations. your state and local Cooperative Extension Models recommended for use with sewage Offices sludge include Nitrogen Leaching and Economic Analysis Package (NLEAP); Crop yield = Amount of plant available for DECOMPOSITION; Chemicals, Run-Off, and harvest. Methods for calculating expected Erosion from Agricultural Management yields include past crop yields for that Systems (CREAMS); and Ground-Water unit, county yield records, soil productivi- Loading Effects of Agricultural Management ty tables, or local research. Systems (GLEAMS).14 NLEAP is a moderately Nutrient credits = Nitrogen residual from complex, field scale model that assesses the past waste applications, irrigation water potential for nitrate leaching under agricultur- nitrate nitrogen, nutrients from commer- al fields. NLEAP can be used to compare cial fertilizer, and other nitrogen credits nitrate leaching potential under different soils from atmospheric deposition from dust and climates, different cropping systems, and and ammonia in rainwater. different management scenarios. The comput- er model DECOMPOSITION is specifically In addition, many states and universities designed to help predict sewage sludge nitro- have developed their own worksheets or cal- gen transformations based on sludge charac- culations for developing an agronomic appli- teristics, as well as climate and soil properties cation rate. You should check with your state (organic matter content, mean soil tempera- agency to see if you are subject to an existing ture, and water potential). Finally, the regulation. In setting a preliminary applica- CREAMS and GLEAMS models, developed by tion rate the crop’s nitrogen requirements the USDA, are other potentially useful models often serve as a ceiling, but in some cases, to assist with site-specific management of land phosphorus, potassium, or salt content, rather application operations. Additional computer than nitrogen, will be the limiting factor. models include Cornell Nutrient Management Planning System (NMPS), Fertrec Plus v 2.1, and Michigan State University Nutrient
14 All of these models are referenced in EPA’s Process Design Manual: Land Application of Sewage Sludge and Domestic Septage (U.S. EPA, 1995b). According to that source, the NLEAP software, developed by Shaffer et al., is included in the purchase of Managing Nitrogen for Groundwater Quality and Farm Profitability by Follet, et al., which also serves as reference for information on parameters required for nitrogen calculations. Four regional soil and climatic databases (Upper Midwest, Southern, Northeastern, and Western) also are available on disk for use with NLEAP. These materials can be obtained from: Soil Science Society of America Attn: Book Order Department, 677 S. Segoe Road, Madison, WI 53711, 608/273-2021; Book $36.00; Regional Databases $10.00 each. Current updates of the NLEAP program can be obtained by sending original diskettes to: Mary Brodahl, USDA-ARS-GPSR, Box E, Fort Collins, CO 80522. Additional information on the DECOMPOSITION model, developed by Gilmour and Clark, can be obtained from: Mark D. Clark, Predictive Modeling, P.O. Box 610, 7C-20 Fayetteville, AR 72702. The CREAMS and GLEAMS models were developed by USDA. Protecting Ground Water—Designing A Land Application Program
Management v1.1.15 If assistance is required in should reevaluate your use of land applica- determining an appropriate agronomic rate for tion. Adjusting the application rate, adding a waste, you should contact the regional, state, pretreatment, or switching to another means or county agricultural cooperative extensions, of waste management might be necessary. or a similar organization. After reevaluation, you should examine whether corrective action might be necessary to remediate the contaminated ground water. You should pay particular attention to ensure VIII. Monitoring that applications are not exceeding the soil’s Monitoring ground water can be helpful to assimilative capacity. verify whether waste constituents have migrat- ed to ground water. Some state, tribal, or You should also consider testing soil sam- other regulatory authorities require ground- ples periodically during the active life of a water monitoring at certain types of land land application unit. For this testing to be application units; you should consult with the meaningful, it is important that you first appropriate regulatory agency to determine determine baseline conditions by sampling whether such a requirement applies to the the soil before waste application begins. This unit. Even if the unit is not required to moni- might already have been done in preparation tor ground water, instituting a ground-water for greenhouse/field studies or for site charac- monitoring program is recommended for terization. Later, when applying waste to the long-term, multiple application units where unit, you should collect and analyze samples wastes contain the designated ground-water at regular intervals (such as annually or after constituents. Such units are more likely to a certain number of applications). Consider pose a threat to ground water than are single- analyzing samples for macronutrients, application units or units receiving waste micronutrients, and any of the designated without these constituents. ground-water constituents reasonably expect- ed to be present in the waste. The location In most cases, lysimeters should be suffi- and number of sampling points, frequency of cient to monitor ground water. A lysimeter is sampling, and constituents to be analyzed a contained unit of soil, often a box or cylin- will depend on site-specific soil, water, plant, der in the ground which is filled with soil, and waste characteristics. Local agricultural open on the top, and closed at the bottom, so extension services, which have experience that the water that runs through it can be col- with monitoring, especially when coupled lected. It is usually more simple and econom- with ground-water monitoring, can detect ical to construct and operate than a contamination problems. Early detection monitoring well. You can consult with a qual- allows time to change processes to remedy ified professional to develop an appropriate the problems, and to conduct corrective ground-water monitoring program for your action if necessary before contamination land application unit. becomes widespread. If ground-water results indicate unaccept- Testing soils after the active life of a unit able constituent levels, you should suspend ends might also be appropriate, especially if land application until the cause is identified. the waste is likely to have left residues in the You should then correct the situation that led soil. The duration of monitoring after closure, to the high readings. If a long-term change in like the location and frequency of monitoring the industrial process, rather than a one-time during active life, is site-specific and depends incident, caused the elevated levels, you on similar factors. For further information
15 These models are referenced in the Northeast Regional Agricultural Engineering Cooperative Extension’s Nutrient Management Software: Proceedings from the Nutrient Management Software 7C-21 Workshop from December 11, 1996. Protecting Ground Water—Designing A Land Application Program
about testing soil after the active life of a unit location, characteristics, the time and date, ends, refer to Chapte 11—Performing existing meteorological conditions, suspected Closure and Post-Closure Care. specific source, information that indicates rel- ative strength compared to other events, and when during the day the odors are noticed. IX. Odor Controls Measuring odors can be accomplished in Odors are sometimes a common problem two manners: olfactometry and analytical. at land application facilities and an odor The olfactometry method uses trained indi- management plan can allow facility managers viduals who determine the strength of an to respond quickly and effectively to deal odor. Both of these methods have advantages with odor complaints. A plan should involve and disadvantages. Some of the advantages of working to prevent odors from occurring, the olfactometry method are that it is accu- working with neighbors to resolve odor com- rately correlated with human response, it is plaints, and making changes if odors become fast at providing a general chemical classifica- an unacceptable condition. The plan should tion, and it is usually cost effective as a field also identify the chemical odor constituents, screening method. Disadvantages include the determine the best method for monitoring requirement of highly trained individuals, odor, and develop acceptable odor thresh- and it does not address the chemistry of the olds. These odor management plans can be odor problem. Analytical methods use gas stand-alone plans or part of your company’s chromatographs and mass spectrophotome- environmental management system. ters to analyze vapor concentrations captured from a sample. Some of the advantages of the To effectively deal with odor complaints, it analytical method are that it allows detection is important to consider creating an odor of odorants at levels near human detection, it detection and response team to identify the is precise and repetitive, and it provides source of, and quickly respond to, potential chemical specificity. Disadvantages include a nuisance odor conditions. Document the very high capital cost which might not accu- problem as well as how it was or was not rately correlate with human responses. You resolved, and notify facility managers as soon should contact your state for more informa- as possible. Odor complaints should be doc- tion on odor management plans and measur- umented immediately in terms of the odor’s ing odors.
7C-22 Protecting Ground Water—Designing A Land Application Program
Designing a Land Application Program Activity List
■ Use the framework to design and evaluate a land application program and to help determine a pre- liminary waste application rate. ■ Be familiar with waste parameters, such as total solids content, pH, organic matter, nutrients, car- bon and nitrogen levels, salts, soil buffering capacity, and pathogens. ■ When examining potential application sites, give special consideration to physical and chemical properties of soil, topography, and any site characteristics that might encourage runoff or odor. ■ Choose crops for the unit considering plant uptake of nutrients and constituents. ■ Account for climate and its effects. ■ Determine an agronomic application rate. ■ Evaluate ground-water and air risks from land application units and consider potential exposure pathways. ■ Consider implementing a ground-water monitoring program and periodic sampling of unit soils.
7C-23 Protecting Ground Water—Designing A Land Application Program
Resources
Brandt, R.C. and K.S. Martin. 1996. The Food Processing Residual Management Manual. September.
Borrelli, J. and D. Brosz. 1986. Effects of Soil Salinity on Crop Yields.
Evanylo, G.K. and W. L. Daniels. 1996. The Value and Suitability of Papermill Sludge and Sludge Compost as a Soil Amendment and Soilless Media Substitute. Final Report. Virginia Department of Agriculture and Consumer Services. April.
Fipps, G. 1995. Managing Irrigation Water Salinity in the Lower Rio Grande Valley.
Gage, J. 2000. Operating by Progressive Odor Management Plan. Biocycle Journal of Composting & Recycling. Vol. 41 No. 6. June.
Idaho Department of Health and Welfare. 1988. Guidelines for Land Application of Municipal and Industrial Wastewater. March.
Michigan Department of Natural Resources, Waste Characterization Unit. 1991. Guidance for Land Application of Wastewater Sludge in Michigan. March.
Michigan Department of Natural Resources, Waste Characterization Unit. 1991. Guide to Preparing a Residuals Management Plan. March.
Minnesota Pollution Control Agency. 1993. Land Treatment of Landfill Leachate. February.
Nagle, S., G. Evanylo, W.L. Daniels, D. Beegle, and V. Groover. Chesapeake Bay Regional Nutrient Management Training Manual. Virginia Cooperative Extension Service. Crop & Soil Environmental Sciences. Virginia Polytechnic Institute and State University. Blacksburg, VA. 1997.
Northeast Regional Agricultural Engineering Cooperative Extension. 1996. Nutrient Management Software: Proceedings from the Nutrient Management Software Workshop. NRAES-100. December.
Northeast Regional Agricultural Engineering Cooperative Extension. 1996. Animal Agriculture and the Environment: Nutrients, Pathogens, and Community Relations. NRAES-96. December.
Northeast Regional Agricultural Engineering Cooperative Extension. 1993. Utilization of Food Processing Residuals. Selected Papers Representing University, Industry, and Regulatory Applications. NRAES-69. March.
North Carolina Cooperative Extension Service. 1994. Soil facts: Careful Soil Sampling—The Key to Reliable Soil Test Information. AG-439-30. 7C-24 Protecting Ground Water—Designing A Land Application Program
Resources (cont.)
Oklahoma Department of Environmental Quality. Title 252. Oklahoma Administrative Code, Chapter 647. Sludge and Land Application of Wastewater.
Rowell, D.L. 1994. Soil Science: Methods and Applications.
Striebig, B. and R. Giani. 2000. Briefing: The Odor Index and Its Use as a Management Tool for Biosolids Land Application. Penn State University and Pennsylvania Department of Environmental Protection.
Texas Water Commission. 1983. Industrial Solid Waste Management Technical Guideline No. 5: Land Application. December.
University of Nebraska Cooperative Extension Institute of Agriculture and Natural Resources. 1991. Guidelines for Soil Sampling. G91-1000-A. February.
U.S. Department of Agriculture, Natural Resources Conservation Service. 1999. Agricultural Phosphorus and Eutrophication. July.
U.S. Department of Agriculture, Natural Resources Conservation Service. 1999. Conservation Practices Standard: Nutrient Management, Code 590. April.
U.S. Department of Agriculture, Natural Resources Conservation Service. 1999. Core Conservation Practices, Part 2: Nutrient Management. August.
U.S. Department of Agriculture, Natural Resources Conservation Service. 1999. National Soil Survey Handbook. September.
U.S. Department of Agriculture, Natural Resources Conservation Service. 1999. Soil Taxonomy: A Basic System of Soil Classification for Making and Interpreting Soil Surveys. September.
U.S. EPA. 1995a. A Guide to the Biosolids Risk Assessments for the EPA Part 503 Rule. EPA832-B-93- 005. September.
U.S. EPA. 1995b. Process Design Manual: Land Application of Sewage Sludge and Domestic Septage. EPA625-R-95-001. September.
U.S. EPA. 1995c. Process Design Manual: Surface Disposal of Sewage Sludge and Domestic Septage. EPA625-R-95-002. September.
U.S. EPA. 1995d. Laboratory Methods for Soil and Foliar Analysis in Long-term Environmental Monitoring Programs. EPA600-R-95-077.
7C-25 Protecting Ground Water—Designing A Land Application Program
Resources (cont.) U.S. EPA. 1994a. Land Application of Sewage Sludge: A Guide for Land Appliers on the Requirements of the Federal Standards for the Use or Disposal of Sewage Sludge, 40 CFR Part 503. EPA831-B-93- 002b. December.
U.S. EPA. 1994b. Guide to Septage Treatment and Disposal. EPA625-R-94-002. September.
U.S. EPA. 1994c. A Plain English Guide to the EPA Part 503 Biosolids Rule. EPA832-R-93-003. September.
U.S. EPA. 1994d. Biosolids Recycling: Beneficial Technology for a Better Environment. EPA832-R-94- 009. June.
U.S. EPA. 1993. Domestic Septage Regulatory Guidance: A Guide to the EPA 503 Rule. EPA832-B-92- 005. September.
U.S. EPA. 1992. Control of Pathogens and Vector Attraction in Sewage Sludge. EPA625-R-92-013. December.
U.S. EPA. 1990. State Sludge Management Program Guidance Manual. October.
U.S. EPA. 1983. Process Design Manual for Land Application of Municipal Sludge. EPA625-1-83-016. October.
U.S. EPA, U.S. Army Corps of Engineers, U.S. Department of Interior, and U.S. Department of Agriculture. 1981. Process Design Manual for Land Treatment of Municipal Wastewater. EPA625-1-81- 013. October.
U.S. EPA. 1979. Methods for Chemical Analysis of Water and Wastes. EPA600-4-79-020.
Viessman Jr., W. and M.J. Hammer. 1985. Water Supply and Pollution Control. 4th ed.
Washington State Department of Ecology. 1993. Guidelines for Preparation of Engineering Reports for Industrial Wastewater Land Application Systems. Publication #93-36. May.
Webber, M.D. and S.S. Sing. 1995. Contamination of Agricultural Soils. In Action, D.F. and L.J. Gregorich, eds. The Health of Our Soils.
Wisconsin Department of Natural Resources. 1996. Chapter NR 518: Landspreading of Solid Waste. April.
7C-26 Part V Ensuring Long-Term Protection
Chapter 8 Operating The Waste Management System Contents
I. An Effective Waste Management System ...... 8-1
II. Maintenance and Operation of Waste Management System Components ...... 8-2 A. Ground-Water Controls ...... 8-4 B. Surface-Water Controls ...... 8-5 C. Air Controls ...... 8-5
III. Operational Aspects of a Waste Management System...... 8-7 A. Operating Plan ...... 8-7 B. Waste Analysis ...... 8-8 C. Waste Inspections ...... 8-8 D. Daily Cover...... 8-9 E. Placing Wastes ...... 8-10 F. Sludge Removal...... 8-10 G. Climate Considerations ...... 8-11 H.Security Measures, Access Control, and Traffic Management...... 8-11 I. Providing Employee Training ...... 8-12 J. Emergency Response Plan and Procedures ...... 8-14 K. Record Keeping ...... 8-16 L. Addressing Nuisance Concerns...... 8-17
Operating the Waste Management System Activity List ...... 8-20
Resources ...... 8-21 Ensuring Long-Term Protection—Operating the Waste Management System
Operating the Waste Management System
This chapter will help you: • Develop a waste management system that includes procedures for monitoring performance and measuring progress towards environmental goals. The waste management system should identify operational procedures that are necessary to achieve those environmental goals and to make continual improve- ments in waste management operations.
mplementing a waste management sys- I. An Effective tem that achieves protective environmen- tal operations requires incorporating Waste performance monitoring and measure- ment of progress towards environmental Management Igoals. An effective waste management system System can help ensure proper operation of the many Having an effective waste management sys- interrelated systems on which a unit depends tem requires an understanding of environ- for waste containment, leachate management, mental laws and an understanding of how to and other important functions. If the elements comply with these laws. An effective waste of an overall waste management system are not management system also requires that proce- regularly inspected, maintained, improved, dures be in place to monitor performance and and evaluated for efficiency, even the best- measure progress towards clearly articulated designed unit might not operate efficiently. and well understood environmental goals. Implementing an effective waste management Lastly, an effective waste management system system can also reduce long- and short-term involves operational procedures that integrate costs, protect workers and local communities, continual improvements in waste management and maintain good community relations. operations to ensure continued compliance with environmental laws. In addition to what is discussed in this chapter, you can consider This chapter will address the following reviewing and implementing, as appropriate, questions. the draft voluntary standards for good envi- ronmental practices developed by the • What is an effective waste management International Standards Organization (ISO). system? The ISO 14000 series of standards identify • What maintenance and operational management system elements that are intend- aspects should be developed as part of ed to lead to improved performance. These a waste management system? include: a method to identify significant envi- ronmental aspects; a policy that includes a
8-1 Ensuring Long-Term Protection—Operating the Waste Management System
commitment to regulatory compliance, the rest are standards that provide optional guid- prevention of pollution, and continual ance for companies developing and imple- improvement; environmental objectives and menting management systems and product targets for all relevant levels and functions in standards. The ISO 14001 specification stan- the organization; procedures to ensure perfor- dard contains only those requirements that mance, as well as compliance procedures to can be objectively audited for certification, monitor and measure performance; and a sys- registration, and self-declaration purposes. For tematic management review process. more information about EPA’s involvement in the ISO 14000 and 14001 standards, refer to The ISO 14000 series of standards include the ISO 14000 Resource Directory, October a “specification” standard, ISO 14001. The 1997, (U.S. EPA, 1997). Information on obtaining the ISO 14000 series of standards is provided in the text box above. An example of Additional Information on an integrated EMS can be found at ISO 14000
8-2 Ensuring Long-Term Protection—Operating the Waste Management System
for evidence of overtopping, sudden drops in How should effective inspections liquid levels, ice formation, and deterioration be conducted? of dikes or other containment devices. Overtopping, or the flowing of waste over the To help ensure that routine inspections are top of the walls of an impoundment, can performed regularly and consistently, consider occur as a result of insufficient freeboard, developing a written inspection schedule and wind or wave action, or other unusual condi- ensure that staff follow the schedule. The tions including the formation and movement schedule could state the type of inspections to of ice within a surface impoundment which be conducted, the inspection methods to be can also puncture or tear synthetic liners. used, the frequency of the inspections, and a One method of protecting liners from ice plan of action highlighting preventative mea- damage is to install a liner cover consisting of sures to address potential problems. Consider sand and rip rap along the edge of the liner. conducting additional inspections after extra- Another option is the use of a double liner ordinary site-specific circumstances, such as system. The higher cost of a double liner is storms or other extreme weather conditions. offset by reducing the need for rip rap and Staff conducting the inspections should offers enhanced ground-water protection. look for malfunctioning or deteriorating Regardless of which method is implemented, equipment, such as broken sump pumps, liner systems should be inspected for damage leaking fittings, eroding dikes, or corroded and be repaired if necessary after periods of pipes or tanks; discharges or leaks from ice formation. Also, make visual inspections valves or pipes; and operator errors. A writ- periodically to check waste levels, weather ten schedule for inspections should be main- conditions, or draining during periods of tained at the facility, and inspections should heavy precipitation. In addition, it is impor- be recorded in a log containing information tant to consider devising a contingency plan such as date of inspection, name of inspector, to reinforce dikes when failure is imminent. conditions found, and recommended correc- Waste piles and landfills should be tive action. Inspection personnel should be inspected for adequate surface-water protec- familiar with the inspection log to identify tion systems, leachate seeps, dust suppression any malfunctions or deficiencies that remain methods, and daily covers, where applicable. uncorrected from previous inspections. Land application sites should be inspected for When designing an inspection form for a adequate surface-water protection systems unit, add appropriate items for the unit type. and dust suppression methods, as applicable. You can check with the appropriate state reg- Inspections of pipes, monitoring of mechani- ulatory agency to see if it has an inspection cal equipment, and safety, emergency, and form that can be used. For example, a landfill security devices will help to ensure that a form would include a section about waste unit operates in a safe manner. In addition, placement and a surface impoundment form inspections often prevent small problems might have an entry for sufficient freeboard. from growing into more costly ones. If ground water is monitored, you can make ground-water monitoring part of the unit inspection, and add check boxes for each monitoring point to ensure that inspectors collect samples from all monitoring points according to the specified schedule. After an
8-3 Ensuring Long-Term Protection—Operating the Waste Management System
inspection, it is important that all inspection trap for fine sand and silt which bypasses the reports are reviewed in a timely manner so filter pack and screen and settles out within that any necessary repairs and improvements the well. This sediment collects within the can quickly be identified and implemented. sump rather than within the screen, and there- You should consult with your state agency to fore, does not reduce the functional screened help determine if improvements are necessary. length of the well and minimizes the need for periodic cleanouts of the screen. Regardless of the type of ground-water monitoring well A. Ground-Water Controls installed, the well should be protected with a Ground-water protection controls, such as cap or plug at the upper end to prevent con- ground-water monitoring systems, unit covers, densation, rust, and dirt from entering into the leachate collection and removal systems, and manhole or protective casing. In addition, it is leak detection systems should be incorporated important to inspect the outer portion of the into the design and construction of a unit. wells to ensure that they have not been dam- aged by trucks or other unit operations, and to Ground-water monitoring wells require ensure that the cap or plug is intact. continued maintenance. A major reason for maintenance is plugging of the gravel pack or You also should inspect and maintain unit screen. (See Chapter 9–Monitoring covers to ensure that they are intact. For opti- Performance for a discussion on the construc- mal performance, covers should be designed tion of ground-water monitoring wells.) The to minimize permeability, surface ponding, most common plugging problems are caused and the erosion of cover material. The cover by precipitation of calcium or magnesium car- should also prevent the buildup of liquids bonates and iron compounds. Acid is most within the unit. Consult Chapter commonly used to clean screens clogged with 11–Performing Closure and Post-Closure Care calcium carbonate. In many instances, howev- for a more detailed discussion on maintaining er, the cost of attempted restoration of a moni- cover systems. toring well can be more than the installation of It is essential that all components of a a new well. Because many wells are installed leachate collection and removal system and a in unconsolidated sand formations, silt and leak detection system be maintained properly. clay can be pumped through the system and The main components include the leachate cause it to fail. Silt and sand grains are abra- collection pipes, manholes, leachate collection sive and can damage well screens, pumps (if tanks and accessories, and pumps. You should present), flow meters, and other components. consider cleaning the leachate pipes once a In some cases, the well can fill with sedi- year to remove any organic growth and visual- ment and must be cleaned out. The most fre- ly inspecting the manholes, tanks, and pumps quent method of cleaning is to pull the pump once a year as leachate can corrode metallic from the well, circulate clean water down the parts. Annual inspections and necessary well bore through a drop, and flush the sedi- repairs will prevent many future emergency ment out. If large amounts of sediments are problems such as leachate overflow from the expected to enter a monitoring well, consider tank due to pump failure. Maintain a record of incorporating a sediment sump (also called a all repair activities as necessary to assess (or silt trap or sediment trap) into the monitoring claim) long-term warranties on pumps and well construction. The sump consists of a other equipment. blank section of pipe placed below the base of the screen. Its purpose is to provide a catch-
8-4 Ensuring Long-Term Protection—Operating the Waste Management System
In surface impoundments, monitor waste design and construction of a unit. Berms or liquid levels. An unexpected decrease in liq- dikes are often constructed from earthen uid levels can be an indication of a release materials, concrete, or other materials from the impoundment. If a surface designed to be safely traversed during inspec- impoundment fails, it is important to discon- tion or monitoring activities. Vegetation also tinue adding waste to the impoundment and is often used for erosion control. Trees or contain any discharge that has occurred or is other deep rooted vegetation, however, occurring. Repair leaks as soon as possible. If should not be used near liners or other struc- leaks cannot be stopped, empty the tures that could be damaged by roots. Grass impoundment if possible. If the size of the is often used for soil stabilization around sur- unit or amount of waste present prohibits face impoundments. For a more detailed dis- emptying, see Chapter 9–Monitoring cussion of storm-water issues, consult Performance and consult with state officials Chapter 6–Protecting Surface Water. about beginning an assessment monitoring Most if not all of these surface-water con- program. Clean up any released waste (see trols should be inspected by the operator reg- Chapter 10–Taking Corrective Action) and ularly, especially after large storm events. notify the appropriate state authorities of the Structures should be maintained as installed failure and the remedial actions taken. and any structural damage should be repaired as soon as possible to prevent further damage B. Surface-Water Controls or erosion. Any trapped sediments should be removed and disposed of properly. Vegetative If a unit has a point source discharge, the controls frequently need watering after planti- unit must have a National Pollutant ng and during periods of intense heat or lack Discharge Elimination System (NPDES) per- of rain. mit (or equivalent) and, in some states, might require a state discharge permit. Point source discharges include the release of leachate C. Air Controls from a leachate collection or onsite treatment Gases, including methane, carbon dioxide, system into surface waters, disposal of indus- and hydrogen, are often produced at waste trial waste into surface waters, or release of management units as byproducts of the surface-water runoff (e.g., storm water) that is microbial decomposition of wastes containing directed by a runoff control system into sur- organic material. Additionally, volatile organic face waters. Even if there are no point source compounds (VOCs) can be present in the discharges, surface-water controls might be waste, and particulate emissions and dust can necessary to prevent pollutants from being be generated during unit operations. It is discharged or leached into surface waters, important to analyze wastes carefully prior to such as lakes and rivers. If a facility is dis- designing a waste management unit to deter- charging wastewater to a local publicly mine what airborne emissions are likely to owned treatment works (POTW), check with come from these wastes. If airborne emission the POTW and local regulatory authorities to controls are needed in the design of a unit, determine whether pretreatment standards maintenance of these controls should be con- exist for the facility. sidered as part of a waste management sys- Soil erosion and sedimentation controls, tem. For further information on airborne such as ditches, berms, dikes, drains, and silt emission controls, consult Chapter 5– fences, should be incorporated into the Protecting Air Quality.
8-5 Ensuring Long-Term Protection—Operating the Waste Management System
Methane is a particular concern at some Gas control systems generally include waste management units. Methane is odorless mechanisms designed to control gas migra- and can cause fires or explosions that can tion and to minimize the venting of gas emis- endanger employees and damage structures sions into the atmosphere. Passive gas control both on and off site. Hydrogen gas can also systems use natural pressure and convection form, and is also explosive, but it readily mechanisms to remove gas from the waste reacts with carbon or sulfur to form methane management unit. Examples of passive gas or hydrogen sulfide. Hydrogen sulfide can be control system elements include ditches, easily identified by its sulfur or “rotten egg” trenches, vent walls, perforated pipes sur- smell. Methane, if not captured, will either rounded by coarse soil, synthetic membranes, escape to the atmosphere or migrate under- and high moisture, fine-grained soil. Active ground. Underground methane can enter gas control systems use mechanical means to structures, where it can reach explosive con- remove gas from the unit. Gas extraction centrations or displace oxygen, creating the wells are an example of an active gas control danger of asphyxiation. Methane in the soil system. profile can damage the vegetation on the sur- Gas monitoring and extraction systems face of the landfill or on the land surrounding require regular maintenance to operate effi- the landfill, thereby exposing the unit to ciently. As wastes settle over time, pipes can increased erosion. Finally, methane is a fail and condensate outlets can become potent “greenhouse” gas that contributes to blocked. Extracted gas is saturated, which global warming. causes moisture to collect within the pipes. Methane is explosive when present in the Therefore, the condensate within the pipes ranges of 5 to 15 percent by volume in the must be dealt with, otherwise it will affect the air. The 5 percent level is known as the lower pumping suction pressure. Since the plumb- explosive limit (LEL) and 15 percent as the ing on the top of the unit is quite involved, upper explosive limit (UEL). At levels above develop and adhere to a gas maintenance 15 percent by volume, methane will not schedule to ensure the efficient operation of explode when exposed to a source of igni- gas systems. tion. Levels above the UEL remain a concern, If generated gas is not removed from a however, as methane will burn at these con- unit, uplift pressure can cause bubbles within centrations and can still cause asphyxiation. the unit that displace the cover soil at the In the event that methane gas levels exceed surface. Gas bubbles also can decrease the 25 percent of the LEL in facility structures or normal stress between the geomembrane and other closed spaces, initiate safety measures, its underlying material leading to slippage of such as evacuating the site and structures. In the geomembrane and all overlying materials. such cases, or when the methane level This creates high tensile stresses evidenced by exceeds 25 percent of the LEL in the soil at a folding at the toe of the slope and tension monitoring point, implement a remediation cracks near the top. plan to decrease gas levels and prevent future buildup of gases.
8-6 Ensuring Long-Term Protection—Operating the Waste Management System
• Lists of current equipment holdings III. Operational and of future equipment needs. Aspects of a • Procedures to inspect for inappropri- ate wastes and to respond when their Waste presence is suspected. Management • Procedures for addressing extreme System weather conditions. This section identifies and briefly discusses • Personnel needs and equipment uti- some of the important operational aspects of lization, including backup. a waste management system, including devel- • Procedures to address emergencies, oping an operating plan, performing waste such as medical crises, fires, and spills. analyses and inspections, installing daily cov- • Quality control standards. ers, placing wastes in a unit, removing sludge, considering climate, implementing • Record keeping protocols. security and access control measures, provid- • Means of compliance with local, ing employee training, addressing nuisance state, and federal regulations. concerns, developing emergency response plans and procedures, and maintaining The daily procedures component of the plan important records. Consider developing prac- outlines the day-to-day activities necessary to tices to ensure compliance with applicable place waste, operate environmental controls, laws and regulations, to train workers how to and inspect and maintain the waste manage- handle potential problems, and to ensure that ment unit in accordance with its design. Daily all necessary improvements or changes are procedures should be concise enough to be cir- made to a waste management system. Proper culated among all employees at the unit and planning and implementation of these operat- flexible enough to allow for any adjustments ing practices are important elements in the necessary to accommodate weather variability, efficient and protective operation of a unit. changing waste volume, and other contingen- cies. You should revise and update daily proce- dures as needed to ensure the unit’s continued A. Operating Plan safe operation within the parameters of the An operating plan should serve as the pri- overall operating plan. mary resource document for operating a Since a unit will likely operate for several waste management unit. It should include the years, it is important that staff periodically technical details necessary for a unit to oper- review the operating plan to refresh their ate as designed throughout its intended memories and to ensure long-term conformi- working life. At a landfill, for example, the ty with the plan. If modifications to the oper- operating plan should illustrate the chrono- ating plan are necessary, the changes and the logical sequence for filling the unit, and it date they were made should be noted within should be detailed enough to allow the facili- the plan itself. Documented operating proce- ty manager to know what to do at any point dures can be crucial, especially if questions in the active life of the unit. arise in the future regarding the adequacy of An operating plan should include: site construction and management. • A daily procedures component.
8-7 Ensuring Long-Term Protection—Operating the Waste Management System
B. Waste Analysis To effectively manage waste and ensure proper handling (e.g., preventing the mixing of incompatible wastes, use of incompatible liners or containers), knowledge of the chem- ical and physical composition of the wastes is imperative. Determining waste characteristics can be done by performing a comprehensive waste analysis or through process knowledge. To ensure that this information remains accu- rate, it might be necessary to repeat the An effective waste management system analysis whenever there is a change in the relies on accurate knowledge of the waste industrial process generating the waste. For being handled. further information, consult Chapter 2–Characterizing Waste. tions, such as checking random loads of waste on a random day each week or every incom- ing load on one random day each month. C. Waste Inspections Base the frequency of random inspections on The purpose of performing waste inspec- the type and quantity of wastes expected to be tions is to identify waste that might be inap- received, the accuracy and confidence desired, propriate for the waste management unit, and and any state inspection requirements. to prevent problems and accidents before Inspections need to be performed prior to they happen. Hazardous wastes, PCBs, liq- placement of wastes in a unit. uids (in landfills and waste piles), and state- Training employees to recognize inappro- designated wastes are prohibited from priate wastes during routine operations disposal in units designated solely for indus- increases the chances that inappropriate trial nonhazardous waste. Some states have waste arriving on non-inspection days will be developed more stringent screening require- detected. Some indications of inappropriate ments that require a spotter to be present at a wastes are color, texture, or odor different unit to detect unauthorized wastes and to from those of the waste a unit normally weigh and record incoming wastes. receives. Also, laboratory testing can be per- As part of a waste management system, formed to identify different wastes. screening procedures should be implemented A waste management system should to prevent inappropriate wastes from entering include procedures to address suspected a unit. For units receiving waste exclusively inappropriate waste. The procedures to from on site, only limited waste screening implement, when inappropriate wastes are might be necessary. For facilities receiving found, should include the following: waste from off site, screening procedures typi- cally call for screening waste as it enters a • Segregate the suspicious wastes. unit. Ideally, all wastes entering a unit should • Use appropriate personal protective be screened, but this is not always practical or equipment. necessary. A decision might be made, there- fore, to screen a percentage of incoming • Contact the part of the industrial waste. It might be practical to use spot inspec- facility that generated the waste to find out more about it.
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• Contact laboratory support to analyze the waste, if required. • Call the appropriate state, tribal or federal agencies in accordance with the opertaing plan. • Notify a response agency, if necessary. Should liquids be restricted from being placed in some units? Inspect waste to ensure that hazardous Bulk or containerized liquids should not be placed in landfills or waste piles, as liquids waste is not placed in a unit. increase the potential for leachate generation. including coproducts,2 foam, geotextiles, and Liquid waste includes any waste material plastic sheets or tarps. Examples of coprod- determined to contain free liquids as defined ucts that have been used as daily cover by Method 9095 (also known as the paint fil- include granular wastes, automobile shredder ter test) in EPA’s Test Methods for Evaluating fluff, foundry sand, dewatered sludges, and Solid Waste, Physical/Chemical Methods (SW- synthetic soils. When using coproduct covers 846). Sludges are a common waste that can that can themselves contain contaminants, contain significant quantities of liquids. You ensure that run-on is either diverted before it should consider methods such as drying beds contacts the cover material or captured and to dewater sludges prior to placement in handled appropriately after contacting it. landfills and waste piles.1 Granular wastes used as daily cover should be low in fine-grained particles to avoid waste being transported by wind. Before using alter- D. Daily Cover native covers, especially coproducts, you It might be necessary to apply a daily should consult the state to determine what, if cover to operating landfills and waste piles. any, regulations apply. Covering the waste helps control nuisance factors, such as the escape of odors, dust, and Daily cover should be applied after the airborne emissions, and can control the pop- waste has been placed, spread, and compact- ulation of disease vectors where necessary. ed. Cover frequency is most often determined Some cover materials, due to their ability to by the type of industrial waste disposed of at hold moisture, can reduce the infiltration of the landfill or waste pile. Frequent applica- rain water, decreasing the generation of tion of earthen material might be required if leachate and the potential for surface-water undesirable conditions persist. A typical daily and ground-water contamination. soil cover thickness is 6 inches, but different thicknesses might be sufficient. When using How is daily cover applied? earthen cover, it is important to avoid soils with high clay content. Clay, due to its low Covers most often consist of earthen mate- permeability, can block vertical movement of rial, although there are several alternative water and channel it horizontally through the daily covers being used in the industry today, landfill or waste pile.
1 EPA is investigating the potential of bioreactor landfills as the concept applies to the operation of a municipal landfill. The idea of a bioreactor landfill might be considered appropriate in select cases for an industrial landfill at some time in the future. 2 In Pennsylvania a coproduct is defined as “materials which are essentially equivalent to and used in place of an intentionally manufactured product or produced raw material and...[which present] no 8-9 greater risk to the public or the environment.” Ensuring Long-Term Protection—Operating the Waste Management System
Using alternative daily cover materials can occur. To avoid these problems, it is impor- save valuable space in a waste management tant to ensure that waste is properly placed unit. Some types of commercially available and, if possible, compacted to ensure stability daily cover materials include foam that usual- of the final cover. ly is sprayed on the working face at the end To protect liner integrity in lined surface of the day, and geosynthetic products, such as impoundments, consider placing an erosion a tarp or fabric panel that is applied at the guard or a concrete pad on the liner at the end of the working day and removed at the point where waste discharges into the unit. beginning of the following working day. Otherwise, pressure from the waste hitting Some of these materials require specially the liner can accelerate liner deterioration in designed application equipment, while others that area. Inlet pipes can also be arranged so use equipment generally available at most that liquid waste being discharged into the units. Criteria to consider when selecting an unit is diffused upward or to the side. alternative daily cover material include avail- Although inlet pipes can enter the surface ability and suitability of the material, precipi- impoundment above the water level, the tation, chemical compatibility with waste, point of discharge should be submerged to equipment requirements, and cost. avoid generating odor and disturbing the cir- culation of stratified ponds. Discharging liq- E. Placing Wastes uid waste straight into the unit without diffusion is not recommended as this can dis- To protect the integrity of liner systems, rupt the intended treatment. the waste management system should pre- scribe proper waste placement practices. The primary physical compatibility issue is punc- F. Sludge Removal ture of the liner by sharp objects in the waste. If significant amounts of sludge accumu- Ensure that the liner is protected from items late on the bottom of an impoundment, it angular and sharp enough to puncture it. might be necessary to remove the sludge and Similarly, facility employees should be dispose of it periodically. There are two ways instructed to keep heavy equipment off the to remove the sludge: dewater the cell and liner. Another physical compatibility issue is remove the sludge after it has dried, or keeping fine-grained waste materials away dredge the impoundment. Many different from drainage layers that could be clogged by methods exist for dredging an impoundment. such materials. Examples include a tanker truck outfitted Differential settlement of wastes is another with a vacuum hose, manned and remote problem that can be associated with waste dredges, and submersible pumps on steel placement. To avoid differential settlement, pontoons used as a floating dredge or focus on how the waste is placed on the liner dragged on the pond bottom. You should material or on the protective layer above the work with your state and sludge removal pro- liner. Uneven placement of waste, or uneven fessionals to choose or create a method that compaction can result in differential settle- works best at your facility. ment of succeeding waste layers or of final There are two main concerns regarding cover. Differential settlement, in turn, can lead sludge management: protecting the liner to ponding and infiltration of water and dam- while cleaning out sludge from the impound- age to liners or leachate collection systems. In ment (if a liner is used) and properly dispos- extreme cases, failure of waste slopes can ing of any removed sludge. During dredging,
8-10 Ensuring Long-Term Protection—Operating the Waste Management System
heavy equipment can damage the liner. You H. Security Measures, can avoid this by selecting equipment and Access Control, and methods that protect the liner during sludge removal. Further, any sludge removed should Traffic Management be evaluated and managed in an appropriate To prevent injury to members of the pub- manner, based on its chemical properties. lic, consider implementing security and access control measures to block unautho- rized entry to a unit. These measures can also G. Climate Considerations help to prevent scavenging, vandalism, and Waste management operations can be illegal dumping of unauthorized wastes. affected by weather conditions, especially Providing access controls for the facility with- rain, snow, or wind. Rainy or snowy weather in which the unit is located is an example of can create a variety of problems, such as hin- providing such measures for the unit. dered vehicle access and difficulty in spread- Examples of access control measures ing and compacting waste. To combat these include fences, locked gates, security guards, difficulties, consider altering drainage pat- and surveillance systems; and natural barriers terns, maintaining storm-water controls, such as, berms, trees, hedges, ditches, and maintaining all-weather access roads (if embankments. The site perimeter should be appropriate), or designating a wet-weather clearly marked or fenced. Additionally, consid- disposal area. er posting signs that warn of restricted access Extremely cold conditions can prevent effi- and alert the public to the potential for harm cient excavation of soil from a borrow pit and associated with heavy equipment operations. can also inhibit the spreading and com- paction of soil cover on the waste. Freezing How can onsite traffic best be temperatures can also inflict excessive wear managed? on equipment. To combat these problems, you can use coarse-textured soil during win- Even though access to the unit is limited, ter operations, stockpile cover soil for winter it is important to provide clear transportation use, and protect cover soil with leaves, plas- routes for emergency response equipment to tics, or other insulating materials. access the waste management unit. Traffic management is often overlooked as part of Consider using special inclement weather waste management unit operations. Proper disposal areas during extreme wet and windy traffic routing can help a unit operate more weather. In wet weather, placing waste in a smoothly and prevent injuries and deter part of the unit near the entrance reduces the intruders. Access roads should be designed likelihood of trucks causing ruts on site road- and built to be safe and efficient, and blind ways or being stranded in mud. Under windy spots or unmarked intersections should be conditions, waste might need to be wetted or minimized. They should also be located to placed in downwind areas of a unit to reduce provide long-term service without requiring blowing waste or particulates. relocation. Posting clear directional signs can help direct traffic and reduce the potential for vehicle accidents. Providing all-weather access roads (if appropriate) and temporary storage areas can improve waste transport to and from a unit and allow equipment to
8-11 Ensuring Long-Term Protection—Operating the Waste Management System
move about more freely. In addition, you can ments, and any time a new health or safety consider imposing onsite speed limits or con- hazard is introduced into the work area. A structing speed bumps. good training program uses concrete exam- ples to improve and maintain employee skill, Access roads should be maintained proper- safety, and teamwork. Training can be provid- ly at all times. Adequate drainage of road ed by in-house trainers, trade associations, beds is essential for proper operation of a computer programs, or specialized consul- unit. Heavy, loaded vehicles traveling to and tants. In some states, proactive safety and from a unit deteriorate the roads on which training programs are required by law. they travel. Equipment without rubber tires should be restricted from the paved stretches of roads as they can damage the roads. Sufficient funds should be allocated up front for the maintenance of access roads. What are some other prudent safety measures? There are a number of safety considera- tions associated with ground-water monitor- Classroom training helps familiarize employees ing wells. The tops of monitoring wells with operating procedures. should be clearly marked and accessible. In traffic areas, posts and bumper guards around monitoring wells can help protect above- What types of training can be ground installations from damage. Posts and provided for employees? bumper guards come in various sizes and strengths and are typically constructed for Safety is a primary concern because waste high visibility and trimmed with reflective management operations can present a variety tape or highly visible paint containing reflec- of risks to workers. In addition, employee tive material. right-to-know laws require employers to pro- vide training and information about safety Proper labeling of monitoring wells is also issues pertinent to a given occupation. important for several reasons. Monitoring Furthermore, accidents can be expensive, wells should be distinguished from under- with hidden costs often amounting to several ground storage tank fill lines, for example. times the apparent costs. Accidents at waste Also, different monitoring wells should be management units can include injury from distinguished from each other. Monitoring explosions or fire, inhalation of contaminants wells, therefore, should be labeled on immov- and dust, asphyxiation from poorly vented able parts of the well. leachate collection system manholes or tanks, falls from vehicles, injury associated with I. Providing Employee operating heavy earth-moving equipment, Training exposure to extreme cold or heat, and onsite traffic accidents. One of the most important aspects of a waste management system is employee train- To minimize risks to workers, it is rec- ing. Employees should be trained before their ommended that you provide an ongoing initial assignment, upon changing assign- safety training program to ensure all staff
8-12 Ensuring Long-Term Protection—Operating the Waste Management System
are properly and regularly trained on safety issues. A safety training program should be Sample Manager and consistent with the requirements specified Supervisor Training Agenda by the U.S. Occupational Safety and Health Administration (OSHA) and include initial • Introduction training and frequent refresher sessions on • Unit basics: at least the following topics: —Siting • Waste management operations. —Waste containment • Hazardous waste identification. —Daily operations • Monitoring equipment operations. • Owning and operating costs • Emergency shut-off procedures. • Machine types • Overview of safety, health, and other • Equipment maintenance hazards present at the site. • Maximizing airspace • Symptoms and signs of overexposure to hazards. • Labor management • Proper lifting methods, material han- • Production analysis dling procedures, equipment opera- • Application of production rate data tion, and safe driving practices. • Budgets and data tracking: • Emergency response topics, such as spill response, fire suppression, haz- —Operating budget ard analysis, and location and op- —Cover soil budget eration of emergency equipment. —Airspace budget • Requirements for personal protective gear, such as hard hats, gloves, gog- • Waste handling techniques gles, safety shoes, and high-visibility • Waste management techniques vests. • Cover soil placement Weave a common thread of teamwork into • Safety issues and safety meetings every training program. Breaks in communica- tion between site engineers and field opera- • Record keeping tions personnel can occur. Bridging this gap is • Emergency response plan an important step toward building an effective unit team that can work together. Consider • State requirements for operation periodic special training to update employees Bolton, N. 1995. The Handbook of Landfill on new equipment and technologies, to Operations: a Practical Guide for Landfill improve and broaden their range of job-related Engineers, Owners, and Operators. (ISBN 0- skills, and to keep them fresh on the basics. 9646956-0-X). Reprinted by permission. Training can also include such peripheral top- ics as liability concerns, first aid, avoidance of substance abuse, and stress management.
8-13 Ensuring Long-Term Protection—Operating the Waste Management System
establishing regular (at least monthly) safety Equipment Operator meetings, during which specific topics can be Training Agenda addressed and employees can voice concerns, ask questions, and present ideas. Keep meet- • Introduction ings short and to the point, and steer discus- • Unit basics: sion toward topics that are applicable to those employees present. In addition, do not —Siting waste time talking about issues not applica- —Waste containment ble to a site. If a site experiences extreme weather conditions, develop safety meeting —Daily operations topics that address weather-related safety. • Heavy equipment types and applications: Many safety-related videos are available and —Scraper, dozer, and compactor can add variety to meetings. operations Closely monitor worker accident and —Support equipment injury reports to try to identify conditions that warrant corrective or preventive mea- —Fluids sures. In addition, it is wise to document all —Fueling, maintenance and its safety meetings. Assistance in establishing a hazards, and fuel spill prevention safety program is available from insurance companies with worker’s compensation pro- • Cover operations: grams, the National Safety Council, safety —Types of cover soil consultants, and federal and state government safety organizations. The overall cost of an —Placement of cover soil aggressive, preventive safety program is • Drainage control almost certain to be offset by the savings from • Surveying and staking a decrease in lost work time and injuries. • Unit safety: J. Emergency Response —Emergency response plans Plan and Procedures —Safe operating techniques There are three major types of waste man- • Owning and operating costs agement emergencies: accidents, spills, and Bolton, N. 1995. The Handbook of Landfill fires/explosions. A waste management system Operations: a Practical Guide for Landfill should include emergency response plans for Engineers, Owners, and Operators. (ISBN 0- each of these scenarios that considers not 9646956-0-X). Reprinted by permission. only the waste management unit but also all surrounding facility areas. The plans should be reviewed and revised periodically to keep How should training programs the procedures fresh in employees’ minds and be conducted? to reflect any changes in such items as the unit operating procedures, facility operations, You should keep records of the type and physical and chemical changes in the wastes, amount of training provided to employees, generated volumes, addition or replacement and obtain documentation (employee signa- of emergency equipment, and personnel tures) whenever training is given. Consider changes. If an emergency does arise, or if haz-
8-14 Ensuring Long-Term Protection—Operating the Waste Management System
ardous waste is inadvertently disposed of in a • Designation and training of several unit, notify appropriate agencies, adjacent first aid administrators. land owners, and emergency response person- • Location of and operating procedures nel, if needed. After emergency conditions for all fire control, spill control, and have been cleared, review the waste manage- decontamination equipment. ment system and revise it, if necessary, to pre- vent similar mishaps in the future. • Location of hoses, sprinklers, or water spray systems and adequate A facility might be required to prepare sim- water supplies. ilar emergency response or contingency plans under other regulatory programs [e.g., Spill • Description and listing of emergency Prevention Control and Countermeasures and response equipment. Response Plan requirements (40 CFR Part 112.7(d) and 112.20-21); Risk Management Sample Laborer Training Program regulations (40 CFR Part 68); and HAZWOPER regulations (29 CFR 1910.120)]. Agenda EPA encourages facilities to consolidate emer- • Introduction gency response plans whenever possible to • Unit basics: elimante redundancy and confusion. The National Response Team, chaired by EPA, has —Siting prepared its Integrated Contingency Plan —Waste containment Guidance (61 FR 28642; June 5, 1996) as a model for integrating such plans. —Daily operations • Traffic management and safety How should an appropriate • Interacting with the public emergency response plan be • Load segregation and placement developed? • Hazardous material identification pro- An emergency response plan should con- cedure sider the following: • Unit equipment types and applications • Description of types of emergencies that would necessitate a response action. • Cover operations • Names, roles, and duties of primary • Equipment maintenance and alternate emergency coordinators. • Unit safety: • Spill notification procedures. —Heavy equipment safety • Who should be notified. —Traffic safety • Fire department or emergency —Personal protective equipment response telephone number. • Emergency response plans • Hospital telephone number. Bolton, N. 1995. The Handbook of Landfill • Primary and secondary emergency Operations: a Practical Guide for Landfill staging areas. Engineers, Owners, and Operators. (ISBN 0- 9646956-0-X). Reprinted by permission. • Location of first aid supplies.
8-15 Ensuring Long-Term Protection—Operating the Waste Management System
• Maintenance and testing log of emer- response to handle public affairs during a gency equipment. major emergency. These employees should work with the press to ensure that the public • Plans to familiarize local authorities, receives an accurate account of the emergency. local emergency response organiza- tions, and neighbors with the charac- teristics of the unit and appropriate K. Record Keeping and inappropriate responses to vari- ous emergency situations. Record keeping is a vital part of cost-effec- tive, efficient waste management unit opera- • Information on state emergency tions. Records should be maintained for an response teams, response contractors, appropriate period of time, but it is a good and equipment suppliers. idea to keep a set of core records indefinitely. • Properties of the waste being handled Some facilities have instituted policies that at the unit, and types of injuries that records are to be maintained for up to 30 could result from fires, explosions, years while other facilities maintain records releases, or other mishaps. for only 3 years. Some states have record keeping requirements for certain waste man- • An evacuation plan for unit person- agement units and associated practices. You nel (if applicable). should check with state authorities to deter- • Prominent posting of the above mine what, if any, record keeping is required information. by law and to determine how long records should be kept. The emergency plan should instruct all employees what to do if an emergency arises, Besides being required by some states, and all employees should be familiar with the records help evaluate and optimize unit per- plan and their responsibilities under it. In formance. Over time, these records can serve order to ensure that everyone knows what to as a valuable almanac of activities, as well as do in an emergency, EPA recommends con- a source of cost information to help fine tune ducting periodic drills. These practice re- future expenditures and operating budgets. sponses could be planned ahead of time or Data on waste volume, for example, can they could be unannounced. Either way, the allow a prediction of remaining site life, any drills are treated as real emergencies and special equipment that might be needed, and serve to hone the skills of the employees who personnel requirements. Furthermore, if a might have to respond to actual emergencies. The key to responding effectively to an emer- gency is knowing in advance what to do. Communication is vital during an emer- gency and should be an inherent component of any emergency response plan. Two-way radios and bullhorns can prove invaluable in the event of an emergency, and an alarm sys- tem can let employees know that an emer- gency situation is at hand. It is recommended that you designate one or more employees Keeping accurate records is an essential part who will not be essential to the emergency of unit operations.
8-16 Ensuring Long-Term Protection—Operating the Waste Management System
facility is ever involved in litigation, accurate, • Personal information and work history dated records can be invaluable in establish- for each employee, including health ing a case. information such as illness reports. What type of records should be • Accident records. kept? • Work environmental records. • Occupational safety records, includ- Operational records that should be main- ing safety training and safety surveys. tained include the following, as appropriate: • Waste analysis results. L. Addressing Nuisance • Liner compatibility testing (where a liner system is considered appropriate). Concerns Minimizing nuisances, such as noise, odor, • Waste volume. and disease vectors, is of great importance for • Location of waste placement, includ- the health of personnel working in the indus- ing a map. trial facility and of neighbors that live or work • Depth of waste below the final cover near a unit. This section describes many of surface. the nuisance concerns typical of waste man- agement units and offers measures to address • Inventory of daily cover material them. Measures besides those listed can also used and stockpile. be used to achieve the same objective. • Frequency of waste application. How can noises be minimized? • Equipment operation and mainte- nance statistics. Noise resulting from the operation of heavy equipment can be a concern for waste • Environmental monitoring data and management units located near residential results. areas. Noise can also disrupt animal habitats • Inspection reports, including pho- and behavior. In addition, workers’ hearing tographs. and stress levels can be adversely affected by long-term exposure to noise. At waste man- • Design documents, including draw- agement units where noise is a concern, lim- ings and certifications. iting hours of operation can reduce potential • Cost estimates and other financial problems. Design access routes to minimize data. the impact of site traffic noise on nearby neighborhoods. Equipment should also be • Plans for unit closure and post-clo- maintained to minimize unnecessary noise, sure care. and affected workers should wear ear protec- • Information on financial assurance tion (plugs or muffs). Berms, wind breaks, or mechanisms. other barriers can be erected to help mute sounds. OSHA has established standards for • Daily log of activities. occupational exposure to noise (see 29 CFR • Calendar of events. §1910.95). Health and safety records that should be maintained include the following:
8-17 Ensuring Long-Term Protection—Operating the Waste Management System
How can odor be minimized? menting gas controls if odors are associated with gases generated from a unit. Increased urbanization has led to industri- al facilities being situated in close proximity If odors emanate from surface impound- to residential areas and commercial develop- ments, there are several options available for ments. This has resulted in numerous com- control, including biological and chemical plaints about odors from industrial waste treatment. The type of treatment for an management units and industrial processes impoundment should be determined on a such as poultry processing, slaughtering and site-specific basis, taking into account the rendering, tanning, and manufacture of chemistry of the waste. volatile organics. Some of the major sources Practices to control odor are especially of odors are hydrogen sulfide and organic important at land application units. If land compounds generated by anaerobic decom- application is used, it is important to apply position. The latter can include mercaptans, waste at appropriate rates for site conditions, indole, skatole, amines, and fatty acids. Odor and design and locate waste storage facilities might be a concern at a unit, depending on to minimize odor problems. Make it a priority proximity to neighbors and the nature of the to minimize potential odors by applying wastes being managed. In addition to causing wastes as soon as possible after delivery and complaints, odors can be a sign of toxic or incorporating wastes into the soil as soon as irritating gases or anaerobic conditions in a possible after application. Cleaning trucks, unit that could have adverse health effects or tanks, and other equipment daily (or more fre- environmental impacts. Plan to be proactive quently, if necessary) can also help reduce in minimizing odors, and establish proce- odor. Avoid applying waste when soils are wet dures to respond to citizen complaints about or frozen or when other soil or slope condi- odor problems and to correct the problems. tions would cause ponding or poor drainage. Odors can be seasonal in nature and, Chapter 7 Section C– Designing a Land therefore, can often be anticipated. Some Application Program presents information odors at landfills, waste piles, and land appli- concerning an odor management plan for land cation units arise either from waste being application facilities. unloaded or from improperly covered in- Other methods of controlling odors place waste. If odor from waste being include: unloaded becomes a problem, it might be necessary to place these loads in a portion of • Covering or enclosing the unit. the unit where they can be immediately cov- • Adding chemicals such as chlorine, ered with soil. At land application units, lime, and ferric chloride to reduce quick incorporation or injection of waste can bacterial activity and oxidize many help prevent odor. It also might be prudent to products of anaerobic decomposition. establish a system whereby unit personnel are • Using biofilters. notified when odorous wastes are coming to the unit to allow them to prepare accordingly. • Applying a deep soil cover, whose Odors from in-place waste can effectively be upper layers consist of silty soils or minimized by maintaining the integrity of soils containing a large percentage of cover material over everything but the cur- carbon or humic material. rently active face. Proper waste compaction • Applying a layer of relatively imper- also helps to control odors. Consider imple- meable soil, so as to reduce gas gen-
8-18 Ensuring Long-Term Protection—Operating the Waste Management System
eration rates by reducing the amount How can disease vectors be of rainfall water percolating into the controlled? waste. • Restoring landfill surface covers when Disease vectors are animals or insects, such subsidence and cracks occur. as rodents, birds, flies, and mosquitos, that can transmit disease to humans. Burrowing Choosing a method for controlling odors animals, such as gophers, moles, and ground- involves a comprehensive understanding of hogs, can also damage vital unit structures, wastes and how they react under certain cir- such as liners, final cover materials, drainage cumstances. Consult with state agencies to ditches, and sedimentation ponds. As a result, determine the most effective odor control these animals can create costly problems. method for the wastes in question. Consider the following methods to control In addition to these steps to control odor disease vectors: generation, consider steps to manage those odors that are generated. When designing a • Apply adequate daily cover. This sim- waste management unit, consider installing ple action is often all that is needed barriers such as walls, berms, embankments, to control many disease vectors. and dense plantings of trees set at right • Make sure the unit is properly angles to the flow of cold, odorous night- drained, reducing the amount of time air. These measures can help to impede standing water that acts as a breeding the odor and dilute it through mixture with medium for insects. higher layers of fresh air. Alternatively, con- • As a last resort, or when the applica- sider placing an impermeable fence or wall tion of cover material is impractical, on top of a berm or embankment, on its consider using repellents, insecticides, downwind side. This will increase odor rodenticides, or pest reproductive con- plume height, and odors will be diluted on trol. Care must be taken to make sure the steep downslope side of the barrier as a that pesticides are used only in accor- result of turbulent mixing of air layers as the dance with specified uses and applica- cold air flows over it. Try to locate such barri- tion methods. Follow the instructions ers as close to the unit as possible. carefully when using these products. Another design suggestion is to plant fast- Trapping animals might also be con- growing evergreen trees which have good sidered, but trapping alone rarely windbreak properties in buffer-zones around a eliminates the problem. unit. In addition to dispersing odors, dense If land applying wastes, subsurface injection plantings of evergreen trees will also help to and prompt incorporation of waste can help protect the unit itself from strong winds, reduc- control vectors. Both of these methods work ing the possibility of windblown soil erosion. by using the soil as a barrier between the waste and the vectors. If a waste storage facili- ty exists, these can attract vectors as well and should not be overlooked in the implementa- tion of vector control. If vector problems arise
8-19 Ensuring Long-Term Protection—Operating the Waste Management System
Operating the Waste Management System Activity List ■ Develop a waste management system identifying the standard procedures necessary for a unit to operate according to its design throughout the intended working life. ■ Provide proper maintenance and operation of ground-water, surface-water, and air controls. ■ Develop daily procedures to place waste, operate environmental controls, and inspect and maintain the unit. ■ Review at a regular interval, such as annually, whether the waste management system needs to be updated. ■ Develop a waste analysis procedure to ensure an understanding of the physical and chemical composition of the waste to be managed. ■ Develop regular schedules for waste screening and for unit inspections. ■ If daily cover is recommended, select an appropriate daily cover and establish processes for placing and covering waste. ■ Consider how operations can be affected by climate conditions. ■ Implement security measures to prevent unauthorized entry. ■ Provide personnel with proper training. ■ Establish emergency response procedures and familiarize employees with emergency equipment. ■ Develop procedures for maintaining records. ■ Establish nuisance controls to minimize dust, noise, odor, and disease vectors.
8-20 Ensuring Long-Term Protection—Operating the Waste Management System
Resources
ASTM. 1993. Standard Practice for Maintaining Health and Safety Records at Solid Waste Processing Facilities. E 1076-85.
Bagchi, A. 1994. Design, Construction, and Monitoring of Landfills. John Wiley & Sons Inc.
Bolton, N. 1995. The Handbook of Landfill Operations: A Practical Guide for Landfill Engineers, Owners, and Operators. Blue Ridge Solid Waste Consulting.
Robinson, W. 1986. The Solid Waste Handbook: A Practical Guide. John Wiley & Sons Inc.
U.S. EPA. 1997. ISO 14000 Resource Directory. EPA625-R-97-003.
U.S. EPA/National Response Team. 1996. The National Response Teams Integrated Contingency Plan Guidance; Notice. (61 FR 28642; June 5, 1996).
U.S. EPA. 1998. CAMEO: Computer-Aided Management of Emergency Operations. EPA550-F-98-003.
U.S. EPA. 1995. Decision-Maker’s Guide to Solid Waste Management, Second Edition. EPA530-R-95-023.
U.S. EPA. 1995. State Requirements for Industrial Nonhazardous Waste Management Facilities.
U.S. EPA. 1994. Seminar Publication: Design, Operation, and Closure of Municipal Solid Waste Landfills. EPA625-R-94-008.
U.S. EPA. 1993. Solid Waste Disposal Facility Criteria: Technical Manual. EPA530-R-93-017.
U.S. EPA. 1991. Technical Resource Document: Design, Construction, and Operation of Hazardous and Nonhazardous Waste Surface Impoundments. EPA530-SW-91-054.
U.S. EPA. 1989. Test Methods for Evaluating Solid Waste, Physical/Chemical Methods. SW-846.
U.S. EPA. 1988. RCRA Inspection Manual. OSWER Directive 9938.2A.
U.S. EPA. 1988. Subtitle D of RCRA, “Criteria for Municipal Solid Waste Landfills” (40 CFR Part 258), Operating Criteria (Subpart C). Draft/Background Document.
8-21 Part V Ensuring Long-Term Protection
Chapter 9 Monitoring Performance Contents
I. Ground-Water Monitoring ...... 9 - 2 A. Hydrogeological Characterization ...... 9 - 2 B. Monitoring Methods ...... 9 - 4 1. Conventional Monitoring Wells ...... 9 - 4 2. Direct-Push Ground-Water Sampling ...... 9 - 4 3. Geophysical Methods ...... 9 - 5 C. Number of Wells...... 9 - 6 D. Lateral and Vertical Placement of Wells...... 9 - 7 1. Lateral Placement ...... 9 - 7 2. Vertical Placement and Screen Lengths ...... 9 - 8 E. Monitoring Well Design, Installation, and Development...... 9 - 9 1. Well Design ...... 9 - 9 2. Well Installation ...... 9 - 12 3. Well Development ...... 9 - 12 F. Duration and Frequency of Monitoring ...... 9 - 13 G. Sampling Parameters...... 9 - 13 H.Potential Modifications to a Basic Ground-Water Monitoring Program ...... 9 - 14 1. Duration and Frequency of Monitoring ...... 9 - 14 2. Sampling Parameters ...... 9 - 16 3. Vadose-Zone Monitoring...... 9 - 16
II. Surface-Water Monitoring ...... 9 - 21 A. Monitoring Storm-Water Discharges ...... 9 - 22 B. Monitoring Discharges to POTWs...... 9 - 25 C. Monitoring Surface Water Conditions...... 9 - 26
III. Soil Monitoring ...... 9 - 28 A. Determining the Quality of Soil ...... 9 - 29 B. Sampling Location and Frequency ...... 9 - 30 C. Sampling Equipment ...... 9 - 31 D. Sample Collection...... 9 - 31
IV. Air Monitoring...... 9 - 32 A. Types of Air Emissions Monitoring ...... 9 - 33 1. Emissions Monitoring...... 9 - 33 2. Ambient Monitoring ...... 9 - 33 3. Fugitive Monitoring ...... 9 - 34 4. Meteorological Monitoring ...... 9 - 34 Contents
B. Air Monitoring and Sampling Equipment ...... 9 - 36 1. Ambient Air Monitoring ...... 9 - 36 2. Source Emissions Monitoring ...... 9 - 37 C. Test Method Selection...... 9 - 38 D. Sampling Site Selection...... 9 - 38
V. Sampling and Analytical Protocols and Quality Assurance and Quality Control ...... 9 - 39 A. Data Quality Objectives ...... 9 - 41 B. Sample Collection...... 9 - 41 C. Sample Preservation and Handling ...... 9 - 42 D. Quality Assurance and Quality Control ...... 9 - 42 E. Analytical Protocols ...... 9 - 44
VI. Analysis of Monitoring Data, Contingency Planning, and Assessment Monitoring...... 9 - 45 A. Statistical Approaches ...... 9 - 45 B. Contingency Planning...... 9 - 46 C. Assessment Monitoring...... 9 - 46
Monitoring Performance Activity List...... 9 - 48
Resources ...... 9 - 50
Tables: Table 1: Factors Affecting Number of Wells Per Location ...... 9 - 9 Table 2: Potential Parameters for Basic Groundwater Monitoring ...... 9 - 15 Table 3: Recommended Components of a Basic Ground-Water Monitoring Program ...... 9 - 16 Table 4: Comparison of Manual and Automatic Sampling Techniques ...... 9 - 24 Table 5: Types of QA/QC Samples...... 9 - 43
Figures: Figure 1: Cross-Section of a Generic Monitoring Well...... 9 - 5 Figure 2: Major Methods for In Situ Monitoring of Soil Moisture or Matrix Potential...... 9 - 18 Figure 3: Example Methods for Collecting Soil-Pore Samples ...... 9 - 19 Figure 4: Soil Gas Sampling Systems...... 9 - 20 Figure 5: Schematic Diagram of various Types of Sampling Systems...... 9 - 36 Figure 6: Sampling Train...... 9 - 38 Ensuring Long-Term Protection—Monitoring Performance
Monitoring Performance This chapter will help you: • Carefully design and implement a monitoring program that is essen- tial to evaluating whether a unit meets performance objectives and whether there are releases to, and impacts on, the surrounding environment that need to be corrected. • Design effective monitoring programs that protect the environment, improve unit performance, and help reduce long-term costs and lia- bilities associated with industrial waste management.
of the environment caused by the unit. The onitoring the performance of detection information obtained from a moni- a waste management unit is toring program can be used to ensure that the an integral part of a compre- proper types of wastes are being managed in hensive waste management the unit, discover and repair any damaged system. A properly imple- area(s) of the unit, and determine if an alter- mented monitoring program provides an M native management approach might be indication of whether a waste management appropriate. By implementing a monitoring unit is functioning in accordance with its program, facility managers can identify prob- design, and detects any changes in the quality lems or releases in a timely fashion and take the appropriate measures to limit contamina- This chapter will address the following tion. Continued detection of contamination questions. in the environment could result in the imple- mentation of more aggressive corrective • What site characterizations are needed to action measures to remediate releases. develop an effective monitoring program? This chapter highlights issues associated • What are the basic elements of a moni- with establishing a ground-water monitoring toring program? program because most industrial waste man- • How should sampling and analytical pro- agement units need to have such a program. tocols be used in a monitoring program? The chapter also provides a discussion of air, surface water, and soil monitoring that might • What procedures should be used to be applicable to some units managing industri- evaluate monitoring data? al waste. You should consult with qualified • What elements of the basic monitoring professionals, such as engineers and ground- program can be modified to address water specialists,1 for technical assistance in site conditions? making decisions about the design and opera- tion of a ground-water monitoring program. In
1 For the purpose of this chapter, a qualified “ground-water specialist” refers to a scientist or engineer who has received a baccalaureate or post-graduate degree in the natural sciences or engineering and has sufficient training and experience in ground-water hydrology and related fields as demonstrated by state registration, professional certifications, or completion of accredited university programs that enable that individual to make sound professional judgements regarding ground-water monitoring, contaminant fate and transport, and corrective action. 9-1 Ensuring Long-Term Protection—Monitoring Performance
addition when questions arise concerning soil, air, or surface-water monitoring, you should Why is it important to use also consult specialists in these areas as each media requires different expertise. a qualified professional? • Site characterizations can be extremely complex. I. Ground-Water • Incorrect or incomplete characteriza- tions could result in inaccurate detec- Monitoring tion of contamination in the ground The basic elements of a ground-water water due to improper placement of monitoring program include: ground-water monitoring wells and can cost a significant amount of money. • The monitoring method. Incorrect or incomplete characteriza- • The number of wells. tions could also result in the installation of unnecessary monitoring wells at sig- • Location and screened intervals of nificant cost. wells. • You should always use a qualified pro- • Well design, installation, and devel- fessional to conduct site characteriza- opment. tions. Check to see if the professional • The duration and frequency of moni- has sufficient training and experience in toring. ground-water hydrology and related • Sampling parameters to be monitored. fields, as demonstrated by state registra- tion, professional certification, or com- The remainder of this section provides a pletion of accredited university brief overview of the six basic elements of a programs. These professionals should ground-water monitoring program, along be experienced at analyzing ground- with a discussion of the importance of a water flow and contaminant fate and hydrogeological characterization. transport and at designing ground- water monitoring systems. Ensure that these professionals are familiar with the A. Hydrogeological contaminants in the waste and thor- Characterization oughly check their references. An accurate hydrogeological characteriza- tion is the foundation of an effective ground- • The lateral and vertical extent of the water monitoring system. The goal of a uppermost aquifer. hydrogeological characterization is to acquire site-specific data to enable the development • The lateral and vertical extent of the of an appropriate ground-water monitoring upper and lower confining units/layers. program for a site. In some instances, a com- • The geology at the waste manage- plete hydrogeological characterization might ment unit’s site, such as stratigraphy, not be necessary due to the type of unit lithology, and structural setting. being considered, the type of waste being managed, or the climate. The design of the • The chemical properties of the upper- ground-water monitoring program should be most aquifer and its confining layers based upon the following site-specific data:
9-2 Ensuring Long-Term Protection—Monitoring Performance
relative to local ground-water chem- • Site geology. A geologic unit is typi- istry and wastes managed at the unit. cally considered to be any distinct or definable native rock or soil stratum. • Ground-water flow, including: Characterize thickness, stratigraphy, - The vertical and horizontal direc- lithology, and hydraulic characteris- tions of ground-water flow in the tics of saturated and unsaturated geo- uppermost aquifer. logic units and fill materials overlying - The vertical and horizontal compo- the uppermost aquifer, in the upper- nents of the hydraulic gradient in most aquifer, and in the lower con- the uppermost aquifer and any fining unit of the uppermost aquifer hydraulically connected aquifer. using soil borings, drilling, or geo- physical methods. Conventional soil - The hydraulic conductivities of the borings are typically used to charac- materials that comprise the uppermost terize onsite soils through direct sam- aquifer and its confining units/layers. pling. Geophysical equipment, such - The average linear horizontal veloci- as ground-penetrating radar, electro- ty of ground-water flow in the magnetic detection equipment, and uppermost aquifer. electrical resistivity arrays, can pro- vide non-invasive measurements of To perform a hydrogeological characteriza- physical, electrical, or geochemical tion and develop an understanding of a site’s properties of the site. Understanding hydrogeology, a variety of sources and kinds the different strata can help identify of information should be considered. the appropriate ground-water moni- • Existing information. This can toring well locations and screen include the history of the site, includ- depths. ing documented records describing • Ground-water flow beneath the wastes managed on site and releases. site. Across the United States, This information can help you char- ground-water flow velocities range acterize the area of the waste manage- from several feet to over 2,000 feet ment unit and better understand per year. To determine hydraulic gra- background conditions. Some hydro- dient and flow rate, you should geological information might also implement a water-level monitoring have been developed in the past, for program and estimate hydraulic con- example during the siting process ductivity. This program should (see Chapter 4–Considering the Site). include measurements of seasonal It might be useful to conduct litera- and temporal fluctuations in flow, the ture reviews for research performed effect of site construction and opera- in the area of the unit and examine tions on ground-water flow direction, federal and state geological and envi- and variations in ground-water eleva- ronmental reports related to the site tion. Information on water-level or to the region where the site is to monitoring programs and procedures be located. This review can often for obtaining accurate water level assist in better understanding the measurements can be found in EPA’s overall site geology and ground-water Municipal Solid Waste Landfill Technical flow beneath the unit. Guidance Document (U.S. EPA, 1988).
9-3 Ensuring Long-Term Protection—Monitoring Performance
The level of effort one employs to character- depth at a single location, you should install ize a site sufficiently to design an adequate conventional monitoring wells in clusters or ground-water monitoring system depends on with multilevel sampling devices. the geologic and hydrogeologic complexity of the site. The complexity of a site should not be 2. Direct-Push Ground-Water assumed; a soil boring program can help determine the complexity of a site’s hydrogeol- Sampling ogy. The American Society for Testing and Using the direct-push technique, ground Materials’ (ASTM) Annual Book of ASTM water is sampled by hydraulically pressing Standards2 provides more than 80 guides and and/or vibrating a probe to the desired depth practices related to waste and site characteriza- and retrieving a ground-water sample through tion and sampling. For additional information the probe. The probe is removed for reuse on ground-water monitoring, see EPA’s elsewhere after the desired volume of ground Ground-Water Monitoring: Draft Technical water is extracted. It is important to clean the Guidance (U.S. EPA, 1993a) and Solid Waste probe with an appropriate decontamination Disposal Facility Criteria: Technical Manual (U.S. protocol after each use to avoid potential EPA, 1993b). cross-contamination. What are the benefits of direct- B. Monitoring Methods push sampling? Ground-water monitoring usually involves the installation of permanent monitoring wells Given favorable geology, the direct-push for periodic collection of ground-water sam- method of ground-water sampling can be a ples. Waste constituent migration can be mon- simpler and less expensive alternative to con- itored by sampling ground water for either ventional wells. Conventional monitoring contaminants or geophysical parameters. wells, because they are semi-permanent, gen- Ground water also can be sampled through erally cost more and take longer to install. semi-permanent conventional monitoring Direct-push technology, however, does not wells or by temporary direct-push sampling. provide a semi-permanent structure from Conventional monitoring wells, direct-push which to sample the ground water over an sampling, and geophysical methods are extended period of time, as do conventional described below. wells. Also, some states only allow the use of direct-push technology as an initial screening technique or as a complement to conventional 1. Conventional Monitoring Wells monitoring wells. The conventional monitoring well is the In sandy aquifers, however, the direct-push most common type used to target a single technology can be used to install a well similar screened interval. Figure 1 presents an illustra- to a conventional monitoring well. Relatively tion of a single screened interval. Specific con- recent advances in direct-push technology use struction features are described in more detail pre-packed screens with grouts and seals below. The conventional monitoring well is attached to a metal pipe that are driven into semi-permanent, meaning it can be used for the ground, forming an assembly similar to a sampling over an extended period of time and conventional well. The appropriate state should be located by professionally surveyed agency will be able to tell you whether direct- reference points. To monitor more than one push well installations are acceptable.
2 ASTM’s Annual Book of ASTM Standards is available in hard copy or on CD-ROM through ASTM’s online bookstore at
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Figure 1. Cross-Section of a Generic Monitoring Well
Source: U.S. EPA, 1993a
3. Geophysical Methods es in the levels of certain soluble metals in Geophysical methods measure potential ground water can change the resistive proper- changes in ground-water quality by measur- ties of the ground water, which can be mea- ing changes in the geophysical characteristics sured using surface resistive technologies. of the sub-surface soils, and in some cases, in Similarly, changes in the resistive properties the ground water itself. For example, increas- of the vadose zone might indicate the migra- tion of leachate toward ground water.
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Geophysical characteristics, such as DC-resis- selection of appropriate statistical method. If tivity, electromagnetic induction, pH, and an insufficient number of background wells temperature, can provide important prelimi- are used, the use of an inter-well evaluation nary indications of the performance of the might not be possible. Site-specific condi- liner system design. You should consult with tions that influence the number of upgradient the appropriate state agency regarding the and downgradient wells include: use of a geophysical method. (See Subsurface • Geology of the waste management Characterization and Monitoring Techniques unit site. (U.S. EPA, 1993) for additional information on the use of geophysical methods). • Ground-water flow direction and velocity, including seasonal and tem- How useful is geophysical poral fluctuations. method data? • Permeability or hydraulic conductivi- Geophysical methods are more commonly ty of any water-bearing formations. used to map the initial extent of contamination • Physical and chemical characteristics at waste management units than for ongoing of contaminants. monitoring. Initial monitoring data can guide • Area of waste management unit. the placement of permanent monitoring wells for ongoing monitoring. As discussed later, The number of wells is dependent on the geophysical methods, used in conjunction with lateral and vertical placement of monitoring ground-water monitoring, can reduce the fre- wells, which is determined by the geology quency of well sampling, which could reduce and hydrogeology of the site. Other factors monitoring costs. The usefulness of geophysi- influencing the number of wells include the cal methods, however, will depend on the local number of potential contaminant migration hydrogeology, the contaminant concentration pathways; the spatial distribution of potential levels, and type of contaminants. contaminant migration pathways; and the depth and thickness of stratigraphic horizons that can serve as contaminant migration C. Number of Wells pathways. The number of wells needed will It is recommended that a ground-water also vary according to the need for samples monitoring system have a minimum of one from different depths in the aquifer. This is a upgradient (or background) monitoring well, function of hydrogeologic factors and the and three downgradient monitoring wells to chemical and physical characteristics of cont- make statistically meaningful comparisons of aminants. The next section provides a ground-water quality. The upgradient or detailed discussion of the lateral and vertical background well(s) permit the assessment of placement of monitoring wells. the background quality of onsite ground A larger number of monitoring wells might water. The downgradient wells permit detec- be needed at sites with complex hydrogeology. tion of any contaminant plumes from a waste If a site has multiple waste management units, management unit. The actual number of use of a multi-unit ground-water monitoring upgradient and downgradient wells will vary system can reduce the necessary number of from unit to unit depending on the actual wells. You should consult with the appropriate site-specific conditions. The actual number of state agency when determining a site’s ground- upgradient and downgradient monitoring water monitoring well requirements. wells and their distribution will influence the
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D. Lateral and Vertical more complex. Potential migration pathways Placement of Wells are influenced by site geology including changes in hydraulic conductivity, fractured The lateral and vertical placement of moni- or faulted zones, and soil chemistry. Human- toring wells is very site-specific. (Monitoring made features that influence ground-water wells should yield ground-water samples flow should also be considered. These fea- from the targeted aquifer(s) that are represen- tures include ditches, filled areas, buried pip- tative of both the quality of background ing, buildings, leachate collection systems, ground water and the quality of ground water and other adjacent disposal units. at a downgradient monitoring point.) Locate monitoring wells at the closest practicable Another point of consideration is seasonal distance from the waste management unit change in ground-water flow. Seasonal boundary to detect contaminants before they changes in ground-water flow can result from migrate away from the unit. Early detection seasonal changes in precipitation patterns, provides a warning of potential waste man- tidal influences, lake or river stage fluctua- agement unit design failure and allows time tions, well pumping, or land use pattern to implement appropriate abatement mea- changes. At some sites it might even be possi- sures and potentially eliminate the need for ble that ground water flows in all directions more extensive corrective action. It also from a waste management unit. These contin- reduces the area exposed and can limit over- gencies might call for placement of monitor- all liability. ing wells in a circular pattern to monitor on all sides of the waste management unit. Seasonal fluctuations might cause certain 1. Lateral Placement wells to be downgradient only part of the Monitoring wells should be placed laterally time, but such configurations ensure that along the down-gradient edge of the waste releases will be detected. management unit to intercept potential conta- Lateral placement of monitoring wells also minant migration pathways. Ground-water depends upon the chemical and physical flow direction and hydraulic gradient are two characteristics of a waste management unit’s major determining factors in monitoring well constituents. Consider potential contaminant placement. Placement of monitoring wells characteristics such as solubility, Henry’s law should also take into account the number constant, partition coefficients, specific gravity and spatial distribution of potential contami- (density), potential for natural attenuation and nant migration pathways and the depths and the resulting reaction or degradation products, thickness of stratigraphic horizons that can and the potential for contaminants to degrade serve as contaminant migration pathways. In confining layers. A dense non-aqueous phase homogeneous, isotropic hydrogeologic sites, liquid (DNAPL), for instance, because of its ground-water flow direction and hydraulic density might not necessarily migrate only in gradient, along with the potential contami- the direction of the ground-water flow. The nant’s chemical and physical characteristics, presence of DNAPLs, therefore, can result in will primarily determine lateral well place- placing wells in more locations than just the ment. In a more complex site where hydroge- normal downgradient sites. ology and geology are variable and preferential pathways exist, (a heterogeneous, anisotropic hydrogeologic site, for example) the well placement determination becomes
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2. Vertical Placement and Screen Well screen lengths are also determined by Lengths site- and constituent-specific parameters. These parameters and the importance of tak- Similar to lateral placement, vertical well ing vertically discrete ground-water samples, placement in the ground water around a factor into the determination of well screen waste management unit is determined by size. Highly heterogeneous (complex) geolog- geologic and hydrogeologic factors, as well as ic sites require shorter well screen lengths to the chemical and physical characteristics of allow for the sampling of discrete migration the potential contaminants. The vertical pathway. Screens that span more than a single placement of each well and its screen lengths contaminant migration pathway can cause will be determined by the number and spatial cross contamination, possibly increasing the distribution of potential contaminant migra- extent of contamination. Shorter screen tion pathways and the depth and thickness of lengths allow for more precise monitoring of potential migration pathways. Site-specific the aquifer or the portion of the aquifer of geology, hydrogeology, and constituent char- concern. Excessively large well screens can acteristics influence the location, size, and lead to the dilution of samples making conta- geometry of potential contaminant plumes, minant detection more difficult. which in turn determine monitoring well depths and screen lengths. The depth or thickness of an aquifer also influences the length of the well screen. Sites The chemical and physical characteristics with highly complex geology or relatively of potential contaminants from a waste man- thick aquifers might require multiple screens agement unit play a significant role in deter- at varying depths. Conversely, a relatively mining vertical placement. The specific thin and homogenous aquifer might allow for properties of a particular contaminant will fewer wells with longer screen lengths. Table determine what potential migration pathway 1 below summarizes the recommended fac- it might take in an aquifer. The specific char- tors to consider when determining the num- acteristics of a contaminant, such as its solu- ber of wells needed per sampling location. bility, Henry’s law constant, partition coefficients, specific gravity (density), poten- You should consult with state officials on tial for natural attenuation and the resulting the lateral and vertical placement of monitor- reaction or degradation products, and the ing wells including well screening lengths. In potential for contaminants to degrade confin- the absence of specific state requirements, it ing layers, will all influence the vertical place- is recommended that the monitoring points ment and screen lengths of a unit’s be no more than 150 meters downgradient monitoring wells. A DNAPL, for instance, will from a waste management unit boundary, on sink to the bottom of an aquifer and migrate facility property, and placed in potential cont- along geologic gradients (rather than hydro- amination migration pathways. This maxi- geologic gradients), thus a monitoring well’s mum distance is consistent with the approach vertical placement should correspond with taken in many states in order to protect the depth of the appropriate geologic feature. waters of the state. LNAPLs (light non-aqueous phase liquids), on the other hand, would move along the top of an aquifer, and result in placement of wells and wells screens at the surface of the aquifer.
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Table 1 Factors Affecting Number of Wells Per Location (CLUSTER)
One Well per Sampling Location More Than One Well Per Sampling Location
No light non-aqueous phase liquids Presence of LNAPLs or DNAPLs (LNAPLs) or dense non-aqueous phase liquids (DNAPLs) (immiscible liquid phases)
Thin flow zone (relative to screen Thick flow zones length) Vertical gradients present Horizontal flow predominates
Homogeneous isotropic uppermost Heterogeneous anisotropic uppermost aquifier, aquifier, simple geology complicated geology - multiple, interconnected aquifiers - variable lithology - perched water zones - discontinuous structures Discrete fracture zones in bedrock Solution conduits, such as caves, in karst terrains Cavernous basalts
E. Monitoring Well Design, Ground-Water Monitoring Wells (U.S. EPA, Installation, and 1989) also contains this information. Development 1. Well Design Ground-water monitoring wells are tai- lored to suit the hydrogeologic setting, the The typical type of constituents to be monitored, the components of a overall purpose of the monitoring program, monitoring well and other site-specific variables. You should include a well consult with the appropriate state agency and casing, a well qualified professionals to discuss the design intake, a filter specifications for ground-water monitoring pack, an annular wells before beginning construction. Figure 1 and surface seal, illustrates the design components that are dis- and surface com- cussed in this section. The Annual Book of pletion. Each of ASTM Standards includes guides and practices these compo- related to monitoring well design, construc- nents is briefly tion, development, maintenance, and decom- described below. missioning. EPA’s Handbook of Suggested Practices for the Design and Installation of
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Well Casing The three most common types of casing The well casing is a pipe which is installed materials are fluoropolymer materials, includ- temporarily or permanently to counteract ing polytetrafluoroethylene (PTFE) and tetra- caving and to isolate the zone being moni- fluoroethylene (TFE); metallic materials, tored. The well casing provides access from including carbon steel, galvanized steel, and the surface of the ground to some point in stainless steel; and thermoplastic materials, the subsurface. The casing, associated seals, including polyvinyl chloride (PVC) and acry- and grout prevent borehole collapse and lonitrile butadiene styrene (ABS). Threaded, interzonal hydraulic communication. Access flush casing joints that do not require glue to the monitored zone is through the casing should be used. Another option is the use of and either the screened intake or the open PTFE tape or o-rings at the threaded joints. borehole. (Note: some states do not allow the use of open borehole monitoring wells. Well Screen Check with the state agency to determine A well screen is a filtering device used to whether this type of monitoring well design retain the primary or natural filter pack; it is is acceptable.) The casing thus permits piezo- usually a cylindrical pipe with openings of a metric head measurements and ground-water uniform width, orientation, and spacing. It is quality sampling. often important to design the monitoring well A well casing can be made of an appropri- with a well intake (well screen) placed oppo- ate rigid tubular material. The most frequently site the zone to be monitored. The intake evaluated characteristics that directly influence should be surrounded by materials that are the performance of casing material in ground- coarser, have a uniform grain size, and have a water monitoring applications are strength, higher permeability than natural formation chemical resistance, and interference. The material. This allows ground water to flow monitoring well casing should be strong freely into the well from the adjacent forma- enough to resist the forces exerted on it by the tion material while minimizing or eliminating surrounding geologic materials and the forces the entrance of fine-grained materials, such as imposed on it during installation. Casings clay or sand, into the well. should exhibit structural integrity for the A well screen design should consider: expected duration of the monitoring program intake opening (slot) size, intake length, under natural and man-induced subsurface intake type, and corrosion and chemical- conditions. Well casing materials should also degradation resistance. Proper sizing of moni- be durable enough to withstand galvanic or toring well intake openings is one of the most electrochemical corrosion and chemical degra- important aspects of monitoring well design. dation. Metallic casing materials are most sub- The selection of the length of a monitoring ject to corrosion and thermoplastic casing well intake depends on the purpose of the materials are most subject to chemical degra- well. Most monitoring wells function as both dation. In addition, casing materials should ground-water sampling points and piezome- not exhibit a tendency to either sorb chemical ters3 for a discrete interval. To accomplish constituents from (i.e., take constituents out these objectives, well intakes are typically 2 of solution by either adsorption or absorption) to 10 feet in length and only rarely equal or or leach chemical constituents into the water exceed 20 feet in length. The hydraulic effi- that is sampled from the well. If casing mate- ciency of a well intake depends primarily on rials sorb selected constituents, the water- the amount of open area available per unit quality sample will not be representative. length of intake. The amount of open area in
3 A piezometer is a non-pumping well, generally of small diameter, used to measure the elevation of the water table. 9-10 Ensuring Long-Term Protection—Monitoring Performance
a well intake is controlled by the type of well on top of the filter pack to minimize migra- intake it is and its opening size. Many types tion of annular seal material (see below) into of well intakes have been used in monitoring the filter pack. wells, including: the louvered (shutter-type) intake, the bridge-slot intake, the machine- Annular Seal slotted well casing, and the continuous-slot wire-wound intake. Annular space is the space between the casing and the borehole wall. Any annular space that is produced as a result of the Filter Pack installation of well casing in a borehole pro- Filter pack is the material placed between vides a channel for vertical movement of the well screen and the borehole wall that water and/or contaminants unless the space is allows ground water to flow freely into the sealed. The annular seal in a monitoring well well while filtering out fine-grained materials. is placed above the filter pack in the annulus It is important to minimize the distortion of between the borehole and the well casing. the natural stratigraphic setting during con- The seal serves several purposes: to provide struction of a monitoring well. Hence, it protection against infiltration of surface water might be necessary to filter-pack boreholes and potential contaminants from the ground that are over-sized with regard to the casing surface down the casing/borehole annulus; to and well intake diameter. The filter pack pre- seal off discrete sampling zones, both vents formation material from entering the hydraulically and chemically; and to prohibit well intake and helps stabilize the adjacent vertical migration of water. Such vertical formation. The filter-pack materials should be movement can cause “cross contamination” chemically inert to avoid the potential for which can influence the representativeness of alteration of ground-water sample quality. ground-water samples. The annular seal can Commonly used filter-pack materials include be comprised of several different types of per- clean quartz sand, gravel, and glass beads. manent, stable, low-permeability materials You should check with the state regulatory including pelletized, granular, or powdered agency to determine if state regulations speci- bentonite; neat cement grout; and combina- fy filter pack grain size, either in absolute tions of both. The most effective seals are terms or relative to the grain size of the water obtained by using expanding materials that bearing zone, or a uniformity coefficient. will not shrink away from either the casing or the borehole wall after curing or setting. The filter pack should generally extend from the bottom of the well intake to approx- imately two to five feet above the top of the Surface Seal well intake, provided the interval above the A surface seal is an above-ground seal that well intake does not result in a hydraulic protects a monitoring well from surface water connection with an overlying zone. To ensure and contaminant infiltration. Monitoring wells that filter pack material completely surrounds should have a surface seal of neat cement or the screen and casing without bridging, the concrete surrounding the well casing and fill- filter pack can be placed with a tremie pipe (a ing the annular space between the casing and small diameter pipe that carries the filter the borehole at the surface. The surface seal pack material directly to the filter screen can be an extension of the annular seal without creating air pockets within the filter installed above the filter pack, or it can be a pack). A layer of fine sand can also be placed separate seal placed on top of the annular
9-11 Ensuring Long-Term Protection—Monitoring Performance
seal. The surface seal will generally extend to tive casing and the well casing. This drain at least three feet away from the well casing at allows trapped water to drain away from the the surface and taper down to the size of the casing. In high-traffic areas or in areas where borehole within a few feet of the surface. In heavy equipment might be working, consider climates with alternating freezing and thawing the installation of additional protection such conditions, the cement surface should extend as “bumper guards.” Bumper guards are below the frost depth to prevent potential well brightly-painted posts of wood, steel, or some damage caused by frost heaving. other durable material set in cement and located within three or four feet of the well. Surface Completions Surface completions are protective casings 2. Well Installation installed around the well casing. Two types of To ensure collection of representative surface completions are common for ground- ground-water samples, the well intake, filter water monitoring wells: above-ground com- pack, and annular seal need to be properly pletion, and flush-to- ground completion. installed. In cohesive unconsolidated material The primary purposes of either type of com- or consolidated formations, well intakes pletion are to prevent surface runoff from should be installed as an integral part of the entering and infiltrating down the annulus of casing string by lowering the entire unit into the well and to protect the well from acciden- the open borehole and placing the well intake tal damage or vandalism. opposite the interval to be monitored. In an above-ground completion, which is Centralizing devices are typically used to cen- the preferred alternative, a protective casing is ter the casing and intake in the borehole to generally installed around the well casing by allow uniform installation of the filter pack placing the protective casing into the cement material around the well intake. In non-cohe- surface seal while it is still wet and uncured. sive, unconsolidated materials there are other The protective casing discourages unautho- standardized techniques to ensure the proper rized entry into the well, prevents damage by installation of wells, such as the use of a cas- contact with vehicles, and reduces degrada- ing hammer, a cable tool technique, the dual- tion caused by direct exposure to sunlight. wall reverse-circulation method, or The protective casing should be fitted with a installation through the hollow stem of a hol- locking cap and installed so that there are at low-stem auger. least one to two inches clearance between the top of the in-place, inner well, casing cap and 3. Well Development the bottom of the protective casing locking Monitoring well development is the cap when in the locked position. removal of fine particulate matter, commonly Like the inner well casing, the outer pro- clay and silt, from the geologic formation tective casing should be vented near the top near the well intake. If particulate matter is to prevent the accumulation and entrapment not removed, as water moves through the for- of potentially explosive gases and to allow mation into the well, the water sampled will water levels in the well to respond naturally be turbid, and the viability of the water quali- to barometric pressure changes. Additionally, ty analyses will be impaired. When pumping the outer protective casing should have a during well development, the movement of drain hole installed just above the top of the water is unidirectional toward the well. cement level in the space between the protec- Therefore, there is a tendency for the particu-
9-12 Ensuring Long-Term Protection—Monitoring Performance
lates moving toward the well to “bridge” monitoring frequency to ensure that samples together or form blockages that restrict subse- collected are physically and statistically inde- quent particulate movement. These blockages pendent. For example, in areas with high can prevent the complete development of the ground-water flow velocity, more frequent well capacity. This effect potentially impacts monitoring might be necessary to detect a the quality of the water entering the well. release before it migrates and contaminates Development techniques should remove such large areas. In areas with low flow velocity, bridges and encourage the movement of par- less frequent monitoring might be appropri- ticulates into the well. These particulates can ate. It is important to analyze background then be removed from the well by bailer or ground-water conditions, such as flow direc- pump and, in most cases, the water produced tion, velocity, and seasonal fluctuations to will subsequently be clear and non-turbid. help determine a suitable monitoring fre- quency for a site. You should consult with the In most instances, monitoring wells appropriate state agency to determine an installed in consolidated formations can be appropriate monitoring frequency. In the developed without great difficulty. Monitoring absence of state requirements, it is recom- wells also can usually be developed rapidly mended that semi-annual monitoring be con- and without great difficulty in sand and grav- ducted to detect contamination as part of a el deposits. However, many installations are basic monitoring program. made in thin, silty, and/or clayey zones. It is not uncommon for these zones to be difficult to develop sufficiently for adequate samples G. Sampling Parameters to be collected. Selection of parameters to be monitored in a ground-water monitoring program should be F. Duration and Frequency based on the characteristics of waste in the of Monitoring management unit. Additional sampling and analysis information can be found in EPA SW- The duration of ground-water monitoring 846 Test Methods for Evaluating Solid Waste (U.S. will depend on the length of the active life of EPA, 1986) and in ASTM’s standards. The the waste management unit and its post-clo- Annual Book of ASTM Standards also identifies sure care period. Continued monitoring after 18 ASTM guides and practices for performing a waste management unit has closed is waste characterization and sampling. important because the potential for contami- nant releases remains even after a unit has What are sampling parameters? stopped receiving waste. Monitoring frequen- cy should be sufficient to allow detection of Analyzing a large number of ground-water ground-water contamination. This frequency quality parameters in each sampling episode usually ranges from quarterly to annually. can be costly. To minimize expense, select only contaminants and geochemical indicators What site characteristics should that can be reasonably expected to migrate to be evaluated to determine the the ground water. These are called sampling parameters. Sampling parameters should pro- frequency of monitoring? vide an early indication of a release from a waste management unit. Once contamination Ground-water flow velocity is important in is detected, consider expanding the original establishing an appropriate ground-water
9-13 Ensuring Long-Term Protection—Monitoring Performance
sampling parameters and monitor for addi- H. Potential Modifications tional constituents to fully characterize the to a Basic Ground-Water chemical makeup of the release. Monitoring Program What sampling parameters It might be appropriate to modify certain should be used? elements of the basic ground-water monitoring program described above to accommodate site- Due to the broad universe of industrial specific circumstances. When using the IWEM solid waste, it is not possible to recommend a software to evaluate the need for a liner system, list of indicator papameters that are capable if the recommendation is to use a composite of identifying every possible release. It is rec- liner, then the basic ground-water monitoring ommended to begin by analyzing for a broad program should probably be enhanced. If the range of parameters to establish background recommendation using the software is that no ground-water quality, and then use the results liner is appropriate, then it might be possible to to select the sampling parameters to be moni- scale back some aspects of the basic ground- tored subsequently at a site. Table 2 lists water monitoring program. potential parameters for a basic ground-water monitoring program, by different categories. Components that might be subject to mod- Modify these parameters, as appropriate, to ification include the duration and frequency address site-specific circumstances. Your of monitoring, sampling parameters, and the knowledge of the actual waste streams or use of vadose zone monitoring. Possible mod- existing analytical data is a preliminary guide ifications of these elements are discussed fur- for what should be monitored, and leachate ther below. You should consult with the sampling data is also useful to select or adjust appropriate state officials on their require- sampling parameters. Where there is uncer- ments for ground-water monitoring programs. tainty concerning the chemistry of the waste, In some states, a unit might be eligible for a you should perform metal and organic scans no-migration exemption from the state’s at a minimum. You should consult with the ground-water monitoring requirements. appropriate state agency to ensure that appro- priate sampling parameters are selected. 1. Duration and Frequency of Monitoring What are the minimum The duration of monitoring (active life components of a basic plus post-closure care) is not likely to be monitoring program? modified in either a reduced or an enhanced ground-water monitoring program. Table 3 summarizes the recommended Adjustments to the frequency of monitoring, minimum components of a basic ground- however, might be appropriate, based primar- water monitoring program described above. ily on the mobility of contaminants and Potential modifications to the basic monitor- ground- water velocity. For example, if the ing program that might be appropriate based sampling parameters are slow moving metals, on site-specific waste management unit con- annual rather than semi-annual monitoring ditions are discussed later in this chapter. might be appropriate. Conversely, quarterly monitoring might be considered at a unit with a rapid ground-water flow rate or a
9-14 Ensuring Long-Term Protection—Monitoring Performance
Table 2 Potential Parameters for Basic Ground-Water Monitoring (Potential Parameters Should be Selected Based on Site-Specific Circumstances)
Category Specific Parameters
Field-Measured Parameters Temperature pH Specific electrical conductance Dissolved oxygen Eh oxidation-reduction potential Turbidity
Leachate Indicators Total organic carbon (TOC-filtered) pH Specific conductance Manganese (Mn) Iron (Fe) Ammonium (NH4) Chloride (Cl) Sodium (Na) Biochemical oxygen demand (BOD) Chemical oxygen demand (COD) Volatile organic compounds (VOCs) Total Halogenated Compounds (TOX) Total Petroleum Hydrocarbons (TPH) Total dissolved solids (TDS)
Additional Major Water Quality Parameters Bicarbonate (HCO3) Boron (Bo) Carbonate (CO3) Calcium (Ca) Fluoride (Fl) Magnesium (Mg) Nitrate (NO3) Nitrogen (disolved N2) Potassium (K) Sulfate (SO4) Silicon (H2SiO4) Strontium (Sr) Total dissolved solids (TDS)
Minor and Trace Inorganics Initial background sampling of inorganics for which drink- ing water standards exist (arsenic, barium, cadmium, chromium, lead, mercury, selenium, silver); ongoing moni- toring of any constituents showing background near or above drinking water standards.
Waste-Specific Constituents Selected based on knowledge of waste characteristics (ini- tial metals and organic scans at a minimum).
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Table 3 Recommended Components of a Basic Ground-Water Monitoring Program
Monitoring Component Recommended Minimum
Number of Wells Minimum 1 upgradient and 3 downgradient.4
Point of Monitoring Waste management unit boundary or out to 150 meters down gradient of the waste management unit area.5
Duration of Monitoring Active life plus post-closure care.
Frequency of Monitoring Semi-annual during active life.6
Sampling Parameters Metal and organic scans, use of indicators, leachate analysis, and/or knowledge of the waste. See the categories listed in Table 2.
mobile contaminant such as cyanide over a can range in thickness from several feet to permeable sand and gravel aquifer. hundreds of feet. Vadose-zone monitoring can detect migration of contaminants before 2. Sampling Parameters they reach ground water, serving as an early warning system if a waste management unit The basic recommended ground-water is not functioning as designed. It can also monitoring program already recommends the reduce the time and cost of remediation, and use of a parameter list that is tailored to the the extent of subsequent ground-water moni- waste characteristics and site hydrogeology. toring efforts. Where the use of the IWEM software indi- cates no liner is appropriate, it might be pos- If site conditions permit, it might be desir- sible to reduce the list of parameters able to include vadose-zone monitoring as routinely analyzed in downgradient wells to part of the overall ground-water program. If only a few indicator parameters. More com- vadose-zone monitoring is incorporated, the plete analysis would only be initiated if a sig- recommended number of ground-water mon- nificant change in the concentration of an itoring wells would be determined by the indicator parameter had occurred. basic ground-water monitoring program, and background quality would still need to be characterized with ground-water monitoring. 3. Vadose-Zone Monitoring The ground-water monitoring program The vadose zone is the region between the becomes a backup, however, with full use ground surface and the saturated zone. only being initiated if contaminant migration Depending on climate, soils, and geology, it is detected in the vadose zone. The sections
4 The actual number of both upgradient and downgradient wells will vary from unit-to-unit and will depend on the actual site-specific conditions. 5 Discussion of EPA’s rationale for the point of monitoring being out to 150 meters from a unit’s bound- ary can be found in 40 CFR Part 258 criteria. 6 Ground-water flow rate might dictate that more or less frequent monitoring might be appropriate. More frequent monitoring might be appropriate at the start of a monitoring program to establish background. Less frequent and/or reduced in scope monitoring might also be appropriate during the post-closure 9-16 care period. Ensuring Long-Term Protection—Monitoring Performance
below describe some of the commonly used methods for vadose zone monitoring, vadose zone characterization, and elements to con- sider in the design of a vadose zone monitor- ing system.
Vadose-Zone Monitoring Methods There are dozens of specific techniques for indirect measurement and direct sampling of the vadose zone. The more commonly used methods with potential value for waste man- water content or soil-moisture tension, agement units are described briefly below. depending on how they are calibrated. Time- domain reflectometry probes (Figure 2c) Soil-Water and Tension Monitoring measure water content using induced electro- magnetic currents. For vadose-zone monitor- Measuring changes over time in soil-water ing applications, the devices are usually content or soil-water tension is a relatively placed during construction of a waste man- simple and inexpensive method for leak agement unit and electrical cables run to one detection. Periodic measurements of soil water or more central locations for periodic mea- content or soil moisture tension beneath a surement. The other commonly used method lined waste management unit, for example, for monitoring soil-water content is to use should show only small changes. Significant neutron or dielectric probes. These require increases in water content or decreases in placement of access tubes, through which moisture tension would indicate a leak. probes are lowered or pulled, and allow con- What method should be used to tinuous measurement of changes in water content along the length of the tubes. measure soil moisture? Soil-moisture characteristics can be mea- Soil-Pore Liquid Sampling sured in two main ways: 1) water content, Sampling and analysis of soil-pore liquids usually expressed as weight percentage, and can determine the type and concentration of 2) soil-moisture tension, or suction, which contaminants that might be moving through the measures how strongly water is held by soil vadose zone. Soil-pore liquids can be collected particles due to capillary effects. As soil-water by applying either a vacuum that exceeds the content increases, soil-moisture tension soil moisture tension, commonly done using decreases. Measurements will not indicate, vacuum or pressure-vacuum lysimeters, or by however, whether contaminants are present. burying collectors that intercept drain water. Figure 2 shows three major methods that Figures 3a and 3b illustrate different methods are available for insitu monitoring of soil- for collecting soil-pore liquids. moisture changes. Porous-cup tensiometers (Figure 2a) measure soil-moisture tension, Soil-Gas Sampling with the pressure measurements indicated by Soil-gas sampling is a relatively easy and using either a mercury manometer, a vacuum inexpensive way to detect the presence or gauge, or pressure transducers. Soil-moisture movement of volatile contaminants and gases resistivity sensors (Figure 2b) measure either associated with degradation of waste within a
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Figure 2. Major Methods for In Situ Monitoring of Soil Moisture or Matrix Potential
(a) Three Types of Porous Cup Tensiometers, (b) Resistance Sensors, and (c) Time Domain Reflectometry Probes Sources: (a) Morrison, 1983. (b) U.S. EPA, 1993. (c) Topp and Davis, 1985, by permission.
waste management unit, such as carbon draws soil-gas to the surface, and a syringe dioxide and methane. Of particular concern used to extract the gas sample, as shown in are gases associated with the breakdown of Figure 4a. Installing soil-gas probes at multi- organic materials and toxic organic com- ple levels, as shown in Figure 4b, allows pounds. Permanent soil-gas monitoring detection of downward or upward migration installations consist of a probe point placed of soil gases. It is important to note, however, above the water table, a vacuum pump which that the performance of soil-gas sampling can
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Figure 3. Example Methods for Collecting Soil-Pore Samples
(a) Vacuum Lysimeter, (b) Pressure-Vacuum Lysimeter Source: ASTM, 1994. Copyright ASTM. Reprinted with permission.
be limited by some types of soil, such as tight moisture tension, and hydraulic conductivity clays or tight, saturated clays. should be measured or estimated. Unsaturated zone numerical modeling pro- Vadose Zone Characterization grams, such as HYDRUS 2-D or Seep (2-D) are designed to characterize the vadose zone. Just as the design of ground-water moni- toring systems requires an understanding of the ground-water flow system, the design of Vadose-Zone Monitoring System Design vadose zone monitoring systems requires an A vadose zone monitoring system com- understanding of the vadose zone flow sys- bined with a ground-water monitoring sys- tem. For example, in ground water systems, tem can reduce the cost of corrective hydraulic conductivity does not change over measures in the event of a release. Remedial time at a particular-location, whereas in the action is usually easier and less expensive if vadose zone, hydraulic conductivity changes employed before contaminants reach the with soil-water content and soil-moisture ten- ground-water flow system. sion. To estimate the speed with which water The design and installation of a vadose-zone will move through the vadose zone, the rela- monitoring system are easiest with new waste tionship between soil-water content, soil-
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Figure 4. Soil Gas Sampling Systems
(a) Gas Sampling Probe and Sample Collection Systems, (b) Typical Installation of Nested Soil Gas Probes Source: Reprinted with permission from Wilson, et al., Handbook of Vadose Zone Characterization and Monitoring, 1995. Copyright CRC Press, Boca Raton, Florida.
management facilities, where soil-water moni- network include: 1) consideration of the toring and sampling devices can be placed potential area of downward leakage, and 2) below the site. Relatively recent improvements determination of the effective detection area of in horizontal drilling technology, however, now the monitoring device. allow installation of access tubes for soil-mois- Cullen et al. (1995) suggest an approach ture monitoring beneath existing facilities. to vadose zone monitoring that includes the Important factors in choosing the location and following: depth of monitoring points in a leak-detection
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• Identification and prioritization of • Identifying the types and amounts of critical areas most vulnerable to cont- constituents present in the water body. aminant migration. • Designing a pollution prevention pro- • Selection of indirect monitoring gram or establishing best manage- methods that provide reasonably ment practices (BMPs). comprehensive coverage and cost- • Determining whether surface-water effective, early warning of contami- regulations and permit conditions are nant migration. being satisfied. • Selection of direct monitoring meth- • Responding to emergencies, such as ods that provide diagnostic confirma- accidental discharges or spills. tion of the presence and migration of contaminants. Some types of monitoring activities meet several of these purposes simultaneously, • Identification of background moni- while others are specifically designed for one toring points that will provide hydro- purpose, such as to determine compliance geologic monitoring data with permit conditions. representative of preexisting site con- ditions. If your facility is subject to a federal, state, or local permit that requires monitoring and • Identification of a cost-efficient, tem- sampling, you must collect and analyze sam- poral monitoring plan that will pro- ples according to the permit requirements. vide early warning of contaminant Otherwise, you should consider implement- migration in the vadose zone. ing a sampling program to monitor the quali- This approach is very similar to what is ty of runoff, the performance of BMPs, and described for the basic ground-water moni- any impacts on surface waters. For further toring program. information on BMPs relating to surface- water quality, refer to Chapter 6–Protecting Surface Water. Implementation of BMPs, along with regular maintenance inspections II. Surface-Water and upkeep, will greatly reduce the potential Monitoring for surface-water contamination. Controlling constituent discharges to sur- When establishing any type of sampling face water from industrial waste management and monitoring program, there are certain units is another component of responsible common sense guidelines to follow. waste management. Monitoring can be con- Inadequate frequency of data collection and ducted for many purposes, such as: incomplete monitoring might be useless while high-frequency monitoring and sam- • Characterizing surface-water condi- pling for numerous constituents can be costly tions and identifying changes or and could create a backlog of unusable data. trends in water quality over time. The following discussion summarizes what • Identifying existing or emerging you should consider when establishing sam- water quality problems. pling programs to effectively perform surface water monitoring.
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A. Monitoring Storm-Water stituents in the sampled runoff will not be so Discharges concentrated or so dilute as to be unrepre- sentative of the overall runoff. As discussed in Chapter 6–Protecting Surface Water, NPDES permits establish lim- Determining the sample type. A grab its on what constituents (and at what sample is a discrete, individual sample taken amounts or concentrations) facilities may dis- within a short period of time, usually less charge to receiving surface waters. Some than 15 minutes. Analysis of a grab sample waste management units, such as surface characterizes the quality of a storm water-dis- impoundments, might have an NPDES per- charge at the time the sample was taken. mit to discharge wastewaters directly to sur- These types of samples can be used to char- face waters. Other units might need an acterize the maximum concentration of a NPDES permit for storm-water discharges. constituent in the discharge. An NPDES permit will also contain limits on A composite sample is a mixed or com- what can be discharged, monitoring and bined sample that is formed by combining a reporting requirements, and other provisions series of individual and discrete samples of to ensure that the discharge does not impair specific volumes at specified intervals. These surface-water quality or human health. Due intervals can be either time-weighted or flow- to the variable nature of storm-water flows weighted. Time-weighted composite samples during a rainfall event and the different ana- are collected and combined in proportion to lytical considerations for certain constituents, time, while flow-weighted composite samples the sampling requirements for different waste are combined in proportion to flow. management unit types and sampling loca- Composite samples characterize the quality tions will vary as well. The guidelines and of a storm-water discharge over a specific general sampling procedures outlined below period of time, such as the duration of a should be considered when developing a storm event. storm-water sampling program to comply Determining the sample techniques. with permit requirements or to monitor the quality of runoff and determine the effective- Grab and composite samples can be collected ness of BMPs. by either manual or automatic sampling tech- niques. Manual samples are simply collected Sampling a representative storm. Using by hand, while automatic samples are collect- climatic data, you can determine the average ed by powered devices according to prepro- rainfall depth and duration of rainfall events grammed criteria. Both techniques have at the waste management unit site. You advantages and disadvantages that need to be should sample during a representative storm weighed when choosing a sampling tech- event. The representative storm should be nique for a specific site. The advantages of preceded by at least 72 hours of dry weather manual sampling include its appropriateness and, when possible, should be between 50 for all constituents and its lower cost com- and 150 percent of the average depth and pared to automatic sampling. Manual sam- duration. The time to collect individual grab pling, however, can be labor intensive, can samples is during the first flush (i.e., the first expose personnel to potentially hazardous 30 minutes of the event), and composite conditions, and is subject to human error. samples should then be collected over the first 3 hours, or the entire event if less than 3 The advantages of automatic sampling are hours. These guidelines help ensure that con- the convenience it offers, its minimum labor requirements, its reduction of personnel
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exposure to hazardous conditions, and its resentative of the runoff, samples might need low risk of human error. Unfortunately, auto- to be taken at a point further upstream of the matic sampling is not suitable for all con- discharge pipe or at several locations to best stituent types. Volatile organic compounds characterize site runoff. (VOC), for example, can not be sampled Coordinating with the laboratory. It is automatically due to the agitation during important to collect adequate sample vol- sample collection. This agitation can cause umes to complete all necessary analyses. the VOC constituents to completely volatilize When testing for certain constituents, sam- from the sample. Other constituents such as ples might need to be cooled or otherwise fecal streptococcus, fecal coliform, and chlo- preserved until analyzed to yield meaningful rine might also not be amenable to automatic results. Section 3.5 of EPA’s NPDES Storm sampling due to their short holding times. Water Sampling Guidance Document (U.S. EPA, Since sample temperature and pH need to be 1992) contains information on proper sample measured immediately, the option for using handling and preservation procedures. automatic sampling for these parameters is Submitting the proper information to the lab- limited as well. Automatic sampling can also oratory is important in ensuring proper sam- be expensive, and does require a certain ple handling by the laboratory. Proper sample amount of training. Table 4 presents a com- documentation guidelines are outlined in parison of manual and automatic sampling Section 3.7 of the NPDES Storm Water techniques. Sampling Guidance Document. Coordination Sampling at the outfall point. Storm- with the laboratory that will be performing water samples should be taken at a storm- the analysis will help ensure that these issues water point source. A “point source” is are adequately addressed. defined as any discernible, confined, and dis- You are required to follow all sampling crete conveyance. The ideal sampling loca- and monitoring requirements in an NPDES tion is often the lowest point in a drainage permit. If there are no sampling require- area where a conveyance discharges, such as ments, analyze runoff for basic constituents, the discharge at the end of a pipe or ditch. such as oil and grease, pH, biochemical oxy- The sample point should be easily accessible gen demand (BOD), chemical oxygen on foot and in a location that will not cause demand (COD), total suspended solids hazardous sampling conditions. You should (TSS), phosphorus, and nitrogen, as well as not sample during dangerous wind, light- any other constituents known or suspected to ning, flooding, or other unsafe conditions. If be present in the waste, such as heavy metals these conditions are unavoidable during an or other toxic constituents. event, then the sampling should be delayed until a less hazardous event occurs. Additional sampling guidance can be Preferably, the sampling location will be obtained from EPA’s NPDES Storm Water located onsite, but if it is not, obtain permis- Sampling Guidance Document (U.S. EPA, sion from the owner of the property where 1992) and Interim Final RCRA Facility the discharge is located. Inaccessible dis- Investigation (RFI) Guidance: Volume III (U.S. charge points, numerous small point dis- EPA, 1989). In addition, state and local envi- charges, run-on from other properties, and ronmental agencies also have guidance on infinite other scenarios can cause logistical appropriate sampling methods. problems with sampling locations. If the dis- There is a national system that provides charge is inaccessible or not likely to be rep- permitting information for facilities holding
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Table 4 Comparison of Manual and Automatic Sampling Techniques
Sample Method Advantages Disadvantages
Manual Grabs • Generally appropriate for all •Labor-intensive constituents •Environment possibly dangerous to field personnel • Minimum equipment required • Might be difficult to get personnel and equipment to the storm water outfall within the first 30 minutes of the event • Possible human error
Manual Flow- • Generally appropriate for all •Labor-intensive Weighted constituents • Environment possibly dangerous to field personnel Composites • Minimum equipment required •Human error can have significant impact on (multiple grabs) sample representativeness •Requires that flow measurements be taken during sampling
Automatic Grabs • Minimizes labor requirements •Samples not collected for oil and grease, might • Low risk of human error not be representative • Reduced personnel exposure to •Automatic samplers generally cannot properly unsafe conditions collect samples for VOC analysis • Sampling can be triggered •Costly if numerous sampling sites require the remotely or initiated according to purchase of equipment present conditions • Can require equipment installation and maintenance; can malfunction • Can require operator training • Might not be appropriate for pH and temperature • Might not be appropriate for parameters with short holding times (e.g., fecal streptococcus, fecal coliform, chlorine) • Cross-contamination of aliquot if tubing/bottles not washed
Automatic Flow- • Minimizes labor requirements •Generally not acceptable for VOC sampling Weighted • Low risk of human error •Costly if numerous sampling sites require the Composites • Reduced personnel exposure to purchase of equipment unsafe conditions •Can require equipment installation and • Can eliminate the need for maintenance; can malfunction manual compositing of aliquots •Can require operator training • Sampling can be triggered remotely •Can require that flow measures be taken during or initiated according to onsite sampling conditions •Cross-contamination of aliquot if tubing/bottles not washed
Source: U.S. EPA, 1992.
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NPDES permits. This system is called the issued by the local control authority might Permits Compliance System (PCS) and it require more frequent monitoring (see 40 allows users to retrieve information regarding CFR Section 403.12 (g) and (h)). The local facilities holding NPDES permits, including municipality will develop and implement permit limits and actual monitoring data. You standard operating procedures and policies can specify the desired information by using that specify the sample collection and han- any combination of facility name, geographic dling protocols in accordance with 40 CFR location, standard industrial classification Part 136. (SIC) code, and chemical names. The PCS Sampling for constituents such as pH, database can be accessed at
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oratory) (see 40 CFR Section 403.12(o)). seasonal basis (e.g., during periods of intense Consult EPA’s Introduction to the National rainfall); or on an emergency basis (i.e., an Pretreatment Program document (U.S. EPA, accidental spill or discharge). 1999) for further information on monitoring requirements under the National Why is the monitoring taking Pretreatment Program. place? You should first determine the purpose of C. Monitoring Surface establishing a surface-water monitoring pro- Water Conditions gram. Reasons for monitoring surface water can include developing baseline characteriza- In order to determine if runoff from your tion data prior to a waste management unit waste management unit is impacting adjacent being constructed, documenting water quali- surface waters you might want to consider ty changes over time, screening for potential establishing a surface-water quality monitor- water quality problems, determining the ing program. Chemical, physical, and biolog- effectiveness of BMPs, or determining the ical data can provide information about the impact of the waste management unit on sur- effectiveness of BMPs. The data collected will face waters. help you to characterize any overall water quality at the selected monitoring sites, iden- How will the data be used? tify problem areas, and document any changes in water quality. The data collected will help you to identify constituents of concern, the impacts of pollu- In designing your program, one of the tion and pollution control activities (i.e., most important things to consider is what BMPs), and trends in water quality. Note that types of parameters to monitor (chemical, the data you collect might also be useful to physical, and/or biological) that will enable regional or local water quality planning you to determine how your waste manage- offices that might already be collecting simi- ment unit might be impacting the aquatic lar data in other parts of the watershed. ecosystem. Determining where you should set-up a monitoring station is also very What parameters or conditions important and will depend on relevant hydrologic, geologic, and meteorologic fac- will be monitored? tors. For assistance and more information on The basic parameters that are indicators of establishing water quality sampling stations general water quality health, include dissolved and a sampling program you should consult oxygen (DO), pH, total suspended solids with state and local water quality planning (TSS), nitrogen, hardness, temperature, and agencies. Additional guidance on establishing phosphorous. In addition, you might choose sampling and monitoring programs can be to monitor parameters that would indicate obtained from EPA’s Volunteer Stream whether the designated use (e.g., fisheries, Monitoring Document (U.S. EPA, 1997) and recreation) of the water body is being met (as Volunteer Lake Monitoring Document (U.S. discussed in Chapter 6–Protecting Surface EPA, 1991). Monitoring can be conducted at Water). Further, based on the types of con- regular sites on a continuous basis (“fixed stituents associated with the waste manage- station” monitoring); at selected sites on an ment unit, you should also sample for as needed basis or to answer specific ques- contaminants that would indicate whether tions (“intensive surveys”); on a temporary or your surface-water protection measures are
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functioning properly (e.g., heavy metals, pling methods. EPA’s SW-846 also provides organics, or other materials associated with the guidance on selecting the appropriate sam- unit). In many cases, a few surrogate con- pling methods. stituents can be selected instead of analyzing a complete spectrum of constituents. For exam- When will the monitoring occur? ple, lead, zinc, or cadmium are often selected You need to establish how frequently mon- to indicate pollution by toxic metals. Instead itoring will take place, what time of year is of analyzing for every possible pathogenic best for sampling, and what time of day is microorganism, total and fecal coliform bacte- best for sampling. Monitoring at the same ria analyses are commonly used to indicate time of day and at regular intervals helps bacterial and viral contamination. Chemical ensure comparability of data over time. In oxygen demand (COD) and total organic car- general, monthly chemical sampling and bon (TOC) are used in high-frequency grab twice yearly biological sampling are consid- sampling programs as indicators of pollution ered adequate to identify water quality by organics. changes over time. If you are conducting bio- Where should the monitoring logical sampling, it should be conducted at the same time each year because of natural sites/stations be located? seasonal variations in the aquatic ecosystem. In order to determine if the waste manage- Note that the frequency of sampling should ment unit is having an impact on surface be increased during the rainy season as this is water it is important to determine the quality when contamination from waste management of the water upstream from the unit as well as units is expected to increase due to storm- downstream. You should also consider the water runoff. number of sites to establish how accessible, How can the quality of the data safe, and convenient potential sites are. In addition, it is important to determine if poten- collected be ensured? tial sites are near tributary inflows, dams, You should develop a quality assurance bridges, or other structures that might affect plan to ensure that quality assurance and the sampling results. You should also deter- quality control procedures are implemented mine if you will establish permanent sampling at all times. In addition, the personnel con- stations (i.e., structures or buildings) or if the ducting the sampling should be properly stations will simply be designated points with- trained and consider how to manage the data in the watershed. after the data have been collected. What sampling methods should Hydrologic and water quality information be used? is also collected and published regularly by EPA and the U.S. Geological Survey (USGS). You must decide how the samples will be Both agencies have computerized systems for collected, what sampling equipment will be storing and retrieving information on water used (e.g., automatic samplers or by hand), quality that are available on the Internet. what equipment preparation methods are Water quantity and flow data in streams is necessary (e.g., container sterilization, meter also available from USGS which has offices in calibration), and what protocols will be fol- every state. USGS also operates two national lowed. Refer to Part II, Section A of this stream water quality networks, the chapter for a discussion of determining sam- Hydrologic Benchmark Network (HBN) and
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the National Stream Quality Accounting EPA’s Water Quality Data Network (NASQAN). These networks were Management Systems established to provide national and regional descriptions of stream water quality condi- EPA maintains two data management sys- tions and trends, based on uniform monitor- tems containing water quality information: ing of selected watersheds throughout the the Legacy Data Center (LDC) and STORET. United States, and to improve our under- The LDC contains historical water quality standing of the effects of the natural environ- data dating back to the early part of the 20th ment and human activities on water quality. century and collected up to the end of 1998. Stream water quality measurements are avail- STORET (short for STOrage and RETrieval) able for the approximate periods 1973 to contains data collected beginning in 1999, 1995 for NASQAN and 1962 to 1995 for along with older data that has been properly HBN. For more information on how to documented and migrated from the LDC. obtain this water quality information, visit Both systems contain biological, chemi- the USGS Web site at
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migration before they reach ground water. an inaccurate soil characterization which Characterizing the soil properties at a land could lead to improper application of waste application site can also help you determine and failure of the unit to properly assimilate the application rates that will maximize waste the applied waste. assimilation. To obtain site-specific data on actual soil A. Determining the Quality conditions, the soil should be sampled and characterized. The number and location of of Soil samples necessary for adequate soil character- Soil quality is an assessment of how well ization is primarily a function of the variabili- soil performs all of its functions, not just how ty of the soils at a site. If the soil types occur well it assimilates waste. Measuring crop yield, in simple patterns, a composite sample of nutrient levels, water quality, or any other sin- each major soil type can provide an accurate gle outcome alone will not give you a com- picture of the soil characteristics. The depth plete assessment of a soil’s quality. The to which the soil profile is sampled, and the minerals and microbes in soil are responsible extent to which each horizon is vertically for filtering, buffering, degrading, immobiliz- subdivided, will depend on the parameters to ing, and detoxifying organic and inorganic be analyzed, the vertical variations in soil materials, including those applied to the land character, and the objectives of the soil sam- and deposited by the atmosphere. Determining pling program. You should rely on a qualified the quality of a soil is an assessment of how it soil scientist to perform this characterization. performs all of these functions in addition to Poorly conducted soil sampling can result in waste assimilation. For assessing soil quality in relation to land application units, it will be
Examples of Indicators of Soil Quality
Indicator Relationship to Soil Health Soil organic matter (SOM). Soil fertility, structure, stability, nutrient retention, soil erosion. PHYSICAL: soil structure, Retention and transport of water depth of soil, infiltration and bulk and nutrients, habitat for density, water holding capacity. microbes, estimate of crop productivity potential, compaction, water movement, porosity, workability. CHEMICAL: pH, electrical Biological and chemical activity conductivity, extractable nitrogen- thresholds, plant and microbial phosphorous-potassium. activity thresholds, plant available nutrients and potential for nitrogen and phosphorous loss. BIOLOGICAL: microbial biomass, Microbial catalytic potential and carbon and nitrogen, potentially repository for carbon and mineralizable nitrogen, soil nitrogen, soil productivity and supplying potential, microbial respiration. activity measure.
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important for the soil to be able to filter the soil level and mixed to provide a composite waste constituents and cycle nutrients such as sample for the area. From the mixed cores a carbon, nitrogen, and phosphorus. composite subsample should be taken and analyzed. Each grab sample can be analyzed Measuring soil quality requires the use of individually, rather than combined, as part of physical, chemical, and biological indicators, a composite sample (discussed below), but which can be assessed by qualitative or quan- composite samples generally provide reliable titative techniques. After measurements are data for soil characterization. collected, they can be evaluated by looking for patterns and comparing results to mea- Soil core grab samples can be collected at surements taken at a different time or field. random or in a grid pattern. Random collec- For more information, consult the Guidelines tion generally requires the least amount of for Soil Quality Assessment prepared by the time, but cores must be collected from the Soil Quality Institute of the Natural entire area to ensure reliable site characteriza- Resources Conservation Service (formerly the tion. When performed properly, random U.S. Soil Conservation Service). sampling will provide an accurate assessment of average soil nutrient and constituent lev- els. While the preparation required for col- B. Sampling Location and lecting core samples in a grid pattern can be Frequency more costly and time consuming, it does Prior to sampling, divide the land applica- ensure that the entire area is sampled. An tion unit into uniform areas, then collect rep- advantage of grid sampling is the ability to resentative samples from each area. These generate detailed nutrient level maps for a divisions should be based upon soil type, land application unit. This requires analysis slope, degree of erosion, cropping history, of each individual grab sample from an area, known crop growth differences, and any rather than compositing samples. Analyzing other factors that might influence nutrient each individual grab sample is time consum- levels in the soil. One recommended ing and expensive, but software and comput- approach is to divide the unit into areas no erized applicators are becoming available that larger than 20 acres and to collect at least can use these data to tailor nutrient applica- one sample from each of these areas. tion to soil needs. Each sample for a designated area consists You should determine baseline conditions of a predetermined number of soil cores. A by sampling the soil before waste application soil core is an individual boring at one spot begins. Subsequent sampling will depend on in the field. The recommended number of land use and any state or local soil monitor- cores per sample are 15-20 cores for a sur- ing requirements. After waste is applied to face soil sample and 6-8 cores for a subsur- the land application unit, you should collect face sample. If using a soil probe, a single and analyze samples at regular intervals, or core can be separated into its horizontal lay- after a certain number of applications. You ers to provide samples for each layer being should sample annually, at a minimum, or analyzed. For example, a single core could be more frequently, if appropriate. divided into four predefined layers such as The frequency of sampling, the micronu- surface soil, subsurface soil, and two deep trients, the macronutrients, and the con- subsurface soil. For a designated area, all the stituents to be analyzed will depend on individual cores are combined according to site-specific soil, water, plant, and waste
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characteristics. Local agricultural extension D. Sample Collection services, which have experience with design- Initial soil characterization samples are ing soil-sampling programs, can assist in this typically taken from each distinct soil horizon area. Soil monitoring, especially when cou- down to a depth of 4-5 feet (120-150 cm). pled with ground-water monitoring, can For example, a single core sample might pro- detect contamination problems. Early detec- vide the following four horizon samples: sur- tion allows changes to be made to the land face (0-6 inches), subsurface (6-18 inches), application process to remedy the problems and two deep subsurface (18-30 inches and and to conduct corrective action if necessary. 30-42 inches). For subsequent evaluations, it Finally, soil testing after the active life of the is important to sample more than just the unit has ended is recommended to determine surface layer to determine if the land applica- if any residues remain in the soil. tion rate is appropriate and that the quality of soil is not being detrimentally affected. C. Sampling Equipment Sampling subsurface layers will indicate whether waste constituents are being There are a number of soil sampling removed and assimilated as expected and are devices available. A soil probe or tube is the not leaching into subsurface layers or the most desirable, as it provides a continuous groundwater. As a minimum practice, sample core with minimal disturbance of the soil. at least the upper soil layer (0-6 inches) and Sample cores from a soil probe can be divid- at least one deeper soil layer (e.g., 18-30 ed by depth and provide surface, subsurface, inches). You should consult the local agricul- and deep subsurface samples from a single tural extension service, the county agricultur- boring. When the soil is too wet, too dry, or al agent, or other soil professionals for frozen, however, soil probes are not very recommended soil sampling depths for the effective. The presence of gravel in the soil specific area in which your land application will also prevent the use of a soil probe. unit is located. When sampling excessively wet, dry, or Once the samples have been obtained, frozen soils, or soils with gravel, a soil auger they must be prepared for chemical analysis. can be used in place of a soil probe. Because This typically is done by having the sample of their tendency to mix soils from different air dried, ground, and mixed, and then depths during sample collection, a soil auger passed through a 2 millimeter sieve as soon should only be used when the use of a soil as possible after collection. If the samples are probe is not possible. A spade can also be to be analyzed for nitrate, ammonia, or used for surface samples, but it is not effec- pathogens, then they should be refrigerated tive for subsurface sampling. Post-hole dig- under moist field conditions and analyzed as gers can be used for collecting deeper soon as possible. For more information on subsurface samples, but they present the handling and preparing soil samples, refer to same mixing problem as soil augers. EPA’s the “General Protocol for Soil Sample Description and Sampling of Contaminated Soils: Handling and Preparation” section in EPA’s A Field Pocket Guide (U.S. EPA, 1991) con- Description and Sampling of Contaminated Soils: tains a description of various hand-held and A Field Pocket Guide (U.S. EPA,1991). ASTM power-driven tube samplers. The guide also method D-4220 Practices for Preserving and outlines the recommended applications and Transporting Soil Samples also addresses prop- limitations for each sampling device. er soil sample handling protocols.
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The exact procedure for drying is not criti- Prior to sampling, all containers and cal as long as contamination is minimized equipment that are to be used for soil collec- and excessive temperatures are avoided. The tion (i.e., those that will come in contact recommended drying procedure for routine with the soil being sampled) should be soil analysis is to dry the samples overnight, rinsed in warm tap water to remove any using forced air at ambient temperatures. residual soil particles from previous sampling Supplemental heating can be used, but it is runs. They should then be rinsed with an recommended that soil samples to be used aluminum chloride solution. Avoid using for routine analyses not be dried at greater anhydrous aluminum chloride due to its vio- than 36°C. Microwave drying can alter the lent reaction with water. A four percent analytical results and should be avoided. hydrogen chloride solution can also be used if the soil is not to be analyzed for chlorine. Because soil is defined as having a particle The containers and equipment should be size of less than 2 millimeters, this sieve size rinsed twice in distilled or deionized water (# 10 mesh) is recommended for routine soil and allowed to dry prior to use. testing. Commercial soil grinders and crush- ers, such as mortar and pestles, hammer- You should obtain professional assistance mills, or roller-crushers, are typically long from qualified soil scientists and laboratories and motorized. The amount of coarse frag- to properly interpret the soil-sample results. ments common in some samples limits the For more information about how to obtain use of some of these. In general, it is desir- representative soil samples and submit them able to get most of the sample to less than 2 for analysis, you can consult various federal mm with the least amount of grinding. If the manuals, such as EPA’s Laboratory Methods sample is to be analyzed for micronutrients, for Soil and Foliar Analysis in Long-Term all contact with metal surfaces should be Environmental Monitoring Programs (U.S. EPA, avoided during crushing and sieving unless it 1995b), or state guides, such as Nebraska’s has been clearly demonstrated that the metal Guidelines for Soil Sampling (G91-1000-A). is not a source of contamination. Cross-cont- The following ASTM methods might also amination between samples can be avoided prove useful when conducting soil sampling: by minimizing soil-particle carry over on the D-1452 Practice for Soil Investigation and crushing and sieving apparatus. For Sampling by Auger Borings; D-1586 Test macronutrient analysis, removal of particles Method for Penetration Test and Split-Barrel by brushing or jarring should be adequate. If Sampling of Soils; D-1587 Practice for Thin- micronutrient or trace element analysis is to Walled Tube Sampling of Soils; and D-3550 be performed, a more thorough cleaning of Practice for Ring-Lined Barrel Sampling of Soils. the apparatus by brushing or wiping between samples might be required. The bulk soil sample should be thorough- IV. Air Monitoring ly homogenized by mixing with a spatula, The development of appropriate air-moni- stirring rod, or other implement. As much of toring data can be technically complex and the sample as possible should be loosened resource intensive. The Industrial Waste Air and mixed together. No segregation of the (IWAIR) Model on the CD ROM version of sample by aggregate size should be apparent this Guide provides a simple tool that relies after mixing. You should dip into the center on waste characterization information, rather of the mixed sample to obtain a subsample than actual air monitoring data, to evaluate for analysis.
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risks from VOC emissions at a unit. The air- source is an immobile unit from which air modeling tool uses an emissions model to pollutants are released. Examples include estimate emissions from a waste management incinerators, boilers, industrial furnaces, unit based on the waste characterization. You landfills, waste piles, surface impoundments, should review Chapter 5–Protecting Air and other waste management units. The pur- Quality, and the supporting background doc- pose of source sampling is to obtain as accu- ument developed for the IWAIR model to rate a sample as possible of the material understand the limitations of the model and entering the atmosphere. The major reasons determine whether it is applicable to a specif- for which source testing is required are to ic unit. If the model is not appropriate for a demonstrate compliance with regulations or specific site or if it indicates that there is a permit conditions, to collect engineering data problem with VOC emissions, use an alterna- (e.g., to evaluate the performance of air pol- tive (emissions) model that is more appropri- lution control equipment), to support perfor- ate for the site or consider air monitoring to mance guarantees (e.g., checking to confirm gather more site-specific data. that the air pollution control equipment is meeting the guaranteed degree of perfor- mance), and to provide data for air modeling. A. Types of Air Emissions Monitoring 2. Ambient Monitoring There are generally four different types of The second type of air monitoring involves air emissions monitoring: source, ambient, ambient air monitoring at selected locations fugitive, and indoor. Source, ambient, and around the waste management unit or site. fugitive monitoring can provide data for use The data are used to monitor dispersion of in emission and dispersion modeling. In airborne contaminants to the surrounding addition, the monitoring of meteorological areas. Ambient testing usually involves conditions at sites is generally conducted “fenceline” testing. Typically, the air is moni- whenever source emissions or ambient moni- tored at the four fenceline compass points. At toring is performed, as discussed below. As least one additional measuring station is the vast majority of industrial waste manage- placed either in the predominant upwind (or ment units are located outdoors, indoor air downwind) location or in a direct line quality and monitoring issues typically will between your site and a neighboring facility not apply. Consequently, this guide does not or property. The resulting data should yield address this issue. For more information on information concerning the concentration of indoor air quality and monitoring visit the ambient emissions leaving your property Occupational Safety and Health (minus the emissions from adjacent facilities). Administration’s (OSHA) Web site at
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impact the operation of your facility. For be preferred. This is a box that isolates a por- example, many facilities are required to con- tion of the pond to determine volumetric tinuously monitor downwind fenceline emis- flow. The box acts as a floating stack in which sion of hydrocarbons. If a neighboring facility’s emissions are captured into a canister for emissions of hydrocarbons or adjacent freeway analysis. For material transfer operations or hydrocarbon emissions drift across your fence- vehicular traffic from unpaved roads, it is line and combine with your own hydrocarbon obviously not practical to use a handheld ana- emissions, your total facility hydrocarbon lyzer or to “bag” the source (especially some- emission limit could be violated. thing as large as a waste pile). In such cases of particulate matter fugitive emissions, a high- 3. Fugitive Monitoring volume ambient PM10 sampling system is used, or the emissions are ducted through a Fugitive testing is a hybrid of ambient and temporary stack for direct measurement using source testing and generally involves the a sampling train (see Figure 6). monitoring of either particulate or gaseous emissions from sources open to the atmos- phere. It can involve testing sources such as 4. Meteorological Monitoring valves, flanges, pumps, and similar equipment Another form of air monitoring measures and hardware for leaks, and it can include meteorological conditions at a site. Site-spe- quantifying emissions from open drums, open cific meteorological information can be col- vats, landfills, waste piles, and surface lected for use in air emission and dispersion impoundments such as lagoons, pits, and set- modeling. This type of monitoring involves tling ponds. It is typically conducted using measurement of wind speed, wind direction, one or more of the following techniques: use temperature, etc., and can be performed of a handheld organic analyzer; “bagging” sus- when other offsite meteorological informa- pect sources for subsequent analysis; captur- tion might not adequately characterize the ing and scrubbing fugitive emissions using a weather conditions at the site. Local wind floating flux chamber/summa canister; or systems are usually quite significant in terms measuring particulate matter greater than or of the transport and dispersion of air con- less than 10 microns in diameter (PM10) fol- stituents. Therefore, local meteorological lowing promulgated EPA test methods. monitoring will most likely be important for mountainous or hilly terrain (where solar Selection of the test method depends on heating and radiational cooling influence factors such as the type of emissions, source how wind moves) or for a site near a large type, temperature, pressure, constituent con- body of water (where the differential heating centration, etc. (test methods are discussed of land and water can result in thermals and later in this chapter). For example, a plant subsidence over water). Also, the initial operator who suspects that a valve is leaking direction of transport of constituents from might use a handheld organic analyzer to ver- their source is determined by the wind ify the presence of a leak. If the analyzer is direction at the source. not able to quantify the concentration of the leaking gas, then the bagging technique can To make meteorological measurements, be employed. To determine the amount and three components are typically needed: a type of organic emissions escaping from a set- detector or sensor, an encoder or digitizer, tling pond or wastewater treatment tank, a and a data logger. Most detectors are analog, floating flux chamber/summa canister might providing a continuous output as a function
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of varying meteorological conditions. The output signal must then be sampled to pro- Sensors Used To Measure duce a discrete digital record, using some sort Meteorologic Parameters of encoder or analog-to-digital converter. The The following types of sensors can be used to resulting discrete series of data must be monitor meteorological conditions at a site (note recorded, often on magnetic tape, magnetic that this list is not meant to be exhaustive): disks, or optical disks. “Instrument system” or “instrument package” is the name given to Temperature—thermometers. the set of all three components listed above. Direct sensors: Remote sensors: wax thermostat microwave sounders Additional components might also be nec- thermistor sodar essary including: an instrument platform, a bimetallic strip thermistor means of calibration, and display devices. thermocouple Platforms, such as a tower, can often hold liquid (mercury or alcohol) in glass many instrument systems. Calibration against radiometers known standards should be performed peri- Humidity—hygrometers. odically during the measuring program, or Direct sensors: Remote sensors: should be accomplished continuously as a psychrometers lidar function of the sensor or instrument package. hair hygrometer radar All data must be calibrated. Finally, the mea- chilled mirror (dew pointer) sured values should be displayed on printers, hygristor plotters, or video displays in order to confirm Wind—velocity (anemometers) and the proper operation of the instrument. direction (vanes). Direct senors: Remote sensors: A large variety of sensors have been devel- cup Doppler radar oped to measure various meteorologic para- propellar meters. Direct sensors are ones that are wind vane placed on an instrument platform to make in bivane situ measurements of the air at the location of Pressure—barometers and microbarographs. the sensor. Remote sensors measure waves Direct sensors: that are generated by, or modified by, the aneroid elements atmosphere at locations distant from the sen- capacitive elements sor. These waves propagate from the genera- mercury in glass tion or modification point back to the sensor. Disadvantages of direct sensors include modi- Remote sensors: None that use wave propagation directly, but fication of the flow by the sensor or its plat- some that measure temperature and velocity form and the requirement to physically fluctuations as mentioned above, and infer position the sensor where the measurement is pressure perturbations as residual from govern- to be made. Disadvantages of remote sensors ing equations. include their size, cost, and complexity. Advantages of direct sensors include sensitivi- Radiation—radiometers. Radiometers can be designed to measure radia- ty, accuracy, and simplicity. Advantages of tion in specific frequency bands coming from remote sensors include the fact that they can specific directions: radiometer, net radiometer, quickly scan a large area while remaining sta- pyranometer, and net pyranometer. tionary on the ground.
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B. Air Monitoring and for dissolving gases, a filter surface for col- Sampling Equipment lecting particles, or a chamber to contain an aliquot of air for analysis. The flow device measures the volume of air associated with 1. Ambient Air Monitoring the sampling system. Examples of flow For ambient air monitoring, the principal devices include mass flow meters and requirement of a sampling system is to obtain rotameters. a sample that is representative of the atmos- phere at a particular place and time. The Gaseous Constituents major components of most sampling systems Sampling systems for gaseous constituents are an inlet manifold, an air mover, a collec- can take several forms and might not neces- tion medium, and a flow measurement sarily have all four components as shown in device. The inlet manifold transports material Figure 5. The sampling manifold’s only func- from the ambient atmosphere to the collec- tion is to transport the gas from the manifold tion medium, or analytical device, preferably inlet to the collection medium. The manifold in an unaltered condition. The inlet opening must be made of nonreactive material and no can be designed for a specific purpose. All condensation should be allowed to occur in inlets for ambient sampling must be rain- the sampling manifold. The volume of the proof. Inlet manifolds are made out of glass, manifold and the sampling flow rate deter- Teflon, stainless steel, or other inert materials mine the time required for the gas to move and permit the remaining components of the from the inlet to the collection medium. This system to be located at a distance from the residence time can be minimized to decrease sample manifold inlet. The air mover (i.e., the loss of reactive species in the manifold by pump) provides the force to create a vacuum keeping the manifold as short as possible. or lower pressure at the end of the sampling system. The collection medium for a sam- The collection medium for gases can be pling system can be a liquid or solid sorbent liquid or solid sorbents, and evacuated flask,
Figure 5. Schematic Diagram of Various Types of Sampling Systems
Source: Fundamentals of Air Pollution.
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or a cryogenic trap. Each design is an attempt extracting particles from an airstream are fil- to optimize gas flow rate and collection effi- tration and impaction.7 All sampling tech- ciency. Higher flow rates permit shorter sam- niques must be concerned with the behavior pling times. Liquid collection systems take of particles in a moving airstream. Care must the form of bubblers which are designed to be taken to move the particles through the maximize the gas-liquid interface. However, manifold to the collection medium in an excessive flow rates can result in lower collec- unaltered form. Potential problems arise if tion efficiency. manifold systems are too long or too twisted. Gravitational settling in the manifold will Diagram A is typical of many extractive remove a fraction of the very large particles. sampling techniques (e.g., SO in liquid sor- 2 Larger particles are also subject to loss by bents and polynuclear aromatic hydrocarbons impaction on walls at bends in a manifold. on solid sorbents). Diagram B is used for Particles can also be subject to electrostatic “open-face” filter collection, in which the fil- forces which will cause them to migrate to ter is directly exposed to the atmosphere the walls of nonconducting manifolds. Other being sampled. Diagram C is an evacuated potential problems include condensation or container used to collect an aliquot of air or agglomeration during transit time in the man- gas to be transported to the laboratory for ifold. These constraints require particulate chemical analysis, (e.g., polished stainless sampling manifolds to be as short as possible steel canisters are used to collect ambient and to have as few bends as possible. hydrocarbons for air toxic analysis). Diagram D is the basis for many of the automated con- tinuous analyzers, which combine the sam- 2. Source Emissions Monitoring pling and analytical processes in one piece of For source emissions monitoring, the sam- equipment (e.g., continuous ambient air pling system is tailored to the unique proper- monitors for SO2, O3, and NOx). ties of the emissions from a particular process. It is necessary to take into account Particulate Constituents the specific process, the nature of the control devices, the peculiarities of the source, and Sampling for particulate constituents in the the use of the data obtained. In source moni- atmosphere involves a different set of parame- toring, the sample is obtained from a stack ters from those used for gases. Particles are that is discharging to the atmosphere using a inherently larger than the molecules of N and 2 “sampling train”. A typical sample train is O in the surrounding air and behave differ- 2 shown in Figure 6. The figure shows the min- ently with increasing diameter. When sam- imum number of components, but in some pling for particulate matter in the atmosphere, systems the components can be combined. three pieces of information are of particular Extreme care must be exercised to assure that interest: the concentration, the size, and the no leaks occur in the train and that the com- chemical composition of the particles. Particle ponents of the train are identical for both cal- size is important in determining adverse ibration and sampling. Standard sampling effects and atmospheric removal processes. trains are specified for some tests. The primary approach is to separate the Continuous emission monitors (CEMs) are particles from a known volume of air and also available to monitor opacity and certain subject them to weight determination and gaseous emissions. chemical analysis. The principle methods for
7 Filtration consists of collecting particles on a filter surface by three processes: direct interception, iner- tial impaction, and diffusion. Filtration attempts to remove a very high percentage of the mass and number of particles by these processes. Any size classification is done by a preclassifier, such as an impactor, before the particle stream reaches the surface of the filter 9-37 Ensuring Long-Term Protection—Monitoring Performance
Figure 6. Sampling Train
Source: Fundamentals of Air Pollution.
C. Test Method Selection have no promulgated test methods. Air emis- sion testing specialists or consultants can Correct method selection is both scientific often determine appropriate test methods for and subjective. Knowing when to utilize the most of these compounds. Usually, the test- appropriate method for a given circumstance ing involves adapting an existing method to is very important, since incorrect or inaccu- the constituent of interest. It is best to use an rate measurement can lead to incorrect existing method whenever possible. If using results. The test methods to be used for air an existing method is impractical, you can emission monitoring are typically specified develop a test method particular to that con- by applicable regulations; and the type of stituent to monitor for it. You should seek facility will often determine the regulations or the advice or assistance of a professional if standards which are applicable. In general, this is the case and consult your state and most EPA test methods applicable to a facility local air quality offices. will be contained in the Code of Federal Regulations (40 CFR Parts 60, 61, 63, and 51). Other test methods might be specified D. Sampling Site Selection by the EPA Office of Solid Waste or the Sampling activities are typically undertaken National Institute for Occupational Safety to determine the ambient air quality for com- and Health (primarily for indoor air monitor- pliance with air quality standards, to evaluate ing). Additionally, some states and local air the effectiveness of air pollution control tech- pollution control agencies have their own test niques being implemented at the site, to eval- methods that differ from EPA methods, the uate hazards associated with accidental spills, use of which might be required in lieu of and to collect data for air emissions and dis- EPA methods. The CFR specifies test meth- persion modeling. The purpose or use of the ods for testing for numerous compounds and results of the monitoring program determines various parameters necessary for determining the sampling site selection. The fundamental constituent concentrations and emission reason for controlling air pollution sources is rates. New regulations, however, are being to limit the concentration of contaminants in developed for many compounds that, as yet,
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the atmosphere so that adverse effects do not meters above ground (Boubel, p. 192.), in a occur. Sampling sites should therefore be place where the results are not influenced by a selected to measure constituent levels close to nearby source such as a roadway. Sampling or representative of exposed populations of sites might require electrical power and ade- people, plants, trees, materials, or structures. quate protection (which can be as simple as a As a result, ambient air monitoring sites are fence). A shelter, such as a small building, typically located near ground level, about 3 might be necessary. Permanent sampling sites (when necessary) will require adequate heat- ing and air conditioning to provide a stable EPA Test Methods environment for the sampling and monitoring EPA test methods are available for a equipment. variety of compounds and parameters, including but not limited to the follow- ing examples: V. Sampling and • Particulate Matter Analytical • Volatile Organic Compounds (VOC) • Sulfur Dioxide Protocols and • Nitrogen Oxide Quality • Visible Emissions Assurance and • Carbon Monoxide Quality Control • Hydrogen Sulfide The best designed monitoring program • Inorganic Lead will not provide useful data in the absence of sound sampling and analytical protocols. • Total Fluoride Sampling and analytical protocols are gener- • Landfill Gas (gas production flow ally contaminant specific. A correctly rate) designed and implemented sampling and analysis protocol helps ensure that sampling • Nonmethane Organic Compounds results accurately represent media quality and (NMOC) (in landfill gases) can be compared over time. The accurate • Hydrogen Chloride representation is demonstrated through statis- tical analysis. • Gaseous Organic Compounds Whether or not an established quality • Polychlorinated Dibenzo-p-dioxins assurance and quality control (QA/QC) pro- and Polychlorinated Dibenzofurans gram is required on a federal, state, or local • Stack Gas Velocity and Volumetric level, it is a good management practice to Flow Rate develop and strictly implement such a plan. The sampling protocol should incorporate • Gas Analysis for Carbon Dioxide, federal, state, and local QA/QC requirements. Excess Air, and Dry Molecular Weight Sampling QA/QC procedures detail steps for • Moisture Content in Stack Gases collection and handling of samples. Sample collection, preservation, shipment, storage,
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and analysis should be performed in accor- • Description of the methods used for dance with an approved QA/QC program to sampling and analysis. ensure data of known quality are generated. • Sampling manifold and instrument You should rely on qualified professionals configuration. who are properly trained to conduct sam- • Appropriate multipoint calibration pling. Poorly-conducted sampling can give procedures. false evidence of a contamination problem or can miss early warnings of contaminant • Zero/span checks and record of leaching. Erring in either direction is an adjustments. avoidable and costly mistake. • Control specification checks and their frequency. • Control limits for zero, span, and other control limits. • The corrective actions to be taken when control limits are exceeded. • Preventative maintenance. • Recording and validation of data. • Documentation of quality assurance activities. At a minimum, you should include the States have developed guidance docu- following in your sampling protocol: ments addressing sampling plans, protocols, • Data quality objectives including lists and reports. You should work with the state of important tracking parameters, to develop an effective sampling protocol. such as the date and name of sam- • You should consult with soil special- ples. ists at the state and local environ- • Sample collection procedures, mental/planning offices, your local including description of sample col- cooperative extension service office, lection methods, and lists of neces- or the county conservation district sary field analyses. office before implementing a soil • Instructions for sample preservation monitoring program for your unit. and handling. (For more information, visit the USDA Cooperative State Research, • Other QA/QC procedures such as Education, and Extension Service chain-of-custody. Web site at:
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potentialities and problems of use for tion. The SOURCE also includes con- the soils in your area. You can also nections to technical material consult the Natural Resources through an automatic facsimile link Conservation Service (NRCS) Web and with technical staff during work- site at
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contamination of samples. (As an example of • Sample preservation. The time some of the sample collection guidance avail- between sampling and sample analy- able, Section A.4 of the Annual Book of ASTM sis can range from several hours to Standards lists guides for ground-water sam- several weeks. Immediate sample pling.) You should consider the following fac- preservation and storage assists in tors when preparing for sample collection. maintaining the natural chemistry of the samples. The latest edition of • Sample collection. The equipment SW-846 provides specific preserva- used to collect samples should be tion methods and holding times for appropriate for the monitoring para- each constituent analyzed. SW- 846 meters. Sampling equipment should recommends preservation methods, cause minimal agitation of the sam- such as pH adjustment, chemical ple and reduce or eliminate contact addition, and refrigeration. between the sample and environmen- tal contaminants during transfer to • Sample transport. To document ensure it is representative. sample possession from the time of collection to the laboratory, include a • Field analysis. Some constituents or chain-of-custody record in every sam- parameters can be physically or chem- ple shipment. A chain-of- custody ically unstable and should be tested in record generally includes the date the field rather than waiting for ship- and time of collection, signatures of ment to a laboratory. Examples of those involved in the chain of posses- unstable parameters include pH, sion, time and dates of possession, redox (oxidation-reduction) potential, and other notations to trace samples. dissolved oxygen, temperature, and specific conductance. D. Quality Assurance and C. Sample Preservation Quality Control and Handling To verify the accuracy of field sampling procedures, you should collect field quality Sample preservation and handling proto- control samples, such as trip blanks, field cols are designed to minimize alterations of blank, equipment blanks, spilt samples, the chemistry of samples between the time blinds, and duplicates. Table 5 below sum- the sample is collected and when it is ana- marizes these common types of QA/QC sam- lyzed. You should consider the following. ples. Analyze quality control samples for the • Sample containers. To avoid altering required monitoring parameters. Other sample quality, transfer samples from QA/QC practices include sampling equip- the sampling equipment directly into ment calibration, equipment decontamina- a contaminant free container. SW- tion, and use of chain-of-custody forms. 846, identifies proper sample con- ASTM Guide D-5283 Standard Practice for tainers for different constituents and Generation of Environmental Data Related to media. Samples should not be com- Waste Management Activities: Quality Assurance bined in a common sample container and Quality Control Planning and and then split later in the field. Implementation provides guidance on QA/QC
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Table 5 Types of QA/QC Samples
Type of Sample Purpose Frequency
Trip Blank Used for volatile organic com- Trip blanks provide a quality assur- One trip blank for each cooler pounds (VOCs) only. Trip blanks ance test for detecting contamination used during a sampling episode are prepared at the analyzing labo- from improper sample container should be prepared for each ratory and transported to the field (vial) cleaning prior to shipping to volatile organic method to be used with the empty vials to be used in the field, the use of contaminated in the field. For example, if 2 the VOC field sampling. They con- water in analyzing the samples in volatile organic methods are to be sist of a sealed vial filled with ana- the laboratory, VOC contamination used over 2 days with samples lyte-free water (i.e., de-ionized occurring during sample storage or being sent to the lab at the end of water). The water should be the transport, and any other environ- each day, then a total of 4 trip same as the water the laboratory mental conditions that could result blanks would be needed (i.e., Day will use in analyzing the actual in VOC contamination of samples 1: 1 cooler with samples from 2 samples collected in the field, and during the sampling event. methods = 2 trip blanks; Day 2: 1 include any preservatives or addi- cooler with samples from 2 tives that will be used. They are methods = 2 trip blanks; total trip handled, stored, and transported blanks = 4). in the exact same manner as the field samples. Trip blanks should never be opened in the field.
Field Blank A sample collected in the field by Field blanks are used to evaluate the One field blank should be filling a vial with analyte-free water effects of onsite environmental conta- prepared for each parameter being and all preservatives or additives minants, the purity of the preserva- sampled and analyzed per day, or that will be added to actual sam- tives and additives used, and general at a rate of 5 percent of the ples. Field blanks should be pre- sample collecting and container filling. samples in a parameter group per pared under the exact same day, whichever is larger. For conditions in the same location as example if 3 parameter groups actual samples either in the middle were to be sampled over 2 days or at the end of each sampling then 6 field blanks would be episode. They also should be han- required (i.e., 3 parameter groups dled, stored, and transported in x 2 days = 6 field blanks). the exact same manner as the actu- al samples.
Equipment Blank A sample prepared by pouring Equipment blanks are used to deter- At least one equipment blank analyte-free water through or over mine the effectiveness of the field should be prepared for each piece a decontaminated piece of sam- cleaning of sampling equipment. of equipment used in sampling pling equipment. The blank Generally, they are necessary when that must be field cleaned. Each should be prepared on site. sampling equipment must be time an equipment blank is Equipment blanks should be han- cleaned in the field and reused for required, a sample should be dled, stored, and transported in subsequent sampling. prepared for each parameter group the exact same manner as the actu- being assessed. For example, if al samples. samples are taken for 3 parameter groups, and a piece of sampling equipment requires cleaning then a total of 3 equipment blanks will be required for each required cleaning (i.e., 1 piece of equipment x 3 parameter groups = 3 equipment blanks per cleaning).
9-43 Ensuring Long-Term Protection—Monitoring Performance
Table 5 Types of QA/QC Samples (cont.)
Type of Sample Purpose Frequency
Split (Replicate) Sample A sample that is divided into 2 or Split samples are used to assess sam- (No guidance on frequency more containers and sent for pling and analytical techniques. provided) analysis by separate laboratories. Samples can be divided into por- tions (split) at different points in the sampling and analysis process to assess the precision of various com- ponents of the sampling and analysis system. For example, a sample split in the field (field replicate) is used to assess sample storage, shipment, preparation, analysis, and data reduction. A sample split just prior to laboratory analysis (analysis repli- cate) is used to assess the precision of analytical instrumentation.
Duplicates Samples collected simultaneously Duplicate samples are used to assess (No guidance on frequency from the same source under identi- the precision of sampling techniques provided) cal conditions (e.g., same type of and laboratory equipment. sampling techniques and equip- ment).
Blinds A sample prepared prior to a sam- Blinds are used to validate the accu- (No guidance on frequency pling episode by the laboratory or racy and precision of the analyzing provided) an independent source. The blind laboratories sample analyses. contains a specific amount of ana- lyte known by the preparer, but that is unknown to the analyst at the time of analysis.
planning and implementation for waste man- program. Most facility managers use commer- agement activities. Chapter 1 of SW-846 also cial laboratories to conduct analyses of sam- provides guidance on QA/QC practices. ples; others might use their own internal laboratories if they are equipped and qualified to perform such analyses. In selecting an ana- E. Analytical Protocols lytical laboratory, check for the following: lab- Monitoring programs should employ ana- oratory certification by a state or professional lytical methods that accurately measure the association for the type of analyses needed; constituents being monitored. SW-846 rec- qualified lab personnel; good quality analyti- ommends specific analytical methods to test cal equipment with back-up instrumentation; for various constituents. Similarly, individual a laboratory QA/QC program; proper lab doc- states might recommend other analytical umentation; and adherence to standard proce- methods for analysis. dures for data handling, reporting, and record keeping. Laboratory QA/QC programs should Ensure the reliability and validity of analyt- describe chain-of-custody procedures, calibra- ical laboratory data as part of the monitoring tion procedures and frequency, analytical
9-44 Ensuring Long-Term Protection—Monitoring Performance
standard operating procedures, and data vali- normal or lognormal). Examples of two statis- dation and reporting procedures. A good tical approaches include inter-well (upgradient QA/QC program helps ensure the accuracy of vs. downgradient) or intra-well comparisons. laboratory data. After consulting with the state agency and sta- tistical professional and selecting a statistical approach, continue to use the selected method in all statistical analyses. Do not VI. Analysis of switch to a different test when the first Monitoring Data, method generates unfavorable results. Contingency What is important in selecting a Planning, and statistical approach? An appropriate statistical approach will Assessment minimize false positives or negatives in terms Monitoring of potential releases. The approach should account for historical data, site conditions, Once monitoring data have been collected, site operating practices, and seasonal varia- the data are analyzed to determine whether tions. While there are numerous statistical contaminants are migrating from a waste man- approaches used to evaluate monitoring data, agement unit. You should develop a contin- check with the state to determine if a specific gency plan to address the situations where statistical approach is recommended. contamination is detected. Common methods for evaluating monitoring data include the following statistical approaches: A. Statistical Approaches • Tolerance intervals. Tolerance inter- Statistical procedures should be used to vals are statistical intervals construct- evaluate monitoring data and determine if ed from data designed to contain a there is evidence of a release from a waste portion of a population, such as 95 management unit. Anomalous data can result percent of all sample measurements. from sampling uncertainty, laboratory error, or seasonal changes in natural site conditions. • Prediction intervals. These intervals Qualified statistical professionals can deter- approximate future sample values mine if statistically significant changes have from a population or distribution occurred or whether the quantified differences with a specific probability. Prediction could have arisen solely because of one of the above-listed factors. Selecting the appropriate statistical method is very important to avoid generating false positive or false negatives. In monitoring groundwater, for example, the selection of the appropriate statistical method will be contingent upon an adequate review and evaluation of the background groundwa- ter data. These data should be evaluated for properties such as independence, trends, detection frequency and distribution (e.g.,
9-45 Ensuring Long-Term Protection—Monitoring Performance
intervals can be used both for com- tions of contamination. Once a statistically parison of current monitoring data to significant change has been confirmed for previous data for the same site. one or more of the sampling parameters, you should determine whether the change was • Control charts. These charts use his- caused by factors unrelated to the unit. torical data for comparison purposes Factors unrelated to the unit that might cause and are, therefore, only appropriate a change in the detected concentration(s) are: for initially uncontaminated sites. • Contaminant sources other than the There are many different ways to select an waste management unit being moni- appropriate statistical method. For more tored. detailed guidance on statistical methods for ground-water contaminant detection moni- • Natural variations in the quality of toring, consult Addendum to Interim Final the media being monitored. Guidance Document on Statistical Analysis of • Analytical errors. Ground-Water Monitoring Data at RCRA Facilities (U.S. EPA, 1993); Guidance • Statistical errors. Document on Statistical Analysis of Ground- • Sampling errors. Water Monitoring Data at RCRA Facilities- Interim Final Guidance (U.S. EPA, 1989); and If the change was caused by a factor unre- ASTM provisional guide PS 64- 96 in the lated to the unit, then additional measures Annual Book of ASTM Standards. might not be necessary and the original mon- itoring program can be resumed. If, however, these factors have been ruled out, you should B. Contingency Planning begin an assessment monitoring program. Contingency plans identify the procedures You should consult with the state agency to to follow if a statistically significant change in determine the type of assessment monitoring one or more constituents has been detected. to conduct at the unit. Assessment monitor- A contingency plan should include proce- ing typically involves resampling at all sites, dures to determine whether a change in sam- and analyzing the samples for a larger list of ple concentrations was caused by the waste parameters than used during the basic moni- management unit or by unrelated factors; toring program. More than one sampling procedures for developing and conducting an event might be necessary and additional assessment monitoring program; procedures monitoring might need to be performed to for remediating the waste management unit adequately determine the scope or extent of to stop the release of contaminants; and a any contamination. It is recommended that determination of the magnitude of contami- you work with state officials to establish nation that would require initiation of correc- background concentrations and protection tive action, such as a statistical exceedance of standards for all additional constituents that an HBN, an MCL for surface or ground were detected during assessment monitoring. water, or a site-specific risk-based number. If assessment monitoring results indicate there is not a statistically significant change in the concentrations of one or more of the C. Assessment Monitoring constituents over the established protection The purpose of assessment monitoring is standards, then you can resume the original to evaluate the rate, extent, and concentra- monitoring program. If, however, there is a
9-46 Ensuring Long-Term Protection—Monitoring Performance
statistically significant change in any of these constituents, consult with state officials to identify the next steps. It might be necessary to perform additional monitoring to charac- terize the nature and extent of the contamina- tion and to notify persons who own or reside on any land directly impacted by the contam- ination if it has migrated beyond the facility boundary. Detection of contamination can be an indi- cator that the waste management unit’s con- tainment system is not working properly. During this assessment phase, component(s) of the unit (cover, liner, or leachate collection system) that are not working properly should be identified and, if possible, remediated. For example, sometimes sealing a hole in the liner of a small surface impoundment can be sufficient to stop the source of contamination. Other times, more extensive response might be required. One example could be the extensive subsidence of a unit’s final cover creating the need for repair. In some cases, liner and leachate collection system repairs might not be possible, such as in a large sur- face impoundment or a landfill with several tons of waste already in place. If remediation is not possible, consult with state officials about beginning assessment monitoring and consult Chapter 10–Taking Corrective Action.
9-47 Ensuring Long-Term Protection—Monitoring Performance
Monitoring Performance Activity List
You should consider the following for each media when developing a monitoring program for industrial waste management units:
Ground Water ■ Perform a site characterization, including investigation of the site’s geology, hydrology, and subsur- face hydrogeology to determine areas for ground-water monitoring; select parameters to be moni- tored based on the characteristics of the waste managed. ■ Identify qualified engineers and ground-water specialists to assist in designing and operating the ground-water monitoring program. ■ Consult with qualified professionals to identify necessary program components including the mon- itoring well design, the number of monitoring wells, the lateral and vertical placement of the wells, the duration and frequency of monitoring, and the appropriate sampling parameters. ■ Determine the appropriate method(s) of ground-water monitoring, including conventional well monitoring, direct push sampling, geophysical monitoring, and vadose zone monitoring as possi- bilities. ■ Use qualified laboratories to analyze samples.
Surface Water ■ Collect and analyze samples according to the requirements of a site’s federal or state storm-water permit. ■ If not subject to permit requirements, implement a storm-water sampling program to monitor the quality of runoff and determine the effectiveness of BMPs. ■ If applicable, collect and analyze discharges to POTWs according to any requirements of a local pretreatment program. ■ Implement a surface-water sampling program to monitor water quality and determine the effec- tiveness of BMPs. ■ Perform regular inspections and maintenance of surface-water protection measures and BMPs to reduce the potential for surface-water contamination. ■ Use qualified laboratories to analyze samples.
Soil Monitoring ■ Determine the number and location of samples needed to adequately characterize soil according to the variability of the soil at a site. ■ Follow established soil-sampling procedures to obtain meaningful results. ■ Use qualified laboratories to analyze samples.
9-48 Ensuring Long-Term Protection—Monitoring Performance
Monitoring Performance Activity List (cont.)
■ Determine baseline soil conditions by sampling prior to waste application. ■ Collect and analyze samples at regular intervals to detect contaminant problems.
Air Monitoring ■ Use the Industrial Waste Air (IWAIR) Model to evaluate risks from VOC emissions. ■ Use an alternative emissions model if the IWAIR Model indicates a problem with VOC emission or is not appropriate for your site. ■ If collecting air monitoring data, determine the type of monitoring necessary to evaluate the effec- tiveness of air pollution control techniques employed on site or for input into air emissions and dispersion models. ■ Select the proper test methods. ■ Establish guidelines to ensure the quality of the data collected prior to implementing an air moni- toring program. ■ Consult with air modeling professionals, state and local air quality offices, EPA regional air pro- gram offices, or EPA’s Office of Air Quality Planning and Standards before implementing an air monitoring program or choosing an alternative emission model to evaluate risks. ■ Use qualified laboratories to analyze samples.
Sampling and Analytical Protocols QA/QC ■ Develop sample collection, preservation, storage, transport, and handling protocols tailored to data needs, and establish quality assurance and quality control procedures to check the accuracy of the monitoring samples. ■ Eliminate cross-contamination or background contamination of any samples by purging the wells, using appropriate sampling equipment, and ensuring that any unstable parameters, such as pH, dissolved oxygen, and temperature, have been tested at the site. ■ Identify the appropriate analytical methods and statistical approach for the sampling data includ- ing parametric analysis of variance (ANOVA), tolerance intervals, prediction intervals, and control charts as possibilities. ■ Evaluate the need for assessment monitoring and abatement.
9-49 Ensuring Long-Term Protection—Monitoring Performance
Resources
Site Characterization American Society for Testing and Materials. 2001. Annual Book of ASTM Standards. ASTM.
American Society for Testing and Materials. 1994. ASTM Standards on Ground Water and Vadose Zone Investigations, 2nd Edition. ASTM.
ASTM D-1452. 1980. Practice for Soil Investigation and Sampling by Auger Borings.
ASTM D-1586. 1984. Test Method for Penetration Test and Split-Barrel Sampling of Soils
ASTM D-1587. 1983. Practice for Thin-Walled Tube Sampling of Soils.
ASTM D-3550. 1988. Practice for Ring-Lined Barrel Sampling of Soils..
ASTM D-4220. 1989. Practices for Preserving and Transporting Soil Samples.
ASTM D-5792. 1995. Standard Practice for Generation of Environmental Data Related to Waste Management Activities: Development of Data Quality Objectives.
Boulding, J.R. 1995. Practical Handbook of Soil, Vadose Zone, and Ground Water Contamination: Assessment, Prevention and Remediation. Lewis Publishers.
CCME. 1994. Subsurface Assessment Handbook for Contaminated Sites, CCME EPC-NCSRP-48E, Canadian Council of Ministers of the Environment.
Morrison, R.D. 1983. Groundwater Monitoring Technology. Timco Mfg. Inc.
Sara, M.N. 1994. Standard Handbook for Solid and Hazardous Waste Facility Assessments. Lewis Publishers.
Topp, G.C. and J.L. Davis. 1985. “Measurement of Soil Water Using Time-Domain Reflectometry (TDR): A Field Evaluation,” Soil Science Society of America Journal. 49:19-24.
U.S. EPA. 1993. Subsurface Characterization and Monitoring Techniques: A Desk Reference Guide. Volume I: Solids and Ground Water, Appendices A and B. EPA625-R-93-003a.
U.S. EPA. 1993. Subsurface Characterization and Monitoring Techniques: A Desk Reference Guide. Volume II: The Vadose Zone, Field Screening and Analytical Methods, Appendices C and D. EPA625- R-93-003b.
9-50 Ensuring Long-Term Protection—Monitoring Performance
Resources (cont.)
U.S. EPA. 1988. Criteria for Municipal Solid Waste Landfills: Draft background Document. EPA530- SW- 88-042.
U.S. EPA. 1987. DRASTIC: A Standardized System for Evaluating Ground Water Pollution Potential Using Hydrogeologic Settings. EPA600-2-87-035.
Wilson, L.G., L.G. Everett, and S.J. Cullen (eds.). 1995. Handbook of Vadose Zone Characterization and Monitoring. Lewis Publishers.
Ground-Water Monitoring Well Design, Installation, and Development Cullen, S.J. 1995. Vadose Zone Monitoring: Experiences and Trends in the United States. Ground Water Monitoring Review 15(3):136-143.
Cullen, S.J., J.K. Kramer, and J.R. Luellen. 1995. A Systematic Approach to Designing a Multiphase Unsaturated Zone Monitoring Network. Ground Water Monitoring Review 15(3):124-135.
Geoprobe Systems. 1996. Geoprobe Prepacked Screen Monitoring Well: Standard Operating Procedure. Technical Bulletin No. 96-2000.
Hayes, J.P. and D.C. Tight. 1995. Applying Electrical Resistance Blocks for Unsaturated Zone Monitoring at Arid Sites. Handbook of Vadose Zone Characterization and Monitoring. L.G. Wilson, L.G. Everett, and S.J. Cullen (eds.). Lewis Publishers. pp. 387-399.
Kramer, J.H., S.J. Cullen, and L.G. Everett. 1992. Vadose Zone Monitoring with the Neutron Moisture Probe. Ground Water Monitoring Review 12(3):177-187.
Ohio Environmental Protection Agency. 1995. Technical Guidance Manual for Hydrogeologic Investigations and Ground Water Monitoring.
Robbins, G.A. and M.M. Gemmell. 1985. Factors Requiring Resolution in Installing Vadose Zone Monitoring Systems. Ground Water Monitoring Review 5:76-80.
U.S. EPA. 1993a. Ground-Water Monitoring: Draft Technical Guidance. EPA530-R-93-001.
U.S. EPA. 1993b. Solid Waste Disposal Facility Criteria: Technical Manual. Chapter 5. EPA530-R-93- 017.
U.S. EPA. 1991. Handbook: Ground Water. Volume II: Methodology. EPA625-6-90-016b.
9-51 Ensuring Long-Term Protection—Monitoring Performance
Resources (cont.)
U.S. EPA. 1990. Handbook: Ground Water. Volume I: Ground Water and Contamination. EPA625-6-90- 016a.
U.S. EPA. 1989. Handbook of Suggested Practices for the Design and Installation of Ground- Water Monitoring Wells. EPA600-4-89-034.
Sample Procedures ASTM. D-5283. 1997. Standard Practice for Generation of Environmental Data Related to Waste Management Activities: Quality Assurance and Quality Control Planning and Implementation.
Benson, R.C., R.A. Glaccum, and M.R. Noel. 1984. Geophysical Techniques for Sensing Buried Wastes and Waste Migration. EPA600-7-84-064.
Bond, W.R. 1995. Case Studies of Vadose Zone Monitoring and Sampling Using Porous Suction Cup Samplers. Handbook of Vadose Zone Characterization and Monitoring. L.G. Wilson, L.G. Everett, and S.J. Cullen (eds.). Lewis Publishers. pp. 523-532.
Federal Remediation Technologies Roundtable. 2001. Field Sampling and Analysis Technologies Matrix. Version 1.0.
Gibbons, R.D. 1990. Estimating the Precision of Ground-Water Elevation Data. Ground Water, 28, 357- 360.
Minnesota Pollution Control Agency. 1995. Ground Water Sampling Guidance: Development of Sampling Plans, Protocols and Reports.
Texas Natural Resource Conservation Commission. 1994. TNRCC Technical Guidance: Guidelines for Preparing a Ground-Water Sampling and Analysis Plan (GWSAP).
Thomson, K.A. 1995. Case Studies of Soil Gas Sampling. Handbook of Vadose Zone Characterization and Monitoring. L.G. Wilson, L.G. Everett, and S.J. Cullen (eds.). Lewis Publishers. pp. 569-588.
U.S. EPA. 1995a. Ground Water Sampling—A Workshop Summary. EPA600-R-94-205.
U.S. EPA. 1995b. Laboratory Methods for Soil and Foliar Analysis in Long-term Environmental Monitoring Program. EPA600-R-95-077
9-52 Ensuring Long-Term Protection—Monitoring Performance
Resources (cont.)
U.S. EPA. 1995c. Low Flow Ground-Water Sampling. EPA540-S-95-504.
U.S. EPA. 1994a. Industrial User Inspection and Sampling Manual for POTWs.
U.S. EPA. 1994b. Region VIII Guidance, Standard Operating Procedures for Field Sampling Activities.
U.S. EPA. 1992. NPDES Storm Water Sampling Guidance Document. EPA833-B-92-001.
U.S. EPA. 1991. Description and Sampling of Contaminated Soils: A Field Pocket Guide. EPA625-12- 91-002
U.S. EPA. 1989. Interim Final RCRA Facility Investigation (RFI) Guidance: Volumes I-III. EPA530- SW- 89-031.
U.S. EPA. 1986. Test Methods for Evaluating Solid Waste—Physical/Chemical Methods. EPA SW-846, 3rd edition. PB88-239-233.
Surface Water Monitoring Novotny, V., and H. Olem. 1994. Water Quality: Prevention, Identification, and Management of Diffuse Pollution. Van Nostrand Reinhold.
U.S. EPA. 1999. Introduction to the National Pretreatment Program. EPA833-B-98-002.
U.S. EPA. 1997. Volunteer Stream Monitoring Document. EPA841-B-97-003.
U.S. EPA. 1991. Volunteer Lake Monitoring Document. EPA440-4-91-002.
Soil Monitoring Delaware Cooperative Extension Service. 1995. Recommended Soil Testing Procedures for the Northeastern United States. 2nd Edition. Northeastern Regional Publication No. 493.
North Carolina Cooperative Extension Service. 1994. Soil facts: Careful Soil Sampling - The Key to Reliable Soil Test Information. AG-439-30.
Rowell, D.L. 1994. Soil Science: Methods and Applications.
Soil Quality Institute of the National Resources Conservation Service, USDA. 2001. Guidelines for Soil Quality Assessment in Conservation Planning.
9-53 Ensuring Long-Term Protection—Monitoring Performance
Resources (cont.)
University of Nebraska Cooperative Extension Institute of Agriculture and Natural Resources. 1991. Guidelines for Soil Sampling. G91-1000-A. February.
U.S. EPA. 1995d. Laboratory Methods for Soil and Foliar Analysis in Long-Term Environmental Monitoring Programs. EPA600-R-95-077.
U.S. EPA. 1989. RCRA Facility Investigation Guidance: Volume II: Soil, Ground Water and Subsurface Gas Releases. EPA530-SW-89-031
Air Monitoring Boubel, R. W., D. L. Fox, D. B. Turner, and A. C. Stern. 1994. Fundamentals of Air Pollution. 3rd Edition. Academic Press.
Stull, Roland B. 1988. An Introduction to Boundary Layer Meteorology. Kluwer Academic Publishers.
Yoest, H. and R. W. Fitzgerald. February 1996. Chemical Engineering Progress. Stationary Source Testing: The Fundamentals.
U.S. EPA. 1993. Air/Superfund National Technical Guidance Study Series: Compilation of Information on Real-time Air Monitoring for Use at Superfund Sites. EPA451-R-93-008.
U.S. EPA. 1993. Air/Superfund National Technical Guidance Study Series: Volume 4: Guidance for Ambient Air Monitoring at Superfund Sites, Revised. EPA451-R-93-007.
U.S. EPA. 1990. Guidance on Applying the Data Quality Objectives Process for Ambient Air Monitoring Around Superfund Sites (Stages 1 and 2). EPA450-4-90-005.
U.S. EPA. 1990. Air/Superfund National Technical Guidance Study Series: Contingency Plans at Superfund Sites Using Air Monitoring. EPA450-1-90-005.
U.S. EPA. 1989. Air/Superfund National Technical Guidance Study Series, Volume 4: Procedures for Dispersion Modeling and Air Monitoring for Superfund Air Pathway Analysis, Interim Report, Final. EPA450-1-89-004.
U.S. EPA. 1986. Test methods for Evaluating Solid Waste. 3rd Edition. Office of Solid Waste and Emergency Response. SW-846.
Statistical References Davis, C.B. and McNichols, R.J. 1987. One-Sided Intervals for at Least p of m Observations from a Normal Population on Each of r Future Occasions. Technometrics, 29, 359-370.
9-54 Ensuring Long-Term Protection—Monitoring Performance
Resources (cont.)
Gibbons, R.D. 1994. Statistical Methods for Ground-Water Monitoring. John Wiley & Sons.
Gibbons, R.D. 1992. An Overview of Statistical Methods for Ground-Water Detection Monitoring at Waste Disposal Facilities. In Ground-Water Contamination at Hazardous Waste Sites: Chemical Analysis. S. Lesge and R.E. Jackson (eds.), New York: Marcel Dekker, Inc.
Gibbons, R.D., Dolan, D., Keough, H., O’Leary, K., and O’Hara, R. 1992. A Comparison of Chemical Constituents in Leachate from Industrial Hazardous Waste and Municipal Solid Waste Landfills. Proceedings of the Fifteenth Annual Madison Waste Conference, University of Wisconsin, Madison.
Gibbons, R.D., Gams, N.E., Jarke, F.H., and Stoub, K.P. 1992. Practical Quantitation Limits. Chemometrics and Intelligent Laboratory Systems, 12, 225-235.
Gibbons, R.D. 1991. Some Additional Nonparametric Prediction Limits for Ground-Water Monitoring at Waste Disposal Facilities. Ground Water, 29, 729-736.
Gibbons, R.D., Jarke, F.H., and Stoub, K.P. 1991. Detection Limits: For Linear Calibration Curves with Increasing Variance and Multiple Future Detection Decisions. Waste Testing and Quality Assurance. 3, ASTM, SPT 1075, 377-390.
Gibbons, R.D. and Baker, J. 1991. The Properties of Various Statistical Prediction Limits. Journal of Environmental Science and Health. A26-4, 535-553.
Gibbons, R.D. 1991. Statistical Tolerance Limits for Ground-Water Monitoring. Ground Water 29.
Gibbons, R.D. 1990. A General Statistical Procedure for Ground-Water Detection Monitoring at Waste Disposal Facilities. Ground Water, 28, 235-243.
Gibbons, R.D., Grams, N.E., Jarke, F.H., and Stoub, K.P. 1990. Practical Quantitation Limits. Proceedings of Sixth Annual U.S. EPA Waste Testing and Quality Assurance Symposium. Vol. 1, 126- 142.
Gibbons, R.D., Jarke, F.H., and Stoub, K.P. 1989. Methods Detection Limits. Proceedings of Fifth Annual U.S. EPA Waste Testing and Quality Assurance Symposium. Vol. 2, 292-319.
Gibbons, R.D. 1987. Statistical Prediction Intervals for the Evaluation of Ground-Water Quality. Ground Water, 25, 455-465.
9-55 Ensuring Long-Term Protection—Monitoring Performance
Resources (cont.)
Gibbons, R.D. 1987. Statistical Models for the Analysis of Volatile Organic Compounds in Waste Disposal Facilities. Ground Water 25, 572-580.
Gilbert, R.O. 1987. Statistical Methods for Environmental Pollution Monitoring. Van Nostrand Reinhold, New York.
Starks, T.H. 1988. Evaluation of Control Chart Methodologies for RCRA Waste Sites. U.S. EPA Technical Report CR814342-01-3.
Patil, G.P. and Rao, C.R. eds, Elsevier. 1993. Handbook of Statistics, Vol 12: Environmental Statistics.
U.S. EPA. 1993. Addendum to Interim Final Guidance Document Statistical Analysis of Ground-Water Monitoring Data at RCRA facilities. EPA530-R-93-003.
U.S. EPA. 1989. Guidance Document on Statistical Analysis of Ground-Water Monitoring Data at RCRA Facilities–Interim Final Guidance.
9-56 Part V Ensuring Long-Term Protection
Chapter 10 Taking Corrective Action Contents
I. Corrective Action Process...... 10-1 A. Unit Assessment ...... 10-2 B. Unit Investigation ...... 10-4 1. Specific Considerations for Ground-Water Investigations ...... 10-5 2. Specific Considerations for Soil Investigations ...... 10-6 3. Specific Considerations for Surface-Water Investigations ...... 10-6 4. Specific Consideration for Air-Release Investigations ...... 10-7 C. Interim Measures ...... 10-8 D. Evaluating Potential Corrective Measures ...... 10-10 1. Meeting Cleanup Standards ...... 10-11 2. Evaluating Treatment Technologies...... 10-12 3. Evaluating the Long- and Short-Term Effectiveness of the Remedy...... 10-18 4. Evaluating the Effectiveness of Reducing or Eliminating the Source of Contamination...... 10-19 5. Evaluating the Ease of Implementation...... 10-19 6. Measuring the Degree to Which Community Concerns are Met ...... 10-20 E. Implementing Corrective Measures ...... 10-20 1. Institutional Controls ...... 10-20 2. Monitoring and Site Maintenance ...... 10-22 3. No Further Action and Site Closure ...... 10-22
Taking Corrective Action Activity List ...... 10-23
Resources ...... 10-24
Figures: Figure 1. Corrective Action Process...... 10-2 Figure 2. Screening Process for Selecting Appropriate Treatment Technologies ...... 10-17
Tables: Table 1 Factors To Consider in Conducting a Unit Assessment...... 10-3 Table 2 Chemical Characteristics...... 10-3 Table 3 Site Characteristics ...... 10-4 Table 4 Potential Release Mechanisms for Various Unit Types...... 10-7 Table 5 Examples of Interim Corrective Measures ...... 10-8 Ensuring Long-Term Protection—Taking Corrective Action
Taking Corrective Action This chapter will help you: • Monitor the performance of a waste management unit and take appropriate steps to remediate any contamination associated with its operation. • Locate and characterize the source of any contamination. • Identify and evaluate potential corrective measures. • Select and implement corrective measures to achieve attainment of the established cleanup standard. • Work closely with the state and community representatives.
ffective operation of a waste man- I. Corrective agement unit involves checking the performance of the waste man- Action Process agement system components. The purpose of a corrective action program When components are not operat- is to assess the nature and extent of the releas- Eing effectively or when a problem develops, es of waste or constituents from the waste corrective action might be needed to protect management unit(s); to evaluate unit charac- human health and the environment. teristics; and to identify, evaluate, and imple- Corrective action involves identifying expo- ment appropriate corrective measures to sure pathways of concern, selecting the best protect human health and the environment. corrective measure to achieve the appropriate The overall goal of any corrective action cleanup standard, and consulting with state should be to achieve a technically and eco- and community representatives. nomically feasible cleanup standard at a speci- fied point on the facility property. For new This chapter will help address the follow- facilities this point should be on facility prop- ing questions. erty, no more than 150 meters from the waste management unit boundary (as established in • What steps are associated with correc- Chapter 9–Monitoring Performance). Existing tive action? facilities can either use this same 150 meter • What information should be collected monitoring point standard or work with their during investigations? state agencies to determine an alternate set of acceptable monitoring and cleanup criteria. • What factors should be considered in Using the ground-water pathway as an exam- selecting an appropriate corrective mea- ple, the corrective action goal should be to sure? reduce constituent concentration levels to the • What is involved in implementing the applicable maximum contaminant levels selected remedy? (MCLs) or health based numbers at the moni-
10-1 Ensuring Long-Term Protection—Taking Corrective Action
toring point (i.e., for new units, no more than Figure 1 Corrective Action Process 150 meters from the waste management unit). A corrective action program generally has Unit Assessment the components outlined here and in Figure 1 (and explained in greater detail below). The detail required in each of these components Unit Investigation varies depending on the unit and its com- plexity and only those tasks appropriate for your site should be conducted. We recom- Interim Measures mend that you coordinate with the state dur- ing all phases of corrective action. Corrective Measures • Perform a unit assessment to locate Evaluation the actual or potential source(s) of the release(s) of contaminants based on waste management unit monitor- Corrective Measures ing information and the use of other Implementation existing information. • Perform a unit investigation to char- acterize the nature and extent of con- to ensure that human health and the tamination from the unit and any environment are being protected. contamination that might be migrat- ing beyond the facility boundary, identify areas and populations threat- A. Unit Assessment ened by releases from the unit, and Often the first activity in the corrective determine short- and long-term action process is the unit assessment. A unit threats of releases from the unit to assessment identifies potential and actual human health and the environment. releases from the unit and makes preliminary • Identify, evaluate, and implement determinations about release pathways, the interim measures, if needed. Interim need for corrective action, and interim mea- measures are short-term actions sures. If appropriate, evaluate the possibility taken to protect human health and of addressing mul- the environment while a unit assess- tiple units as the ment or a unit investigation is being corrective action performed or before a corrective process proceeds. measure is selected. Table 1 identifies a • Identify, evaluate, and implement number of factors corrective measures to abate the fur- to consider during ther spread of contaminants, control a unit assessment. the source of contamination, and to Tables 2 and 3 pre- remediate releases from the unit. sent some useful properties and • Design a program to monitor the parameters that maintenance and performance of any define chemical interim or final corrective measures
10-2 Ensuring Long-Term Protection—Taking Corrective Action
Table 1 Factors To Consider in Conducting a Unit Assessment
Unit/Site Chemical Migration Evidence of Release Exposure Characteristics Characteristics Pathways Potential
Contamination Type of waste Facility’s Prior inspection reports Proximity to Parameters placed in the unit geological affected – Concentrations setting Citizen complaints population – Depth and location of Volatilization contamination parameters Facility’s Monitoring data Proximity to hydrogeological sensitive Physical Parameters Toxicological setting Visual evidence, such as environments – Geology characteristics discolored soil, seepage, – Depth to ground water Atmospheric discolored surface water Likelihood of – Flow characteristics Physical and conditions or runoff migration to – Climate chemical properties potential Topographic Other physical evidence receptors Historical Information Chemical class characteristics such as fish kills, – History of unit worker illness, or odors – Knowledge of waste Soil sorption/ Manmade generation practices degradation features (e.g., Sampling data parameters pipelines, underground Offsite water wells utility lines)
Table 2 Chemical Characteristics
Property/Parameter Characteristics
Chemical properties Density, viscosity
Chemical class Acid, base, polar neutral, nonpolar neutral, inorganic
Chemical reactivity Oxidation, reduction, hydrolysis, polymerization, precipitation, biotic/abiotic
Soil sorption parameters Cation exchange capacity, anion exchange capacity, soil/water
partition coefficient (Kd), octanol/water partition coefficient (Kow)
Soil degradation parameters Half-life, intermediate products of degradation
Volatilization parameters Henry’s law constant, vapor pressure
10-3 Ensuring Long-Term Protection—Taking Corrective Action
Table 3 Site Characteristics
Parameter/Information Characteristics
Contamination parameters Concentration in soil, water, and subsurface gas; depth and location of contamination
Physical parameters Permeability, particle size distribution, organic matter, geology, moisture content, flow characteristics, depth to ground water, pH, wind directions, climate
Historical information History of the waste management unit, knowledge of waste generation processes, waste quantity
Additional information on performing unit assessments can be found in RCRA Facility Assessment Guidance (U.S. EPA, 1986).
and site characteristics that you should consid- tion of the appropriate response action. It is er when characterizing your site and environ- important to tailor unit investigations to spe- mental setting. cific conditions and circumstances at the unit and focus on releases and potential pathways. A beginning step is to review available site Although each medium will require specific information regarding unit characteristics, data and methodologies to investigate a waste characteristics, contaminant migration release, a general strategy for this investigation, pathways, evidence of release, and exposure consisting of two elements, can be described potential. Much of this information should as follows. have been gathered in the site assessment (see Chapter 4–Considering the Site) and waste • Collect and review monitoring data, characterization phases (see Chapter data which can be gathered from out- 2–Characterizing Waste). Conducting a visual side information sources on parame- site inspection of the unit will re-affirm avail- ters affecting the release, or new able information and enable you to note any information such as aerial photogra- visual evidence of releases. If necessary, per- phy or waste characterization. form sampling to confirm or disprove suspect- • Formulate and implement field inves- ed releases before performing an extensive unit tigations and sampling and analysis or investigation. monitoring procedures designed to verify suspected releases. Evaluate the B. Unit Investigation nature, extent, and rate of migration of verified releases. Refer to Chapter A unit investigation is conducted after a 9–Monitoring Performance to help release from the operating unit has been con- design a monitoring program. firmed. The purpose of the investigation is to gather enough data to fully characterize the Detailed knowledge of source characteristics nature, extent, and rate of migration of conta- is valuable in identifying constituents for minants to determine and support the selec- which to monitor, indicator parameters, and
10-4 Ensuring Long-Term Protection—Taking Corrective Action
Unit investigations can result in significant Guidance on Performing amounts of data, including the results of Unit Investigations chemical, physical, or biological analyses. This can involve analyses of many constituents, in Additional guidance on performing different media, at various sampling locations, unit inspections can be found in the fol- and at different times. Data management pro- lowing EPA documents: cedures should be established to effectively • RCRA Facility Investigation Guidance process these data such that relevant data Volume I: Development of an RFI Work descriptions, such as sample numbers, loca- Plan and General Considerations for tions, procedures, and methods, are readily RCRA Facility Investigations (U.S. EPA, accessible and accurately maintained. 1989a) • RCRA Facility Investigation Guidance 1. Specific Considerations for Volume II: Soil, Ground Water, and Ground-Water Investigations Subsurface Gas Releases (U.S. EPA, To facilitate ground-water investigations 1989b) consider the following parameters: • RCRA Facility Investigation Guidance • Ability of the waste to be dissolved or Volume III: Air and Surface Water to appear as a distinct phase. Releases (U.S. EPA, 1989c) • Degradability of the waste and its • RCRA Facility Investigation Guidance decomposition products. Volume IV: Case Study Examples (U.S. EPA, 1989d) • Geologic and • Guidance for Conducting Remedial hydrolog- Investigations and Feasibility Studies ic factors Under CERCLA (U.S. EPA, 1988a) which • Draft Practical Guide for Assessing and affect the Remediating Contaminated Sites (U.S. release EPA, 1989f) pathway. • Site Characterization for Subsurface • Regional Remediation (U.S. EPA, 1991c) and site- specific ground- possible release pathways. It is also helpful in water linking releases to a particular unit. flow Monitoring information collected by a pro- regimes gram described in Chapter 9–Monitoring that might affect the potential magni- Performance can be helpful. Waste and unit tude of the release pathways and possi- characteristics can also provide information ble exposure routes. for determining release rates and for deter- mining the nature and scope of any corrective Exposure routes of concern include inges- measures which might be applied. Refer to tion of ground water as drinking water and Chapter 2–Characterizing Waste for informa- near-surface flow of contaminated ground tion on how to characterize a waste. water into basements of residences or other
10-5 Ensuring Long-Term Protection—Taking Corrective Action
structures. It is important to also address the • The waste’s affinity for soil particles. potential for the transfer of contaminants in • The waste’s degradability and its ground water to other environmental media decomposition products. through processes such as discharge to surface water and volatilization to the atmosphere. • Surface features such as topography, erosion potential, land-use potential, Use existing ground-water monitoring infor- and vegetation. mation, where it exists, to determine the nature, extent, and rate of contaminant release • Stratigraphic/hydrologic features such from the unit(s) to the ground water. as soil profile, particle-size distribution, Investigation of a suspected release might be hydraulic conductivity, pH, porosity, terminated based on results from an initial and cation exchange capacity. monitoring phase if these results show that an • Meteorological factors such as temper- actual release has not, in fact, occurred. If, ature, precipitation, runoff, and evap- however, contamination is found, you should otranspiration. characterize the release through subsequent monitoring to help determine the detailed con- Relevant physical and chemical properties of stituent composition and concentrations, the the soil should be assessed to help determine horizontal and vertical extent of the contami- potential mobility of any contaminants in the nant release, as well as its rate of migration as soil. Also, consider the potential for transfer of appropriate to assess the risk. This should be contaminants in the soil to other environmental accomplished through direct sampling and media such as overland runoff to surface water, analysis and, when appropriate, can be supple- leaching to ground water, and volatilization to mented by indirect means such as geophysical the atmosphere. In addition, you should estab- assessment and fate and transport modeling. lish whether a potential release involved a point source (localized) or a non-point source. Point sources might include container handling 2. Specific Considerations for Soil and storage areas, tanks, waste piles, and bulk Investigations chemical transfer areas. Non-point sources When performing soil investigations, con- might include airborne particulate contamina- sider the following parameters: tion originating from a land application unit and widespread leachate seeps from a landfill. • Ability of the waste to be dissolved by Table 4 presents important mechanisms of con- infiltrating precipitation. taminant release to soils for various unit types. This information can be used to identify areas for initial soil monitoring.
3. Specific Considerations for Surface-Water Investigations When conducting surface-water investiga- tions, the following factors should be consid- ered: • The release mechanism, such as over- topping of an impoundment.
10-6 Ensuring Long-Term Protection—Taking Corrective Action
Table 4 Potential Release Mechanisms for Various Unit Types
Unit Type Release Mechanism
Surface impoundment Releases from overtopping
Leakage through dikes or unlined portions to surrounding soils
Landfill Migration of releases outside the unit’s runoff collection and containment system
Seepage through underlying soils
Waste pile Migration of releases outside the unit’s runoff collection and containment system
Seepage through underlying soils
Land application unit Migration of runoff outside the application area
Passage of leachate into the soil horizon
• The nature of the source area, such as environmental media such as soil contamina- point or non-point. tion as a result of flooding of a contaminated creek on the facility property. • Waste type and degradability. During the initial investigation, particular • Local climate. attention should be given to sampling runoff • Hydrologic factors such as stream from contaminated areas, leachate seeps, and flow conditions. other similar sources of surface-water contami- • The ability for a contaminant to accu- nation, as these are the primary overland release mulate in stream bottom sediments. pathways for surface water. Releases to surface water via ground-water discharge should be Also, address the potential for the transfer addressed as part of the ground-water investiga- of contaminants in surface water to other tion for greater efficiency. See Chapter 9–Monitoring Performance, Section II: Surface- Water Monitoring for information on proper surface-water monitoring techniques.
4. Specific Consideration for Air- Release Investigations The intent of an air-release investigation is to determine any actual or potential effects at a nearby receptor. This might involve emis-
10-7 Ensuring Long-Term Protection—Taking Corrective Action
sion modeling to estimate unit-specific emis- might involve a unit in an isolated location, sion rates, air monitoring to determine con- where an acceptable modeling or monitoring centrations at a nearby receptor, emission database indicates that the air release can be monitoring at the source to determine emis- considered insignificant and, therefore, fur- sion rates, and dispersion modeling to esti- ther studies are not warranted. In many mate concentrations at a nearby receptor. See cases, however, further release characteriza- Chapter 9–Monitoring Performance, Section tion might be necessary. IV: Air Monitoring for more information on air monitoring and Chapter 5–Protecting Air for more information on air modeling. C. Interim Measures As in other media-specific investigations, Many cleanup programs recognize the the first step is to collect, review, and evaluate need for interim measures while site charac- available waste, unit, environmental setting, terization is underway or before a final reme- and release data. Evaluation of these data can dy is selected. Typically, interim measures are indicate the need for corrective measures or used to control or abate ongoing risks before that no further action is required. For exam- final remedy selection. Examples of interim ple, the source might involve a large, active measures for various types of waste manage- storage surface impoundment containing ment units and various release types are list- volatile constituents adjacent to residential ed in Table 5. More information is available housing. Action, therefore, instead of further through the RCRA Corrective Action Interim studies, might be appropriate. Another case Measures Guidance—Interim Final (U.S. EPA,
Table 5 Examples of Interim Corrective Measures
Unit/Release Interim Measure
Containers Overpack or redrum Construct storage area Move to new storage area Segregation Sampling and analysis Treatment or storage Temporary cover
Tanks Construct overflow/secondary containment Leak detection or repair Partial or complete removal
Surface Impoundments Reduce head Remove free liquids and highly mobile wastes Stabilize or repair side walls, dikes, or liner(s) Temporary cover Run-on or runoff control (diversion or collection devices) Sample and analyze to document the concentration of constituents Interim ground-water measures
10-8 Ensuring Long-Term Protection—Taking Corrective Action
Table 5 Examples of Interim Corrective Measures (cont.)
Unit/Release Interim Measure
Landfills Run-on or runoff control (diversion or collection devices) Reduce head on liner or leachate collection and removal system Inspect leachate collection and removal system, or french drain Repair leachate collection and removal system, or french drain Temporary cap Waste removal Interim ground-water measures
Waste Piles Run-on or runoff control (diversion or collection devices) Temporary cover Waste removal Interim ground-water measures
Soils Sampling or analysis Removal and disposal Run-on or runoff control (diversion or collection devices) Temporary cap or cover
Ground Water Delineation or verification of gross contamination Sampling and analysis Interceptor trench, sump, or subsurface drain Pump-and-treat In situ treatment Temporary cap or cover
Surface-Water Releases Overflow or underflow dams (Point and Non-Point) Filter fences Run-on or runoff control (diversion or collection devices) Regrading or revegetation Sample and analyze surface waters and sediments or point source discharges
Gas Mitigation Control Barriers Collection Treatment Monitoring
Particulate Emissions Truck wash (decontamination unit) Revegetation Application of dust suppressant
Other Actions Fencing to prevent direct contact Sampling offsite areas Alternate water supply to replace contaminated drinking water Temporary relocation of exposed population Temporary or permanent injunction
10-9 Ensuring Long-Term Protection—Taking Corrective Action
1988b) and RCRA Corrective Action Stabilization Technologies (U.S. EPA, 1992b). Potential Corrective Interim measures can be separate from the Measures comprehensive corrective action plan, but should be consistent with and integrated into Additional guidance on potential cor- any longer term corrective measure. To the rective measures is available from the extent possible, interim measures should not following documents: seriously complicate the ultimate physical • Corrective Action: Technologies and management of wastes or constituents, nor Applications (U.S. EPA, 1989c) should they present or exacerbate a health or • Handbook: Stabilization Technologies for environmental threat. RCRA Corrective Actions (U.S. EPA, 1991b) D. Evaluating Potential • RCRA Corrective Action Stabilization Corrective Measures Technologies (U.S. EPA, 1992b) The corrective measure or measures select- • Pump-and-Treat Ground-Water ed should meet the corrective action goals, Remediation: A Guide for Decision such as a state or local cleanup standard, and Makers and Practitioners (U.S. EPA, control or remove the source of contamina- 1996c) tion to reduce or eliminate further releases. • Handbook: Remediation of Most corrective measures fall into one of Contaminated Sediments (U.S. EPA, three technology categories—containment 1991a) technologies, extraction or removal technolo- gies, or treatment technologies. The perfor- • Abstracts of Remediation Case Studies mance objectives of the corrective measures (U.S. EPA, 1995) relate to source reduction, cleanup goals, and • Bioremediation Resource Guide (U.S. cleanup timeframe. These measures might EPA, 1993) include the repair or upgrade of existing unit components, such as liner systems, leachate • Groundwater Treatment Technology collection systems, or covers. Resource Guide (U.S. EPA, 1994a) You should base selection of corrective • Physical/Chemical Treatment Technology measures on the following considerations and Resource Guide (U.S. EPA, 1994b) contact the state and community representa- • Soil Vapor Extraction Treatment tives before finalizing the selection: Technology Resource Guide (U.S. EPA, • The ability to meet appropriate 1994d) cleanup standards.
• The appropriateness and effectiveness • The effectiveness of the remedy in of the treatment technology in rela- reducing further releases. tion to waste and site characteristics. • The ease of implementing the remedy. • The long- and short-term effectiveness including economic, technical feasibil- • The degree to which local communi- ity, and protectiveness of the remedy. ty concerns have been addressed.
10-10 Ensuring Long-Term Protection—Taking Corrective Action
1. Meeting Cleanup Standards Quality, for instance, promulgated its Risk Work with your state and community rep- Evaluation/Corrective Action Program resentatives to establish risk-based cleanup (RECAP) final rule, on June 20, 2000. standards for the media of concern before Likewise, the Texas Natural Resource identifying potential corrective measures. For Conservation Commission (TNRCC) finalized example, if there is a statistically significant the Texas Risk Reduction Program in 1999 increase of constituent concentrations over (Title 30 Texas Administrative Code (TAC) background in the ground water, cleanup Chapter 350). Your state and community rep- standards would include reducing contami- resentatives can tell you whether similar RBCA nant concentrations to the MCL or health- standards exist in your state and the appropri- based level at the point of monitoring. ateness of such an approach. ASTM also offers two training courses on RBCA: Risk-Based Several approaches have been developed to Corrective Action for Chemical Releases, and identify appropriate cleanup standards. One of Risk Based Corrective Action Applied at the more recent approaches is the Risk-Based Petroleum Release Sites. These courses are Corrective Action (RBCA) standard developed open to all individuals from federal, state, trib- by some states and the American Society for al, and local regulatory agencies as well as pro- Testing and Materials (ASTM) Committee. The fessionals from the private sector. RBCA standard provides guidance on how to integrate ecological and human-health, risk- RBCA Tier 1 Evaluation based, decision-making into the traditional corrective action process described above. A Tier 1 evaluation classifies a site accord- RBCA is a decision-making process for the ing to the urgency for corrective action using assessment and response to chemical releases. broad measures of release and exposure. This This standard is applicable to all types of tier is used to identify the source(s) of the chemical-release sites, which can vary greatly chemical release, obvious environmental in terms of their complexity, physical and impacts, potential receptors, and significant chemical characteristics, and the risk they pose exposure pathways. During a Tier 1 evalua- to human health and the environment. RBCA tion, site-specific contaminant concentrations uses a tiered approach that begins with simple are compared against a standard table of risk- analyses and moves to more complex evalua- based screening levels (RBSLs) that have been tions when necessary. The foundation of the developed using conservative, nonsite-specif- RBCA process is that technical policy decisions ic exposure assumptions. If a site’s contami- are identified in the front-end of the process to nant concentrations are found to be above ensure that data collected are of sufficient the RBSLs, then corrective action or further quantity and quality to answer questions evaluation would be considered. Continued posed at each tier of the investigation. The monitoring might be the only requirement if RBCA standard is not intended to replace site-specific contaminant concentrations are existing regulatory programs, but rather to below the RBSLs. provide an enhancement to these programs. At the end of the Tier 1 evaluation, initial The RBCA process allows for a three-tiered corrective action responses are selected while approach as described below. additional analysis is conducted to determine In recent years, many states have adopted final remedial action, if necessary. The stan- similar risk-based guidance or rules. The dard includes an exposure scenario evalua- Louisiana Department of Environmental tion flowchart to help identify appropriate
10-11 Ensuring Long-Term Protection—Taking Corrective Action
receptors and exposure scenarios based on measures of the fate and transport of contam- current and projected reasonable land use inants. Where simplified, site-specific mea- scenarios, and appropriate response actions. sures of the fate and transport are used in the Site conditions should also be compared to Tier 2 evaluation, much more sophisticated relevant ecological screening criteria (RESC) models and data will be used in this Tier. applicable to the site which might include These models might rely on probabilistic qualitative or quantitative benchmarks, com- approaches and on alternative toxicity and parison of site conditions to local biological biodegradability data. and environmental conditions, or considera- tions related to the exposed habitat areas. 2. Evaluating Treatment Technologies RBCA Tier 2 Evaluation In nearly every phase of the corrective The user might decide to conduct a Tier 2 action process, some information about treat- evaluation after selecting and implementing ment technologies is important. Many docu- the appropriate initial response action to the ments exist that describe candidate Tier 1 evaluation. The purpose of this tier is technologies in detail and give their respec- to determine site-specific target levels (SSTLs) tive applicability and limitations. Below are and appropriate points of compliance when it descriptions and examples of the three major is determined that Tier 1 RBSLs have been technology categories: containment, extrac- exceeded. While a Tier 2 evaluation is based tion, and treatment. on similar screening levels as those used in the Tier 1 evaluation, some of the generic Containment technologies are used to stop assumptions used in the earlier evaluation are the further spread or migration of contami- replaced with site-specific measurements to nants. Some examples of common contain- develop the SSTLs. The intent of Tier 2 is to ment techniques for constituents in incorporate the concept that measured levels land-based units include waste stabilization, of contamination can decline over the dis- solidification, and capping. Capping and tance from source to receptor. Thus, simple other surface-water diversion techniques, for environmental fate and transport modeling is instance, can control infiltration of rainwater used to predict attenuation over that distance. to the contaminated medium. Typical ways to If site-specific contaminant concentrations are contain contaminated ground-water plumes above the SSTLs, corrective action is needed include ground-water pumping, subsurface and further analysis might be required. drains, and barrier or slurry walls. These ground-water containment technologies con- trol the migration of contaminants in the RBCA Tier 3 Evaluation ground-water plume and prevent further dis- A Tier 3 evaluation involves the same steps solution of contaminants by water entering as those taken during the Tier 1 and Tier 2 the unit. evaluations, except that a significant increase Ground-water pumping. in effort is employed to better define the • Ground- scope of the contamination. Actual levels of water pumping can be used to contamination are compared to SSTLs that manipulate and manage ground are developed for this Tier. The Tier 3 SSTLs water for the purpose of removing, differ from Tier 2 SSTLs in the level of diverting, and containing a contami- sophistication used to develop site-specific nated plume or for adjusting ground-
10-12 Ensuring Long-Term Protection—Taking Corrective Action
water levels to prevent plume move- bentonite, or barriers of engineered ment. For example, pumping systems materials (sheet piling). A chemical consisting of a series of extraction analysis of wall/contaminant compati- wells located directly downgradient bility is necessary for the final selec- from a contaminated source can be tion of materials. The installation of a used to collect the contaminated low permeability barrier usually plume. The success of any contami- entails a great deal of earth moving, nant capture system based upon requires a significant amount of land pumping wells is dependent upon area, and is expensive. Once in place, the rate of ground-water flow and the however, it represents a long-term, rate at which the well is pumped. low maintenance system. Thus, the zone of capture for the Extraction or removal technologies physi- pumping system must be established. cally remove constituents from a site. • Subsurface drains. Subsurface Extraction techniques might remove the con- drains are essentially permeable bar- stituent of concern only, or the contaminated riers designed to intercept the media itself. For example, vapor extraction ground-water flow. The water is col- might just remove the constituent vapors from lected at a low point and pumped or the soil, while excavation could remove all of drained by gravity to the treatment the contaminated soil. Extraction technologies system. Subsurface drains can also be used to isolate a waste disposal area by intercepting the flow of unconta- minated ground water before it enters into a contaminated site. Subsurface drains are most useful in preliminary containment applications for control- ling pollutant migration, while a final treatment design is developed and implemented. They also provide a measure of long-term protection against residual contaminants follow- ing conclusion of treatment and site include excavation, pumping, product recov- closure. ery, vapor extraction or recovery, and soil washing. • Barrier walls. Low permeability bar- riers are used to direct the uncontam- Treatment or destruction technologies ren- inated ground-water flow around a der constituents less harmful through physi- particular site or to prevent the cont- cal, biological, chemical, and thermal aminated material from migrating processes including ground-water treatment, from the site. Barrier walls can be pH adjustment, oxidation and reduction, made of a wide variety of materials, bioremediation, and incineration. as long as they have a lower perme- • Ground-water pump-and-treat is ability than the aquifer. Typical mate- one of the most widely used ground- rials include mixtures of soil and water treatment technologies. bentonite, mixtures of cement and Conventional methods involve
10-13 Ensuring Long-Term Protection—Taking Corrective Action
pumping contaminated water to the chemical processes required might surface for treatment. Pump-and- include pH adjustment, lysis, oxida- treat systems are used primarily for tion, reduction, or a combination of hydraulic containment and treatment these. In addition, chemical treat- to reduce the dissolved contaminant ment is often used to prepare for or concentrations in ground water so facilitate the treatment of wastes by that the aquifer complies with clean- other technologies. up standards or the treated water - The function of pH adjustment is to withdrawn from the aquifer can be neutralize acids and bases and to put to beneficial use. A thorough, promote the formation of precipi- three-dimensional characterization of tates, which can subsequently be subsurface soils and hydrogeology, removed by conventional settling including particle-size distribution, techniques. Typically, pH adjust- sorption characteristics, and ment is effective in treating inor- hydraulic conductivity, provides a ganic or corrosive wastes. firm basis for appropriate placement of pump-and-treat wells. The follow- - Oxidation and reduction reactions ing techniques can be useful in effec- are utilized to change the chemical tively designing and operating the form of a hazardous material, in pump-and-treat system: order to render it less toxic or to change its solubility, stability, sepa- - Using capture zone analysis, opti- rability, or otherwise change it for mization modeling, and data handling or disposal purposes. In obtained from monitoring the any oxidation reaction, the oxida- effects of initial extraction wells to tion state of one compound is identify the best locations for wells. raised (i.e., oxidized) while the oxi- - Phasing the construction of extrac- dation state of another compound tion and monitoring wells so that is lowered (i.e., reduced). In the information obtained from the reaction, the compound supplying operation of the initial wells the oxygen (or chlorine or other informs decisions about siting sub- negative ion) is called the oxidizer sequent wells. or oxidizing agent, while the com- pound accepting the oxygen (i.e., - Phasing pumping rates and the supplying the positive ion) is called operation of individual wells to the reducing agent. The reaction enhance containment, avoid stagna- can be enhanced by catalysis, elec- tion zones, and ensure removal of trolysis, or photolysis. the most contaminated ground water first. - The basic function of lysis process- es is to split molecules to permit • Chemical treatment is a class of further treatment. Hydrolysis is a processes in which specific chemicals chemical reaction in which water are added to wastes or to contami- reacts with another substance. In nated media in order to achieve the reaction, the water molecule is detoxification. Depending on the ionized while the other compound nature of the contaminants, the
10-14 Ensuring Long-Term Protection—Taking Corrective Action
is split into ionic groups. Photolysis, growth of the microbial community, another lysis process, breaks chemi- in addition to providing them suffi- cal bonds by irradiating a chemical cient food (organic material), are pH, with ultraviolet light. Catalysis uses temperature, oxygen concentration, a catalyst to achieve bond cleavage. nutrients, and toxicity. • Biological treatment is a destruction - Typically, a biological treatment sys- process relying primarily on oxidative tem operates best when a waste or reductive mechanisms. The two stream is at a pH near 7. However, types of biological treatment process- waste treatment systems can operate es are aerobic and anaerobic. Aerobic (with some exceptions) between pH processes are oxidative processes and values of 4 and 10. The exceptions are the most widely used. These are aerobic systems in which
processes require a supply of molecu- ammonia is oxidized to NOx as well lar oxygen and include suspended as anaerobic methane fermenting growth systems, fixed-film systems, systems. For these, the pH should hybrid reactors, and in situ applica- be between 6 and 8; outside this tion. Anaerobic processes achieve the range, efficiency will suffer. reduction of organic matter to - Waste treatment systems can func- methane and carbon dioxide in an tion over a temperature range of 5° oxygen-free environment. The use of to 60°C. Most waste treatment sys- biological treatment processes is tems operate between 15° to 45°C directed toward accomplishing and use mesophilic organisms. destruction of organic contaminants, oxidation of organic chemicals - Microorganisms need a certain whereby the organic chemicals are amount of oxygen not only to sur- broken down into smaller con- vive but also to control their reac- stituents, and dehalogenation of tions. Therefore, the residual organic chemicals by cleaving a chlo- dissolved oxygen concentrations rine atom(s) or other halogens from a should be maintained at approxi- compound. mately 2 mg/l or greater within a typical liquid biotreatment system. Biological processes can be used on a broad class of biodegradable organic - The quantity of nutrients needed contaminants. It should be noted, depends on the biochemical oxygen however, that very high concentra- demand (BOD) of the waste. The tions as well as very low concentra- higher the BOD, the higher the num- tions of organic contaminants are ber of cells produced and the greater difficult to treat via biological the quantity of nutrients required. processes. Since microorganisms need - The presence of toxic substances appropriate conditions in which to will obviously produce adverse con- function, you must provide an opti- ditions in a biological system. mum environment, whether above- Unfortunately, it is difficult to cite ground in a reactor or belowground specific toxic materials because toxi- for an in situ application. The prima- city depends on concentration. ry conditions which can affect the Nutrients can be toxic in higher
10-15 Ensuring Long-Term Protection—Taking Corrective Action
concentrations and all types of bilized product has a structural organic compounds which can be strength sufficient to prevent fractur- used as food by bacteria can be ing over time. Solidification accom- toxic if their concentrations are plishes the intended objective by high enough. Frequently, toxicity changing a non-solid waste material concerns can be avoided by waste into a solid, monolithic structure that dilution and microbe acclimation. ideally will not permit liquids to per- colate into or leach materials out of • Thermal treatment, or incineration, the mass. Stabilization, on the other is a treatment technology applicable hand, binds the hazardous con- to the treatment of wastes containing stituents into an insoluble matrix or a wide range of organic concentra- changes the hazardous constituent to tions and low concentrations of an insoluble form. Other objectives water, metals, and other inorganics. of solidification/stabilization process- Incineration is the thermal decompo- es are to improve handling of the sition of organic constituents via waste and produce a stable solid (no cracking and oxidation reactions at free liquid) for subsequent use as a high temperatures that can be used construction material or for landfill- for detoxification, sterilization, vol- ing. Major categories of industrial ume reduction, energy recovery, and waste solidification/stabilization sys- by-product chemical recovery. A tems are cement-based processes. well-designed and properly operated Waste characteristics such as organic incinerator will destroy all but a tiny content, inorganic content, viscosity, fraction of the organic compounds and particle size distribution can contained in the waste. Incinerator affect the quality of the final solidi- emission gases are composed primar- fied product. These characteristics ily of carbon dioxide and water. The inhibit the solidification process by type and quantity of other com- affecting the compatibility of the pounds emitted depends on the com- binder and the waste, the complete- position of the wastes, the ness of encapsulation, and the devel- completeness of the combustion opment of preferential paths for process, and the air pollution control leaching due to spurious debris in equipment with which the incinera- the waste matrix. tor is equipped. Incinerators are designed to accept wastes of varying In selecting a treatment technology or set physical forms, including gasses, liq- of technologies, it is important to consider the uids, sludges, and solids. information obtained from the waste and site characterizations, see Chapter • Stabilization/solidification process- 2–Characterizing Waste and Chapter es immobilize toxic or hazardous 4–Considering the Site. For example, the constituents in a waste by changing waste characterization should tell the location the constituent into immobile forms, of the waste and in what phase(s) the waste binding them in an immobile matrix, should be expected to be found, (e.g., sorbed or binding them in a matrix which to soil particles). Waste characterization infor- minimizes the waste material surface mation also allows for the assessment of the exposed to solvent. Often, the immo- leaching characteristics of the waste, its ability
1 U.S. EPA, 1991. Site Characterization for Subsurface Remediations.
10-16 Ensuring Long-Term Protection—Taking Corrective Action
to be degraded, and its tendency to react with Figure 2 chemicals. The site characterization informa- Recommended Screening Process for tion should reveal important information Selecting Appropriate Treatment Technologies about subsurface flow conditions and other physical characteristics, such as organic car- Evaluate waste and site-specific information and bon content. You should use the information identify potential treatment technologies from the waste and site characterizations to select the appropriate treatment technology. Develop a conceptual design for each technolo- A screening process for selecting an appro- gy including: priate technology is presented in Figure 2. In • Process description some cases, a treatment train, a series of tech- • Process flow diagram nologies combined together, might be appro- • Layout drawing priate.1 This step-by-step approach helps • Preliminary sizing of equipment, utility, and land requirements ensure that technologies that might be applic- • Chemical requirements able at a site are not overlooked. In addition, • Expected residuals the rationale for the elimination of specific technologies will be available to justify deci- sions to interested parties. Compare technologies using: • Effectiveness and reliability of technology Additional information regarding the use meeting cleanup goals and development of innovative treatment • Beneficial and adverse effects on the environ- technologies is available from EPA’s ment Hazardous Waste Clean-up Information • Beneficial and adverse effects on human (CLU-IN) Web site
10-17 Ensuring Long-Term Protection—Taking Corrective Action
3. Evaluating the Long- and tation of the corrective measure. Because Short-Term Effectiveness of waste characteristics vary from site to site, the Remedy the effect of a treatment technology with a particular waste might be unknown. It is Evaluating the long- and short-term effec- important, therefore, to consider performing tiveness of the remedy, involves analyzing the a treatability study to evaluate the effective- risks associated with potential exposure path- ness of one or more potential remedies. ways, estimates of potential exposure levels, Spending the time and money up-front to and the duration of potential exposure asso- better assess the effectiveness of a technology ciated with the construction and implemen- on a waste can save significant time and money later in the process. To judge the technical certainty that the remedy will attain Treatability Studies the corrective action goal, also consider reviewing case studies where similar tech- The four general types of treatability nologies have been applied. studies are laboratory-scale, bench-scale, pilot-scale, and field-scale. It is also important to analyze the time to complete the corrective measure, because it • Laboratory-scale studies are small directly impacts the cost of the remedy. It is scale screening studies that generate therefore important to carefully evaluate the qualitative information concerning long-term costs of the remedial alternatives the general validity of a treatment and the long-term financial condition of the approach. facility. Consider including quality control • Bench-scale studies are intermediate measures in the implementation schedule to studies conducted in the laboratory. assess the progress of the corrective measure. Bench scale studies are intended to It is also important to determine the degree answer specific design, operation, and to which the remedy complies with all cost questions, and are more detailed applicable state laws. than laboratory studies. The Federal Remediation Technologies • Pilot-scale studies are large scale Roundtable
10-18 Ensuring Long-Term Protection—Taking Corrective Action
They are meant to serve as primary reference cient conditions at a waste management unit sources, and they contain information on site should be quantified in terms of anticipated background and setting, contaminants and effectiveness according to current and future media treated, technology, cost and perfor- conditions. This evaluation should determine mance, and points of contact for the technol- what is technically and financially practicable. ogy application. Health considerations and the potential for unacceptable exposure(s) to both workers EPA has also prepared an overview of and the public can affect an evaluation. ground-water cleanup at 28 sites entitled Groundwater Cleanup: Overview of Operating Experience at 28 Sites (U.S. EPA, 1999a) that is 5. Evaluating the Ease of also available from CLU-IN. This overview Implementation presents a range of the types of cleanups typi- The ease of implementing the proposed cally performed at sites with contaminated corrective measure will affect its schedule. To ground water and summarizes information evaluate the ease of implementation of a spe- about the remediation systems at the 28 sites. cific corrective measure, it is important to Summarized information includes design, operation, and performance of the systems; capital, operating, and unit costs of the sys- Selecting a Corrective tems; and factors that potentially affect the cost Action Specialist and performance of the systems. Once it has been determined that cor- EPA’s TIO Web site
10-19 Ensuring Long-Term Protection—Taking Corrective Action
consider the availability of technical expertise any identified contamination and proposed and equipment, the ability to properly man- remedies. You also should identify any public age, dispose, or treat wastes generated by the concerns that have been expressed, via writ- corrective measure, and the likelihood of ten public comments or from public meet- obtaining local permits and public accep- ings, about the facility’s contamination and tance for the remedy. Consider also the should address these concerns by the correc- potential for contamination to transfer from tive measures being evaluated. The best reme- one media to another as part of the overall dy selected and implemented will be the one feasibility of the remedy. Cross-media that is agreed upon by the state or local regu- impacts should be addressed as part of the latory agency, the public, and the facility implementation phase. Develop a corrective- owner. Review Chapter 1–Understanding Risk measure schedule identifying the beginning and Building Partnerships before selecting any and end periods of the permitting, construc- final remedies. tion, treatment, and source control measures. E. Implementing 6. Measuring the Degree to Corrective Measures Which Community Concerns The implementation of corrective mea- are Met sures encompasses all activities necessary to Prior to selecting the corrective measure(s), initiate and continue remediation. During the you should hold a public meeting to discuss evaluation and assessment of the nature and the results of the corrective action assessment extent of the contamination, you should and to identify proposed remedies. Consider decide whether no further assessment is nec- notifying adjacent property owners via mail of essary, whether institutional controls are nec- essary to protect human health and the Citizen Guides to environment, whether monitoring and site maintenance are necessary, and whether no Treatment Technologies further action and closure are appropriate for EPA’s Technology Innovation Office the unit. has developed a series of fact sheets that explain, in basic terms, the operation 1. Institutional Controls and application of innovative treatment technologies for remediating sites. The Institutional controls are those controls fact sheets address issues associated with that can be utilized by responsible parties innovative treatment technologies as a and regulatory agencies in remedial programs whole, bioremediation, chemical dehalo- where, as part of the program, certain levels genation, in situ soil flushing, natural of contamination will remain on site in the attenuation, phytoremediation, soil soil or ground water. Institutional controls vapor extraction and air sparging, soil can also be considered in situations where washing, solvent extraction, thermal des- there is an immediate threat to human orption, and the use of treatment walls. health. Institutional controls can vary in both English and Spanish versions of these form and content. Agencies and landowners fact sheets can be downloaded from can invoke various authorities and enforce- CLU-IN
10-20 Ensuring Long-Term Protection—Taking Corrective Action
state could adopt a statutory mandate, for address uses that might disturb a example, requiring the use of deed restric- containment cap or any unremediat- tions as a way of enforcing use restrictions ed soils under the surface or below a and posting signs. Commonly used institu- building. A prohibition on drinking tional controls include deed restrictions, use onsite or offsite ground water might restrictions, access controls, notices, registry also be appropriate. Well restriction act requirements, transfer act requirements, areas can be a form of institutional and contractual obligations. Additional infor- control by providing notice of the mation on institutional controls is available at existence of contaminants in ground EPA’s Office of Solid Waste and Emergency water and by prohibiting or condi- Response Web site at
10-21 Ensuring Long-Term Protection—Taking Corrective Action
must comply with regulatory require- and rights of private parties to freely ments in regard to use and transfer of negotiate these liabilities. Another the site. The use of a site listed on avenue is for the landowner or the registry can not be changed with- responsible party to obligate itself to out permission from the state agency. the state by contract. The state might require a contractual commitment • Transfer act requirements. Some from the party to provide long-term states have transfer act programs that monitoring of the site, use restric- require full evaluation of all environ- tions, and the means of continued mental issues before or after the funding for remediation. transfer occurs. It might be that, within such a program, institutional controls can be established by way of 2. Monitoring and Site consent order, administrative order, Maintenance or some other technique that estab- In many cases, monitoring might need to lishes implementation and continued be conducted to demonstrate the effective- responsibility for institutional con- ness of the implemented corrective measures. trols. A typical transfer act imposes Consult with your state to determine the obligations and confers rights on par- amount of time that monitoring should be ties to a land transaction arising out conducted. Some corrective measures, such of the environmental status of the as capping, hydraulic control, and other property to be conveyed. Transfer physical barriers, can require long-term acts impose information obligations maintenance to ensure integrity and contin- on the seller or lessor of a property. ued performance. Upon completion and veri- That party must disclose general fication of cleanup goals, reinstitute your information about strict liability for original or modified ground-water monitor- clean-up costs as well as property- ing program if the unit is still in active use. specific information, such as the presence of hazardous substances, permitting requirements and status, 3. No Further Action and Site releases, and enforcement actions Closure and variances. When the corrective action goals have • Contractual obligations. One sys- been achieved, and monitoring and site tem for ensuring future restrictions maintenance are no longer necessary to on the use of a site, or the obligation ensure that this condition persists, reinstitute to remediate a site, is to require pri- your original or modified ground-water mon- vate parties to restrict use by con- itoring program if the unit is still in active tract. While this method is often use. It might be necessary, however, to ensure negotiated among private parties, it is that any selected institutional controls remain difficult, if not impossible, to institu- in place. Refer to Chapter 11–Performing tionalize control over the process Closure and Post-Closure Care for additional without interfering with the abilities information on site closures.
10-22 Ensuring Long-Term Protection—Taking Corrective Action
Taking Corrective Action Activity List
Consider the following when developing a corrective action program for industrial waste management units: ■ Locate the source(s) of the release(s) of contaminants and determine the extent of the contamina- tion. ■ Consult with the state, community representatives, and qualified remedial experts when develop- ing a corrective action program. ■ Identify and evaluate all potential corrective measures including interim measures. ■ Select and implement corrective measures based on the effectiveness and protectiveness of the remedy, the ease of implementing the remedy, and the degree that the remedy meets local commu- nity concerns and all applicable state laws. ■ Design a program to monitor the maintenance and performance of corrective measures to ensure that human health and the environment are being protected.
10-23 Ensuring Long-Term Protection—Taking Corrective Action
Resources
ASTM. 1997. Standard Provisional Guide for Risk-Based Corrective Action (PS104). February.
ASTM. 1994. Emergency Standard Guide for Risk-Based Corrective Action Applied at Petroleum Release Sites. May.
Louisiana Department of Environmental Quality. 2000. Risk Evaluation/Corrective Action Program (RECAP) June.
Texas Natural Resource Conservation Commission (TNRCC). 1999. Texas Risk Reduction Program, Title 30 Texas Administrative Code (TAC) Chapter 350.
Texas Natural Resource Conservation Commission (TNRCC). 1995. TNRCC Technical Guidance: Selecting an Environmental Consultant/Corrective Action Specialist. February.
U.S. EPA. 2002. Draft Superfund Lead-Contaminated Residential Sites Handbook. OSWER 9285.7-50.
U.S. EPA. 2001a. Development of a Data Evaluation: Decision Support System for Remediation of Subsurface Contamination. EPA600-R-01-044.
U.S. EPA. 2001b. Development of Recommendations and Methods to Support Assessment of Soil Venting Performance and Closure. EPA600-R-01-070.
U.S. EPA. 2001c. Evaluation of the Protocol for Natural Attenuation of Chlorinated Solvents: Case Study at the Twin Cities Army Ammunition Plant. EPA600-R-01-025.
U.S. EPA. 2001d.Handbook of Groundwater Protection and Cleanup Policies for RCRA Corrective Action. EPA530-R-01-015.
U.S. EPA. 2001e. Multispecies Reactive Tracer Test in a Sand and Gravel Aquifer, Cape Cod, Massachusetts. Parts I-II. EPA600-R-01-007a-b.
U.S. EPA. 2001f. Summary of the Phytoremediation State of the Science Conference, Boston Massachusetts, May 1-2, 2000. EPA625-R-01-001a.
U.S. EPA. 2000a. Abstracts of Remediation Case Studies. Volume 4. EPA542-R-00-006.
U.S. EPA. 2000b. Statistical Estimation and Visualization of Ground-Water Contamination Data. EPA600-R- 00-034.
10-24 Ensuring Long-Term Protection—Taking Corrective Action
Resources (cont.)
U.S. EPA. 1999a. Groundwater Cleanup: Overview of Operating Experience at 28 Sites. EPA542-R-99- 006.
U.S. EPA. 1999b. In Situ Permeable Reactive Barrier for the Treatment of Hexavalent Chromium and Trichloroethylene in Ground Water: Volume 1 Design and Installation. EPA600-R-99-095a.
U.S. EPA. 1999c. In Situ Permeable Reactive Barrier for the Treatment of Hexavalent Chromium and Trichloroethylene in Ground Water: Volume 2 Performance Monitoring. EPA600-R-99-095b.
U.S. EPA. 1999d. In Situ Permeable Reactive Barrier for the Treatment of Hexavalent Chromium and Trichloroethylene in Ground Water: Volume 3 Multicomponent Reactive Transport Modeling. EPA600-R- 99-095c.
U.S. EPA. 1999e. Laser Fluorescence EEM Probe for Cone Penetrometer Pollution Analysis. EPA600-R-99- 041.
U.S. EPA. 1998a. Application of the Electromagnetic Borehole Flowmeter. EPA600-R-98-058.
U.S. EPA. 1998b. Permeable Reactive Barrier Technologies for Contaminant Remediation. EPA600-R-98- 125.
U.S. EPA. 1998c. Technical Protocol for Evaluating natural Attenuation of Chlorinated Solvents in Ground Water, EPA600-R-98-128.
U.S. EPA. 1996a. A Citizen’s Guide to Innovative Treatment Technologies. EPA542-F-96-001.
U.S. EPA. 1996b. Corrective Action for Releases from Solid Waste Management Units at Hazardous Waste Management Facilities: Advance Notice of Proposed Rulemaking. Fed. Reg. 61(85): 19,431- 19,464. May 1.
U.S. EPA. 1996c. Pump-and-Treat Ground-Water Remediation: A Guide for Decision-Makers and Practitioners. EPA625-R-95-005.
U.S. EPA. 1995. Abstracts of Remediation Case Studies. EPA542-R-95-001.
U.S. EPA. 1994a. Groundwater Treatment Technology Resource Guide. EPA542-B-94-009.
U.S. EPA. 1994b. Physical/chemical Treatment Technology Resource Guide. EPA542-B-94-008.
10-25 Ensuring Long-Term Protection—Taking Corrective Action
Resources (cont.)
U.S. EPA. 1994c. RCRA Corrective Action Plan. EPA520-R-94-004.
U.S. EPA. 1994d. Soil Vapor Extraction Treatment Technology Resource Guide. EPA542-B-94-007.
U.S. EPA. 1993. Bioremediation Resource Guide. EPA542-B-93-004.
U.S. EPA. 1992a. A Guide for Conducting Treatability Studies under CERCLA. EPA540-R-92-071.
U.S. EPA. 1992b. RCRA Corrective Action Stabilization Technologies Proceedings. EPA625-R-92-014.
U.S. EPA. 1991a. Handbook: Remediation of Contaminated Sediments. EPA625-6-91-028.
U.S. EPA. 1991b. Handbook: Stabilization Technologies for RCRA Corrective Action. EPA625-6-91- 026.
U.S. EPA. 1991c. Site Characterization for Subsurface Remediation. EPA625-4-91-026.
U.S. EPA. 1989a. RCRA Facility Investigation Guidance: Volume I: Development of an RFI Work Plan and General Considerations for RCRA Facility Investigations. PB89-200-299.
U.S. EPA. 1989b. RCRA Facility Investigation Guidance: Volume II: Soil, Ground Water, and Subsurface Gas Releases. PB89-200-299.
U.S. EPA. 1989c. RCRA Facility Investigation Guidance: Volume III: Air and Surface Water Releases. PB89- 200-299.
U.S. EPA. 1989d. RCRA Facility Investigation Guidance: Volume IV: Case Study Examples. PB89-200-299.
U.S. EPA. 1989e. Seminar Publication: Corrective Action: Technologies and Applications. EPA625-4-89-020.
U.S. EPA. 1989f. Practical Guide for Assessing and Remediating Contaminated Sites: Draft.
U.S. EPA. 1988a. Guidance for Conducting Remedial Investigations and Feasibility Studies Under CERCLA. Interim Final. EPA540-G-89-004.
U.S. EPA. 1988b. RCRA Corrective Action Interim Measures Guidance - Interim Final. EPA530-SW-88-029.
U.S. EPA. 1986. RCRA Facility Assessment Guidance. PB87-107769.
10-26 Part V Ensuring Long-Term Protection
Chapter 11 Performing Closure and Post-Closure Care Contents
I. Closure Plans ...... 11- 1
II. Selecting a Closure Method...... 11- 3
III. Closure by Use of Final Cover Systems...... 11- 4 A. Purpose and Goal of Final Cover Systems ...... 11- 4 B. Technical Considerations for Selecting Cover Materials ...... 11- 5 C. Components of a Final Cover ...... 11- 8 D. Capillary-Break Final Covers ...... 11- 16 E. The Hydrologic Evaluation of Landfill Performance (HELP) Model ...... 11- 17 F. Recommended Cover Systems ...... 11- 18
IV. Closure by Waste Removal ...... 11- 21 A. Establishing Baseline Conditions ...... 11- 22 B. Removal Procedures...... 11- 22 C. Disposal of Removed Wastes ...... 11- 23 D. Final Sampling and Analysis ...... 11- 23
V. Post-Closure Care Considerations When Final Cover Is Used...... 11- 24 A. Maintenance...... 11- 24 B. Monitoring During Post-Closure Care ...... 11- 25 C. Recommended Length of the Post-Closure Care Period ...... 11- 25 D. Closure and Post-Closure Cost Considerations ...... 11- 26
Performing Closure and Post-Closure Care Activity List ...... 11- 34
Resources ...... 11- 35
Tables: Table 1: Types of Layers in Final Cover Systems...... 11- 9 Table 2: Types of Recommended Final Cover Systems ...... 11- 18 Table 3: Example Closure/Post-Closure Cost Estimate Form ...... 11- 27 Table 4: Sample Summary Cost Estimating Worksheet ...... 11- 29 Table 5: Estimated Closure and Post-Closure Care Costs ...... 11- 31
Figures: Figure 1: Regional Depth of Frost Penetration in Inches ...... 11 - 6 Figure 2: Drainage Layer Configuration ...... 11 - 11 Contents (cont.)
Figure 3: Geonet with Geotextile Filter Design for Drainage Layer ...... 11 - 12 Figure 4: Passive Gas Venting System ...... 11 - 15 Figure 5: Active Gas Venting System...... 11 - 15 Figure 6: Example of a Capillary-Break Final Cover System ...... 11 - 17 Figure 7: Recommended Final Cover System For a Unit With a Double Liner or a Composite Liner ....11 - 19 Figure 8: Recommended Final Cover System For a Unit With a Single Clay Liner ...... 11 - 19 Figure 9: Recommended Final Cover System For a Unit With a Single Clay Liner in an Arid Area ...... 11 - 20 Figure 10: Recommended Final Cover System For a Unit With a Single Synthetic Liner ...... 11 - 20 Figure 11: Recommended Final Cover System For a Unit With a Natural Soil Liner ...... 11 - 21 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
Performing Closure and Post-Closure Care This chapter will help you: • Provide closure and post-closure care as an integral part of a unit’s overall design and operation. • Provide long-term environmental protection by reducing or elimi- nating potential threats and the need for potential corrective action at the site. • Plan and accomplish the goals of closure and post-closure care by requiring that adequate funding be set aside to cover the planned costs of closure and post-closure care. For post-closure care, the overall goal is to he overall goal of closure is to minimize the infiltration of water into a unit minimize or eliminate potential by providing maintenance of the final cover. threats to human health and the Maintenance should be continued until such environment and the need for time as it is determined that care is no longer future corrective action at the site. necessary. Also, during post-closure care, If removing the wastes, containment devices, T closed units should be monitored to verify and any contaminated subsoils from a unit, and document that no unacceptable releases the unit should be returned to an acceptable are occurring. risk level so that it is not a current or future threat. If wastes will be left in place at clo- sure, the unit should be closed in a manner that also reduces and controls current or I. Closure Plans future threats. Steps should also be taken to A well-conceived closure plan is the pri- avoid future disruptions to final cover sys- mary resource document for the final stage in tems and monitoring devices. the life of a waste management unit. The pur- pose of a closure plan is to consider all This chapter will help address the follow- aspects of the closure scenario. It should be ing questions. comprehensive so that staff who will imple- ment it years after its writing will clearly • How do I develop a closure plan? understand the activities it specifies. It also • What factors should I consider when needs to provide enough detail to allow cal- choosing a closure method? culation of closure and post-closure care costs • What are the components of a final for determining how much funding needs to cover? be set aside for those activities. • What costs are associated with post- closure care?
11 - 1 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
What should be considered when • Waste removal information (if applica- developing a closure plan? ble). • Parameters to assess performance of You should tailor a closure plan to account the unit throughout the post-closure for the unique characteristics of the unit, the period. waste managed in the unit, and anticipated future land use. Each unit will have different The plan should address the types of waste closure activities. Closing a surface impound- that have been or are expected to be deposited ment, for example, involves removal of in the management unit and the constituents remaining liquids and solidifying sludges that can reasonably be associated with those prior to placing a final cover on the unit. wastes. The types of expected wastes will affect both the design of the final cover and The following information is important to the types of activities that should be undertak- consider when developing a closure plan: en during the post-closure care period. • Overall goals and objectives of closure. Biodegradable waste, for example, can cause a final cover to subside due to decomposition • Future land use. and can also require gas management. • Type of waste management unit. The closure plan should provide other • Types, amount, and physical state of information that will address the closure strat- waste in the unit. egy. If, for instance, a final cover is planned, • Constituents associated with the wastes. then the closure plan should consider season- al precipitation that could influence the per- • Whether wastes will be removed or formance of both the cover and the left in place at closure. monitoring system. Information concerning • Schedule (overall and interim). freeze cycles and the depth of frost perme- ation will provide supporting information • Costs to implement closure. with which to assess the adequacy of the • Steps to monitor progress of closure cover design. Similarly, arid conditions should actions, including inspections, mainte- be addressed to support a decision to use a nance, and monitoring (e.g., ground- particular cover material, such as cobbles. water and leachate monitoring). The closure plan should address the closure • Health and safety plans, as necessary. schedule, stating when closure is expected to begin, and when closure is expected to be com- • Contingency plans. pleted. You should consider starting closure • Description of waste treatment or sta- when the unit has reached capacity or has bilization (if applicable). received the last expected waste for disposal. For units containing inorganic wastes, you • Final cover information (if applicable). should complete closure as soon as possible • Vegetation management. after the last expected waste has been received. • Run-on and runoff controls. A period of 180 days is a good general guide for completing closure, but the actual time • Closure operations and maintenance. frame will be dictated by site-specific condi- • Erosion prevention and repair. tions. For units receiving organic wastes, more time might be needed for the wastes to stabilize
11 - 2 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
prior to completing closure. Similarly, other final cover and the proper operation of the gas site-specific conditions, such as precipitation migration and/or drainage control strategies. or winter weather, can also cause delay in If wastes will be removed at closure, the clo- completing closure. For these situations, you sure plan should estimate volumes of waste and should complete closure as soon as feasible. contaminated subsoil and the extent of contam- You should also consult with the state agency inated devices to be removed during closure. It to determine if any requirements exist for clo- should further state waste removal procedures, sure schedules. establish performance goals, and address any Even within a waste management unit, state or local requirements for closure by waste some areas will be closed on different sched- removal. The plan should identify numeric ules, with certain areas in partial closure, clean-up standards and existing background while other areas continue to operate. The concentrations of constituents. It also should schedules and partial closure activities (such discuss the sampling plan for determining the as intermediate cover) should be considered effectiveness of closure activities. Finally, it in the closure plan. Although the processes should describe the provisions made for the dis- for closing such areas might not be different posal of removed wastes and other materials. than those for closing the unit as a whole, it The closure plan should also provide a is still more efficient to integrate partial clo- detailed description of the monitoring that sure activities into the closure plan. will be conducted to assess the unit’s perfor- If the closure plan calls for the stabiliza- mance throughout the post-closure period. tion, solidification, or other treatment of These measurements include monitoring wastes in the unit before the installation of a leachate volume and characteristics to ensure final cover, the plan should describe those that a cover is minimizing infiltration. It is activities in detail. Waste stabilization, solidi- important to include appropriate ground- fication, or other treatment has four goals: water quality standards with which to com- pare ground-water monitoring reports. You • Removing liquids, which are ill-suit- should develop the performance measures ed to supporting the final cover. section of the plan prior to completing clo- • Decreasing the surface area over sure. This section establishes the parameters which the transfer or escape of conta- that will describe successful closure of the minants can occur. unit. If limits on these parameters are exceed- • Limiting the solubility of leachable ed, it will provide an early warning that the constituents in the waste. final cover system is not functioning as designed and that measures should be under- • Reducing toxicity of the waste. taken to identify and correct problems. For closure strategies that will use engi- neering controls, such as final covers, the plan should provide detailed specifications. This II. Selecting a includes descriptions of the cover materials in each layer and their permeability as well as Closure Method any drainage and/or gas migration control Factors to consider in deciding whether to measures included in the operation of the perform closure by means of waste removal final cover. Also the plan should identify mea- or through the use of a final cover include the sures to verify the continued integrity of the following:
11 - 3 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
• Feasibility. Is closure by waste This approach is common for landfill units and removal feasible? For example, if the some surface impoundment units where some waste volumes are large and underlying waste is left in place. The choice of final cover soil and ground water are contaminat- materials and design should be the result of a ed, closure by total waste removal careful review and consideration of all site-spe- might not be possible. If the unit is cific conditions that will affect the performance contaminated, consult Chapter of the cover system. If you are not knowledge- 10–Taking Corrective Action to identify able about the engineering properties of cover activities to address the contamination. materials, you should seek the advice of profes- In some cases partial removal of the sionals or representatives of state and local waste might be useful to remove the environmental protection agencies. source of ground-water contamination. This section addresses the more important • Cost-effectiveness. Compare the cost technical issues that should be considered of removing waste, containment when selecting cover materials and designing a devices, and contaminated soils, plus cover system. It discusses the various potential subsequent disposal costs at another components of final cover systems, including facility, to the cost of installing a final the types of materials that can be used in their cover and providing post-closure care. design and some of the advantages and disad- vantages of each. This section also examines • Long-term protection. Will the final the interaction between the various compo- cover control, minimize, or eliminate nents as they function within the system. post-closure escape of waste con- stituents or contaminated runoff to ground or surface waters to the extent A. Purpose and Goal of necessary to protect human health and the environment? Final Cover Systems The principal goals of final cover systems • Availability of alternate site. Is an are to: alternate site available for final dispos- al or treatment of removed waste? You • Provide long-term environmental pro- should consult with the state agency tection of human health and the envi- to determine whether alternate dispos- ronment by reducing or eliminating al sites are appropriate. potential risk of contaminant release. Sections III and V address closure by use of • Minimize infiltration of precipitation final cover systems and associated post-closure into the waste management unit to care considerations. Alternatively, Section IV minimize generation of leachates with- addresses closure by waste removal. in the unit by promoting surface drainage and maximizing runoff. • Minimize risk by controlling gas migra- III. Closure by Use tion (as applicable), and by providing physical separation between waste and of Final Cover humans, plants, and animals. Systems • Minimize long-term maintenance needs. You might elect to close a waste manage- The final cover should be designed to pro- ment unit by means of a final cover system. vide long-term protection and minimization of
11 - 4 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
leachate formation. Final cover systems can How can climate affect a final be inspected, managed, and repaired to main- cover? tain long-term protection. For optimal perfor- mance, the final cover system should be Freeze and thaw effects can lead to the designed to minimize infiltration, surface development of microfractures in low perme- ponding, and the erosion of cover material. ability soil layers. These effects also can cause To avoid the accumulation of leachate within the realignment of interstitial fines (silts and a unit, the cover system should be no more clays), thereby increasing the hydraulic con- permeable than the liner system. For exam- ductivity of the final cover. As a result, you ple, if a unit’s bottom liner system is com- should determine the maximum depth of posed of a low-permeability material, such as frost penetration at a site and design covers compacted clay or a geomembrane, then the accordingly. In other words, barrier layers cover should also be composed of a low-per- should be below the maximum frost penetra- meability material unless an evaluation of tion depth. Information regarding the maxi- site-specific conditions shows an equivalent mum frost penetration depth for a particular reduction in infiltration. If the cover system is area can be obtained from the Natural more permeable than the liner, leachate will Resource Conservation Service with the U.S. accumulate in the unit. This buildup of liq- Department of Agriculture, local utilities, uids within a unit is often referred to as the construction companies, local universities, or “bathtub effect.” In addition, since many state agencies. Figure 1 illustrates the regional units can potentially generate gas, cover sys- depth of frost penetration. You should ensure tems should be designed to control gas that vegetation layers are thick enough that migration. Proper quality assurance and qual- low permeability soil layers in the final cover ity control during construction and installa- are placed below the maximum frost penetra- tion of the final cover are essential in order to tion depth. ensure that the final cover performs in accor- dance with its design. For general informa- How can settlement and subsi- tion on quality assurance during construction dence affect a final cover? of the final cover, refer back to the construc- tion quality assurance section of Chapter 7, When waste decomposes and consolidates, Section B–Designing and Installing Liners. settlement and subsidence can result. Recommendations for the type of final cover Excessive settlement and subsidence can sig- system to use will depend on the type of liner nificantly impair the integrity of the final and the gas and liquids management strategy cover system by causing ponding of water on employed in a unit. the surface, fracturing of low permeability infiltration layers, and failure of geomem- branes. The degree and rate of waste settle- B. Technical Considerations ment are difficult to estimate, but they should for Selecting Cover be considered during design and development Materials of closure plans. Waste settlement should also be considered when determining the timing of Several environmental and engineering con- closure. Steps should be taken to minimize cerns can affect cover materials and should be the degree of settlement that will occur after considered in the choice of those materials. the final cover system has been installed.
11 - 5 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
Figure 1. Regional Depth of Frost Penetration in Inches
Source: U.S. EPA, 1989a. How can erosion affect the per- • Locally adapted perennial plants that formance of a final cover? are resistant to various climatic changes reasonably expected to occur Erosion can adversely affect the perfor- at the site. mance of the final cover of a unit by causing • Roots that will not disrupt the low- rills that require maintenance and repair. permeability layer. Extreme erosion can lead to the exposure of the infiltration layer, initiate or contribute to • The ability to thrive in low-nutrient sliding failures, or expose the waste. soil with minimum nutrient addition. Anticipated erosion due to surface-water • The ability to survive and function runoff for a given design criteria can be with little or no maintenance. approximated using the USDA Universal Soil Loss Equation1 (U.S. EPA, 1989a). By evaluat- Why are interfacial and internal ing erosion loss, you might be able to opti- friction properties for cover com- mize the final cover design to reduce maintenance through selection of the best ponents important? available soil materials. A vegetative cover not Adequate friction between cover compo- only improves the appearance of a unit, but it nents, such as geomembrane barrier layers also controls erosion of the final cover. and soil drainage layers, as well as between The vegetation components of the erosion any geosynthetic components, is needed to layer should have the following characteristics: prevent extensive slippage or interfacial shear. Water and ice can affect the potential for
1 USDA Universal Soil Loss Equation: X = RKLSCP where: X = Soil loss (tons/acre/year); R = Rainfall ero- sion index; K = Soil erodibility index; L = Slope length factor; S = Slope gradient factor; C = Crop man- 11 - 6 agement factor; P = Erosion control practice. For minimal long-term care X < 2.0 tons/acre/year. Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
cover components to slip. Sudden sliding can can potentially breach the underlying barrier tear geomembranes or cause sloughing of layer. Strategies for mitigating the effects earthen materials. Internal shear can also be a described here are discussed below in the concern for composite or geosynthetic clay context of protection layers composed of liner materials. Measures to improve stability gravel or cobbles. include using flatter slopes or textured geosynthetic membranes, geogrids designed Is it necessary to stabilize wastes? to resist slipping forces, otherwise reinforcing Before installing a final cover, liquid or the cover soil, and providing drainage. semi-liquid wastes might need to be stabi- Can dry soil materials affect a lized or solidified. Stabilization or solidifica- tion might be necessary to allow equipment final cover? on the unit to install the final cover or to Desiccation, the natural drying of soil ensure adequate support, or bearing capacity, materials, can have an adverse affect on the for the final cover. With proper bulk cover soil layers compromising the final cover. technique, it might be feasible to place the Although this process is most commonly cover over a homogeneous, gel-like, semi-liq- associated with layers of low permeability uid waste. When selecting a stabilization or soil, such as clay, it can cause problems with solidification process, it is important to con- other soil types as well. Desiccation causes sider the effectiveness of the process and its cracks in the soil surface extending down- compatibility with the wastes. Performance ward. Cover layers are not very thick, and specifications for stabilization or solidification therefore these cracks can extend through an processes include leachability, free-liquid con- entire layer, radically changing its hydraulic tent, physical stability, bearing capacity, reac- conductivity or permeability. Care should be tivity, ignitability, biodegradability, strength, taken to detect desiccation at an early stage in permeability, and durability of the stabilized time to mitigate its damage. Also, the tenden- and solidified waste. You should consider cy for final covers to become dry makes root seeking professional assistance to properly penetration even more of a problem in that stabilize or solidify waste prior to closure. plants respond to drought by extending their Where solidification is not practical, you root systems downward. should consider reinforcement and construc- tion of a specialized lighter weight cover sys- Can plants and animals have an tem over unstable wastes. This involves using effect on a final cover? combinations of geogrids, geotextiles, geonets, geosynthetic clay liners, and When selecting the plant species to geomembranes. For more detail on this prac- include in the vegetative cover of a waste tice, consult references such as the paper by management unit, you should consider the Robert P. Grefe, Closure of Papermill Sludge potential for root systems to grow through Lagoons Using Geosynthetics and Subsequent surface cover layers and penetrate underlying Performance, and the Geosynthetic Research drainage and barrier layers. Such penetration Institute proceedings, Landfill Closures: will form preferential pathways for water Geosynthetics Interface Friction and New infiltration and compromise the integrity of Developments, cited in the Resources section. the final cover system. Similarly, the presence of burrowing animals should be foreseen when designing the final cover system. Such animals can burrow in the surface layers and
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How can wastes be stabilized? situ mixing and mobile plant mixing. In situ mixing is the simplest technique, using com- Many stabilization and solidification mon construction equipment, such as back- processes require the mixing of waste with hoes, excavators, and dump trucks. In situ other materials, such as clay, lime, and ash. mixing is most suitable where large amounts These processes include either sorbents or of materials are added to stabilize or solidify encapsulating agents. Sorbents are nonreac- the waste. The existing waste management tive and nonbiodegradable materials that soak area, such as a surface impoundment, can be up free liquids to form a solid or near-solid used as the mixing area. The in situ mixing mass. Encapsulating agents enclose wastes to process is open to the atmosphere, so envi- form an impermeable mass. The following are ronmental and safety issues, such as odor, examples of some commonly used types of dust, and vapor generation, should be taken waste stabilization and solidification methods. into consideration. For mobile plant mixing, • Cement-based techniques. Portland wastes are removed from the unit, mechani- cement can use moisture from the cally mixed with treatment materials in a waste (sludge) for cement hydration. portable processing vessel, and deposited The end product has high strength, back into the unit. Mobile plant mixing is good durability, and retains waste generally used for treating sludges and other effectively. wastes with a high liquid content. • Fly ash or lime techniques. A com- bination of pozzolanic fly ash, lime, C. Components of a Final and moisture can form compounds Cover that have cement-like properties. Cover systems can be designed in a variety • Thermoplastic techniques. Asphalt, of ways to accomplish closure goals. This tar, polyolefins, and epoxies can be flexibility allows a final cover design system mixed with waste, forming a semi- to integrate site-specific technical considera- rigid solid after cooling. tions that can affect performance. This section • Organic polymer processes. This discusses the potential components or layers technique involves adding and mixing of a final cover system, their functions, and monomer with a sludge, followed by appropriate materials for each layer. Since the adding a polymerizing catalyst. This materials used in cover systems are the same technique entraps the solid particles. as those used in liner systems, refer to Chapter 7, Section B–Designing and After evaluating and selecting a stabilization Installing Liners for a more detailed discus- or solidification process, you should conduct sion of the engineering properties of the vari- pilot-scale tests to address issues such as safe- ous materials. ty, mix ratios, mix times, and pumping prob- lems. Testing will help assess the potential for Table 1 presents the types of layers and an increase in waste volume. It will also help typical materials that might exist in a final to plan the production phase, train operators, cover. The minimum appropriate thicknesses and devise construction specifications. of each of the five types of layers depends upon many factors including site drainage, When conducting full-scale treatment erosion potential, slopes, types of vegetative operations, options exist for adding and mix- cover, type of soil, and climate. ing materials. These options might include in
11 - 8 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
Table 1 Types of Layers in Final Cover Systems
Layer Type of Layer Typical Materials
1 Surface (Erosion, Vegetative Cover) Topsoil, Geosynthetic Erosion Control Layer, Layer Cobbles
2 Protection Layer Soil, Recycled or Reused Waste Materials, Cobbles
3 Drainage Layer Sand and/or Gravel, Geonet or Geocomposite, Chipped or Shredded Tires
4 Barrier (Infiltration) Layer Compacted Clay, Geomembrane, Geosynthetic Clay Liner
5 Foundation/Gas Collection Layer Sand or Gravel, Soil, Geonet or Geotextile, Recycled or Reused Waste Material
Source: Jesionek et al., 1995 What function does the surface What types of materials can be layer serve? used in the surface layer? The role of the surface layer in the final cover Topsoil has been by far the most common- system is to promote the growth of native, non- ly used material for surface layers. The princi- woody plant species, minimize erosion, restore pal advantages of using topsoil in the surface the aesthetics of the site, and protect the barrier layer include its general availability and its layer. The surface layer should be thick enough suitability for sustaining vegetation. When top- so that the root systems of the plants do not soil is used as a surface layer, the roots of penetrate the underlying barrier layer. The vege- plants will reinforce the soil, reduce the rate of tation on the surface layer should be resistant to erosion, decrease runoff, and remove water drought and temperature extremes, able to sur- from the soil through evapotranspiration. To vive and function with little maintenance, and achieve these benefits, however, the soil also be able to maximize evapotranspiration, should have sufficient water-holding capacity which will limit water infiltration to the barrier to sustain plant growth. There are some con- layer. It is recommended that you consult with cerns with regard to using topsoil. For exam- agriculture or soil conservation experts concern- ple, topsoil requires ongoing maintenance, ing appropriate cover vegetation. Finally, the especially during periods of drought or heavy surface layer should be thick enough to with- rainfall. Prolonged drought can lead to crack- stand long-term erosion and to prevent desicca- ing in the soil, creating preferential pathways tion and freeze/thaw effects of the barrier layer. for water infiltration. Heavy rainfall can lead to The recommended minimum thickness for the erosion causing rills or gullies, especially on surface layer is at least 12 inches. The state newly-seeded or steeply sloping covers. If the agency can help to determine the appropriate topsoil does not have sufficient water holding minimum thickness in cold climates to protect capacity, it can not adequately support surface against freeze-thaw effects. plant growth, and evapotranspiration can
11 - 9 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
excessively dry the soils. In this case, irrigation intrusion by plant roots or burrowing ani- will be required to restore the water balance mals. This layer adds depth to the surface within the soil structure. Topsoil is also vulner- layer, increasing its water storage capacity able to penetration by burrowing animals. and protecting underlying layers from freez- ing and erosion. In many cases, the protec- Geosynthetic erosion control material can tion layer and the surface layer are combined be used as a cover above the topsoil to limit to form a single cover layer. erosion prior to the establishment of a mature vegetative cover. The geosynthetic material can What types of materials can be include embedded seeds to promote plant growth, and can be anchored or reinforced to used in the protection layer? add stability on steeply sloped areas. Soil will generally be the most suitable Geosynthetic material, however, does not material for this layer, except in cases where enhance the water-holding capacity of the soil. special design requirements exist for the pro- In arid or semi-arid areas, therefore, the soil tection layer. The advantages and disadvan- might still be prone to wind and water erosion tages of using soil in the protection layer are if its water-holding capacity is insufficient. the same as those stated above in the discus- Cobbles can be a suitable material for the sion of the surface layer topsoil. Factors surface layer in arid areas or on steep slopes impacting the thickness and type of soil to use which might hinder the establishment of veg- as a protection layer include freeze and thaw etation. If they are large enough they will properties and the interaction between the soil provide protection from wind and water ero- and drainage layers. Other types of materials sion without washout. Cobbles can also pro- that can be used in the protection layer tect the underlying barrier layer from include cobbles with a geotextile filter, gravel intrusion by burrowing animals, but cobbles and rock, and recycled or reused waste. might not be available locally, and their use Cobbles with a geotextile filter can form does not protect the underlying barrier layer a good barrier against penetration by plant from water infiltration. Because cobbles create roots and burrowing animals in arid sites. a porous surface through which water can The primary disadvantage is that cobbles percolate, they do not ordinarily support veg- have no water storage capacity and allow etation. Wind-blown soil material can fill water percolation into underlying layers. voids between cobbles, and plants can estab- lish themselves in these materials. This plant Gravel and rock are similar to cobbles material should be removed, as its roots are since they can form a good barrier against likely to extend into the underlying barrier penetration by plant roots and burrowing ani- layer in search of water. mals. Again, this use is usually only consid- ered for arid sites, because gravel and rocks What function does the protec- have no water storage capacity and allow tion or biotic barrier layer serve? water percolation into underlying layers. Recycled or reused waste materials such A protection or biotic barrier layer can be as fly ash and bottom ash can be used in the added below the surface layer, but above the protection layer, when available. Check with drainage layer, to protect the latter from the state agency to verify that use of these
11-10 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
materials is allowable. The advantages of drainage layers, the thickness will depend on using these materials in the protection layer the level of performance being designed and are that they store water that has infiltrated the properties of available materials. For past the surface layer, which can then be example, some geonet composites, with a returned to the surface through evapotrans- thickness of less than 1 inch, have a transmis- piration, and that they offer protection sivity equal to a much thicker layer of aggre- against burrowing animals and penetration by gate or sand. The recommended thickness of roots. If planning to use waste material in the the high permeability soil drainage layer is 12 protection layer, consider its impact on sur- inches with at least a 3 percent slope at the face runoff at the unit’s perimeter. Design bottom of the layer. Based on standard prac- controls to ensure runoff does not contribute tice, the drainage layer should have a to surface-water contamination. Consult hydraulic conductivity in the range of 10-2 to Chapter 6–Protecting Surface Water for more 10-3 cm/sec. Water infiltration control through details on designing runoff controls. a drainage layer improves slope stability by reducing the duration of surface and protec- What function does the drainage tion layer saturation. In this role, the drainage layer serve? layer works with vegetation to remove infil- trating water from the cover and protect the A drainage layer can be placed below the underlying barrier layer. If this layer drains surface layer, but above the barrier layer, to the overlying soils too well, it could lead to direct infiltrating water to drainage systems at the need for irrigation of the surface layer to the toe of the cover (see Figure 2) or to inter- avoid desiccation. mittent benches on long steep slopes. For
Figure 2. Drainage Layer Configuration
Source: U.S. EPA, 1991.
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Another consideration for design of drainage layers. Again, be aware of the possi- drainage layers is that the water should dis- bility that a gravel drainage layer might drain charge freely from the toe of the cover or inter- overlying soils so well that irrigation of the mittent benches. If outlets become plugged or surface layer might become necessary. The are not of adequate capacity, the toe of the principal advantage to a gravel/geotextile slope can become saturated and potentially drainage layer is the engineering community’s unstable. In addition, when designing the considerable body of knowledge regarding drainage layer, you should consider using flex- their use as drainage materials. Other advan- ible corrugated piping in conjunction with tages include their ability to protect underly- either the sand and gravel or the gravel with ing layers from intrusion, puncture, geotextile filter material to facilitate the move- temperature extremes, and their common ment of water to the unit perimeter. availability. The geotextile filter provides a cushion layer between the gravel and the What materials can be used in overlying protection layer. the drainage layer? Figure 3. Sand and gravel are a common set of Geonet with Geotextile Filter Design materials used in the drainage layer. The for Drainage Layer principal consideration in their use is the hydraulic conductivity required by the overall design. There can be cases in which the design requires the drainage of a large amount of water from the surface layer, and the hydraulic properties of the sand and grav- el layer might be insufficient to meet these requirements. The advantages of using sand and gravel in the drainage layer include the ability to protect the underlying barrier layer Source: U.S. EPA, 1991. from intrusion, puncture, and temperature extremes. The principal disadvantage to these materials is that they are subject to intrusions Geonet and geotextile filter materials can from the overlying protective layer that can be used to form an effective drainage layer alter their hydraulic conductivity. Similarly, directly above a compacted clay or geomem- fines in the sand and gravel can migrate brane liner (see Figure 3). They are a suitable downslope, undermining the stability of the alternative especially in cases where other cover slope. A graded filter or a geotextile fil- materials, such as sand and gravel, are not ter can be used to separate and protect the locally available. The principal advantage is sand and gravel from intrusions by the over- that lightweight equipment can be used lying protection layer. during installation, reducing the risk of dam- aging the underlying barrier layer. Gravel with a geotextile filter is also a widely-used design, whose applicability can The disadvantages associated with geonet be limited by the local availability of materi- and geotextile materials are that they provide als. The gravel promotes drainage of water little protection for the barrier layer against from the overlying layers, while the geotextile extreme temperature changes, and there can filter prevents the clogging of granular be slippage between the interfaces between the geomembrane, geotextile, and low perme-
11-12 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
ability soil barrier materials. The use of tex- producing waste is present). Dry waste mater- tured materials can be considered to address ial and gas formation within the unit con- slippage. Furthermore, problems can arise in tribute to drying from below, while a range of the horizontal seaming of the geotextile climatological conditions, including drought, drainage layer on long slopes. can affect CCLs from above. Even with extremely thick surface and protection layers, Chipped or shredded tires are an addi- CCLs can still undergo some desiccation. tional option for drainage layer materials. Chipped or shredded tires have been used for Clay liners are also vulnerable to subsi- bottom drainage layers in the past and might dence within the waste unit. This problem be suitable for cover drainage layers as well. can first manifest itself during liner construc- One caution concerning the use of chipped tion. As the clay is compacted with machin- or shredded tires is possible metal contami- ery, the waste might not provide a stable, nants, or pieces of metal that could damage a even foundation for the compaction process. geomembrane liner. You should consult with This will make it difficult to create the evenly the state agency to determine whether this measured lifts comprising the liner. As waste option is an acceptable practice. settles over time, depressions can form along the top of the CCL. These depressions put What function does the barrier differential stresses on the liner, causing layer serve? cracks which compromise its integrity. For instance, a depression of only 5 to 11 inches The barrier layer is the most critical com- across a 6-foot area can be sufficient to crack ponent of the cover system because it pre- the liner materials. vents water infiltration into the waste. It also indirectly promotes the storage and drainage Single geomembrane liners are sheets of of water from the overlying protection and a plastic polymer combined with other ingre- surface layers, and it prevents the upward dients to form an effective barrier to water movement of gases. This layer will be the least infiltration. Such liners are simple and permeable component of the final cover sys- straightforward to install, but they are rela- tem. Typically, the hydraulic conductivity of a tively fragile and can be easily punctured barrier layer is between 10-9 to 10-7 cm/sec. during installation or by movement in surface layer materials. The principal advantage of a What types of materials can be geomembrane is that it provides a relatively used in the barrier layer? impermeable barrier with materials that are generally available. It is not damaged by tem- Single compacted clay liners (CCLs) are perature extremes and therefore does not the most common material used as barrier require a thick surface layer. The geomem- layers in final cover systems. CCL popularity brane is more flexible than clay and not as arises largely because of the local availability vulnerable to cracking as a result of subsi- of materials and the engineering community’s dence within the unit. The principal disad- extensive experience with their use. Drying vantage is that it provides a point of potential and subsidence are the primary difficulties slippage at the interface with the cover soils. posed by CCLs. When the clay dries, cracks Such slippage can tear the geomembrane, appear and provide preferential pathways even if it is anchored. along which water can enter the waste, pro- Single geosynthetic clay liners (GCLs) moting leachate formation, waste decomposi- are composed of bentonite clay supported by tion, and gas formation (when methane
11-13 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
geotextiles or geomembranes held together some types of GCL and other surface layer with stitching or adhesives. These liners are materials. The geomembrane is still vulnerable relatively easy to install and have some self- to puncture, so placement of cover soils is healing capacity for minor punctures. They important to minimize such damage. are easily repaired by patching. The main dis- Textured geomembranes can be used to advantages include low shear strength, low increase the stability of cap side slopes. bearing capacity, vulnerability to puncture Textured geomembranes are nearly identical due to relative thinness, and potential for to standard “smooth” geomembranes differing slippage at interfaces with under- and overly- only in the rough or textured surface that has ing soil materials. When dry, their permeabil- been added. This textured surface increases ity to gas makes GCLs unsuitable as a barrier the friction between the liner and soils and layer for wastes that produce gas, unless the other geosynthetics used in the cap, and can clay will be maintained in a wet state for the help prevent sliding failures. In general, tex- entire post-closure period. tured geomembranes are more expensive than Geomembrane with compacted clay lin- comparable “smooth” geomembranes. ers (CCLs) can be used to mitigate the short- Using textured geomembranes allows cap comings of each material when used alone. In designers to employ steeper slopes which can this composite liner, the geomembrane acts to increase the available airspace in a waste protect the clay from desiccation, while pro- management unit, and therefore increase its viding increased tolerance to differential set- capacity. Textured geomembranes also help tlement within the waste. The clay acts to keep cover soil in place improving overall protect the geomembrane from punctures and liner stability on steep slopes. The degree to tearing. Both components act as an effective which textured geomembranes will improve barrier to water infiltration. The principal dis- frictional resistance (friction coefficients/fric- advantage is slippage between the geomem- tion angles) will vary from site-to-site brane and surface layer materials. depending upon the type of soil at the site Geomembrane with geosynthetic clay lin- and its condition (e.g., moisture content). ers (GCLs) can also be used as a barrier layer. Textured geomembranes are manufactured As with geomembrane and CCL combinations, by two primary methods. Some textured each component serves to mitigate the weak- geomembranes have a friction coating layer ness of the other. The geosynthetic material is added to standard “smooth” geomembranes less vulnerable than its clay counterpart to through a secondary process. Others are tex- cracking and has a moderate capacity to self- tured during the initial production process, heal. The geomembrane combined with the meaning textured layers are coextruded as GCL is a more flexible cover and is less vulner- part of the liner itself. Textured geomem- able to differential stresses from waste settle- branes can be textured on one or both sides. ment. Neither component is readily affected by extreme temperature changes, and both work Textured geomembranes are seam-welded together to form an effective barrier layer. For by the same technologies as standard more information on the properties of geosyn- geomembranes. Due to their textured surface, thetic clay liners, including their hydration however, seam welds can be less uniform after installation, refer to Chapter 7, Section with textured liners than with normal liners. B–Designing and Installing Liners. The poten- Some textured geomembranes have smooth tial disadvantage is slippage between the upper edges on the top and bottom of the sheet to and lower surfaces of the geomembrane and allow for more uniform seam welding.
11-14 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
What function does the gas col- tion of methane rise to dangerous levels. As lection layer serve? with all aspects of a waste containment sys- tem, construction quality assurance plays a The role of the gas collection layer is to critical role in the success of a gas manage- control the migration of gases to collection ment system. vents. This collection layer is a permeable Gas extraction wells are an example of layer that is placed above the foundation active gas control systems. For deep wells, layer. It is often used in cases where the foun- the number, location, and extent of the pipe dation layer itself is not the gas collection perforations are important. Also, the depth of layer. For more information on Clean Air Act the well must be kept safely above the liner requirements for managing gas from landfills system beneath the waste. For continuous gas and other waste management units, refer to Chapter 5–Protecting Air Quality. Figure 4. Passive Gas Venting System Gas control systems generally include mech- anisms designed to con- trol gas migration and to help vent gas emis- sions into the atmo- sphere. Systems using natural pressure and convection mechanisms are referred to as passive gas control systems (see Figure 4). Examples of passive gas control sys- Source: Robinson, W., ed. 1986. The Solid Waste Handbook: A Practical tem elements include Guide. Reprinted by permission of John Wiley & Sons, Inc. ditches, trenches, vent walls, perforated pipes surrounded by coarse Figure 5. Active Gas Venting System soil, synthetic mem- branes, and high mois- ture, fine-grained soil. Systems using mechani- cal means to remove gas from the unit are referred to as active gas control systems. Figure 5 illustrates an active gas system. Gas control systems can also be used as part of correc- tive action measures Source: Robinson, W., ed. 1986. The Solid Waste Handbook: A Practical should the concentra- Guide. Reprinted by permission of John Wiley & Sons, Inc.
11-15 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
collection layers beneath the barrier layer, rier layer. Geotextile and geosynthetic continuity is important for both soils and drainage composites also can make suitable geosynthetics. gas collection layers. In many cases, these can be the most cost-effective alternatives. The Knowing the rate of gas generation is same disadvantages exist with these materials essential to determining the quantity of gas in the gas collection layer as in other layers, that can be extracted from the site. Pumping such as slippage and continuity of flow. an individual well at a greater vacuum will give it a wider zone of influence, which is With a geomembrane in the final cover acceptable, but obviously there are points of barrier system, uplift pressures will be exert- diminishing marginal returns. Larger suction ed unless the gas is quickly and efficiently pressures influence a larger region but conveyed to the wells, vents, or collection involve more energy expended in the pump- trenches. If this is not properly managed, ing. Pumping at greater vacuum also increas- uplift pressure will either cause bubbles to es the potential for drawing in atmospheric occur, displacing the cover soil and appear- air if the pumping rate is set too high. ing at the surface, or decrease the normal Significant air intrusion into the unit can stress between the geomembrane and its result in elevated temperatures and even underlying material. This problem has led to underground fires. You should perform rou- slippage of the geomembrane and all overly- tine checks of gas generation rates to better ing materials creating high tensile stresses ensure that optimal pumping rates are used. evidenced by folding at the toe of the slope and tension cracks near the top. The performance of gas extraction systems is affected by the following parameters, which should be considered when designing D. Capillary-Break Final and operating gas systems: Covers • Daily cover, which inhibits free The capillary-break (CB) approach is an movement of gas. alternative design for a final cover system • Sludge or liquid wastes, which affect (see Figure 6). This system relies on the fact the ease at which gas will move. that for adjacent layers of fine- and coarse- textured material to be in water-potential • Shallow depth of unit, which makes equilibrium, the coarse-grained material it difficult to extract the gas, because (such as crushed stone) will tend to have a atmospheric air will be drawn in much lower water content than the fine- during the pumping. grained material (such as sand). Because the • Permeability of the final cover, which conductivity of water through a soil decreases affects the ability of atmospheric air exponentially with its water content, as a soil to permeate the wastes in the unit. becomes more dry, its tendency to stay dry increases. Therefore, as long as the strata in a What types of materials can be capillary break remain unsaturated (remain used in the gas collection layer? above the water table), the overlying fine-tex- tured soil will retain nearly all the water and Sand and gravel are the most common the coarse soil will behave as a barrier to materials used for gas collection layers. With water percolation due to its dryness. Since these materials, a filter might be needed to this phenomenon breaks down if the coarse prevent infiltration of materials from the bar- layer becomes saturated, this alternative
11-16 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
cover system is most appropriate for semiarid Figure 6. Example of a Capillary-Break Final and desert environments. Cover System What types of materials are used in capillary-break covers? The CB cover system typically consists of five layers: surface, storage, capillary-break, barrier, and foundation. The surface, barrier, and foundation layers play the same role in the cover system as described above. The storage layer consists of fine material, such as silty sand. The capillary-break, or coarse, layer consists of granular materials, such as gravel and coarse sand. A fabric filter is often placed between the coarse and fine layers.
E. The Hydrologic Evaluation of Landfill Performance (HELP) Model Adapted from
11-17 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
F. Recommended Cover geomembrane bottom liner system, for exam- Systems ple, should include, at a minimum, a single geomembrane in its final cover system unless The recommended final cover systems cor- an evaluation of site-specific conditions can respond to a waste management unit’s bot- show an equivalent reduction in infiltration. tom liner system. A unit with a single Table 2 summarizes the minium recommend- Table 2: Minimum Recommended Final Cover Systems*
Type of Bottom Liner Recommended Cover System Thickness Hydraulic Conductivity Layers (From top layer down)a (In inches) (In cm/sec)
Double Liner Surface Layer 12 not applicable Drainage Layer 12b 1×10-2 to 1x10-3 Geomembrane 30mil(PVC) 60mil (HDPE) — Clay Layer 18 less than 1×10-5
Composite Liner Surface Layer 12 not applicable Drainage Layer 12b 1×10-2 to 1x10-3 Geomembrane 30 mil (PVC) 60 mil (HDPE) — Clay Layer 18 less than 1×10-5
Single Clay Liner Surface Layer 12 not applicable Drainage Layer 12b 1×10-2 to 1x10-3 Clay Layer 18 less than 1×10-7
Single Clay Liner in Cobble Layer 2-4 not applicable an Arid Area Drainage Layer 12b 1×10-2 to 1x10-3 Clay Layer 18 less than 1×10-7
Single Synthetic Liner Surface Layer 12 not applicable Drainage Layer 12b 1×10-2 to 1x10-3 Geomembrane 30 mil (PVC) 60 mil (HDPE) — Clay Layer 18 less than 1×10-5
Natural Soil Liner Earthen Material 24c No more permeable than base soil
* Please consult with your state regulatory agency prior to constructing a final cover. a The final selection of geomembrane type, thickness, and drainage layer requirements for a final cover should be design-based and consultation with your state agency is recommended. b This recommended thickness is for high permeability soil material with at least a 3 percent slope at the bottom of the layer. Some geonet composites, with a minimal thickness of less than 1 inch, have a transmissivity equal to a much thicker layer of aggregate or sand. c Thickness might need to be increased to address freeze/thaw conditions.
11-18 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
ed final cover systems based on the unit’s bot- addition, you should consider whether to tom liner system. While the recommended include a protection layer or a gas collection minimum final cover systems include closure layer. Figures 7 through 11 display recom- layer component thicknesses and hydraulic mended minimum final cover systems. conductivity, the cover systems can be modi- fied to address site-specific conditions. In
Figure 7. Recommended Final Cover System for a Unit With a Double or Composite Liner
Figure 8. Recommended Final Cover System for a Unit With a Single Clay Liner
11-19 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
Figure 9. Recommended Final Cover System for a Unit With a Single Clay Liner in an Arid Area
Figure 10. Recommended Final Cover System for a Unit With a Single Synthetic Liner
11-20 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
Figure 11. Recommended Final Cover System for a Unit With a Natural Soil Liner
While these recommendations include the decontamination are complete when the con- use of compacted clay, a facility manager stituent concentrations throughout the unit might want to consider the use of a geomem- and any areas affected by releases from the brane barrier layer in addition to, or in place unit do not exceed numeric cleanup levels. of, a compacted clay barrier layer. Subsidence You should check with the state agency to see of a final cover constructed with a compacted if it has established any numeric cleanup lev- clay barrier layer can allow precipitation to els or methods for establishing site-specific enter the closed unit and increase leachate levels. In the absence of state cleanup levels, production. The use of a geomembrane in metals and organics should be removed to place of compacted clay might be more cost either statistically equivalent background lev- effective. Due to cracking or channeling or els or to maximum contaminant levels continued subsidence, post-closure care of a (MCLs) or health-based numbers (HBNs)2. compacted clay barrier layer can be more Metals and organics might have different expensive to maintain than a geomembrane cleanup levels, but they both should be based barrier layer. A geomembrane barrier layer on either local background levels or on can also accommodate more subsidence with- health-based guidelines. out losing its effectiveness. Future land use considerations can also be important in determining the appropriate level of cleanup. One tool that can be used to IV. Closure by help evaluate whether waste removal is appropriate at the site is the risk-based cor- Waste Removal rective action (RBCA) process described in Closure by waste removal is a term that Chapter 10–Taking Corrective Action. The describes the removal and decontamination RBCA process provides guidance on integrat- of all waste, waste residues, contaminated ing ecological and human health risk-based ground water, soils, and containment devices. decision-making into the traditional correc- This approach is common for waste piles and tive action process. some surface impoundments. Removal and
2 To learn about the regulatory and technical basis for MCLs, access the Integrated Risk Information System (IRIS), a database of human health effects that can result from exposure to environmental contaminants, at
A. Establishing Baseline How are baseline conditions Conditions established? A good management practice is to establish Initial soil and ground-water sampling the baseline conditions for a waste manage- around, within, and below a unit will serve ment unit. Baseline conditions include the to identify baseline conditions. Sampling can background constituent concentrations at a detect contaminant levels that exceed back- site prior to waste placement operations. ground levels or federal, state, or local Identifying the types of contaminants that health-based benchmarks. Contact local envi- might be present can provide an indication of ronmental protection officials for guidance on the potential contamination resulting from the the number and type of samples that should operation of a unit and the level of effort and be taken. If the initial round of sampling resources that can be required to reach clo- does not reveal any contaminant levels that sure. Naturally-occurring elevated background exceed benchmarks, you should proceed levels that are higher than targeted closure lev- with the removal of waste and the restoration els might be encountered. In such cases, con- of the unit. If the sampling does reveal conta- sult with the state agency to determine mination that exceeds the benchmarks, you whether these elevated background levels are a should consider ways to remediate the site in more appropriate targeted cleanup level. The compliance with federal, state, or local identification of potential contaminants will requirements. also provide a guideline for selecting sampling parameters. If constituents other than those initially identified are discovered through sub- B. Removal Procedures sequent soil and water sampling, this might Proper removal procedures are vital to the indicate that contaminants are migrating from long-term, post-closure care of a unit and another source. surrounding land. Properly removing waste In some cases, waste contaminants might can minimize the need for further mainte- have been present at a site before a waste nance, thereby saving time and money and management unit was constructed, or they facilitating reuse of the land. You should per- might have migrated to the site from another form closure by waste removal in a manner unrelated source. In these situations, closure that prevents the escape of waste constituents by waste removal can still proceed, provided to the soil, surface water, ground water, and that any contamination originating from the atmosphere. After removing the waste, you closing unit is removed to appropriate should remove all equipment, liners, soils, cleanup levels. You should determine whether and any other materials containing waste or additional remediation is required under waste residues. Removal verification should other federal or state laws, such as the include specifics as to how it will be deter- Resource Conservation and Recovery Act mined that residues, equipment, liners, and (RCRA), the Comprehensive Environmental soils have been removed to baseline condi- Response, Compensation, and Liability Act tions. Finally, the land should be returned to (CERCLA), or state cleanup laws. the appearance and condition of surrounding land areas to the extent possible consistent with the closure and post-closure plans.
11-22 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
Should a plan for waste removal D. Final Sampling and procedures be prepared? Analysis The waste removal process should be fully The purpose of final sampling and analysis described in a closure plan. The removal is to ensure that target cleanup levels have process description should address estimates been achieved. While initial sampling is of the volumes and types of waste and conta- intended to establish baseline levels of conta- minated equipment or structures to be minants, final sampling is used more as a removed during closure. It should also safeguard to make sure levels have not include the types of equipment to be used, changed. It is important to conduct a final the removal pattern, and the management of sampling, in addition to the initial sampling, loading areas. The closure plan should also because removal actions can increase the con- detail steps to be taken to minimize and pre- taminant levels at the site, and sometimes vent emissions of waste during closure activi- contamination is overlooked in the initial ties. For example, if activities during closure baseline sampling event. Refer to Chapter include loading and transporting waste in 9–Monitoring Performance for a detailed dis- trucks, the closure plan should describe the cussion of sampling and analysis procedures. steps that will be taken to minimize air emis- How should the sampling data sions from windblown dust. Proper quality assurance and quality control during the be used? waste removal process will help ensure that The results of this sampling event should the removal proceeds in accordance with the be compared to the results of the baseline waste removal plan. A key component of the event, and any discrepancies should be waste removal procedure is the consideration noted. The results can be compared to per- of proper disposal or treatment methods for formance measures established at the begin- any wastes or contaminated materials. ning of the closure process with state or local regulators. Closure plans incorporating waste C. Disposal of Removed removal should include a sampling and analysis plan for the initial and final sampling Wastes and analysis efforts. The plan should specify When a unit is closed by removing waste, procedures to ensure that sample collection, waste residues, contaminated ground water, handling, and analysis will result in data of soils, and containment devices, you should sufficient quality to plan and evaluate closure ensure that disposal of these materials is in activities. The sampling and analysis plan compliance with state law. If the composition should be designed to define the nature and of the waste can not be determined using extent of contamination at, or released from, process knowledge, you should test it using the closing unit. The level of detail in the procedures such as those described in Chapter sampling and analysis plan should be com- 2–Characterizing Waste. Then consult with the mensurate with the complexity of conditions state agency to determine which requirements at the closing unit. might apply to the waste.
11-23 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
A regular schedule for site inspections of V. Post-Closure Care maintenance activities during the post-closure Considerations period, as well as prompt repair of any prob- lems found at inspection, can help ensure the When Final proper performance of the cover system. Maintenance of the proper thickness of sur- Cover Is Used face and drainage layers can ensure long-term For units that will close with a final cover, minimization of leachate production and pro- the following factors should be considered: tection of geomembranes, if present. • Routine maintenance of the unit’s sys- What maintenance and repair tems, including the final cover, leachate collection and removal sys- activities should be conducted tems, run-on and runoff controls, gas after the final cover has been and ground-water monitoring sys- installed? tems, and surface-water and gas qual- ity monitoring where appropriate. In the case of damage to the final cover, • The names and telephone numbers you should determine the cause of damage so of facility personnel for emergencies. that proper repair measures can be taken to prevent recurrence. For example, if the dam- • Mechanisms to ensure the integrity of age is due to erosion, potential causes might the final cover system, such as posted include the length and steepness of slopes, signs or notifications on deeds. insufficient vegetation growth due to poor • The anticipated uses of the property planting, or uneven settlement of the waste. during the post-closure period. Sedimentation basins and drainage swales should be inspected after major storms and • The length of the post-closure care repaired or cleaned, as necessary. period. Components of the leachate collection and • Costs to implement and conduct removal system, such as leachate collection post-closure care. pipes, manholes, tanks, and pumps should • Conditions that will cause post-clo- also receive regular inspection and mainte- sure care to be extended or shortened. nance. If possible, flush and pressure-clean the collection systems on a regular basis to reduce sediment accumulation and to pre- A. Maintenance vent clogging caused by biological growth. After the final cover is installed, some The manholes, tanks, and pumps should be maintenance and repair likely will be neces- visually inspected at least annually, and sary to keep the cover in good working con- valves and manual controls should be exer- dition. Maintenance can include mowing the cised even more frequently, because leachate vegetative cover periodically and reseeding, if can corrode metallic parts. Repairs will help necessary. Repair the cover when erosion or prevent future problems, such as leachate subsidence occurs. Maintaining healthy vege- overflow from a tank due to pump failure. tation will ensure the stability of slopes, You should inspect and repair gas and reduce surface erosion, and reduce leachate ground-water monitoring wells during the production by increasing evapotranspiration. post-closure period. Proper operation of
11-24 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
monitoring wells is essential to determine To ensure leachate has not contaminated whether releases from a closed waste manage- ground-water supplies, you should sample ment unit are occurring. For example, ground water regularly. Regular ground-water ground-water monitoring wells should be monitoring detects changes, or the lack there- inspected to ensure that they have not been of, in the quality of ground water. For a more damaged by vehicular traffic or vandalism. detailed discussion, consult Chapter 9– Physical scraping or swabbing might be nec- Monitoring Performance. essary to remove biological clogging or As no cover system is impermeable to gas encrustation from calcium carbonate deposits migration, and if gas production is a concern on well screens. at the unit, you should install gas monitoring wells around the perimeter of the unit to B. Monitoring During Post- detect laterally moving gas. If geomembranes are used in a cover, more gas can escape lat- Closure Care erally than vertically. Gas collection systems Post-closure care monitoring should can also become clogged and stop performing include the leachate collection system, sur- properly. Therefore, you should periodically face-water controls, the ground-water moni- check gas vents and flush and pressure-clean toring system where appropriate, and gas those vents not working properly. controls where appropriate. Post-closure monitoring will serve as your main source of information about the integrity of the final C. Recommended Length cover and liners. A reduction in the intensity of the Post-Closure Care (i.e., frequency) and scope of monitoring Period might be warranted after some period of time during post-closure care. Conversely, an The overall goal of post-closure care is to increase in intensity and scope might become provide care until wastes no longer present a necessary due to unanticipated problems. threat to the environment. Threats to the envi- ronment during the post-closure care period What should be considered when can be evaluated using leachate and ground- monitoring post-closure leachate, water monitoring data to determine whether there is a potential for migration of waste con- ground water, and gas? stituents at levels that might threaten human health and the environment. Ground-water The quantity of leachate generated should monitoring data can be compared to drinking be monitored, as this is a good indicator of water standards or health-based criteria to the performance of the closure system. If the determine whether a threat exists. closure system is effective, the amount of leachate generated should decrease over time. Leachate volumes and constituent concen- In addition, the concentration of contami- trations can also be used to show that the nants in leachate should, in time, reach an unit does not pose a threat to human health equilibrium. An abrupt decline in the conta- and the environment. The threats posed by minant concentration could mean that the waste constituents in leachate should be eval- cover has failed, and surface water has uated based on the potential release of entered the waste and diluted the leachate. leachate to ground and surface waters. Consequently, you should consider doing post-closure care maintenance for as long as
11-25 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
that potential exists. Individual post-closure The amount of financial assurance that care periods can be long or short depending might be necessary is based on site-specific on the type of waste being managed, the estimates of the costs of closure and post-clo- waste management unit, and a variety of site- sure care. The estimates should reflect the specific characteristics. You should contact costs that a third party would incur in con- the appropriate state agency to determine ducting closure and post-closure activities. what post-closure period it recommends. In This recommendation ensures adequate funds the absence of any state guidance on the will be available to hire a third party to carry appropriate length of the post-closure period, out necessary activities. You should consider consider a minimum of 30 years. updating the cost estimates annually to account for inflation and whenever changes are made to the closure and post-closure D. Closure and Post-Closure plans. For financial assurance purposes, if a Cost Considerations state does not have a regulation or guidance The facility manager of a closed industrial regarding the length of the post-closure care unit is responsible for that unit. To ensure period, 30 years could be used as a planning long-term protection of the environment, you tool for developing closure and post-closure should account for the costs of closure and cost estimates. post-closure care when making initial plans. Financial assurance mechanisms do not There are guidance documents available to force anyone to immediately provide full help plan for the costs associated with closing funding for closure and post-closure care. a unit. For example, guides produced by the Rather, they help to ensure the future avail- R.S. Means Co. provide up-to-date cost esti- ability of such funds. For example, trust mates for most construction-related work, funds can be built up gradually during the such as moving soil, and material and labor operating life of a waste management unit. By for installing piping. Table 3 also presents an having an extended “pay-in” period for trust example of a closure/post-closure cost esti- funds, the burden of funding closure and mate form. Table 4 presents a sample summa- post-closure care will be spread out over the ry cost estimating worksheet to assist in economic life of the unit. Alternatively, con- determining the cost of closure. Also you sider the use of a corporate financial test or should consider obtaining financial assurance third-party alternative, such as surety bonds, mechanisms so that the necessary funds will letters of credit, insurance, or guarantees. be available to complete closure and post-clo- sure care activities if necessary. Financial What costs can be expected to assurance planning encourages internalization be associated with the closure of of the future costs associated with waste man- agement units and promotes proper design a unit? and operating practices, because the costs for The cost of constructing a final cover or closure and post-closure care are often less achieving closure by waste removal will for units operated in an environmentally pro- depend on site-specific activities. You should tective manner. You should check with the consider developing written cost estimates state agency to determine whether financial before closure procedures begin. For closure assurance is required and what types of by means of a final cover, the cost of con- financial assurance mechanisms might be structing the final cover will depend on the acceptable. complexity of the cover profile, final slope
11-26 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
Table 3: Example Closure/Post-Closure Cost Estimate Form* (All Costs Shown in ($000)
Provisions Total Closure Total Post- Total Closure/ Costs Yrs. ( - ) Closure Costs Post-Closure Yrs. ( - ) Costs Yrs. ( - )
i Soil Erosion and Sediment Control Plan NA
ii Final Cover NA
iii Final Cover Vegetation NA
iv Maintenance Program for Final Cover and NA Final Cover Vegetation
v Maintenance Program for Side Slopes NA
vi Run-On and Runoff Control Program NA
vii Maintenance Program for Run-On and Runoff NA Control System
viii Ground-water Monitoring Wells NA
ix Maintenance Program for Ground-water NA Monitoring Wells
x Ground-water Monitoring NA
xi Methane Gas Venting or Evacuation System NA
xii Maintenance Program for Methane Gas NA Venting or Evacuation System
xiii Leachate Collection and/or Control System NA
xiv Maintenance Program for Leachate Collection NA and/or Control System
xv Facility Access Control System NA
xvi Maintenance Program for Facility Access NA Control System
xvii Measures to Conform the Site to NA Surrounding Area
xviii Maintenance Program for Site Conformance NA Measures
xix Construction Quality Assurance and NA Quality Control
TOTAL COSTS
* Developed from New Jersey Department of Environmental Protection, Bureau of Landfill Engineering Landfill Permits.
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Table 3: Example Closure/Post-Closure Cost Estimate Form (Cont’d) Provisions Total Post- Year Year Year Year Year Year Year Closure Costs #1 #2 #3 #4 #5 #6 #7
i Soil Erosion and Sediment Control Plan NA
ii Final Cover NA
iii Final Cover Vegetation NA
iv Maintenance Program for Final Cover and Final Cover Vegetation
v Maintenance Program for Side Slopes
vi Run-On and Runoff Control Program NA
vii Maintenance Program for Run-On and Runoff Control System
viii Ground-water Monitoring Wells NA
ix Maintenance Program for Ground- water Monitoring Wells
x Ground-water Monitoring
xi Methane Gas Venting or Evacuation NA System
xii Maintenance Program for Methane Gas Venting or Evacuation System
xiii Leachate Collection and/or Control NA System
xiv Maintenance Program for Leachate Collection and/or Control System
xv Facility Access Control System NA
xvi Maintenance Program for Facility Access Control System
xvii Measures to Conform the Site to NA Surrounding Area
xviii Maintenance Program for Site Conformance Measures
xix Construction Quality Assurance and NA Quality Control
TOTAL COSTS
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Table 4: Sample Summary Cost Estimating Worksheet
Summary Worksheet for Landfills
Activity Some of the activities listed below are routine. The owner or operator Worksheet Cost might elect or be required to conduct additional activities. Italic type Number denotes worksheets for estimating the costs of those additional activities
1 Installation of Clay Layer LF-3 $
2 Installation of Geomembrane LF-4 $
3 Installation of Drainage Layer LF-5 $
4 Installation of Topsoil LF-6 $
5 Establishment of Vegetative Cover LF-7 $
6 Installation of Colloid Clay Liner LF-8 $
7 Installation of Asphalt Cover LF-9 $
8 Decontamination DC-1 $
9 Sampling and Analysis SA-2 $
10 Monitoring Well Installation MW-1 $
11 Transportation TR-1 $
12 Treatment and Disposal TD-1 $
13 Subtotal of Closure Costs (Add lines 1 through 12)
14 Engineering Expenses (Engineering expenses are typically 10% of closure $ costs, excluding survey plat, certification of closure, and post-closure care.)
15 Survey Plat LF-10 $
16 Certification of Closure LF-11 $
17 Subtotal (Add engineering expenses and cost of the survey plat, certification of $ closure, and post-closure care to closure costs [Add lines 12 through 16])
18 Contingency Allowance (Contingency allowances are typically 20% of closure costs, engineering expenses, cost of survey plat, cost of certification of closure, and post- closure care.) $
19 Post-Closure Care PC-1 $
TOTAL COST OF CLOSURE (Add lines 17, 18, and 19) $
Worksheet generated from CostPro©: Closure and Post-Closure Cost Estimating Software. Available from Steve Jeffords of Tetra Tech EM Inc., 404 225-5514, or 285 Peach Tree Center Avenue, Suite 900, Atlanta, GA, 30303.
11-29 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
contours of the cover, whether the entire unit expected. Post-closure care costs should will be closed (or partial closures), and other include both annual costs, such as monitor- site-specific factors. For example, the compo- ing, and periodic costs, such as cap or moni- nents of the final cover system, such as a gas- toring well replacement. vent layer or a biotic layer, will affect costs. In For units closed by means of a final cover, addition, closure-cost estimates would also you should consider the costs for a mainte- include final-cover vegetation, run-on and nance program for the final cover and associ- runoff control systems, leachate collection ated vegetation. The more frequent the timing and removal systems, ground-water monitor- of the maintenance activities, the greater your ing wells, gas-monitoring systems and con- post-closure care costs will be. This program trols, and access controls, such as fences or might include repair of damaged or stressed signs. Closure costs might also include con- vegetation, and maintenance of side slopes. struction quality assurance costs, engineering Costs to maintain the run-on and runoff con- fees, accounting and banking fees, insurance, trol systems, leachate collection and removal permit fees, legal fees, and, where appropri- systems, and ground-water and gas monitor- ate, contingencies for cost overruns, reworks, ing wells should also be expected. In addi- emergencies, and unforeseen expenses. tion, sampling, analysis, and reporting costs For closure by means of waste removal, should be factored into the post-closure cost closure costs would include the costs of estimates. See Table 5 above for estimates of removal procedures, decontamination proce- post-closure care costs. dures, and sampling and analysis. Closure Post-closure costs should be updated cost estimates should also consider the costs annually as a record of actual unit costs is for equipment to remove all waste, transport developed. Some costs, such as erosion con- it to another waste management unit, and trol and ground-water sampling, might be properly treat or dispose of it. In addition, reduced over time as the vegetation on the fugitive dust emission controls, such as dust cover matures and a meaningful amount of suppression practices, might need to be monitoring data is accumulated. Due to site- included as a closure cost. Table 5 presents specific conditions, a shorter or longer post- example estimates of average closure costs for closure period might be determined to be typical closure activities. It also presents esti- appropriate. mates of typical post-closure care costs dis- cussed in more detail below. How can long-term financial What costs can be expected to be assurance for a unit be obtained? associated with post-closure care? Different examples of financial assurance mechanisms include trust funds, surety bond, After a waste management unit is closed, insurance, guarantee, corporate guarantees, you should conduct monitoring and mainte- and financial tests. Trust funds are a method nance to ensure that the closed unit remains whereby cash, liquid assets, certificates of secure and stable. Consider the costs to con- deposit, or government securities are deposit- duct post-closure care and monitoring for ed into a fund controlled by a trustee, or state some period of time, such as 30 years (in the agency. The trust fund amount should be such absence of a state regulation or guidance). If a that the principal plus accumulated earnings unit is successfully closed by means of waste over the projected life of the waste manage- removal, no post-closure care costs would be ment unit would be sufficient to pay closure
11-30 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
Table 5. Example Estimated Closure and Post-Closure Care Costs
Closure Activity Cost Estimate
Estimated average total landfill closure cost $4,000,000 1
Complete site grading $1,222/acre 2
Landfill capping
Total (all capping materials & activities) $80,000 – $100,000/ acre 3
Compacted clay cap $5.17/cubic yard of clay 2
Geosynthetic clay liner cap $16,553/acre 2
Leachate collection and treatment $0.05 – $0.15/gallon 3
$0.25/gallon 2
Reclamation of area (applying 2.5 feet of top soil and seeding) $10,200/acre 3
Install ground-water monitoring wells $2,400/well 4
Install methane monitoring wells (if applicable) $1,300/well 4
Install perimeter fence $13/linear foot 4
Repair/replace perimeter fence $2.20/linear foot 2
Construct surface-water structures $1/linear foot 4
Post-Closure Activity Cost Estimate (based on 30 year post-closure care period)
Estimated average total landfill post-closure care cost $1,000,000 1
Conduct annual inspections $22,000/facility/year 4
$15,000/facility/year 2
Maintain leachate collection systems $60,000 2
Conduct Post-closure ground-water monitoring $15,000 – $25,000/year 3
(sampling and analysis) $12,000/well 4
Conduct methane monitoring $7,200/well 4
Maintain perimeter fence $12/linear foot 4
Maintain surface-water structures $1/linear foot 4
Remove perimeter fence (at end of post-closure care period) $2/linear foot 4
1 ICF Incorporated. Memo to Dale Ruhter, September 11, 1996 ICF’s data show that total closure and post-closure care costs are dependent upon the size of the landfill. The size ranges and corresponding cost estimates were used to calculate the estimated average total costs. 11-31 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
Notes for Table 5 Subtitle D Landfill Closure Costs Subtitle D Landfill Post-Closure Care Costs Size Range Cost Size Range Cost (tons per day) (in 2000 dollars) (tons per day) (in 2000 dollars)
50 – 125 $2,700,000 50 – 125 $820,000
126 – 275 $5,100,000 126 – 275 $980,000
276 – 563 $8,300,000 276 – 563 $1,400,000
564 – 1125 $11,800,000 564 – 1125 $1,700,000
2 Oklahoma Department of Environmental Quality. Table 5.2 Closure Cost Estimate and Table 5.3 Post Closure Estimate from Chapter 5 of Solid Waste Financial Assurance Program Report. December 2000. 3 Jeffrey H. Heath “Landfill Closures: Balancing Environmental Protection with Cost,” MSW Management. January/February 1996. pp. 66-70. 4 Wyoming Department of Environmental Quality, Solid and Hazardous Waste Division. Solid Waste Guideline #12: Participation in the State Trust Account. May 1994.
and post-closure care costs. Surety bond, one or more beneficiaries. The trust insurance, and guarantee are methods to fund should be dedicated to closure arrange for a third party to guarantee pay- and post-closure care activities. ment for closure and post-closure activities if Payments are made annually into the necessary. A financial test is a standard, such fund so that the full amount for clo- as an accounting ratio, net worth, bond rat- sure and post-closure care accumu- ing, or a combination of these standards, that lates before closure and post-closure measures the financial strength of a firm. By care activities start. A copy of the passing a financial test, it is determined that trust agreement, which describes one has the financial strength to pay for clo- how the funds will be used to pay for sure and post-closure costs. closure and post-closure care activi- ties, should be placed in the waste A more detailed explanation of these management unit’s operating record. examples and other potential financial assur- ance mechanisms is provided below. These • Surety bond. A surety bond guaran- mechanisms can be used individually or in tees performance of an obligation, combination. This Guide, however, does not such as closure and post-closure recommend specific, acceptable, financial care. A surety company is an entity assurance mechanisms. that agrees to answer for the debt or default of another. Payment or per- • Trust funds. A trust fund is an formance surety bonds are acceptable arrangement in which one party, the in the event an owner or operator grantor, transfers cash, liquid assets, fails to conduct closure and post-clo- certificates of deposit, or government sure care activities. If you use a sure- securities into a fund controlled by a ty bond or letter of credit, you special “custodian,” the trustee, who should establish a standby trust fund manages the money for the benefit of (essentially the same as a trust fund).
11-32 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
In most cases, a standby trust fund is that they have the financial resources established with an initial nominal to pay for closure and post-closure fee agreed to by the owner or the costs. These tests might require that a operator and the trustee. Further company meet a specified net worth, payments into this fund are not a specified ratio of total liabilities to required until the standby trust is net worth, and a specified net work- funded by a surety company. The ing capital in the United States. surety company should be listed as Implicit in using a financial test is a an acceptable surety in Circular 570 reliance on Generally Accepted of the U.S. Department of Treasury. Accounting Principles (GAAP) to pro- vide fairly represented accounting • Letters of credit. A letter of credit is data. Your financial statements should a formalized line of credit from a be audited by an independent certi- bank or another institution on behalf fied public accountant. If the accoun- of an owner or operator. This agree- tant gives an adverse opinion or a ment states that it will make available disclaimer of opinion of the financial to a beneficiary, such as a state, a spe- statements, you should use a different cific sum of money during a specific financial assurance mechanism. time period. The letter of credit should be irrevocable and issued for • Corporate guarantee. Under a cor- 1 year. The letter of credit should porate guarantee, a parent company also establish a standby trust fund. guarantees to pay for closure and post-closure care, if necessary. The • Insurance. An insurance policy is parent company should pass a finan- basically a contract through which cial test to show that it has adequate one party guarantees another party financial strength to provide the monies, usually a prescribed amount, guarantee. A financial test is a way to perform the closure or post-clo- for guarantors to use financial data to sure care in return for premiums show that their resources are ade- paid. The policy should be issued for quate to meet closure and post-clo- a face amount at least equal to the sure care costs. The guarantee should current cost estimate for closure and only be used by firms with adequate post-closure care. The face amount financial strength. refers to the total amount the insurer is obligated to pay; actual payments • Other financial assurance mecha- do not change the face amount. nisms. If you consider other financial assurance mechanisms, you should • Corporate financial test. Corporate talk to your state to see if the mecha- financial tests are a method for an nism is acceptable. owner and operator to self-guarantee
11-33 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
Performing Closure and Post- Closure Care Activity List
You should consider the following while developing closure and post-closure care activities for industrial waste management units. ■ Develop a closure and post-closure plan, specifying the activities, unit type, waste type, and schedule of the closure. ■ If using a final cover to accomplish closure: — Include the specifications for the final cover in the closure plan. — Determine whether the waste will need stabilization or solidification prior to constructing the final cover. — Address site-specific factors that can affect cover performance. — Select the appropriate materials to use for each layer of the final cover. — Evaluate the effectiveness of the final cover design using an appropriate methodology or modeling program. — Establish a maintenance plan for the cover system. — Establish a program for monitoring the leachate collection system, ground-water quality, and gas generation during the post-closure period. — Ensure proper quality assurance and quality control during final cover installation and post-clo- sure monitoring. ■ If accomplishing closure by waste removal: — Include estimates of the waste volume, contaminated soils and containment structures to be removed during closure. — Establish baseline conditions and check to see if the state requires numeric cleanup levels. — Develop removal procedures. — Develop a sampling and analysis plan. — Ensure proper quality assurance and quality control during sampling. ■ Determine what post-closure activities will be appropriate at the site. ■ Estimate the costs of closure and post-closure care activities and consider financial assurance mecha- nisms to help plan for these future costs.
11-34 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
Resources
ASTM. D-3987-85. Standard Test Method for Shake Extraction of Solid Waste with Water.
ASTM. Standard Methods for Examination of Water and Wastewater.
ASTM, APHA, AWWA, & WPCF. Standard Test Methods for Examination of Water and Wastewater.
Bagchi, A. 1994. Design, Construction, and Monitoring of Landfills. John Wiley & Sons Inc.
Florida Department of Environmental Protection. Solid Waste Section. 1995. Municipal Solid Waste Landfill Alternate Design Closure Guidance.
Geosynthetic Research Institute. 1990. Landfill Closures: Geosynthetics Interface Friction and New Developments. GRI Proceedings.
Grefe, R. P. 1989. Closure of Papermill Sludge Lagoons Using Geosynthetics and Subsequent Performance. Presented at the Twelfth Annual Madison Waste Conference. September.
Heath, Jeffrey H. 1996. “Landfill Closures: Balancing Environmental Protection with Cost,” MSW Management. January/February. pp. 66-70.
ICF Incorporated. 1996. Memorandum to U.S. EPA: Updated Closure and Post-Closure Cost Estimates for Subtitle C. (Nevin and Brawn to Ruhter, September 11, 1996).
Jesionek, K.S., R.J. Dunn, and D.E. Daniel. 1995. Evaluation of Landfill Final Covers. Proceedings Sardinia 95, Fifth International Landfill Symposium. October.
Koerner, R.M. and D.E. Daniel. 1997. Final Covers for Solid Waste Landfills and Abandoned Dumps.
Oklahoma Department of Environmental Quality. 2000. Chapter 5 of Solid Waste Financial Assurance Program Report.
New Jersey Department of Environmental Protection and Energy. 1994. Technical Manual for Division of Solid Waste Management Bureau of Landfill Engineering Landfill Permits.
Texas Natural Resource Conservation Commission. Industrial & Hazardous Waste Division. 1993. Closure Guidance Documents (Draft). September.
Texas Natural Resource Conservation Commission. Industrial Solid Waste Management. 1984. “Closure and Post-Closure Estimates.”
11-35 Ensuring Long-Term Protection—Performing Closure and Post-Closure Care
Resources (cont.)
U.S. EPA. 1996. Test Methods for Evaluating Solid Waste Physical/Chemical Methods. SW-846.
U.S. EPA. 1995. Decision-Maker’s Guide to Solid Waste Management, Second Edition. EPA530-R-95-023.
U.S. EPA. 1994a. Design, Operation, and Closure of Municipal Solid Waste Landfills. EPA625-R-94-008.
U.S. EPA. 1994b. The Hydrologic Evaluation of Landfill Performance (HELP) Model: Users Guide for Version 3. EPA600-R-94-168a.
U.S. EPA. 1994c. The Hydrologic Evaluation of Landfill Performance (HELP) Model: Engineering Documentation for Version 3. EPA600-R-94-168b.
U.S. EPA. 1993. Solid Waste Disposal Facility Criteria: Technical Manual. EPA530-R-93-017.
U.S. EPA. 1991. Seminar Publication: Design and Construction of RCRA/CERCLA Final Covers. EPA625- 4-91-025.
U.S. EPA. 1990. Sites for Our Solid Waste: a Guidebook for Effective Public Involvement. EPA530-SW-90- 019.
U.S. EPA. 1989a. Seminar Publication: Requirements for Hazardous Waste Landfill Design, Construction, and Closure. EPA625-4-89-022.
U.S. EPA. 1989b. Technical Guidance Document: Final Covers on Hazardous Waste Landfills and Surface Impoundments. EPA530-SW-89-047.
U.S. EPA. 1988. Guide to Technical Resources for the Design of Land Disposal Facilities. EPA625-6-88- 018.
U.S. EPA. 1979. Method for Chemical Analysis of Water and Wastes. EPA600-4-79-020.
Washington Department of Ecology, Hazardous Waste and Toxics Reduction Program. 1994. Guidance for Clean Closure of Dangerous Waste Facilities.
Wyoming Department of Environmental Quality, Solid and Hazardous Waste Division. 1994. Solid Waste Guideline #12: Participation in the State Trust Account.
11-36 Glossary
Glossary
24-hour, 25-year a rainfall event of 24 hours duration and of such a magnitude that it storm event has a 4 percent statistical likelihood of occurring in any given year. acceptance and methods used to evaluate the performance of geomembranes. While the conformance testing specific ASTM test methods vary depending on geomembrane type, rec- ommended acceptance and conformance testing for geomembranes includes evaluation of thickness, tensile strength and elongation, and puncture and tear resistance testing, as appropriate. access controls measures, such as fences or security guards, used to restrict entry to a site. active gas control mechanical means, such as a vacuum or pump, to forcibly remove gas systems from a waste management unit. adsorption the process by which molecules of gas, liquid, or dissolved solids adhere to the surface of other particles, such as activated carbon or clay. aerobic processes a biochemical process or condition occurring in the presence of oxygen. agronomic rate in land application, a waste application rate designed to provide the amount of nitrogen needed by a crop or vegetation to attain a desired yield, while minimizing the amount of nitrogen that will pass below the root zone of the crop or vegetation to ground water. anaerobic processes a biological process that reduces organic matter to compounds such as methane and carbon dioxide in an oxygen-free environment. anchor trench a long, narrow ditch along the perimeter of a unit cell in which the edges of a geomembrane are buried or secured. annular seal impermeable material used to prevent infiltration of surface water and contaminants into the space between the borehole wall and the ground- water well casing. attenuation the process by which a compound is reduced in concentration over time through chemical, physical, and biological processes such as adsorption, degradation, dilution, and transformation.
Atterberg limits a soil’s plastic limit (percent moisture at which soil transitions from solid to plastic) and its liquid limit (percent moisture at which soil transitions from plastic to liquid); useful in characterizing soil plasticity when design- ing liners with clay soils.
G-1 Glossary
Glossary (cont.)
barrier (infiltration) in a final cover system, a layer preventing water infiltration into the waste, indirectly promoting the storage and drainage of water from the overlying protection and surface layers, and preventing the upward movement of gases.
barrier walls low permeability partitions used to direct uncontaminated ground-water flow around a disposal site or to prevent contaminated material from migrating from a site.
bathtub effect the buildup of leachate within a unit that occurs when the cover system is more permeable than the liner. Leachate accumulates due to the infil- tration rate through the cover system exceeding the exfiltration rate through the liner system.
bench-scale a study used to evaluate the effectiveness of one or more potential treatability study treatment remedies. It establishes the validity of a technology and gener- ates data indicating the remedy’s potential to meet performance goals.
berm a raised flow diversion structure made from compacted earth or rock fill and used to buttress a slope and prevent run-on from entering a waste management unit.
best management measures used to reduce or eliminate contaminant releases to the practices (BMPs) environment. BMPs can take the form of a process, activity, or physical structure.
bioaccumulation the uptake and concentration of substances, such as waste constituents, by exposed organisms. This phenomenon has the potential to cause high concentrations especially in the tissues of higher predators.
biochemical oxygen the amount of oxygen consumed in the biological processes that break demand (BOD) down organic matter (typically measured in mg oxygen per L waste or leachate).
biodegradable significant component of waste used in land application. Carbon-based organic matter material derived from biological organisms; eventually decomposed by microbes into nontoxic products often useful as plant nutrients. (Compare to synthetic organic compounds.)
biological treatment a process relying primarily on oxidative or reductive mechanisms initiat- ed by microorganisms to stabilize or de-toxify a waste or leachate. Biological treatment can rely either on aerobic or anaerobic processes.
G-2 Glossary
Glossary (cont.) blanks samples of ground water, air, or other media, collected to determine background contaminants in the field; used for comparison purposes when analyzing monitoring data. borrow pit a location where soils are excavated for use as fill or for compaction into liners. buffer zone an area between waste management units and other nearby properties, such as schools. Buffer zones provide time and space to shield sur- rounding properties from ongoing activities and disruptions associated with waste management activities. calcium carbonate a measure of a waste’s ability to neutralize soil acidity—its buffering equivalent (CCE) capacity—compared to pure calcium carbonate. capillary-break (CB) an alternative design for a final cover system that exploits the relative approach differences in porosity between soil types to inhibit water infiltration. carbon to nitrogen in land application, the ratio of the relative quantities of these two ratio elements in a waste. Carbon is associated with the biodegradable organic matter in a waste, and the carbon to nitrogen ratio reflects the level of inorganic nitrogen available in the soil for plant growth. cation exchange the ability of a soil to take up and give off positively charged ions—a capacity process which affects the movement of metals in soil. chain-of-custody a document tracking possession of samples from the time of collection record through laboratory analysis. A chain-of-custody record generally includes the date and time of collection, signatures of those involved in the chain of possession, time and dates of possession, and other notations to allow tracking of samples. chemical oxygen a measure of the oxygen equivalent of the organic matter in a waste demand (COD) or leachate that is susceptible to oxidation by a strong chemical oxi- dant such as chromate. COD is used to determine the degree of conta- mination of a waste or leachate that is not readily biodegradable (see biochemical oxygen demand.) chemical seaming the use of solvents, cement, or an adhesive to join panels or rolls of a liner. Chemical seaming processes include chemical fusion and adhe- sive seaming. chemical treatment a class of processes in which chemicals are added to wastes or to cont- aminated media to reduce toxicity, mobility, or volume.
G-3 Glossary
Glossary (cont.)
closure termination of the active life of a waste management accompanied by one of the following measures: 1) use of engineered controls, such as a final cover, and post-closure care activities to maintain and monitor the controls, or 2) removal of waste and contaminated containment devices and soils.
closure plan a document describing the procedure envisioned for the termination of a waste management unit’s active life. Topics addressed often include future land use, whether wastes will be removed or left in place at clo- sure, closure schedule, steps to monitor progress of closure actions, contingency plans, and final cover information.
collection and an area that retains runoff long enough to allow solids/particles that sedimentation basin are suspended in and being transported by surface water to settle out by gravity.
compacted clay a hydraulic barrier layer composed of natural mineral materials liner (CCL) (natural soils), bentonite-soil blends, and other materials placed and compressed in layers called lifts.
construction quality a planned series of observations and tests of unit components, such as assurance (CQA) liners, as they are being built. CQA is designed to ensure that the com- ponents meet specifications. CQA testing, often referred to as accep- tance inspection, provides a measure of final product quality and its conformance with project plans and specifications.
construction quality an ongoing process of measuring and controlling the characteristics of control (CQC) unit components, such as liners, in order to meet manufacturer’s or project specifications. CQC inspections are typically performed by the contractor to provide an in-process measure of construction quality and conformance with the project plans and specifications, thereby allowing the contractor to correct the construction process if the quali- ty of the product is not meeting the specifications and plans.
control charts a statistical method of evaluating ground-water monitoring data using historical data for comparison purposes. Appropriate only for initially uncontaminated wells.
corrective action the process of taking appropriate steps to remediate any contamination.
critical habitat areas which are occupied by endangered or threatened species and which contain physical or biological features essential to the prolifera- tion of the species.
G-4 Glossary
Glossary (cont.) daily cover a level of soil and/or other materials applied at the end of a day after waste has been placed, spread, and compacted. Covering the waste helps control nuisance factors, such as the escape of odors, dust, and airborne emissions, and can limit disease vectors. deed restriction a notation on a property’s deed or title placing limits and conditions on the use and conveyance of the property. design storm event a storm of an intensity, volume, and duration predicted to recur once in a given number of years, whose effects you are designing a system or structure to withstand. (See 24-hour, 25-year storm event.) destructive testing the removal of a sample from a liner seam or sheet to perform tests to assess quality. dilution/attenuation DAFs are used to measure the difference in the concentration of waste factor (DAF) constituents found in the leachate released from a waste management unit at the source and the same leachate subsequently arriving at a receptor well. DAF is defined as the ratio of the leachate concentration at the source to the receptor well concentration. direct-push sampling a method of sampling ground water by hydraulically pressing and/or vibrating a probe to the desired depth and retrieving a ground-water sample through the probe. The probe is removed for reuse after the desired volume of ground water is extracted. diversion dike a raised land feature built to channel or control the flow of run-on and runoff water around and within a waste management unit. downgradient well a ground-water monitoring installation built to detect contaminant plumes from a waste management unit. In the absence of specific state requirements, monitoring points should be no more than 150 meters downgradient from your waste management unit boundary and placed in potential contamination migration pathways. drainage layer in a final cover system, a stratum that directs infiltrating water to drainage systems at the toe of the cover. The drainage layer can be placed below the surface or protection layer, but above the barrier layer. electrical conductivity the ability of a sample to carry an electrical charge. Used in land (EC) application to estimate the total dissolved solids content of a soil or waste. emergency response procedures to address major types of waste management unit plan emergencies: accidents, spills, and fires/explosions.
G-5 Glossary
Glossary (cont.)
environmental justice the practice of identifying and addressing, as appropriate, dispropor- tionately high and adverse human health or environmental effects of waste manage ment programs, policies, and activities on minority and low-income populations.
environmental stress imperfections or failures in a liner caused by environmental factors cracks before the liner is stressed to its stated maximum strength.
EPA’s Composite EPACMTP is a ground-water fate and transport model. It simulates Model for Leachate subsurface fate and transport of contaminants leaching from the Migration with bottom of a waste management unit and predicts concentrations of Transformation those contaminants in a downstream receptor as well. Products (EPACMTP)
erosion layer (see surface layer.)
expansive soils soils that lose their ability to support a foundation when subjected to certain natural events, such as heavy rain, or human-caused events, such as explosions.
fate and transport a methodology which examines numerous waste and site characteris- modeling tics to determine how waste constituents move through the environ- ment, how they are degraded or changed, and where they end up.
fault a failure that occurs in a geologic material, such as rock, when tectonic, volcanic, or other stresses exceed the material’s ability to withstand them.
field study in land application, a scientific investigation of waste, soil, and plant interaction conducted under natural environmental conditions. (Compare to greenhouse study.)
filter pack in a ground-water monitoring well, a quantity of chemically inert material such as quartz sand, that prevents material from surrounding geological formations from entering the well intake and helps stabilize the adjacent formation. Might be necessary in boreholes that are over- sized with regard to the casing and well intake diameter.
final cover a system of multiple layers of soil; engineered controls, such as liners; and/ or other materials placed atop a closed waste management unit. Typically improves aesthetics, prevents erosion, blocks roots and burrowing animals, collects and drains incoming water, provides a barrier between waste and the environment, and collects gas generated within the unit.
financial assurance a funding instrument, such as a bond or trust, that provides or mechanism guarantees sufficient financial resources for the closure and post-clo- sure care of a unit in the event the owner or operator is unable to pay.
G-6 Glossary
Glossary (cont.) fines silt and clay-sized particles.
100-year floodplain a relatively flat, lowland area adjoining inland and coastal waters that is susceptible to inundation during a 100-year flood. A 100-year flood is a large magnitude occurrence with a 1 percent chance of recurring in any given year. foundation/gas in a final cover system, a stratum of permeable material such as sand collection layer or gravel that controls the migration of gases to collection vents and supports overlying strata. freeboard depth (capacity) intended to remain unused above the expected highest liquid level in a liquid storage facility, such as a surface impoundment. freeze-thaw cycles climatic changes in which water enters a small crack in a material, expands upon freezing, and thereby expands the crack; the process then repeats itself and the crack progressively grows. It can increase the hydraulic conductivity of low permeability soil layers or damage geomembranes in final covers. fugitive dust solid particulate matter, excluding particulate matter emitted from exhaust stacks, that become airborne directly or indirectly as a result of human activity. fugitive emission dust suppression at a waste management unit through measures such control as watering or chemical dust suppression. gabion a structure formed from crushed rock encased in wire mesh and used to check erosion and sediment transport. gas migration the lateral and/or vertical movement of gas through a waste management unit or its cover systems; can convey methane or other dangerous gases to other sites or buildings if gas monitoring is not implemented. geogrid plastic material manufactured into an open, lattice-like sheet configu- ration and typically used as reinforcement; designed with apertures or openings sized to allow strike through of surrounding rock and soil. geomembrane a synthetic sheet composed of one or more plastic polymers with ingre- dients such as carbon black, pigments, fillers, plasticizers, processing aids, cross- linking chemicals, anti-degradants, and biocides. Geomembranes are used as hydraulic barriers in liner and cover systems. geophysical measurement of changes in the geophysical characteristics of monitoring subsurface soils, and in some cases, in the ground water itself, to determine potential changes in ground-water quality.
G-7 Glossary
Glossary (cont.)
geosynthetic clay a factory-manufactured, hydraulic barrier typically consisting of liner (GCLs) bentonite clay (or other very low permeability materials), supported by geotextiles and/or geomembranes held together by needling, stitching, or chemical adhesives.
geotextile a woven, nonwoven, or knitted synthetic fabric used as a filter to pre- vent the passing of fine-grained material such as silt or clay. A geotex- tile can be placed on top of a drainage layer to prevent the layer from becoming clogged with fine material.
gravel soil particles unable to pass through the openings of a U.S. Number 4 sieve, which has 4.76 mm (0.2 in.) openings.
greenhouse study in land application, a scientific investigation of waste, soil, and plant interaction conducted under controlled indoor conditions. (Compare to field study.)
ground-water a borehole in soil outfitted with components typically including a monitoring well casing, an intake, a filter pack, and annular and surface seals; used to collect ground water from one or more soil layers for sampling and analysis.
ground-water The objectives of a ground-water monitoring program are to measure monitoring program the effectiveness of a waste management unit’s design; to detect changes, or the lack thereof, in the quality of ground water caused by the pres- ence of a waste management unit; and to provide data to accurately determine the nature and extent of any contamination that might occur.
ground-water a ground-water remediation technology in which contaminated water pump-and-treat is pumped to the surface for treatment.
ground-water a scientist or engineer who has received a baccalaureate or post- specialist graduate degree in the natural sciences or engineering and has suffi- cient training and experience in ground-water hydrology and related fields as demonstrated by state registration, professional certifications, or completion of accredited university programs that enable that indi- vidual to make sound professional judgements regarding ground-water monitoring, contaminant fate and transport, and corrective action.
health-based number a concentration limit for a waste constituent. The HBN is derived from (HBN) reference doses or reference concentrations that estimate the maximum daily exposure to a waste constituent through a specific pathway (i.e., ingestion) that would be without appreciable risk of deleterious effects during a lifetime.
hydraulic the velocity at which a fluid, such as leachate, flows through a material, conductivity such as a compacted clay liner.
G-8 Glossary
Glossary (cont.) hydraulic loading in land application, the quantity of liquid or aqueous waste that can be capacity assimilated per unit area by the soil system. hydraulic in land application, the application of waste in excess of the liquid or overloading water handling capacity of a soil; can result in ponding, anaerobic waste degradation, and odors. hydrogeologic study and quantification of a site’s subsurface features to determine characterization ground-water flow rate and direction; necessary for an effective ground-water monitoring program.
Hydrologic an EPA model that evaluates the relative performance of various final Evaluation of Landfill cover designs, estimates the flow of water across and through a final Performance (HELP) cover, and determines leachate generation rates. infiltration the entry of precipitation, ground water, waste, or other liquid into a soil layer or other stratum. in-situ soil geological material already present at a site; known as an in-situ liner when used as a barrier layer in place of imported soil or synthetic materials. institutional control a measure that can be used by responsible parties and regulatory agen- cies to prevent use of or access to a site in a remedial program where, as part of the program, certain levels of contamination will remain on site in the soil or ground water. Can also be considered in situations where there is an immediate threat to human health; can include deed restrictions, restrictive covenants, use restrictions, access controls, notices, registry act requirements, transfer act requirements, and con- tractual obligations. interfacial shear the friction or stress between components, such as a compacted clay liner and a geomembrane, that occurs on side slopes of waste manage- ment units. When the interfacial shear is inadequate, a weak plane can form on which sliding can occur. The shift in components can com- promise liner and cover performance, negatively affecting unit stability. interim measure in corrective action, a step taken to control or abate ongoing risks before final remedy selection. internal shear a stress that can lead to tearing of liner or cover components when overlying or underlying pressure upon a liner or cover exceeds its abil- ity to withstand this stress.
ISO 14000 voluntary set of standards for good environmental practices developed procedures by the International Standards Organization (ISO), also known as Environmental Management Standards (EMS). G-9 Glossary
Glossary (cont.)
karst terrain areas containing soluble bedrock, such as limestone or dolomite, that have been dissolved and eroded by water, leaving characteristic phys- iographic features including sinkholes, sinking streams, caves, large springs, and blind valleys.
land application (see land application unit.)
land application unit a waste management unit in which waste (such as sludge or waste- water) is spread onto or incorporated into the land to amend the soil and/or treat or dispose of the waste.
landfills a waste management unit in which waste is compacted in engineered cells for permanent disposal, usually covered daily.
leachate liquid (usually water) that has percolated through waste and taken some of the waste or its constituents into solution.
leachate the concentration (usually in mg/L) of a particular waste constituent in concentration the leachate.
leachate collection a system of porous media, pipes, and pumps that collect and convey and removal system leachate out of a unit and/or control the depth of leachate above a liner.
leachate testing used to characterize waste constituents and their concentrations, and to estimate the potential amount and/or rate of the release of waste constituents under worst case environmental conditions.
leak detection also known as a secondary leachate collection and removal system; a system (LDS) redundant leachate collection and removal system to detect and cap- ture leachate that escapes or bypasses the primary system. Sudden increases in leachate captured by an LDS can indicate failure of a pri- mary leachate collection and removal system.
lifts layers of compacted natural mineral materials (natural soils), ben- tonite-soil blends, and other materials that compose a liner or other compacted stratum.
liner a hydraulic barrier, such as compacted clay or a geomembrane, used to restrict the downward or lateral escape of waste, waste constituents, and leachate. Liners accomplish this by physically impeding the flow of leachate and/or by adsorbing or attenuating pollutants.
in-situ soil geological material already present at a site; known as an in-situ liner when used as a barrier layer in place of imported soil or synthetic materials.
G-10 Glossary
Glossary (cont.) single liner a hydraulic barrier consisting of one soil layer, one geomembrane, or any other individual barrier without a second barrier to impede conta- minants that might breach it. composite liner a liner consisting of both a geomembrane and a compacted clay layer (or a geosynthetic clay liner). double liner a hydraulic barrier between a waste management unit and the natural environment, consisting of primary (top) and secondary (bottom) lev- els. Each level can consist of compacted clay, a geomembrane, or a composite (consisting of a geomembrane and a compacted clay layer or GCL). liquefaction occurs when vibrating motions caused by an earthquake turn saturated sand grains in the soil into a viscous fluid, diminishing the bearing capacity of the soil and possibly leading to foundation and slope fail- ures. lithology the description of geological materials on the basis of their physical and chemical characteristics. lower explosive the minimum percentage of a gas by volume in the air that is necessary limit (LEL) for an explosion. This level is 5 percent for methane. lysimeter a device used to measure the quantity or rate of water movement through or from a block of soil or other material. It collects soil-pore liquids by applying a vacuum that exceeds the soil moisture tension; usually a buried chamber made from wide perforated pipe. material balances used to calculate all input and output streams, such as the annual quantities of chemicals transported to a facility and stored, used, or produced at a facility, and released or transported from a facility as a commercial product or by-product or a waste. Material balances can assist in determining concentrations of waste constituents where ana- lytical test data are limited.
Maximum Achievable national standards that regulate major sources of hazardous air Control Technology pollutants. Each MACT standard specifies particular operations, (MACT) standards processes, and/or wastes that are covered. If a facility is covered by a MACT standard, it must be permitted under Title V. maximum the maximum permissible level of a contaminant in water delivered to contaminant level any user of a public water system. (MCL)
G-11 Glossary
Glossary (cont.)
molding water for natural soils, the degree of saturation of the soil liner at the time of content compaction; influences the engineering properties, such as hydraulic conductivity, of the compacted material.
Monte Carlo analysis an iterative process involving the random selection of model parameter values from specified frequency distributions, followed by simulation of the system and output of predicted values. The distribution of the output values can be used to determine the probability of occurrence of any particular value given the uncertainty in the parameters. In this guidance, used to predict a statistical distribution of exposures and risks for a given site.
National Ambient Air airborne emission limits set by EPA as authorized by the Clean Air Act. Quality Standards EPA has designated NAAQS for the following criteria pollutants: (NAAQS) ozone, sulfur dioxide, nitrogen dioxide, lead, particulate matter, and carbon monoxide.
National Emission national standards regulating 188 hazardous air pollutants listed in Standards for Section 112(b) of the Clean Air Act Amendments of 1990. Hazardous Air Pollutants (NESHAP)
numeric clean-up a state corrective action requirement mandating that a site be cleaned standard up such that concentrations of a waste constituent do not exceed a set level.
operating plan a document that specifies methods of running a waste management unit, such as standard waste-handling practices, management and maintenance activities, employee training, and emergency plans; based on comprehensive knowledge of the chemical and physical composi- tion of the waste managed, unit type, operational schedules, and mon- itoring performed at the unit.
overland flow land application of liquid waste by irrigation methods; can lead to (“flood”) application increased surface runoff of waste if not properly managed and, there- fore, is regulated by some states and localities.
parametric analysis a method of statistical analysis that attempts to determine whether of variance (ANOVA) different monitoring wells have significantly different average con- stituent concentrations.
particulate matter a mixture of solid particles and liquid droplets suspended in the (PM) atmosphere that can cause a variety of respiratory problems, carry adsorbed pollutants far from their source, impair visibility, and stain or damage surfaces, such as buildings or clothes, on which it settles.
G-12 Glossary
Glossary (cont.) passive gas control a gas control system using natural pressure and convection system mechanisms to control gas migration and to help vent gas emissions into the atmosphere; can include ditches; trenches; vent walls; perfo- rated pipes surrounded by coarse soil; synthetic membranes; and high moisture, fine-grained soil. pathogens potentially disease-causing microorganisms, such as bacteria, viruses, protozoa, and the eggs of parasitic worms. peak flow period the phase of a storm event when flood waters are at their highest level. pH A measure of acidity or alkalinity equal to the logarithm of the recipro- cal of hydrogen ion (H+) concentration in a medium. pH is represent- ed on a scale of 0 to 14; 7 represents a neutral state, 0 represents the most acid, and 14 the most alkaline. pH adjustment the neutralization of acids and bases (alkaline substances) and promo- tion of the formation of precipitates, which can subsequently be removed by conventional settling techniques. piezometer a well installed to monitor hydraulic head of ground water or to moni- tor ground-water quality. pilot-scale a small study to evaluate the effectiveness of and determine the treatability study potential for continued development of one or more potential reme- dies; typically conducted to generate information on quantitative per- formance, cost, and design issues. plasticity parameters describing a material’s ability to behave as a moldable characteristics material. plume an elongated and mobile column or band of a contaminant moving through the subsurface. point of monitoring the location(s) where ground-water is sampled; should be appropriate for site conditions and located at waste management boundary or out to 150 meters downgradient of the waste management unit area. post-closure care monitoring of a closed waste management unit to verify and document that unacceptable releases from the unit are not occurring. The overall goal is to ensure that waste constituents are contained until such time as containment is no longer necessary.
G-13 Glossary
Glossary (cont.)
prediction intervals a statistical method of approximating future sample values from a pop- ulation or distribution with a specific probability; used with ground- water monitoring data, both for comparison of downgradient wells to upgradient wells (interwell comparison) and for comparison of current well data to previous data for the same well (intrawell comparison).
process knowledge an understanding of industrial processes used to predict the types of waste generated and to determine the mechanism by which they are generated.
protection layer a stratum in a final cover system that protects the drainage layer from intrusion by plant roots or burrowing animals; located below the sur- face layer and above the drainage layer.
public involvement dialogue between facility owners and operators and public to share information, identify and address issues and concerns, and provide input into the decision-making process.
public notice a document, announcement, or information release that publicizes a meeting, decision, operational change, or other information of interest to the public; usually provides the name and address of the facility owner and operator and information about the issue being publicized.
puncture resistance the degree to which a material, such a liner, will resist rupture by jagged or angular materials which might be placed above or below it.
quality assurance in ground-water sampling, steps for collection and handling of and quality control ground-water samples to ensure accurate results. In liner construction, (QA/QC) procedures steps to ensure that liners are installed according to design and will perform specifications.
rational method a method for calculating the volume of storm water runoff. The ratio- nal method approximates the surface water discharge from a watershed using a runoff coefficient, the rainfall intensity, and the drainage area.
receptor a person or other organism that might be exposed to waste con- stituents, especially an organism whose exposure is addressed by a fate and transport analysis; or, a downgradient ground-water monitoring well that receives ground water which has passed near a waste man- agement unit.
recycling the process of collecting, processing, and reusing waste materials.
redox (oxidation- the capacity of a medium to raise the valence state of molecules (such reduction) potential as metals), add oxygen, or remove hydrogen (oxidation); or to lower the valence state of molecules, remove oxygen, or add hydrogen (reduction).
G-14 Glossary
Glossary (cont.) riprap rock cover used to protect soil in dikes or channels from erosion. risk-based corrective an approach to corrective action that integrates the components of action (RBCA) traditional corrective action with alternative risk and exposure assess- ment practices. States and ASTM have developed RBCA as a three stage process. runoff storm water that flows from a waste management unit to surface waters. run-on storm water that falls directly on a waste management unit or flows toward the unit from adjoining areas. saline soil soil with excessive salt concentrations. sampling parameters for monitoring, those items for which ground water samples will be tested, such as waste constituents reasonably expected to migrate to the ground water and other geochemical indicators of contaminant migration. seaming process the joining of panels or rolls of a liner using thermal, chemical, or other methods compatible with the properties of the liner material. seismic impact zone an area having a 10 percent or greater probability that the maximum horizontal acceleration caused by an earthquake at the site will exceed 0.1g in 250 years. g is a unit of force equal to the force exerted by gravity on a body at rest and used to indicate the force to which a body is subjected when accelerated. setback the placing of a waste management unit or one of its components some distance from an adjoining property, a geologic feature, or other feature that could affect the unit or be affected by the unit. (Compare to buffer zone.) shear strength for soils, the internal resistance per unit area that a soil mass can offer to resist failure and sliding along any plane inside it; in liner design, indicates the degree to which stability problems and desiccation cracks are likely to occur in liner material (such as clay). silt fence a barrier consisting of geotextile fabric supported by wooden posts; slows the flow of water and retains sediment as water filters through the geotextile. slip for soils, to slide downhill in mass movements such as avalanches, land slides, and rock slides; can be caused by inherent properties of the soil or by cutting or filling of slopes during construction.
G-15 Glossary
Glossary (cont.)
slippage movement of a geomembrane liner due to a lack of adequate friction between the liner and the soil subgrade or between any geosynthetic components.
sodic soil soil with excessive levels of sodium ions (Na+) relative to divalent ions, such as calcium (Ca2+) and magnesium (Mg2+).
soil gas sampling collection of gas from soil pores to detect the presence or movement of volatile contaminants and gases, such as carbon dioxide and methane, that are associated with waste degradation.
soil-pore liquids fluids present in spaces between soil particles in the vadose zone; can be collected to determine the type and concentration of contaminants that might be moving within the vadose zone.
soil water content the ratio of the weight of water to the weight of solids in a given vol- ume of soil; usually stated as a percentage and can be greater than 100 percent for very soft clays.
soil water tension a measure of the strength of capillary effects holding water between soil particles; decreases as soil water content increases, so decreases in soil water tension beneath a lined waste management unit might indi- cate the presence of leachate due to a leaking liner.
solidification the conversion of a non-solid waste into a solid, monolithic structure processes that ideally will not permit liquids to percolate into or leach materials out of the mass; used to immobilize waste constituents.
soluble salts materials that could dissolve in or are already in solution in your waste. Major soluble salts include calcium, magnesium, sodium, potas- sium, chloride, sulfate, bicarbonate, and nitrate.
Source Loading and an urban nonpoint source water quality model developed by the Management Model University of Alabama at Birmingham; useful for designing run-on and (SLAMM) runoff controls.
source reduction the prevention or reduction of waste at the point of generation.
spill prevention and procedures for avoiding accidental releases of waste or other response contaminants and promptly addressing any releases that occur.
stabilization process a means of immobilizing waste constituents by binding them into an insoluble matrix or by changing them to insoluble forms.
G-16 Glossary
Glossary (cont.) standard operating established, defined practices for the operation of a waste management procedures unit; useful in maintaining unit safety and protection of human health and the environment; should be recorded in an operating plan to facil- itate employees’ familiarity. storm water pipes, ditches, swales, and other structures or landforms that carry, conveyances divert, or direct run-on and/or runoff.
Storm Water EPA computer model capable of simulating the movement of Management Model precipitation and pollutants from the surface through pipe and (SWMM) channel networks, storage treatment units, and finally to surface water; used in the design of run-on and runoff controls. stratigraphy characterization of the origin, distribution, and succession of geologic strata, such as soil and rock layers. subsidence lowering of the land surface due to factors such as excessive soil load- ing, compaction of soil owing to high moisture content, or reduction in waste volume due to degradation; can significantly impair the integrity of the final cover system by causing ponding of water on the surface, fracturing of low permeability infiltration layers, and failure of geomembranes. sump a low point in a liner system constructed to gravitationally collect leachate from either the primary or secondary leachate collection system. surface completion the part of a ground-water monitoring well constructed at or just above ground level, often consisting of a protective outer casing around the inner well casing, fitted with a locking cap; discourages vandalism and unauthorized entry into the well, prevents damage by contact with vehicles, reduces degradation caused by direct exposure to sunlight, and prevents surface runoff from entering and infiltrating the well. surface a natural or manmade topographic depression, excavation, or diked impoundment area designed to hold liquid waste. surface layer in a final cover system, a stratum that promotes the growth of native, nonwoody plant species, minimizes erosion, restores the aesthetics of the site, and protects the barrier layer. surface seal neat cement or concrete surrounding a ground-water monitoring well casing and filling the space between the casing and the borehole at the surface; protects against infiltration of surface water and potential con- taminants from the ground surface.
G-17 Glossary
Glossary (cont.)
synthetic organic man-made carbon compounds used in a variety of industrial and molecules agricultural processes, sometimes hazardous, and unlike biodegradable organic matter, not necessarily biodegradable, or if biodegradable, not necessarily broken down into nonhazardous byproducts.
Synthetic The SPLP is currently used by several state agencies to evaluate the Precipitation leaching of TC hazardous constituents from wastes and can be used to Leaching Procedure assess the risks posed by wastes placed in a landfill and subject to acid (SPLP) rain. The SPLP is designed to determine the mobility of both organic and inorganic analytes present in liquids, soils, and wastes.
tear resistance the ability of a material, such as a geomembrane, to resist being split due to stresses at installation, high winds, or handling.
tensile behavior the tendency of a material to elongate under strain.
tensiometer an instrument that measures soil water tension.
terraces and benches earthen embankments with flat tops or ridges and channels; used to hold moisture and minimize sediment loadings in runoff.
test pad in liner design, a small-scale replica of a liner system used to verify that the materials and methods tested will yield a liner that provides the desired hydraulic conductivity.
thermal seaming the use of heat to join panels or rolls of a liner.
Title V operating established by the Clean Air Act, these permits are required for any permits facility emitting or having the potential to emit more than 100 tons per year of any air pollutants, as defined by Section 302(g) of the Clean Air Act. Permits are also required for all sources subject to MACT or NSPS standards.
toe the lower endpoint of a slope.
tolerance interval a statistical interval constructed from data designed to contain a por- tion of a population, such as 95 percent of all sample measurements; used to compare data from a downgradient well to data from an upgradient well.
topography the physical features (configuration) of a surface area including relative elevations and the position of natural and constructed features.
total dissolved solids the sum of all ions in solution. (TDS)
G-18 Glossary
Glossary (cont.) total solids content the sum of suspended and dissolved solids in a liquid waste, usually expressed as a percentage.
Toxicity The TCLP is most commonly used by EPA and state agencies to Characteristic evaluate the leaching potential of wastes, and to determine toxicity. Leaching Procedure The TCLP quantifies the extractability of certain hazardous (TCLP) constituents from solid waste under a defined set of laboratory condi- tions. It evaluates the leaching of metals, volatile and semi-volatile organic compounds, and pesticides from wastes. ultraviolet resistance the degree to which a material, such as a geomembrane, can resist degra- dation and cracking from prolonged exposure to ultraviolet radiation. unstable area a location susceptible to human-caused or natural events or forces, such as earthquakes, capable of impairing the integrity of a waste man- agement unit. upgradient well a ground-water monitoring installation built to measure background levels of contamination in ground water at an elevation before it encounters a waste management unit. upper explosive the maximum percentage of a gas by volume in the air that will permit limit an explosion. This level is 15 percent for methane; at higher percent- ages, non- explosive burning is still possible. use restrictions stipulations describing appropriate and inappropriate future uses of a closed site, in an effort to perpetuate the benefits of the remedial action and ensure property use that is consistent with the applied clean-up standard. vadose zone the soil (or other strata) between the ground surface and the saturated zone; depending on climate, soils, and geology, can be very shallow or as deep as several hundred feet. vegetative cover layer (see surface layer.) volatile organic carbon compounds which tend to evaporate at low to moderate compounds (VOCs) temperatures due to their low vapor pressure. waste pile a noncontainerized accumulation of solid, nonflowing waste that is used for treatment or storage.
G-19 Glossary
Glossary (cont.) waste reduction waste reduction practices include source reduction, recycling and reuse, and treatment of waste constituents. Waste reduction minimizes the amount of waste that needs to be disposed of in the first place, and lim- its the environmental impact of those wastes that actually are disposed. water content (see soil water content.) well casing in a ground-water monitoring well, the pipe or tube lowered into the borehole as the outer wall of the well; supports the sides of the hole and prevents water from entering or leaving the well other than by normal ground-water flow. well intake a perforated segment of a ground-water monitoring well designed to (well screen) allow ground water to flow freely into the well from an adjacent geo- logical formation while minimizing or eliminating the entrance of fine- grained materials such as clay or sand. well purging procedures for removing stagnant water from a ground-water monitoring methods well and its filter pack before collecting a sample; employed to ensure collection of samples that accurately represent current ground-water quality. wellhead protection the most easily contaminated zone surrounding a wellhead; officially area (WHPA) designated for protection in many jurisdictions to prevent public drinking water sources from becoming contaminated. wetlands areas, such as tidal zones, marshes, and bottomland forests, that are inundated or saturated by surface or ground water at a frequency or duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in sat- urated soil conditions. working face the area of a waste management unit, especially a landfill, where waste is currently being placed and compacted. zoning local government classification of land into areas designated for differ- ent use categories, such as residential, commercial, industrial, or agri- cultural; used to protect public health and safety, maintain property values, and manage development.
G-20