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2031780 DOE/NV/11508-52

SUNRISE LANDFILL GAS EMISSIONS AND ENERGY PRODUCTION POTENTIAL

prepared by

Hampden Kuhns, Glenn V. Wilson, Mark Green, and David Shafer

submitted to

Nevada Operations Office U.S. Department of Energy

JANUARY 2000

Publication No. 45173 This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Department of Energy, nor any of their employees, nor any of their contractors, subcontractors or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or any third party's use or the results of such use of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, mark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof or its contractors or subcontractors. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

This report has been reproduced directly from the best available copy. Available to the public from: U.S. Department of Commerce National Technical Information Service 5285 Port Royal road Springfield, VA 22161 (703) 487-4650

Available electronically at hrtp://www.doe.gov/bridge/ Available to the U.S. Department of Energy and its contractors in paper form: U.S. Department of energy Office of Scientific and Technical Information P.O. Box 62 Oak Ridge, TN 37831 (423) 576-8401 University and Community College System of Nevada

July 12, 2000

MEMORANDUM

TO: Distribution

FROM: Marjory r ' J yf x Enclosed for your information is a cop/of the final report entitled "Sunrise Landfill Gas Emissions and Energy Production Potential," by H. Kuhns, G. Wilson, M. Green and D. Shafer, DRI Pub. No. 45173, DOE/NV/11508—52. January 2000.

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2215 Raggio Parkway Reno, NV 89512-1095 775-673-7300 DOE/NV/11508-52

SUNRISE LANDFILL GAS EMISSIONS AND ENERGY PRODUCTION POTENTIAL

prepared by

Hampden Kuhns, Glenn V. Wilson, Mark Green, and David Shafer Desert Research Institute University and Community College System of Nevada

Publication No. 45173

submitted to

Nevada Operations Office U.S. Department of Energy

January 2000

The work upon which this report is based was supported by the U.S. Department of Energy under Contract #DE-AC08-95NV11508. Approved for public release; further dissemination unlimited. EXECUTIVE SUMMARY The Sunrise Landfill is located on the eastern side of the Las Vegas Valley and covers an area of approximately 720 acres. The landfill operated from 1963 to 1993 when the last load of refuse was delivered to the site. During this period of operation, waste streams consisted of non-hazardous municipal waste, asbestos-containing materials, medical wastes, septic sludges, and hydrocarbon-impacted soils. While no records of the amount of refuse placed prior to 1991 were available, data on the most recent waste acceptance volumes and population growth trends have been used to estimate the annual disposal rate over the life of the landfill. Recently, residents have filed complaints with the Clark County Health District regarding the uncontrolled emissions of methane from the landfill. The U.S. Department of Energy requested that the Desert Research Institute assess the current and projected methane emissions of the Sunrise Landfill, identify methane extraction methods, and estimate the power generating potential of the emitted methane. Several proven gas collection system designs are described in terms of their appropriateness for the Sunrise location. Once collected, methane from the landfill can either be flared or used for heating or power production. These options were evaluated to determine a cost-effective method for mitigating the landfill gas emissions. Methane emissions were estimated for the landfill using U.S. Environmental Protection Agency's Energy Project Landfill Gas Utilization Software (E-PLUS). Sensitivity tests were applied to the various input parameters to estimate the modeled emissions uncertainty. The analysis suggests that both power generation and sale to nearby users and gas enrichment for injection into existing natural gas pipelines are financially viable uses for the landfill gas over a wide range of expected methane production rates. The net present value of these projects is estimated to be between $6 and $8 million. The gas enrichment option offers environmental benefits in that no substantial emissions from gas combustions are produced on site. Federal regulations mandate that a gas collection and flaring system be installed at the Sunrise Landfill. We recommend that the issue of landfill gas use is revisited when the collection system is in place and methane production rates are known with a higher degree of certainty.

11 CONTENTS EXECUTIVE SUMMARY ii LIST OF FIGURES v LIST OF TABLES viii ACRONYMS ix 1.0 INTRODUCTION 1 1.1 Stage of Decomposition 2 1.2 Manipulation of Decomposition 2 1.3 Landfill Gas to Energy 3 1.4 Regulatory and Economic Drivers 4 2.0 SUNRISE LANDFILL BACKGROUND 6 2.1 Climate and Geologic Setting 7 2.2 Sunrise Landfill Operations and Closure 9 2.3 Post-Closure Conditions and Hydrogeologic Impacts 9 2.4 Regulatory and Community Actions 13 3.0 STUDY OBJECTIVES AND PROJECT ACTIVITIES 14

4.0 GAS TESTING AND RECOVERY OPTIONS 16 4.1 Lysimetry 16 4.2 Flux Testing 18 4.3 Well Testing 20 4.3.1 Single Well with Gas Probes 21 4.3.2 Well Clusters 24 4.3.3 Borehole Site Characterization 25 4.4 Anaerobic Sampling 26 5.0 METHANE EMISSIONS FROM SUNRISE LANDFILL 27 5.1 Methane Emission Estimates 27 5.2 Emissions of Non-Methane Organic Compounds (NMOC) Gases 32 6.0 METHANE USE OPTIONS 35 6.1 Case Studies 35 6.2 Sunrise Landfill Methane Use Options 36 6.2.1 Power Generation Potential 37 6.2.2 Nearby Energy Consumers 37 6.2.2.1 Sunrise Station 37 6.2.2.2 Las Vegas Sewage Treatment Plant (STP) 38 6.2.2.3 Clark County STP 38 6.2.2.4 Clark Station 39 7.0 FINANCIAL ANALYSIS OF METHANE USE OPTIONS 39 7.1 Default Model Inputs 40 7.2 Case 1: Collect and Flare Gas to Achieve Compliance with EPA Regulations 40

in 7.3 Case 2: Collect Gas and Sell to Southwest Gas for Use at Sunrise and Clark Power Stations 41 7.4 Case 3: Collect Gas and Produce Power to Sell to a Power Company Such as Nevada Power 43 7.5 Case 4: Collect Gas and Produce Power to Sell to a Nearby User Such as the Clark County STP 46 7.6 Summary of Economic and Environmental Analysis of Methane Utilization 47 8.0 CONCLUSIONS AND RECOMMENDATIONS 48 9.0 REFERENCES 50 Appendix A Letter to BLM and Letters of Support A-l

Appendix B Email Responses from Alan Gaddy of Republic Silver State Disposal B-l

Appendix C Letter Submitted to EPA Region 9 C-l

Appendix D Model Input and Results for Gas Enrichment and Pipeline Injection D-l

IV FIGURES 1-1. Typical LFG composition during decomposition of MSW (recreated from Farquar and Rovers, 1973) showing the five stages of LFG production (from Ward, 1988) 1

1-2. LFG-to-energy projects and average yearly price of oil per stock-tank barrels (STB), recreated from Hutchinson (1993) 5

2-1. Contour map of the Sunrise Landfill site with the lease boundary depicted by red line and the approximate boundary of the watershed contributing runon to the site depicted by blue line 7

2-2. Schematic of the conceptual framework of the hydrogeology at Sunrise Landfill 11

4-1. Schematic of the lysimeter facility used in ACAP (from Wilson et al., 1999) 17

4-2. The flux chamber design reported by Reinhart etal. (1992) 19

4-3. Single gas withdrawal well in center of three concentric circles of boreholes with probes, noted by solid circles 22

4-4. Two types of multi-level borehole testing 22

4-5. Five-well dice pattern for gas rate production testing 25

5-1. Clark County population and Sunrise Landfill Waste Acceptance (Mg/yr) 28

5-2. Empirically derived versus predicted methane production rates Mm3/yr (EPA,1997b) 29

5-3. Effect upon Sunrise Landfill methane emissions of varying methane generation rate constant k 30

5-4. Effect upon Sunrise Landfill methane emissions of varying methane generation potential LO 30 5-5. Estimated methane emissions rates from Sunrise Landfill for three cases used in economic analysis 32

5-6. NMOC emissions from Sunrise Landfill for ranges of NMOC concentration and methane generation rate constant k 34

5-7. Same as 7-8, except y-axis scale is reduced to show more detail at lower emission levels 34

6-1. Aerial view of Sunrise Landfill and potential users of methane and power produced from the landfill gas 38

7-1. Process diagram for gas enrichment and injection system 41 7-2. Process diagram for energy production and sale 43

D-l. Project financial assumptions D-l

D-2. Landfill waste acceptance and methane emissions using parameters LO = 100 m3/Mg and k = 0.02 yr"1 D-2

D-3. Landfill gas collection stage parameters D-2

D-4. Landfill gas splitter parameters D-3

D-5. Case 2: Landfill gas treatment stage D-3

D-6. Case 2: Landfill gas treatment stage costs D-4

D-7. Case 2: Landfill gas enrichment stage D-4

D-8. Case 2: Landfill gas enrichment costs D-5

D-9. Case 2: Landfill gas compression stage D-5

D-l 0. Case 2: Landfill gas compression stage costs D-6

D-ll. Case 2: Landfill gas pipeline stage D-6

D-12. Case 2: Landfill gas pipeline costs D-7

D-13. Case 2: Landfill gas methane sale stage D-7

D-14. Case 2: Financial analysis of gas sale option for LO = 100 m3/Mg and k = 0.02 yr"1 (i.e., Best estimate methane production) D-8

D-l 5. Case 2: Financial analysis of gas sale option for LO = 50 m3/Mg and k = 0.01 yr"1 (i.e., Low methane production) D-8

D-l 6. Case 2: Financial analysis of gas sale option for LO = 150 m3/Mg and k = 0.03 yr"1 (i.e., High methane production) D-9

D-17. Cases 3 and 4 : Landfill gas treatment stage D-9

D-18. Cases 3 and 4 : Landfill gas treatment stage costs D-10

D-19. Cases 3 and 4: Landfill gas electricity generation stage D-10

D-20. Cases 3 and 4: Landfill gas electricity generation for combustion turbine D-ll

D-21. Cases 3 and 4: Landfill gas electricity generation for combustion turbine costs. ..D-ll

VI D-22. Cases 3 and 4: Landfill gas electricity generation for combustion turbine interconnect stage D-12

D-23. Cases 3 and 4: Landfill gas electricity generation for combustion turbine interconnect stage costs D-12

D-24. Cases 3 and 4: Landfill gas electricity generation for combustion turbine power sale stage D-13

D-25. Cases 3 and 4: Financial analysis for combustion turbine power sale using two different power prices (Best estimate methane production) D-13

D-26. Cases 3 and 4: Financial analysis for combustion turbine power sale using two different power prices (Low estimate methane production) D-14

D-27. Cases 3 and 4: Financial analysis for combustion turbine power sale using two different power prices (High estimate methane production) D-14

D-28. Cases 3 and 4: Landfill gas electricity generation for 1C engine D-15

D-29. Cases 3 and 4: Landfill gas electricity generation for 1C engine costs D-15

D-30. Cases 3 and 4: Landfill gas electricity generation for 1C engine interconnect stage D-16

D.-31. Cases 3 and 4: Landfill gas electricity generation for 1C engine interconnect stage costs D-16

D-32. Cases 3 and 4: Landfill gas electricity generation for 1C engine power sale stage.D-17

D-33. Cases 3 and 4: Financial analysis for 1C engine power sale using two different power prices (Best estimate methane production) D-17

D-34. Cases 3 and 4: Financial analysis for 1C engine power sale using two different power prices (Low estimate methane production) D-18

D-35. Cases 3 and 4: Financial analysis for 1C engine power sale using two different power prices (High estimate methane production) D-18

vn TABLES 1 -1. A 1990 review of gas and energy production from landfill gas utilization plants by Willumsen (1996) 4

2-1. Maximum concentrations detected in soil gases from Sunrise Landfill by CCJM (1998) and literature reported concentrations (EPA, 1997b; and Hutchinson, 1993)... 12

5-1. Annual estimated methane emissions (million cubic meters) from Sunrise Landfill for three cases 31

5-2. Estimates of 1999 NMOC emissions from Sunrise Landfill for five cases 33

7-1. General assumptions for calculating financial feasibility of methane projects 40

7-2. AP-42 emissions factor and estimated emissions from a flare operating at the Sunrise Landfill during 2000 41

7-3. Capital and operating costs of gas enrichment and injection into pipeline 42

7-4. Capital and operating costs of power generation and sale using combustion turbine (Case3a) 44

7-5. Capital and operating costs of power generation and sale using 1C engine (Case3b) 45

7-6. AP-12 emission factors and emissions from a 6.64 MW gas turbine operation on Sunrise Landfill gas (Case 3a) 46

7-7. AP-12 emission factors and emissions from a 7.44 MW natural gas-fired reciprocating engine operating on Sunrise Landfill gas (Case 3b) 46

7-8. Summary of environmental and economic benefits of methane use options 47

7-9. Sensitivity of project NVP to changes in methane production rate and recovery 48

vm ACRONYMS

CCCP Clark County Comprehensive Planning CCHD Clark County Health District CCPW Clark County Public Works DUMPCO Disposal Urban Maintenance Processing Company E-PLUS Energy Project Landfill Gas Utilization Software EPA U.S. Environmental Protection Agency GPS global positioning system GWh gigawatt hour GWP global warming potential 1C internal combustion LEL lower explosive limit LFG landfill gas Mg megagrams msl mean sea level MSW municipal solid waste NMOC nonmethane organic compound NVP net present value NDEP Nevada Division of Environmental Protection PERG Puente Hills Energy Recovery from Gas PET potential evapotranspiration PURPA Public Utilities Regulatory Policies Act RCRA Resource Conservation and Recovery Act RSSD Republic Silver State Disposal STP sewage treament plants TOE tonne oil equivalent VOC volatile organic carbon

IX INTRODUCTION According to the U.S. Environmental Protection Agency (EPA, 1997b), about 57% of solid waste produced in the United States is placed in some 2,500 active landfills. It further estimated that these landfills receive around 189 million megagrams (Mg) of waste annually. Hutchinson (1993) estimated that municipal solid waste (MSW) facilities globally store about one billion metric tons of biodegradable organic waste (labile materials) annually. Barlaz et al. (1989) and Westlake (1990) reported that MSW consist of labile (40-50% cellulose, 12% hemicellulose, and 4% protein), recalcitrant (10-15% nonbiodegradable lignin), and various inert (30% plastics, glass, metals) materials. Decomposition of this MSW produces landfill gas (LFG) that is primarily (50+5%) methane and (45+5%) carbon dioxide. During the operational period of a landfill, the lift of waste deposited each day is covered with an Interim or operational cover that usually consists of about 30 cm of soil. The soil/waste mixture is well aerated during this period. A cap, usually consisting of 100 cm or more of top soil, clay barrier, and geosynthetic barriers, is placed over the operational cover at closure to entomb the waste. The landfill will go anaerobic fairly quickly due to the impedance by the cap to convective and diffusive gas exchange with the atmosphere. Farquar and Rovers (1973) proposed that landfills undergo four stages of gas generation based upon the microbial activity. This was upgraded to the following five stages (Figure 1-1) by Rees (1980) and Ward (1988): I- aerobic, II-microbial transition to anaerobic, Ill-unstable methane formation, TV-stable methane formation, and V-final maturation. Christensen et al. (1996) segregated the final stage (V) into four stages to produce eight distinct stages. With regards to LFG to energy, this final stage or stages is noted by a decline hi methane concentrations to non-useable levels, so these additional stages will not be reviewed.

1 i i ii in i IV V 100—

80- "N \ N, . 1 \ / \ \ \ / * L_._ .«, j */ .3- \ / v \ ' & / \ % :f 40 - i 00, I / "•i V : \ / : \ / \ -••A"* \ Sa- V -, / / \\ 1- \ ! / / \\-\ --<" •* ^ / 0 i %— . i/ A\Afeeks Mrths Yeas Time

Figure 1-1. Typical LFG composition during decomposition of MSW (recreated from Farquar and Rovers, 1973) showing the five stages of LFG production (from Ward, 1988). 1.1 Stage of Decomposition During the aerobic stage (I), organic compounds (cellulose) are decomposed into sugars, amino acids, alcohols, peptides, and fatty acids by aerobic microbes, invertebrates, and fungi. This process lasts for a few days to a couple of weeks. Oxygen (02) and nitrates (NO3) are consumed as electron acceptors with significant amounts of water generated hi this biochemical process. Stage II, lasting up to several months, is characterized by a shift in microbial population from aerobic to facultative anaerobic organisms. Carbon dioxide, fatty acids, hydrogen, and alcohols are produced as cellulose and hemicellulose compounds are catabolized. The decrease in pH limits methanogenic bacteria activity thereby delaying the generation of methane. Initiation of Stage II is noted by increased activity of methanogenic bacteria due to the loss of nitrogen and a steady increase in pH (decrease in hydrogen production). Stage III may last for a couple of months to a couple of years and culminates in the LFG consisting of approximately 55% methane and 40-50% carbon dioxide. Stage IV may last for as much as 80 years (Augenstein and Pacey, 1991), in which steady-state conditions exist in the methane and carbon dioxide concentrations and microbial populations are largely acetogenic and methanogenic bacteria. The resulting loss in cellulose eventually limits the production of methane and carbon dioxide, which characterizes the final stage (V). Hutchinson (1993) stated that Stage V can last from one to 40 years and complete biodegradation of MSW may require ten to 80 years following emplacement. LFG production models are used to estimate the length of time, called generation time, that LFG is generated. Cossu et al. (1996) cited generation time estimates by others from ten to 30 years, with the longer times expected for drier environments. 1.2 Manipulation of Decomposition The microbial processes of decomposition can be manipulated to some degree to influence gas generation. The primary abiotic factors influencing gas generation are: oxygen, pH, nutrients, temperature, and water content. The methanogenic bacteria responsible for waste decomposition are facultative anaerobes and thus explicitly sensitive to redox potentials. Redox potentials below -330 mV are needed for methanogenic activity (Zehnder, 1978). Since the absence of oxygen is critical to their survival and activity, Hutchinson (1993) suggested that a reducing agent such as cysteine can be used to initiate low redox conditions. Pulling too much vacuum on LFG extraction wells can result in oxygen being drawn into the landfill, thereby poisoning the methane generation process (Ham, 1996). It may take months for the microbial activity and gas generation to recover to normal. The redox potential is indirectly related to the moisture content of the waste. Many studies have found that increasing the moisture content to field capacity can improve LFG generation (Rees, 1980; Barlaz et al, 1987; Ward, 1988; Westlake, 1990). Increased water content facilitates low redox potential due to the lower air-filled porosity of the waste. This not only decreases the oxygen and nitrate content available but more importantly it significantly reduces the oxygen diffusion rate, thereby limiting the replenishment following oxygen consumption (Wilson et al., 1985). Additionally, higher water contents serve to solubilize and mobilize nutrients, dilute toxic xenobiotic compounds, and mobilize microorganisms. Rees (1980) and Barlaz et al. (1989) suggested that recirculating landfill leachate could improve LFG generation. Hydrogen, COa, and acetic acid are produced in Stages I and II. These must be converted to other forms or the pH will rapidly decline. Methanogenic bacteria are most active under nearly neutral conditions with a narrow optimum range in pH between 6-8 (Zehnder et al., 1982). If the conversion of hydrogen and acetic acids is inhibited, the pH decrease can inhibit methanogenic activity and the methane generation will decline (Christensen et al., 1996). The waste can be buffered with calcium carbonate (lime) to prevent this (Hutchinson, 1993) or recirculated buffered leachate (Barlaz et al., 1987). Many times, the sewage sludge is sufficiently treated with lime, which eliminates this necessity. Nutrients have been reported to have a rate-limiting effect on gas generation (Barlaz et al, 1989; Ham and Barlaz, 1987; Pohland et al, 1983). The nutrients most often noted as possible limiting factors are nitrogen and phosphorus. Generally, there are sufficient amounts of these in landfills, however, Ham and Barlaz (1987) suggested that the lack of homogenization of the landfill may cause localized nutrient limitations. Other chemicals in the waste can be detrimental to microbial activity. Xenobiotic compounds, such as chlorinated hydrocarbons, heavy metals, and detergents, can be toxic to methanogenic bacteria (Hutchinson, 1993). Fertilization of the waste could have a positive effect on gas generation if nutrients are limiting, however, the difficulty of getting the nutrients distributed in the waste zone limits its use. Methane generation generally increases as temperature increases. While anaerobic decomposition does not produce as much heat as aerobic decomposition, Christensen et al. (1996) reported that elevated temperatures have been reported. The optimum temperature for gas generation is between 37 and 42°C (Pfeffer, 1974; Hartz et al, 1982). While this is not easily manipulated, site location (climate regime) and thickness of waste are important factors to consider. Other manipulations that have been studied include shredding, compaction, precomposting, and sewage sludge addition. Shredding homogenizes the waste and increases the surface area for biodegradation. The advantages may be offset by a delay in the start of methane production (Christensen et al, 1 996). Over-compaction of waste can be detrimental to LFG generation due to water and air permeability being reduced. Sewage sludge addition is generally considered favorable, as it serves as a water and nutrient source and can buffer the pH. However, the latter factor may be just the opposite depending upon the sludge source and pretreatment. 1.3 Landfill Gas to Energy Even without these manipulations, Hutchinson (1990) stated that the methane contained in LFG is a reliable and exploitable energy source. Willumsen (1996) identified around 300 energy production plants from 18 countries as of 1990 where LFG is utilized. The total gas production was estimated to be approximately 1 .2 x 1 09 m3 CIVyr and the corresponding energy production was about 1.1 x 106 Tonne oil equivalent per year (TOE/yr), which equals 12,000 gigawatt-hours per year (GWh/yr). In contrast, Hutchinson (1993) put the global methane generation estimate at two orders of magnitude higher (1.4 x 1011 m3 CFLj/yr). Data hi Table 1-1 for the U.S. are significantly underestimated, as the number of LFG-to- energy plants was reported to be around 150 by Berenyi and Gould (1991) and Giovando and Jones (1998) and around 300 by Walsh (1999a). According to Giovando and Jones (1998), the EPA estimates that around 750 landfills nationwide could economically produce energy from LFG for ten to 30 years.

Table 1-1. A 1990 review of gas and energy production from landfill gas utilization plants by Willumsen (1996). Country # of Plants l,OOOm3CH4/yr TOE/yr GWh/yr USA 79 843,570 746,512 8,419 Germany 80 149,298 132,000 1,490 UK 27 126,653 112,000 1,264 Netherlands 10 19,539 17,250 195 Canada 9 6,520 5,763 65 Sweden 8 12,040 10,640 120 Italy 7 11,322 10,000 113 Denmark 5 4,108 3,640 41 France 5 4,709 4,150 47 Others 16 51,191 45,310 511 Total 246 1,228,950 1,087,265 12,265

1.4 Regulatory and Economic Drivers The proliferation of LFG-to-energy projects is due to economics and environmental regulations. Energy production from LFG began in the 1970s in southern California and by the late 1970s had expanded to around 30 companies across the U.S. (Walsh, 1999a). The relationship between growth and economics can be seen in Figure 1-2. The large increase in oil prices in the early 1980s produced a time-lagged increase in production plants. This growth was enhanced by regulatory drivers. Congress enacted the Public Utilities Regulatory Policy Act (PURPA), which required utilities to buy electricity from small generators like LFG-to-energy plants. Perhaps the most significant factor for growth was the 1980 IRS Section 29 Production Tax Credits. These tax credits provided an economic incentive to landfill owners for producing an alternative energy source to decrease our dependence on foreign oil. While the decreasing prices hi the late 1980s reduced the growth in production plants, the Section 29 tax credits enabled marginally profitable landfills to go into production. Section 29 tax credit policy was terminated on 30 June 1998. To qualify for future tax credits, operators had to have their gas collection system installed by this date. According to Walsh (1999a), this produced a proliferation of LFG-to-energy plants in 1998 such that there were 300 plants either operational or near completion by 1999. The economic situation at present is bleak for the LFG-to-energy Industry. Walsh (1999a) concluded that "the lack of favorable economics owing to recent developments may doom the industry of few new projects and a struggle to continue those already up and running." Without the Section 29 tax credits, many projects are simply not economically viable and at best are a risky profit (Walsh, 1999b). Unfunded federal mandates are currently the main driver to new LFG-to-energy projects. The Resource Conservation and Recovery Act (RCRA) Subtitle D requires installation of LFG control systems. The 1990 Clean Air Act is requiring LFG control systems to limit emissions of non-methane organic compounds (NMOCs). Projects -+- Oil Price

160

120

2 CD CL CO "5 80 o5 1 3

40

1970 1995

Figure 1-2. LFG-to-energy projects and average yearly price of oil per stock-tank barrels (STB), recreated from Hutchinson (1993). Air pollution emissions from MSW landfills are regulated to implement the Clean Air Act of 1990. These regulations are codified in the Code of Federal Regulations (CFR Title 40, Part 60, subparts Cc, WWW, and B). New Source Performance Standards and Emission Guidelines for Municipal Solid Waste landfills were promulgated in March 1996. They apply to MSW landfills with actual or design capacities greater than 2.5 million Mg that began accepting waste on or after May 30, 1991, or have accepted waste since November 8, 1987, or that have capacity available for future use. This category includes the Sunrise Landfill. States with existing MSW landfills meeting the above criteria must submit a plan to the EPA for approval. The regulations outline plan requirements and timetables for meeting these requirements. The regulated pollutant is landfill gases, which contain a mixture of volatile organic compounds (VOCs), other organic compounds, methane, and toxic pollutants. Existing MSW landfills with a capacity to emit more than 50 Mg/yr of NMOCs are required to install controls. While EPA encourages the energy recovery from the landfill gases, flaring of gases to achieve 98% control of NMOCs is required if the gas is not utilized for its energy. Regulations require landfill gas controls to minimize a variety of health and climate concerns. There are also ecosystem concerns, such as damage to vegetation primarily due to removal of oxygen in the root zone, and residential nuisance concerns, such as odors. At high concentrations, ranging from five to 15% by volume in air (Constable et al, 1979; Kjeldsen, 1996), methane may explode or cause surface fires. Kjeldsen (1996) reported 55 cases in the U.S., United Kingdom and Canada in which fires or explosions occurred due to LFG. Campbell (1996) noted that almost all of these cases were associated with former (closed) sites where no concern, or no monitoring, had been noted prior to the incident. The typical carbon dioxide concentration of LFG (50%) is 100 times higher than the threshold value limit of 0.5% for human health. While methane only needs an order of magnitude dilution in the atmosphere to reduce the concentration below the lower explosive limit of 5%, COa needs two orders of magnitude dilution. However, greenhouse effects of methane from landfills are also of concern because methane has 21 times the global warming potential (GWP) of carbon dioxide (molar basis). Thus, converting methane to CC>2 by flaring or later burning for electricity production or heating dramatically reduces its GWP. As discussed hi Sections 1 and 7, the fate of landfill gases (flared or used for energy) depends upon many factors, most importantly the methane emission rates, and the market value of gas or electricity produced compared to the value of other sources of energy. Because regulations require collecting the gases, these costs are incurred regardless of whether the gas is flared or used for energy. Thus, the incremental costs for energy utilization may be significantly lower than the total recovery and energy utilization. Estimates of the costs and revenue from flaring alone and LFG-to-energy use are given in Section 7. VOCs in LFG contribute to tropospheric ozone, while certain VOCs and other organic compounds are carcinogenic. EPA estimates that 255,000 Mg of NMOCs are released from MSW landfills annually (Reinhart et al, 1992). Given the high production of methane (a greenhouse gas) from landfills, additional regulatory mandates are expected in the future to reduce greenhouse gas emissions. Walsh (1999b) concluded that a "new federal incentive program is needed" to help private developers meet the unfunded mandates to reduce emissions. 2.0 SUNRISE LANDFILL BACKGROUND The Sunrise Landfill is located in the Section 1 and 12 of Township 21 South, Range 62 East in Clark County, Nevada. The landfill consists of 291.4 hectares leased, beginning in 1957, by Clark County Public Works (CCPW) from the U.S. Bureau of Land Management (BLM) and operated under contract to Disposal Urban Maintenance Processing Company (DUMPCO). The landfill is unlined and is approximately three kilometers upgradient of Las Vegas Wash, which discharges into Lake Mead. It is situated in a canyon of the Frenchman Mountain range (Figure 2-1). Elevations range from 693 to 579 m above mean sea level (msl) with steep sideslopes (EMCON, 1986) and the waste has been reported to be as much as 100 m deep (CCJM, 1998). 2.1 Climate and Geologic Setting

Meteorological data for Clark County was obtained from the National Weather Service web site (www.wrh.noaa.gov/lasvegas/climate.htm 03/20/00). Average annual precipitation in Clark County is approximately 10.5 cm. Most precipitation comes in two peak seasons, frontal passages during winter months and the convective storms in the summer months. Average monthly precipitation ranges from 0.3 to 1.2 cm. Clark County experiences extreme temperatures, with an annual mean of 19.5°C. Monthly mean temperatures range from about 7.5 to 32.8°C with monthly mean lows of 0.9°C and highs of 41.0°C. Strong winds are common in

tion ojf, ite^tio If n pasi1L •n

Figure 2-1. Contour map of the Sunrise Landfill site with the lease boundary depicted by red line and the approximate boundary of the watershed contributing runon to the site depicted by blue line. the valley with winds over 90 kmph experienced occasionally during vigorous storms. Winter and spring winds are widespread and can generate resuspension of dust. Strong winds experienced during summer months are typically associated with localized thunderstorms. The prevailing wind direction is southwest unless associated with a thunderstorm. The extremely hot summers, high winds, and low relative humidity result hi extremely high values of potential evapotranspiration (PET). PET values for the summer months are much higher than precipitation resulting in low values of actual ET. The estimated pan evaporation at a similar environment on the Nevada Test Site is approximately 310 cm (Magnuson et al, 1992). The northeastern portion of the landfill has shallow soils (< 2 m) over sandstone and limestone bedrock (Martinez and Yeckes, 1994). The southern end of the landfill transitions into Quaternary alluvium and valley-fill sediments. Martinez and Yeckes (1994) noted from drilling logs that the southern end is underlain by 6 to 9 m of loose sandy/gravel sediments that are cemented with carbonate and gypsum. These sediments comprise the Muddy Creek Formation. According to a soil survey by VanDerPuy (1984), the site includes three mapping units: the Aztec-Bracken (unit 419), the Aztec very gravelly sandy loam (unit 415), and the Bracken very gravelly fine sandy loam (unit 134). All soils are high in gypsum, but the Bracken series is particularly high with gypsum crystals clearly evident (75% gypsum). VanDerPuy (1984) noted that the northeast area contains northwest-southeast-trending faults with a southwest dip. He also noted that faults are common in the alluvial fans. He reasoned that these faults would be barriers to lateral groundwater flow but could act as a conduit for downward movement. However, Wilson et al. (1998) reported lateral discharge from a shallow fracture (less than 3 m deep) into an erosion gully in the alluvial fan immediately southwest of the landfill. The seep location, as measured by global positioning system (GPS), was North 36°8' 16", and West 114°59' 43", which is approximately 152 m within the landfill border. It was still flowing at a rate of about 30 L/h nearly two weeks after a major storm event. The strike of this fracture was measured with a Brunton Compass to be 137° from North, which would cut across the lower portion of the landfill. A second seep was also observed in the main erosional channel in the alluvial fan sediments approximately five kilometers southwest of the landfill. It was still discharging at the surface!7 days after the storm event. Wilson et al (1998) also reported evidence of springs in the canyon's watershed immediately upgradient of the landfill. They reasoned that these subsurface springs were contributing water to the landfill waste zone, causing the seeps to continue discharging for extended periods following large storms. EMCON (1986) reported that shallow groundwater flow through the alluvial sediments is possible for short durations folio whig major storm events, but that ten boreholes on the site to a maximum depth of 33.5 m did not reveal a water table. A well drilled to 61 m on-site in the Muddy Creek Formation did contact a free water surface at 52 m deep (534 m msl). The water was of poor quality (TDS = 3,684 mg/L), which is typical of the shallow Las Vegas Valley aquifer (Wild, 1990). Martinez and Yeckes (1994) suggested that the groundwater underlying the landfill is slowly moving westward at 0.3 to 3 m/yr. The review of groundwater data near the landfill by VanDerPuy (1984) suggested that the groundwater table is between 46 and 91 m below surface (497 m msl) with a gradient in the southwest direction.

8 2.2 Sunrise Landfill Operations and Closure The landfill stopped accepting waste in October 1993. It accepted 3,080 Mg/day during the last two years (Martinez and Yeckes, 1994), but records of waste disposal prior to this period are not available. According to Martinez and Yeckes (1994), the landfill was designed for a total refuse capacity of 47,000,000 m3, but with seven years of capacity remaining, it was estimated that a total of 36,000,000 m3 was deposited. The waste consisted of primarily municipal waste but included asbestos, sanitary sludge, construction debris, septage waste, and hydrocarbon- contaminated soil. Martinez and Yeckes (1994) estimated that four million Mg of septage sludges were accepted since the 1950s; 33,572 m3 of medical waste; 69,715 m3 of asbestos; and 100,000 Mg of contaminated soils since 1989. The final cover was to be placed over the existing intermediate (operational) cover that was to be at least 30 cm of soil. The portion of the landfill that accepted waste between 9 October 1991 and 9 October 1993 was closed with a Subtitle D final cover in May 1995 to meet the 40 CFR 258.60(a) requirements for minimizing infiltration and erosion. The final cover was placed over only 72.8 of the 291.4 hectares of landfill property that accepted waste during this period and the remaining area had a cover approved by the Clark County Health District (CCHD). The Subtitle D final cover was designed to have a slope between 3.5% and 3:1 on sideslopes. According to Martinez and Yeckes (1994), the final cover was designed to have a 46-cm barrier layer with a saturated hydraulic conductivity (Ks) less than 1 x 10"5cm/s, and a 15-cm topsoil layer. To protect against erosion, the topsoil would contain 15% gravel and 15 to 20% silt to produce desert armoring. The site was also expected to naturally revegetate due to no periodic grading following cover construction. Surface water runoff would be controlled by a system of culverts (corrugated metal structural plate pipe cut in half), which fed into a trapezoidal open channel that cuts across the eastern side of the landfill. The channel had a 3-m- wide bottom with 3:1 sideslopes, and total depth of 1.8 m. It was lined with a geosynthetic liner and covered with riprap. To design the channel, the HEC-1 code was used to model runon and runoff. Runon from the 44 5-hectare watershed in the canyon upgradient of the landfill was modeled for a 25- and 100-year, six-hour storm event (6.5 and 8.0 cm, respectively). 2.3 Post-Closure Conditions and Hydrogeologic Impacts Dwyer (1997) inspected the cover and found that the depth of cover did not meet the minimum required depth and the Ks of the barrier layer exceeded the maximum allowable value. Numerous cracks were identified that extended completely through the cover. These were considered to be predominantly subsidence cracks (differential settlement) resulting from waste decomposition and exaggerated by the cementing effect of the calcareous soils. Wilson et al. (1998) raised concern that the cementing action would cause a surface seal that limits infiltration. The result would be localized runoff to these cracks, which would serve as preferential flowpaths through the cover and directly into the waste. Severe cover runoff was noted by Dwyer (1997) and Wilson et al. (1998) by the excessive gullying that was evident on the cover. Dwyer (1997) concluded that neither the hundreds of lineal feet of collection pipes nor the erosion protection were working effectively. The landfill has been noted for numerous environmental and regulatory concerns. Before reviewing these, it is important to revisit concerns expressed by VanDerPuy in!984. He stated "the combination of high runoff and steep slopes will result in fast movement of water down canyon. This water would have a great deal of erosive force and would expose cells placed in its path. Continued movement of flow over the landfill would cause erosion and gullying until the entire length of the landfill has been dissected. The contents of the landfill would be washed through the gully and off-site. If sufficient (land)fill material were placed in the canyon, impoundment of water would occur. This water would saturate the impounding (land)fill material and underlying alluvium... the possibility for lateral movement over the underlying bedrock and Muddy Creek formation and through the (land)fill material is good. Such movement would cause the generation of leachate. Saturation of this material would also cause... piping and rapid transport pathways for movement of water and leachate. The ultimate discharge point for such leachate would be the Las Vegas Wash and Lake Mead." Without knowledge of the VanDerPuy report, Wilson et al (1998) made the following observations following a major storm event on 11 September 1998. "It appeared from our inspection that a surface retention basin was either constructed just above the landfill cover to focus runon into the channel or is an artifact of the landfill inadvertently forming a dam. Prior to the construction of the landfill, the watershed between the ridges, was drained by numerous significant drainage channels. Construction of the landfill, (which) occupied the entire valley floor between the two ridges, effectively formed an inadvertent dam for runoff waters from the up-gradient watershed. Inspection of aerial photographs taken during the landfill's operation, indicated that there was no drainage channel to allow runoff waters to bypass the landfill. During closure of the landfill, apparently a single drainage channel was constructed to allow water from the landfill and the up-gradient watershed to exit the landfill. Unfortunately the drainage channel was constructed on top of the landfill. This caused two major design problems: (1) The channel is now at a much higher elevation than the natural valley floor which allows the landfill to serve as a dam, trapping water behind the landfill and probably allowing significant water to flow under and into the waste. During site inspections following the September 11th precipitation event, water marks comprised of vegetative debris indicated that water must have been 1.5 to 1.8 m deep up-gradient of the landfill. (2) With the channel on top of the waste, channel failure can result in waste transported off the site. Additionally, as mentioned earlier, the up-gradient basin was previously drained by multiple channels but is now restricted to a single channel. Given that the September 11 storm event was over 5 cm, it is not surprising that the single channel could not handle the flow and eroded into the waste zone even though, according to our understanding, it was designed for a 100 yr-6 hour event of 8 cm. The overland flow was so intense as it descended the steep grade where the channel was created by the site owner through a mountain toe-slope at the landfill's southeastern border that not only was almost all the channel's rip rap removed, but deeply incised gullies were created down to the bedrock in the alluvial fans down-gradient." As mentioned earlier, Wilson et al (1998) observed lateral flow from a fracture creating a seep in the gully and approximately five kilometers southwest of the landfill. Additionally, Wilson et al (1998) noted that "it is obvious from the numerous rills and erosional gullies that

10 substantial runoff is occurring The cover surface appears to have formed a surface crust (seal) that will limit infiltration and cause preferential flow directly into the waste " Wilson et al (1998) further reported that, during their site inspection after the September 1998 storm event, they "followed the gully from the Las Vegas wash up to its source at the landfill Large rip rap boulders were observed in these gullies at considerable distances from the landfill and channel liner (and waste) was observed all the way to the wash " The findings of Wilson et al (1998) corroborated every single concern expressed by VanDerPuy in 1984 The conceptual framework of the hydrogeology for the Sunrise Landfill can be represented by Figure 2-2 The sources of water in the waste zone that fosters decomposition are infiltration through the cover, particularly through subsidence cracks, percolation into the waste zone from the upgradient surface impoundment, and possibly springs Additionally, there are significant quantities of water both in the waste at deposition and generated by waste decomposition The environmental concerns include the potential, compounded by no bottom liner, of groundwater recharge, subsurface stormflow drainage and surface runoff to the Las Vegas Wash and on to Lake Mead Despite the extremely arid environment, the waste zone will likely remain at high water contents that are ideal for decomposition due to these water sources Thus, there is a high potential for long-term gas emissions from the Sunrise Landfill

Fto»l cover with »bfidence cricks Rainfall Impoundment R*

Fracture plane fMt*xt**tt*****Kft-e*eJite4fi V.ff:

Figure 2-2 Schematic of the conceptual framework of the hydrogeology at Sunrise Landfill Given the concerns for gas emissions noted by Dwyer (1997), the BLM contracted CCJM Environmental Consultants (CCJM, 1998) to conduct an intensive characterization of the composition of gases being generated within the landfill CCJM collected soil gas samples from 97 boreholes in the upper lift (< 3 m deep) of the landfill and off-site locations The majority of the boreholes were in the upper (35 locations) and lower (24 locations) municipal waste cells

The gas samples were analyzed for a suite of NMOCs and fixed gases (O2, CO2, H2S,

11 Petroleum hydrocarbons were detected in 51% of the municipal waste cell boreholes and 39% showed chlorinated solvents. The primary petroleum hydrocarbons detected, Table 2-1, were benzene, toluene, ethylbenzene, and xylenes. For the fixed gases, Oa was near zero at most locations, while CO2 ranged from 10 to 40% and methane levels were as high as 67.3%. This suggests that the landfill was already in Stage 4 gas generation by the beginning of 1998. CCJM also found that HaS exceeded 2,000 mg/L, which is well above the Immediately Dangerous to Life and Health limit of 100 mg/L and even over the Instantaneously Fatal limit of 800 ppm.

Table 2-1. Maximum concentrations detected in soil gases from Sunrise Landfill by CCJM (1998) and literature reported concentrations (EPA, 1997a; and Hutchinson, 1993).

Species CCJM (1998) EPA(1997a) Hutchinson (1993) (Hg/L) (Hg/L) (Hg/L)

Vinyl Chloride <1* 7,340 44,000 to 2,200

Benzene 154 1,910 39,000 to 4

Toluene 55 39,300 280,000 to 58

Ethylbenzene 8 4,610 98,000 to 20

Xylene 14 12,100 220,000 to 56

Tetrachloroethane 13 1,110 16,000 to 110

Methylene Chloride 24 14,300 59,000 to 6

1,1 Dichloroethene 3 200 4,000 to 3 10

Trichloroethene 13 2,820 32,000 to 1 1

cis 1,2 Dichloroethane 3 410 20,000

1,1 Dichloroethane 7 2,350 22,000 to 2,6 15

1,1,1 Trichloroethane 7 480 15,000 to 4 * = Below detection limits

In comparison to the extensive review of LFG emissions from MSW landfills reported in the AP-42 (EPA, 1997a), the NMOC identified in soil gas at Sunrise is typical but the concentrations are considerably lower than normal. However, most of the constituents detected did fall within the range reported in the review by Hutchinson (1993). The lower concentrations are not surprising given that these samples were collected near the surface and not within the gas-generating portion of the waste zone. Subsequent to the CCJM report, Republic Silver State Disposal (RSSD) contracted to Kleinfelder, Inc. to conduct a survey of methane and hydrogen sulfide emissions from Sunrise

12 Landfill (Rajagapolan and Ertler, 1998). They surveyed the surface between July 21 and August 3,1998, by pulling a cart with instruments maintained 5 to 10 cm above the surface. They made traverses on 30.5-m intervals across the entire landfill surface. When concentrations of methane

exceeded 200 mg/L, they recorded the location by GPS, as well as H2S concentration and the lower explosive limit (LEL). They identified 41 locations where the methane concentration exceed 200 mg/L. At four locations, the methane concentrations exceeded the instruments' upper detection limit of 10,000 mg/L and at four different locations the LEL was >100%. The maximum H2S concentration detected was 670 mg/L. Both the CCJM (1998) and Kleinfelder, Inc. (Rajagapolan and Ertler, 1998) reports are limited in value due to the failure to determine the gas flow rates. Concentrations were reported but not the flux, thus the total rate of emissions was not determined. Additionally, both studies report measurements at or near the surface and do not reflect concentrations that would be observed with gas extraction wells.

2.4 Regulatory and Community Actions

In February 1998, just shy of three years after the landfill was closed, the Las Vegas Review Journal (Bach and Rogers, 1998) reported that methane gas was leaking from the landfill. This was based upon findings by Dwyer (1997) that gas emissions exceeded 25% of the lower explosive limit. The report by CCJM (1998) came out a month later and the findings were reported in the Las Vegas Review Journal by Rogers (1998a). At this time, the Review Journal (Rogers, 1998b) reported that EPA was urging the CCHD and RSSD to correct the gas emission problems. On September 11, 1998, a major storm event occurred. It was reported in the Las Vegas Sun (Manning, 1998a) that runoff from the landfill was polluting the Las Vegas Wash. The findings of Wilson et al (1998) were subsequently reported in the Las Vegas Sun (Manning, 1998b). Through these media and research reports, it was evident that hi the few years since the Sunrise Landfill closed, there have been atmospheric discharges, surface water discharges, and groundwater discharges. On 5 October 1998, the Nevada Division of Environmental Protection (NDEP) issued a Finding of Violation and Order to CCPW and RSSD. It charged these parties with evaluating the stormwater control system. On 6 October 1998, the CCHD issued a Corrective Action Order to these same parties, as well as to BLM, requiring them to review the surface water control system and submit plans for changing the runoff-erosion control structures. On 16 October 1998, NDEP issued a second Finding of Violation and Order to CCPW and RSSD. It "requires Clark County and Republic to install groundwater monitoring wells...and to implement a sampling program..." The monitoring plan that RSSD submitted was found to be "completely unacceptable" by NDEP and the plans submitted by RSSD to correct the stormwater control system were found by CCHD to be insufficient. An additional regulatory driver was the fact that CCPW and RSSD did not meet the federal EPA deadline of 9 October 1994, for complete closure. NDEP warned CCPW that "the regulatory consequence is serious. Failure to close within the one-year deadline would trigger all

13 the ground water monitoring requirements." As a consequence, in March 1998, NDEP recommended to CCPW the following actions: 1. Install gas monitoring wells 2. Design and install ground water monitoring system 3. Reevaluate the stormwater drainage system 4. Evaluate the landfill cover 5. Consider an alternative cover design and participation with DRI in Alternative Covers Assessment Program (ACAP). Failure to heed this warning was one reason that RSSD and CCPW were issued a Finding of Violation and Order by NDEP. Due to the lack of progress by the various parties in solving the site problems, on 27 April 1999, EPA Region 9 issued an Administrative Order and a Finding of Violation and Order against CCPW and RSSD. The Order required "implementation of a stormwater control plan, repair and redesign of runon/runoff control systems, installation of a final cover to minimize infiltration and erosion, implementation of methane and groundwater monitoring systems, and maintenance at the site." EPA concluded from its review of reports and site Inspections that "respondents' failure to adequately close and maintain the Site to minimize soil erosion, leachate to groundwater, explosive hazard from landfill gases, and run-on and run-off of stormwater presents or may present an Imminent and substantial endangerment to health or the environment under Section 7003 of RCRA, 42 U.S.C. 6973." 3.0 STUDY OBJECTIVES AND PROJECT ACTIVITIES In February 1999, the Desert Research Institute (DRI) learned that the U.S. Department of Energy, Nevada Operations Office (DOE/NV) was going to study the potential for converting gas emissions from Sunrise Landfill into energy. DRI was contracted to do this work for several reasons: DRI is one of DOE's R&D subcontractors and already has a contract with the Energy Technology Division, which is the division through which this allocation was made; DRI is the lead institution on a national EPA program called Alternative Covers Assessment Program (ACAP) studying the closure of landfills; DRI was already involved hi the Sunrise Landfill, having recently completed the study by Wilson et al (1998) for BLM on groundwater discharges; and DRI has the atmospheric science expertise for studying gas emissions. The guidance provided to DOE/NV by DOE Headquarters was "to evaluate the amount, distribution and best method of extraction and utilization of methane gas from Sunrise Mountain Landfill." Subsequent guidance was that "these funds are to be used to conduct a study of the magnitude and migration of methane gas generation at the closed Sunrise Landfill...methods of extraction and using the methane gas for energy production." DRI proposed to do the following:

14 1. Determine the rate of release 2. Identify extraction methods 3. Estimate the power generation potential 4. Predict the resource life of the methane 5. Determine if gas extraction-energy generation is a positive remediation strategy

To accomplish these objectives, DRI proposed to do a surface gas emission survey and install a series of gas collection wells on the landfill to determine the potential gas production rate. In February, DRI met with all the following parties to discuss the study and to develop collaboration among the parties: CCHD, CCPW, Clark County Comprehensive Planning (CCCP), BLM and RSSD. As managers of the land, BLM requested hi March 1999 that DRI get concurrence from all parties (CCPW, CCHD, CCCP, NDEP, and RSSD) stating that they had reviewed the work plans, so that BLM could grant approval for the study. All parties responded in writing with concurrence except RSSD, and a letter was submitted 3 May 1998 to BLM requesting permission (Appendix A). On April 27, EPA Region 9 cited CCPW and RSSD with the Finding of Violation and Order. After the EPA citation, DRI was informed by BLM that they could grant approval to DOE/NV but not DRI. They also insisted that DRI get approval from EPA Region 9 and RSSD before the BLM would grant approval to DOE/NV. DOE/NV subsequently informed BLM that "their preference is for BLM to authorize DRI." In early May, DRI discussed the impact of the citation on its activity with the EPA Region 9 Technical Coordinator (Steve Wall, personal communication), who encouraged DRI to work with RSSD and CCCP in making the study a part of the site assessment required under the citation. This was discussed with CCCP (Sherri Frakes, personal communication), who informed DRI that RSSD is the lead and for DRI to work with them. Several discussions were held with RSSD (Alan Gaddy, personal communication; and Appendix B) about incorporation of the study as part of their site assessment activities. RSSD took the stand that they cannot use DRI's study because the wells proposed "do not comply with standard EPA approved methods." DRI's plans were developed through significant consultation with industry experts who disagreed with RSSD's view on these methods. This issue was discussed with the Region 9 Technical Coordinator (Steve Wall, personal communication), who expressed the opinion that there are no standard methods under RCRA for wells and that DRI was under no obligation to use any specific EPA methods. DRI made RSSD aware that the proposed methods were acceptable with Region 9, but after a month of discussions, RSSD ultimately decided to not make DRI's study a part of their site assessment. On 28 May 1999 (Appendix C), DRI requested approval from EPA Region 9 for its work plans, since the citation stated that "all contractors, transporters and treatment, storage, disposal or recycling facilities used or proposed for use during this action are subject to EPA approval," and it states "to the extent the Site...is to be used for access...Respondents will use their best effort to obtain Site access agreements from the present owner(s) and/or lessees." DRI did not

15 receive a written response but was verbally informed on June 21 by the EPA Region 9 Project Coordinator (Susanna Trujillo, personal communication), that EPA was not in a position to approve the request since the study was not part of the citation activity. Since DRI was not granted permission for conducting on-site assessments of the gas production rates, in July, the scope was redefined such that this report will cover a literature review on the potential for converting LFG to energy. The report will include mathematical modeling estimates of gas production for Sunrise Landfill, and information gathered on the potential use of these gases, and a recommendation on the methods to be used to assess gas production rates and the associated costs in the event that DOE/NV wishes to pursue this at Sunrise Landfill in the future. 4.0 GAS TESTING AND RECOVERY OPTIONS To estimate the economic potential of LFG to energy at a site, the long-term gas production rate must be determined. Gas production rates can be modeled based upon knowledge of the disposal practices, waste composition and amounts, however, these estimates can be rather crude. Direct measures of the gas composition and generation rate can provide better guidance for the design of an LFG utilization plant. There are four general methods for direct measurements: lysimetry, well testing, flux testing, and anaerobic sampling. Each technique has advantages and disadvantages, but the most common method by far is well testing. 4.1 Lysimetry In 1998, EPA initiated the ACAP to evaluate alternative cover designs based upon a dispersed network of lysimeters across the United States. Wilson et al (1999) identified 19 sites in the U.S. where lysimeters are being used to directly measure the performance of a variety of landfill cover designs, and ACAP will add to these facilities. While lysimeters are a common tool for water balance measurement, it is less common for gas generation measurement. A lysimeter is an enclosure that contains a replica of the landfill from which water balance (runoff, drainage, storage, evapotranspiration) and gas venting can be directly measured. Cover test lysimeters range in size from 0.09 to 1,950 m3 volumes (Wilson et al, 1999), while lysimeters used to test gas generation contain 1,000 to 10,000 Mg of refuse (Ham, 1996). Lysimeters can be as simple as the epoxy-coated steel drums (0.21 m3) used by Barlaz et al (1987) to the geosynthetic-lined pan lysimeters, shown in Figure 4-1, used by ACAP. The side walls and bottom are sealed except for a water collection system at the bottom. Care must be taken to prevent a capillary break at the bottom for accurate drainage measurement. Gas generation is measured by covering the surface and directing the gases through a gas measuring device.

16 Manhole

Cover Matenals: Variable Depth Tipping buckets for runoff and drainage Geosynthetic Root Barrier

French drain, sump pump U Geocomposite Drainage Layer Figure 4-1. Schematic of the lysimeter facility used in ACAP (from Wilson et al, 1999). Lysimeters can provide the most accurate measure of gas generation rate because 100% of the gas is collected from a known source (volume and composition). Even if gas leaks are eliminated, however, there are several complications that limit the validity of results. Covering of the surface creates an artificial upper boundary that can alter water and gas movement. If the surface is permanently covered, natural precipitation must be mimicked by water additions. Nonuniform water application or voids along the sidewalls can artificially create preferential flowpaths. Sidewall flow is a particular concern, as decomposition can result in waste shrinking away from the lysimeter walls. Additionally, surface coverage essentially negates evaporative losses and the lack of plant coverage eliminates transpiration losses. Alternative landfill cover designs are based upon the ability of the soil profile to store water until these evapotranspiration processes remove it via upward movement of water and vapor. Elimination of these processes significantly affects gas movement. This problem can be reduced by covering the surface for short periods of time to provide intermittent measurements of gas generation (Rolston, 1986). However, even during these limited time periods of gas measurement, there can be concern that the collection system causes back-pressures into the soil, thereby underestimating the gas generation rate (Ham, 1996). Additional concerns include: representativeness of the lysimeter to the landfill given the heterogeneity of the landfill waste compared to the relative homogeneity within the lysimeter; artificial thermal conditions due to differential heating and cooling of the lysimeter compared to the landfill; and aeration impacts of the lysimeter drainage collection system.

17 4.2 Flux Testing Flux testing is similar to lysimetry in that the rate of gas movement out of the surface cover is measured, however, flux testing is made on the existing landfill cover without control of the source volume. Often, measurement of the gas flow out of the cover by flex testing is supplemented with gas pressure and concentration measurements within the cover. Gas pressure and concentration gradients allow calculation of convective and diffusive transport rates, respectively. Gas flux collectors can be as simple as a bucket or plastic sheet placed over the surface. These devices range in size from 0.3 to 25 m2 and must be sealed to the soil to prevent leakage. This may include insertion of devices several centimeters into the soil or excavation of trenches to bury the edges of the plastic sheets. More elaborate flux chambers have been used for measuring gas emission rates from landfills, chemical spills, and agrichemical losses (Rolston, 1986; Reinhart et al, 1992; Balfour et al, 1987; Gholson et al, 1991; Eklund et al, 1984). Flux chambers can either be operated as a passive or active gas measurement approach. In the passive mode, the chamber functions much as the simpler devices that cover the surface to collect gas under natural pressure gradients. The passive mode is more commonly called the static chamber method, but Livingston and Hutchinson (1995) concluded that the term non-steady-state chambers is more accurate. In the active mode, air is introduced to the chamber under a controlled rate exceeding the gas emission rate. The clean, dry air introduced into the chamber transports the gas emitted from the surface to a collection device where the gas composition is measured to compute emission rates. Reinhart et al (1992) combined the flux chamber, shown in Figure 4-2, with a soil-gas sampling probe and soil temperature probe to provide improved estimates of gas emission. Their chamber covered a 1,264 cm2 area and included a Styrofoam exterior to minimize temperature fluctuations. They proposed that inclusion of the soil-gas sampling probe enabled direct analysis of NMOCs, which are often too low in municipal LFG to be detected given the air dilution with active-mode flux chambers. Eklund et al (1998) used the flux chamber to estimate gas emissions form the Fresh Kills Landfills in New York. This is the largest landfill in the United States, covering approximately 1,214 ha on Staten Island, which receives approximately 12,000 Mg of MSW per day, six days per week. Eklund et al (1998) referenced EPA (1996a) to conclude that the flux chamber method is an accepted standard EPA sampling method. The major advantages of flux testing, whether by flux chambers or simpler devices, are that it is nonintrusive, flexible, mobile, inexpensive and provides replicated sampling for statistical analysis. The major disadvantage is the small sample support size, which results in preferential gas flowpaths not being captured. The smaller the size, the less representative the gas rates due to heterogeneity of the waste deposition and surface cover conditions. The most common disadvantage mentioned in the literature is the distortion of concentration and pressure

18 Chamber Pressure Gauge

Exit ports Teflon Exit Lines

Styrofoam Continuous (1« thick) analysis port

SoU Temperature Probe Discrete analysis port

Pressure gauge Soil Air Temperature Temperature Probe Probe Sweep Air Port n—th Styrofoam

Stainless Steel

(b)

Figure 4-2. The flux chamber design reported by Reinhart et al. (1992). (a) top view of the flux chamber showing the locations of the five exit ports for gas measurement, (b) side view of the flux chamber showing the internal instrumentation.

19 gradients caused by having the closed chamber on the surface (Healy et al, 1996; Rolston, 1986; Ham, 1996). This alters the surface-atmosphere gas exchange, which generally results in an underestimation of the gas flux. Back pressures, particularly with the active flux chamber method, can result in gas flow bypassing the collection device to be emitted from the surrounding area. The smaller the sample size (area covered), the more likely that a pressure differential will exist between the sample area and the adjacent area. To alleviate this problem, the chamber headspace should be minimized and the chamber intermittently placed on the surface for short periods of time. The length of time on the surface depends upon the detection sensitivity of the particular gas (Rolston, 1986). Ham (1996) concluded that it is these concerns that result in this method rarely being used for estimating LFG emission from full-sized landfills. However, this technique is very useful for determining gas emission rates from preferential flowpaths, such as gas vents (piping) and cracks hi the cover caused by differential subsidence or desiccation of clays.

4.3 Well Testing The most common technique for determining gas production rate is well testing. However, there are many different well designs and sampling schemes that have been used. The most common approach is to use a series of vertical wells, although horizontal wells and trenches have been used. Martin and Fujii (1985) found that vertical wells were less effective than horizontal trenches at the Rossman Landfill in Oregon City, Oregon, due to a high water table restricting gas movement to the wells. They originally installed 68 vertical wells in two phases. Subsequently, two test trenches 45 m long were installed 45 m apart to 3 m and 2 m deep. Since tests showed that horizontal trenches collected two to three times more gas while using lower vacuum (i.e., lower power required), trenches were used instead of vertical wells in Phase 3. Martin and Fujii (1985) state that a system of horizontal trenches is operating successfully at the Puente Hills Landfill in Los Angeles, California. At the time, this was considered the second largest landfill in the U.S. (Reason, 1987). It generates over 17,500 scfm (500 m3) of 420 Btu/ft3 (15,700 kJ/m3) for a 50 MW powerplant. Vertical wells are the preferable option after the landfill has been closed so that the impact on the cover is minimized. Wells typically consist of 30- to 90-cm-diameter boreholes excavated into the landfill. A 10- to 30-cm-diameter pipe, typically PVC, is placed in the borehole. A portion of the pipe is perforated with the annular space around this slotted interval filled with coarse sand or gravel. The annular space above the gravel is grouted, usually with a bentonite mixture, to seal it from the surface. The well casing is connected to a pump that is capable of pulling at least 15 cm gauge vacuum and pumping 1.7 x 10"3 m3/s (100 L/min) per meter of well depth (Ham, 1996). The depth of the borehole depends upon site conditions. If the site has a relatively permeable surface cover, the perforated portion of the borehole may have to be extended deeper to prevent "daylighting." Daylighting is the condition in which atmospheric air enters the system usually due to applying too great of a vacuum. If the site has a clay or geosynthetic impermeable cover, the perforated interval of the borehole may be closer to the surface without daylighting. The increase in overburden stress with landfill depth results in increased compaction of the

20 waste. This is considered to reduce air-permeability, microbial decomposition, and gas movement. Therefore, some feel that extraction wells should be installed relatively close to the surface to where gas naturally rises. Others feel that the more expensive, deeper wells are necessary to extract a higher quality gas (Lofy, 1996). The general method of well testing, called a pump test, is to apply a vacuum to the well and determine the gas production rate while estimating the volume of landfill from which it was withdrawn. The gas production rate and composition is a fairly direct measurement, however, the contributing volume of the landfill, often called the radius or sphere of influence, is highly subjective. The exact approach to determine the production rate and radius of influence is variable. The following are sampling schemes identified in the literature. 4.3.1 Single Well with Gas Probes A common approach that appears to be decreasing in popularity is to install a series of gas probes in smaller-diameter, 10- to 15-cm, boreholes at various distances from a large- diameter (around 60 cm) extraction well. Boreholes are installed in a series of concentric circles, usually three boreholes per circle, at increasing distance from the gas withdrawal well (Figure 4- 3). Ham (1996) stated that probes are seldom extended out beyond 75 m. However, a consultant from Cambrian Energy Development suggested that for the arid conditions at Sunrise Landfill, a radius of influence up to 125 m could be expected (Tudor Williams, personal communication). An alternative is to install probes hi only one direction, thereby creating a transect of boreholes with probes. The advantage is this approach enables a greater distance from the withdrawal well to be tested while requiring fewer boreholes. This is considered important in arid and semi-arid landfills in which gas withdrawal occurs over longer distances. However, the transect approach assumes the portion of the landfill tested is isotropic, i.e., withdrawal is not dependent upon direction. Given the heterogeneity of waste disposal operations and the soil cover, this is usually a poor assumption. According to Ham (1996), it is common for these boreholes to be extended slightly below the middle depth of the perforated Interval of the withdrawal well and the shallowest depth is typically about 4 m. Boreholes are completed similar to the withdrawal well but with the perforated interval being shorter and the inner pipe above the probe being closed to the surface. Constable et al. (1979) proposed using multi-level probes within each borehole, similar to that shown in Figure 4-4a, to measure gas pressures from discrete layers of waste corresponding to the waste disposal lifts. They sealed the annular space between each perforated interval with concrete plugs and compacted backfill. Instead of sealing gas probes into each sampling interval, they routed tubing from each interval of all boreholes to a central location storage unit for gas pressure measurement.

21 Figure 4-3. Single gas withdrawal well in center of three concentric circles of boreholes with probes, noted by solid circles.

Landfill cover

Concrete or clay seal

Backfill

Sand or gravel screen

Refuse

Gas Probes

Figure 4-4. Two types of multi-level borehole testing. The borehole on the left (a) consists of perforated intervals screened with sand or gravel with the tubing routed to a central storage unit for gas pressure measurement (from Constable et al, 1979). The borehole on the right (b) consists of a gas probe in each screened interval with the wiring routed to a central gas pressure measurement board (Lofy, 1996).

22 Before conducting the pump test, ambient gas pressures should be determined with the withdrawal well capped (no extraction) until pressures stabilize. The withdrawal well is then pumped at a low rate, around 2.5 x 10"5 m3/s (1.5 L/min) per meter of well depth and the gas pressures, flow and composition recorded. The gas probes are monitored with tune until gas pressures stabilize. The process is subsequently repeated at a higher withdrawal rate. Either oxygen or nitrogen content of the gas is recorded to determine if air is being pulled in, either through leaks in the piping or through the surface cover. Nitrogen is the better indicator, as oxygen is consumed in the decomposition of waste. The nitrogen content should be around oneto 10% depending on the intended LFG use. Nitrogen contents above 10% indicate over-pumping, which can be detrimental to the methane generation process, which requires anaerobic conditions. The gas production rate is therefore the amount of gas that can be pulled from a well at the maximum vacuum without over-pumping, i.e., daylighting. The radius of influence is determined by the distance from the withdrawal well in which borehole gas probes remain static, i.e., no pressure response. Until recently, this was defined as the zero isopleth or zero vacuum contour line, which separates the positive pressure zone from the negative pressure zone. It was assumed that LFG would always maintain a slight positive pressure within the landfill such that a negative pressure close to the pumped well was an indication of gas withdrawal. Lofy (1996) stated that this is now recognized as being an erroneous assumption. Therefore, a deviation from static conditions is more often used as the indicator. Static conditions should generally hold for all boreholes at that radius at the maximum pumping rate. This radius of influence is used to calculate the contributing landfill volume assuming a cylinder to the average depth of waste. The gas generation rate can then be expressed on a per landfill area, per volume, or per unit weight of waste if the refuse density is known. The radius of influence is then used to determine the spacing between gas recovery wells, thus the total number of wells needed. To test the validity of this method, a landfill test facility was developed at the Puente Hills Landfill in California (Lofy, 1983, 1996). The facility consisted of three wells with multiple extraction intervals and 37 boreholes with multi-level probes (Figure 4-4b) to comprise a three-dimensional monitoring grid. Lofy found that zones of slight negative pressure existed within the landfill under ambient, no withdrawal, conditions and that these zones were dynamic with regards to location, size and pressure. Lofy also found that after termination of gas extraction, high positive pressures were created around the withdrawal well. This brought the definition of radius of influence into serious question. One problem with this method is in the time at which equilibrium conditions are assumed to exist. Theoretically, at a given pumping rate, the radius of influence will continue to progress outward from the well until the entire landfill is impacted. The ability to detect this gradual change depends upon the sensitivity of the probes and the time scale of measurement. Operators typically test for a few days to assure themselves that the radius of influence is stabilized, i.e., no measurable deviation from static conditions. However, Lofy (1982) showed that the radius of influence is not consistent in shape or size from hour to hour or day to day, in part due to barometric pressure changes. The degree of impact of barometric pressure changes depends upon

23 the probe depth and the air permeability of the cover. If the cover is permeable such that barometric pressure directly impacts the probe pressures, the reading can be normalized to gauge pressure by subtracting the atmospheric pressure. However, there may be a lag between the barometric pressure change and the probe response or only a partial response by the probe, which can complicate the analysis. More significantly, the findings of Lofy show that the measurement of negative pressure in a probe is not proof of daylighting or the radius of influence. The bigger problem with this method is the distance at which equilibrium is defined (radius of influence) due to heterogeneity of the landfill. Large differences typically exist between waste disposal composition, compaction, daily cover, etc., across the landfill area that cause large spatial heterogeneity. Ham (1996) stated that it is common to observe a radius of influence of 60 to 70 m in one direction and only 20 to 30 m in another. 4.3.2 Well Clusters In addition to the impacts of heterogeneity on defining the radius of Influence, the single well test represents a small area (point sink) and thus must be conducted at multiple locations across the landfill. To avoid the problems of spatial heterogeneity and basing the radius of influence on gas pressures surrounding the extraction well, the industry has changed methods to the use of a cluster of extraction wells that are interconnected. In discussions with LFG consulting companies, it was learned that the technique of a single well surrounded by gas probes is no longer popular (Steve Cromeens of Cromeco, personal communication, and Pete Soriano of The Regenesis Group, personal communication). Rather than drilling numerous small boreholes for gas probes, an expensive process that at best provides a subjective estimate of the contributing portion of the landfill, companies are installing well clusters. Well clusters cover a larger area of the landfill and therefore provide a more representative estimate of gas production. The most common well cluster design used today is five large-diameter (30 to 60 cm) wells in a dice pattern (Figure 4-5). The well heads are tied together to a common manifold. The pump tests are run as described for the single withdrawal well but with flow rate and gas composition recorded on the integrated sample from the manifold. This provides a better measure of the gas production rate since it is determined over a larger portion of the landfill, which integrates some of the heterogeneity of the landfill. Due to the ambiguity of the radius of influence, less attention is paid to the contributing volume of the landfill. The Regenesis Group has had success using small-diameter (10 to 15 cm diameter) boreholes as wells in contrast to the more expensive, large (30 to 60 cm diameter) wells. For gas production rate testing at Sunrise Landfill, The Regenesis Group proposed using five 10-cm- diameter boreholes to 24.4 m depth that are completed with schedule 80 PVC and connected to a common manifold. The specifications for drilling and completing of wells for these tests are proprietary and cannot be disclosed hi this report. An alternative is to use the traditional large- diameter well as the central extraction well (Figure 4-5) with four small-diameter wells at the corners.

24 Individual wells

Mam extraction well

Individual wells

Figure 4-5. Five-well dice pattern for gas rate production testing. All wells are typically the same diameter, or the method of The Regenesis Group can be used as shown here in which the four outer-wells are small-diameter boreholes and only the center well is the traditional large-diameter well. 4.3.3 Borehole Site Characterization An alternative to deep well pump testing is a site characterization approach in which numerous small-diameter boreholes are drilled and sampled passively, i.e., without casing the borehole or applying a vacuum to the borehole. Boreholes may be drilled (augured) or cored with hydraulic probes such as the Giddings Rig and Geoprobe, or a steel probe can be hydraulically driven by a drive point sampler like the Cone Penetrometer. An example is the reconnaissance study conducted by CCJM (1998) at Sunrise Landfill. A Geoprobe was used to drive a steel pipe with a retractable point to the desired depth (0.6 to 2.3 m below grade). This was done at numerous locations on a "randomly placed off-set grid of 137.2 m." The drill string (pipe) was retracted about 7.5 cm to open the vapor port. Polyethylene tubing was inserted into the drive pipe and connected to the vapor port. The tubing and port were purged of atmospheric air by

25 removal of three pore volumes of air with a syringe. The tubing was then connected to a meter for direct detection of gases (O2, COi, HaS, CJIj). Subsequently, a gas sample was extracted for NMOC analysis. If a void existed between the borehole and drill string, bentonite grout was inserted into the annular space. This technique can also be used to estimate gas production rate by measuring the gas pressures and volume of gas produced passively. To characterize the LFG production rate at Sunrise, CCJM proposed to DRI to install 50 to 100 boreholes to 3 m deep across the landfill. Additionally, they proposed installing ten deep (30.5 m) boreholes with gas pressure and flux measurement made during drilling at 6.1-m intervals. The major advantage of this approach is that shallow drive point sampling is considerably less expensive than deep drilling and completion of wells. This technique is also easily applied to the entire landfill to remove some of the ambiguity in the radius of influence caused by landfill heterogeneity. However, the gas production estimates are questionable due to the shallow nature of the boreholes and the passive sampling. The majority of LFG will be generated much deeper than the depth sampled. These gases will be transported to the surface following paths of least resistance and may bypass the point measurements of the shallow boreholes. One must therefore weigh the advantage of broad areal coverage against the disadvantage of small representative volume being sampled. 4.4 Anaerobic Sampling This method is similar to lysimetry in that the landfill is simulated in an enclosed system, however, the scale is smaller and the waste generating the gas is a direct sample from the landfill. A sample of refuse is removed from the landfill and quickly placed in incubation containers to minimize aeration of the sample. A container is constructed to simulate the landfill conditions and is fitted with gas measuring devices. The waste placed in the container will continue to decompose and the gas generated can then be related directly to the weight or volume of refuse. It is important to control the container temperature to mimic landfill conditions. A water bath or temperature control room is often used. Barlaz et al (1987) used refuse from the Madison Energy Recovery Plant in drum lysimeters to test the impacts of a variety of parameters on gas generation. Samples are often taken at the time of installing boreholes. The major limitation with this technique is the small sample support size limits its representation of the landfill, thereby requiring numerous samples to be processed. The mixing of the refuse by auguring during the sampling can also increase the gas generation initially. The advantage is the cost-effective ability to obtain estimates of gas generation potential from discrete locations or layers within the landfill. This information can assist in the well field design. This is particularly true if good records of waste deposition, particularly sewage sludge, are not available. Our discussions with landfill operators (RSSD, Gaddy, personal communication) corroborated the sentiments of Ham (1996) in that for sites that are likely to be used for LFG production, operators prefer to skip the testing phase and install a well field directly. One advantage of the well cluster design for testing is that it can be used for gas production extraction directly following the testing. This enables a "learn as you go" approach to developing the well

26 field, which can maximize extraction efficiency and minimize costs. EPA (1997a) reported that collection efficiencies are typically between 60 and 85% with an average of 75%. 5.0 METHANE EMISSIONS FROM SUNRISE LANDFILL 5.1 Methane Emission Estimates

The EPA recommended model for methane emissions is a first-order (exponential) decay. The methane emissions Q for a given period of time (e.g., a year) is given by: Q = kRLoe* (1) where:

Q = methane emission rate (methane volume/time)

R = refuse deposited (mass)

T = time since refuse deposited (time)

k = rate of methane generation (time"1)

LQ = waste method generation potential (methane volume/refuse mass).

Typically, the time used is years, mass is metric tons = megagrams (Mg), volume is cubic meters. Equation (1) gives the methane emissions from refuse deposited at a specific time. Emissions from all times of deposit, which have experienced different levels of decay, based on time since deposit, must be summed to get the total emissions per unit time. As a reasonable approximation, these are typically done on a yearly basis. The EPA default methodology assumes that the total refuse deposited is spread out evenly over the period of refuse disposal. This was deemed to be unrealistic due to the rapid growth in population in the area served by the Sunrise Landfill. Refuse deposit for each year would be the best measure to use, but this information is not available. We have made yearly refuse deposit estimates by assuming that the rate of refuse disposal is proportional to Clark County population. The Sunrise Mountain Landfill Closure Plan (Martinez and Yeckes, 1994) gave estimated waste masses of 3,080 Mg/day for the period October 10, 1991 to October 9, 1993. Data obtained from the Nevada State demographer gave an average population of Clark County during this period of about 868,000. The yearly deposits of refuse were scaled by the ratio of each year's population to the population for this period and multiplied by 3,080 Mg/day for the entire period Sunrise Landfill was open. The yearly population and refuse deposit estimates are shown in Figure 5-1.

27 1,400,000 o Clark Co. Population (people)

1,200,000 Estimated Waste Acceptance (Mg/yr)

1,000,000

800,000

1950 1960 1970 1980 1990 2000

Figure 5-1. Clark County population and Sunrise Landfill Waste Acceptance (Mg/yr).

The total methane production is governed by the waste generation potential LQ. Total emissions and annual emissions scale linearly with LO. LO is a function of the type of materials deposited in the landfills and is most closely associated with the amount of organic material 3 (mainly cellulose) (EPA, 1997a). A range of L0 of 6.2 to 270 m /Mg has been noted. The methane generation constant k is dependent upon moisture, pH, temperature, and other factors, including landfill operating conditions, and can range from 0.003 to 0.21 yr"1. Based upon a best fit to empirical data from 21 landfills, EPA recommends a default value of 100 m3 CFLj/Mg waste for LO and 0.04 yr"1 for k, except 0.02 yr"1 for k if annual average precipitation is less than 63.5 cm. For regulatory purposes, default values for LO and k are 170 m3/Mg and 0.05 yr.-'i Predicted methane generation rates using EPA (AP-42) default values versus empirically estimated methane rates for 39 landfills are shown in Figure 5-2. The model-predicted rates varied from a factor of four higher to a factor of 3.3 lower than empirically estimated rates. This implies considerable uncertainty hi the methane production rates.

28 60

50

40

30 -& o o o ^ 20 1 o 'S £ 10

10 20 30 40 50 60

Empirical CH4 (MrrfVyr)

Figure 5-2. Empirically derived versus predicted methane production rates Mm3/yr (EPA, 1997a). For the methane production estimates and economic analyses (Section 7), the assumed default AP-42 values were LO = 100 m3/Mg and k = 0.02 yr"1. Also tested was the sensitivity of the methane production and economic analyses by varying these values as well. The effect of varying the methane generation rate constant k over the range of empirically derived values for an assumed methane generation potential LO of 100 m3/Mg is shown in Figure 5-3. All cases reach their maximum methane generation the year of closure; because the same LO is used, they also produce the same total amount of methane. However, the year-to-year distribution of methane generation varies widely among the cases. For the case with the highest k, production increases sharply during the active period of refuse deposit and decays even more abruptly after 1993 when deposits ceased. In this case, which is very unlikely, especially because of the arid character of the Sunrise Landfill location, little methane would be available for energy use after 2000. In the middle case, which uses the AP-42 default values for arid areas, generation rates decline more slowly, decreasing to half of the peak levels in 2028. In the extreme low rate of decay case, relatively low levels of CHj are produced each year and levels are still within 15% of peak levels in 2050. The effect of varying LO over the range of derived values while holding k at 0.02 yr"1 is shown in Figure 5-4. Again, the middle curve is the default case. These curves are straightforward, as they have the same shape. Varying LO only changes the total methane production. The economic analysis in Section 7 used three combinations of LO and k based upon annual methane emission rates presented in Table 5-1 and Figure 5-5.

29 k=0.02LO=100 k=0.003 L0=100

0 k=0.23 L0=100

1970 1980 1990 2000 2010 2020 2030 2040 2050 Year

Figure 5-3. Effect upon Sunrise Landfill methane emissions of varying methane generation rate constant k (yr"1). The methane generation potential has units of (m3/Mg).

,k=0.02LO=100 o k=0.02 L0=270 k=0.02 L0=6.2 .2 CO .2

c ra i

10 .x£>^ >pxMaxi&pn^^ 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 Year

Figure 5-4. Effect upon Sunrise Landfill methane emissions of varying methane generation potential LO (m3/Mg). The rate constant k has units of yr"1.

30 Table 5-1. Annual estimated methane emissions (million cubic meters) from Sunrise Landfill for three cases. Best estimate (AP-42 default) in bold. Values of LO and k have units of m3/Mg and yr" ', respectively. Year Case 1: Case 2: Case 3: Year Case 1: Case 2: Case 3: L0=150; L0=100; L0=50; L0=150; L0=100; L0=50; k=0.03 k=0.02 k=0.01 k=0.03 k=0.02 k=0.01 1964 1.0 0.4 0.1 2008 38.1 21.7 7.0 1965 2.0 0.9 0.2 2009 37.0 21.2 6.9 1966 3.1 1.4 0.4 2010 35.9 20.8 6.8 1967 4.2 1.9 0.5 2011 34.9 20.4 6.8 1968 5.3 2.4 0.6 2012 33.8 20.0 6.7 1969 6.5 3.0 0.8 2013 32.8 19.6 6.6 1970 7.8 3.6 0.9 2014 31.9 19.2 6.6 1971 9.2 4.2 1.1 2015 30.9 18.8 6.5 1972 10.6 4.9 1.3 2016 30.0 18.4 6.4 1973 12.0 5.6 1.5 2017 29.1 18.1 6.4 1974 13.5 6.3 1.7 2018 28.2 17.7 6.3 1975 15.0 7.0 1.9 2019 27.4 17.4 6.2 1976 16.5 7.8 2.1 2020 26.6 17.0 6.2 1977 18.1 8.6 2.3 2021 25.8 16.7 6.1 1978 19.8 9.4 2.5 2022 25.1 16.4 6.0 1979 21.6 10.3 2.8 2023 24.3 16.0 6.0 1980 23.4 11.2 3.0 2024 23.6 15.7 5.9 1981 25.4 12.1 3.3 2025 22.9 15.4 5.9 1982 27.4 13.2 3.6 2026 22.2 15.1 5.8 1983 29.5 14.2 3.9 2027 21.6 14.8 5.8 1984 31.6 15.2 4.2 2028 20.9 14.5 5.7 1985 33.7 16.3 4.5 2029 20.3 14.2 5.6 1986 35.9 17.4 4.8 2030 19.7 13.9 5.6 1987 38.2 18.6 5.1 2031 19.1 13.7 5.5 1988 40.6 19.8 5.5 2032 18.6 13.4 5.5 1989 43.1 21.1 5.8 2033 18.0 13.1 5.4 1990 45.9 22.5 6.2 2034 17.5 12.9 5.4 1991 48.9 24.0 6.7 2035 17.0 12.6 5.3 1992 52.1 25.6 7.1 2036 16.5 12.4 5.3 1993 55.4 27.3 7.6 2037 16.0 12.1 5.2 1994 58.0 28.6 8.0 2038 15.5 11.9 5.2 1995 56.3 28.1 7.9 2039 15.0 11.6 5.1 1996 54.7 27.5 7.8 2040 14.6 11.4 5.1 1997 53.0 27.0 7.8 2041 14.2 11.2 5.0 1998 51.5 26.4 7.7 2042 13.8 11.0 5.0 1999 50.0 25.9 7.6 2043 13.3 10.8 4.9 2000 48.5 25.4 7.5 2044 12.9 10.5 4.9 2001 47.0 24.9 7.5 2045 12.6 10.3 4.8 2002 45.7 24.4 7.4 2046 12.2 10.1 4.8 2003 44.3 23.9 7.3 2047 11.8 9.9 4.7 2004 43.0 23.5 7.2 2048 11.5 9.7 4.7 2005 41.7 23.0 7.2 2049 11.1 9.5 4.6 2006 40.5 22.5 7.1 2050 10.8 9.3 4.6 2007 39.3 22.1 7.0

31 0k=0.03LO=150 k=0.02LO=100

A k=0.01 L0=50

1960 1980 2000 2020 2040 2060 Year

Figure 5-5. Estimated methane emissions rates from Sunrise Landfill for three cases used in economic 3 1 analysis. L0 has units of m /Mg and k has units of yr" . 5.2 Emissions of Non-Methane Organic Compounds (NMOC) Gases

As discussed in Section 1, control of landfill emissions by flaring or energy recovery is required while NMOC emissions are greater than 50 Mg/yr. This requirement is significant to the cost analysis of options for energy recovery. If the NMOC emissions are greater than 50 mg/yr, gas collection is required; this cost must be expended regardless of whether the gas is used for energy or flared. If gas collection were not required, the incremental costs of collecting the gas would be added to the total cost for energy utilization of the gas. For determining annual emission rates of NMOC for regulatory purposes, EPA methods as described hi the Standards of Performance for New Stationary Sources and Guidelines for Control of Existing Sources: Municipal Solid Waste Landfills (EPA, 1996a) must be used. EPA lists three methods by which the emissions may be estimated for comparison to the 50 Mg/yr level. The first method calculates emissions using the methane generation assuming LO = 170 m3/Mg, k = 0.05 yr"1, and NMOC = 4,000 ppmv as hexane. These values are all conservatively high and would likely greatly overestimate NMOC emissions from Sunrise Landfill. The second method allows for site-specific NMOC concentration data to be used, and specifies the procedures to be used hi collecting the data. In the second method, default values of LO = 170 and k = 0.05 yr"1 are used. In the third method, site-specific data for both k and NMOC

32 concentration are used to estimate emissions, although the default LO of 170 m3/Mg is still used. Any other method to be used must be approved by EPA. Once gas collection has begun, it must be continued until NMOC emissions fall below 50 Mg/yr, or 15 years, whichever is longer. EPA specifies procedures for demonstrating emission rates after collection has begun. It utilizes flow rate data from the collection system and analysis of the gas for NMOC concentration. The flow rate multiplied by the concentration then gives the annual emission rate. NMOC emissions were estimated for 1999 using the regulatory default values, the AP-42 default values and other cases considered possible based upon empirical data from other landfills. The cases considered and their estimated NMOC emissions for 1999 are shown hi Table 5-2.

Table 5-2. Estimates of 1999 NMOC emissions from Sunrise Landfill for five cases. Case 1 2 3 4 5

L0 (m'/Mg) 170 170 170 170 170 k(yr'1) 0.05 0.02 0.02 0.003 0.003 NMOC ppmv 4000 2420 240 2420 240 NMOC Mg/yr 2156 816 81 162 16

For all cases, the required LO of 170 m3/Mg was used. Case 1 used the regulatory required values for k and NMOC concentration, while Case 2 used AP-42 default values (the most likely values). Case 3 used the AP-42 arid region default value for k, and used the lowest empirically derived value for any landfill for NMOC. Case 4 used the AP-42 default for NMOC, and the lowest empirically derived value for k. Case 5 used the extreme low empirical values for both NMOC and k, an unlikely occurrence for any landfill. Without having site-specific data, the most likely value would be that for Case 2. Cases 3 and 4 represent plausible lower limits to the annual NMOC emissions. For all cases except Case 5, a very unlikely occurrence, NMOC emission estimates are greater than the 50 Mg/m3 level, above which a gas collection system must be installed. From these calculations, it can be assumed that a collection system must be installed at Sunrise Landfill. After 15 years of gas collection, if estimated emissions of NMOC based upon measured gas collection rates and NMOC concentrations are less than 50 Mg/m3, collection may be discontinued. The estimated NMOC emission rates for the five cases listed above are shown in Figure 5-6 and Figure 5-7. Except for Cases 2 to 5, the required LO of 170 m3/Mg was replaced by the AP-42 LO of 100 m3/Mg. It can be seen that for all but the cases with very low NMOC concentrations (10% of AP-42 default), emissions of NMOCs are expected to be greater than 50 Mg/yr until after 2050. Although it is not possible to accurately predict NMOC emissions hi the future due to lack of data, it is probable that landfill gas collection will be required significantly longer than the 15-year minimum.

33 3000 ^ 4000 ppm k=0.05 * 2420 ppm k=0.02 2500 -*—»- 240 ppm k=0.02 * A t, B 2420 ppm k=0.003 •& 2000 \ o 240 ppm k=0.003 CO •§ 1500 .52

(0 g 1000 2 z 500

0 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 Year

Figure 5-6. NMOC emissions from Sunrise Landfill for ranges of NMOC concentration and methane generation rate constant k (yr"1). The top curve assumes regulatory default values, the second curve uses AP-42 default values (best guess). The lower curves represent lower limits of empirically derived NMOC concentrations and k.

550 500 ^ 450 •& 400 | 350 .v>1 300 • 4000 ppm k=0.05 250 « 2420 ppm k=0.02 V A 240 ppm k=0.02 0) 200 O B 2420 ppm k=0.00o O 150 o 240 ppm k=0.003 100 50 0 1960 1970 1980 1990 2000 2010 2020 2030 2040 Year

Figure 5-7. Same as Table, except y-axis scale is reduced to show more detail at lower emission levels, k has units of yr"1.

34 6.0 METHANE USE OPTIONS Gipe (1988) stated that about 70% of the LFG projects use the gas on site, 19% transport it to nearby boilers, and 11% produce pipeline quality gas. Regardless of the LFG-to-energy option chosen, capabilities to control the LFG emissions by flaring are necessary. Nearly two thirds of the LFG-to-energy projects use reciprocating engines (Power, 1997) due to simpler gas compression requirements. A common approach for LFG-to-energy is to blend the medium to low Btu LFG with pipeline-quality natural gas for such uses as steam generation. A creative approach is to separate the methane and carbon dioxide to produce a high Btu methane and an industrial COa source, while a promising new technology for LFG gas use is fuel cells. 6.1 Case Studies The Rossman Landfill in Oregon City, Oregon, is a good example of a common small landfill that doesn't produce enough LFG for economic use as an energy source but still needs to control the gas emissions. It is a 40.5-hectare landfill that disposed of around three million Mg of waste from 1970 to 1983 (Martin and Fujii, 1985). The area is characterized by warm, dry summers and cool winters with around 102 cm of precipitation annually. The yearly temperature averages 11°C. The LFG is collected by a series of vertical wells and horizontal trenches. The LFG is flared with dual centrifugal blowers and dual burners with separate combustion air blowers. Reason (1987) stated that at the time of its creation, the Puente Hills Energy Recovery from Gas (PERG) powerplant was the largest electrical-power producing plant from LFG in the world. He credited the Puente Hills Landfill in Los Angeles County, California, with being the second largest landfill hi the U.S., receiving over 12,000 Mg of waste per day. The large volume of LFG enabled it to be used for a gas-fired steam generation plant, PERG included two steam generators, one gas turbine generator, and a series of condensers, condensate pumps, vacuum pumps, heaters and deaerators. In Montreal, Canada, the Gazmont powerplant in 1997 alone produced 202 GWh of electrical power to the grid. The landfill currently generates an astronomical 28,320 m3/h of LFG that contains an average 36% methane. Such electrical power-producing landfills can be as small as the 5 MW plant in Brea, California, which draws LFG through five kilometers of collection pipes from a mere 30 wells that go 38 m into the landfill (Design News, 1985). LFG steam powerplants can also be designed for sensitive residential neighborhoods such as the Palos Verdes Landfill in Rolling Hills Estates, California (Wallace, 1991). It is jointly owned by the Los Angeles County Sanitation District and Los Angeles County. Part of the landfill was developed as the South Coast Botanical Gardens and another portion was developed as a golf course. Nestled in this environmentally sensitive residential area is the high efficiency LFG-to-electrical energy powerplant. The largest landfill hi the U.S. is the Fresh Kills Landfill on Staten Island, New York. It covers 426.5 ha and is 46 m deep. The area receives more than 100 cm/yr of precipitation with significant amounts of snow. It is divided into four sections in which section 1/9 has an active gas collection system. Section 1/9 has 250 extraction wells manifolded together that collect

35 around 5.8 m3/s (504,000 m3/d) of LFG. The total NMOC was reported by Eklund et al (1998) to be around 438 ppm hexane, which is considerably lower than the regulatory value of 4,000 ppm. The LFG is routed to an adjacent processing plant that removes condensate, CO2, and VOCs to produce pipeline quality natural gas. The landfill-generated natural gas is sold to a utility company. Power Magazine (1997) stated that the challenge with systems that blend LFG with natural gas or fuel-oil is finding a user in close proximity. Giovando and Jones (1998) reported on two such systems operating in the U.S. and Canada. The White Street Landfill in Greensboro, North Carolina, transports LFG through five kilometers of pipes to the Cone Mills White Oak steam generation plant. A blower at the landfill transports the LFG at rates above two million scfd through the piping system that includes a series of condensate traps. The burners are designed specifically to fire combinations of LFG and natural gas. Special considerations were made in the design to allow passage of LFG particulate to prevent clogging of burners. The Clover Bar Landfill hi Edmonton, Canada, is a 660 MW plant that blends oil with LFG. Trace impurities in the LFG are removed and the LFG is filtered, compressed, scrubbed, and dehydrated to meet rigorous quality standards. The plant produced 208,000 MW hours of electricity in a five-year period while reducing greenhouse gas emissions by over 182,000 Mg. An interesting note is that the city of Edmonton receives a 5% royalty on all LFG sold. A similar arrangement exists for the city of Montreal, which receives a 10% royalty from the Gazemont powerplant. While the LFG gas is not blended with natural gas or oil by Iowa Electric, Ransom and Parker (1988) reported the Prairie Creek powerplant burns LFG with coal in their boilers to produce electricity. The LFG replaced only about 2% of the coal but was sufficient to produce the equivalent of 2.6 MW of electricity. This was a large improvement over the fires they experienced in 1982 from gases emitted from the landfill. 6.2 Sunrise Landfill Methane Use Options The methane generated from the Sunrise Landfill is an environmental liability because the methane emitted is a greenhouse gas with 21 times the global warming efficiency of carbon dioxide and a fraction of the NMOC emissions are hazardous air pollutants in addition to ozone precursors. Controlling the emissions from the landfill will decrease this environmental liability. Through landfill gas-to-energy conversion, a well-designed control system could also be an economic asset since energy produced from the methane can be sold. Proven options for landfill gas-to-energy conversion include (SCS Engineers, 1995): • Local gas use. This option involves minimal treatment of the landfill gas to remove condensate that may harm the blowers and transport lines used to deliver the gas to a nearby user. The medium Btu gas is typically used to power boilers, but can also be used for kiln operations, drying operations, and cement and asphalt production.

• Electrical generation. Electrical power may be generated from landfill gas using internal combustion engines, gas turbines, steam turbines, and fuel cells. More extensive gas treatment is required for these projects since impurities in the landfill

36 gas can damage mechanical equipment. Energy produced can be sold back to the local power company or sold directly to an end user at a higher price.

• Upgrade to high Btu gas. Treated gas can be injected into nearby pipelines and sold to the local gas company at market prices. This option requires the most extensive treatment of the gas since moisture, corrosive impurities, and carbon dioxide must be removed from the landfill gas.

6.2.1 Power Generation Potential

The first step in developing a landfill gas-to-energy project is to estimate the power potential of the landfill gas emissions. The power potential calculation can be used to determine the scale of the project needed to utilize the landfill gas. Based on the emissions modeling estimates in Section 5, Sunrise Landfill will produce ~7,080 m3/hr (62 x 106 m3/yr) of landfill gas in 2000. The gas produced by the landfill is a medium Btu gas with an energy potential of 18,700 to 26,100 kJ/m3 (500 to 700 Btu/cf). On average, landfill gas collection systems are 75% to 85% efficient with the remaining portion lost to the atmosphere. Assuming 18,700 kJ/m3 (500 Btu/cf) landfill gas and 80% collection efficiency, the heat emission of the landfill is 30 MW (-900,000 million Btu/yr). Internal combustion engines and combustion turbines utilize landfill gas with an efficiency between 8,500 and 12,500 Btu/kWh (EPA, 1996b). Assuming the power generators are in operations 90% of the time due to routine service and maintenance and they operate with an efficiency of 10,000 Btu/kWh, the gross power generation potential of the landfill is ~9 MW.

6.2.2 Nearby Energy Consumers

The proximity of potential users of the landfill gas plays a role in the financial success of the project since gas and power distribution costs can be significant. An aerial view of the landfill and potential users of the gas are shown in Figure 6-1. The Sunrise and Clark natural gas power stations are potential customers for the landfill gas. The Las Vegas and Clark County sewage treatment plants (STPs) are also nearby. These facilities consume significant amounts of power to process the local sewage. Each of the four facilities on the map is described in detail below.

6.2.2.1 Sunrise Station

The Sunrise Station is located approximately 2.5 km west of the Sunrise Landfill. The power station burns natural gas to produce electrical power using a combination of both boilers and turbines. The Sunrise Boiler Unit #1 produces 80 MW of power and could be adapted to accept the landfill gas with only minor treatment and compression. The Sunrise station is a peaking station and is in operation during the summer months when energy demand is high. Since the Sunrise Station uses gas for only a fraction of the year, half of the methane produced by the landfill would not be utilized. Directly supplying landfill gas to the Sunrise Station may be an attractive option if it is combined with an alternate control or use option when the power

37 Figure 6-1 Aerial view of Sunrise Landfill and potential users of methane and power produced from the landfill gas The blue line running between the Clark Station and the Sunrise Station depicts the location of the natural gas pipeline connecting the two facilities

station is not in operation This option should be considered when more precise gas production rates are available

6.2.2.2 Las Vegas Sewage Treatment Plant (STP) The Las Vegas STP is located approximately 5 km from the Sunrise Landfill The plant operates with an anaerobic digester to process the sewage waste At present, the anaerobic digester produces (10 x 106 rrvVyr) of methane The methane is utilized to operate equipment and heat structures on site Approximately (1 7 x 106 nvVyr) of excess methane is flared at the site Currently, the Las Vegas STP has no need for the methane produced at the Sunrise Landfill

6.2.2.3 Clark County STP The Clark County STP is located approximately 6 km southwest of the Sunrise Landfill Unlike the Las Vegas STP, the Clark County STP uses an aerobic process for treatment The effluent is currently aerated with 600 kW each, 3 MW for all five blowers (five 800 HP) electrically powered blowers Three additional blowers will be coming on line in the next two

38 years to meet the demands of the growing population. As a major power consumer, the facility may be interested in utilizing power generated at the landfill site to operate the plant. An alternative option would be to pipe the landfill gas to the facility, which in turn could burn the gas in an engine that would drive the aeration blowers. The latter approach will be more efficient since less energy is lost in the conversion of potential energy in the form of landfill gas to mechanical energy. 6.2.2.4 Clark Station

The Clark Station is currently base loaded and operated year round. Natural gas is supplied to the Clark Station through a pipeline operated by Southwest Gas. The natural gas available in the Las Vegas area is a mixture of 85% methane, 9% ethane, 3% propane and 2% of other gases. Btu densities for natural gas are generally greater than 37,300 kJ/m3 (1,000 Btu/ft3), which is higher than the landfill gas 22,400 kJ/m3 (600 Btu/ft3). The injected gas would need to be upgraded to meet the high purity and Btu specifications of the natural gas supplied by Southwest Gas. A high-pressure gas line rated for 41 bar (600 psi), although typical operating pressures are 20 to 27 bar (300 to 400 psi), connects the Clark and Sunrise power stations to each other. Supplying landfill gas to the Clark Station could be accomplished by injecting the landfill gas into the pipeline between the Sunrise and Clark stations. 7.0 FINANCIAL ANALYSIS OF METHANE USE OPTIONS EPA has produced the Energy Project Landfill Gas Utilization Software (E-PLUS) for estimating the environmental and economic benefits of LFG-to-energy projects (EPA, 1997b). The software is a decision support package that incorporates site-specific gas production information into its analysis. Overall project success is evaluated in terms of the Net Present Value (NPV) of a project. The NPV is the present value of all cash inflows and outflows of a project at a given discount rate (12%/yr) over the life of the project. Projects with high NPVs are likely to be more profitable over the course of the project. Four cases of gas-use options are evaluated using the E-PLUS software. The options are:

• Collect and flare gas to achieve compliance with EPA regulations

• Collect gas and sell to a vendor such as the local gas company Southwest Gas

• Collect gas and produce power to sell to a power company such as Nevada Power

• Collect gas and produce power to sell to a nearby user such as the Clark County STP Each of these options is evaluated in terms of its environmental and economic benefit using E-PLUS in Sections 7.2 through 7.5 of this report.

39 7.1 Default Model Inputs E-PLUS requires several default parameters relating to the size of the landfill and current economic factors to calculate the NPV for each project. Parameters consistent for each of the four analyses are summarized in Table 7-1.

Table 7-1. General assumptions for calculating financial feasibility of methane projects. Parameter Value Waste in Place 17,000,000 Mg (19,000,000 tons) Methane Rate Constant k 0.02 yr'1 3 Methane Generation Potential L0 100m /Mg Total Landfill Gas Production in 2000 50 x 106 nvVyr Methane Content of Landfill Gas 50% Energy Density of Landfill Gas 18,650 kJ/m3 (500 Btu/ft3) Methane Project Lifetime 50 years Landfill Gas Collection Efficiency 80% Down Payment of Initial Project Costs 20% Loan Rate 8% Project Discount Rate 12% Inflation Rate 4% Project Loan Period 10 years Marginal Tax Rate 35% Current Gas Price $2.35/million kJ ($2.50/million Btu) Current Electrical Buyback Price 3.5jz5/kWhr Current Electrical Retail Price 5.7jii/kWhr

7.2 Case 1: Collect and Flare Gas to Achieve Compliance with EPA Regulations Under EPA's landfill rule of 1996 (Federal Register, 1996), all landfills active on or after 8 November 1987 with a capacity of greater than 2.5 million Mg and NMOC emissions greater than 50 Mg/yr are required to install a gas collection and control system. Flaring the landfill gas is the default option for the gas collection system. A flare must be installed on all landfill collection systems to reduce emissions, while alternative gas-use systems are not functions due to routine maintenance or system failure. Landfill gas flaring reduces both methane and NMOC emissions by combustion at temperatures of 900 °C (~1,600 °F). Control efficiencies for these compounds are typically 98% or greater. Emissions from flares include nitrogen oxides, carbon monoxide, hydrocarbons, and soot. Collection systems installed on landfills are assumed to be 80% efficient for collecting the landfill gas. As a result, approximately 20% of the landfill gas emissions are still emitted into the air. Calculations of all gas-use options assume that 80% of the landfill gas is recovered by the gas collection system. EPA's emission Inventory calculation document, AP-42, prescribes the emissions factors for industrial flares. The emissions factors and estimated emissions from the Sunrise Flaring System (assuming landfill gas with 18,650 kJ/m3 (500 Btu/cf) and collection rate of 40 x 106 m3/yr (1,400 mmcf/yr) of landfill gas composed of 50% methane) are presented in Table 7-2.

40 Emissions of hydrocarbons and carbon monoxide can be greatly reduced from these estimated values by precisely controlling the mix of air with the landfill gas in the flare's combustion chamber Thermal nitrogen oxide emissions are produced when ambient oxygen and nitrogen pass through the combustion chamber at high temperature

Table 7-2 AP-42 emissions factor and estimated emissions from a flare operating at the Sunrise Landfill during 2000 Emissions Factor Estimated Emissions from Sunnsc (kg/K)6Btu) Landfill Flare (MgA r) Total Hydrocarbons 0064 46 Carbon Monoxide 0 168 120 Nitrogen Oxides 0031 22 A recent settlement between Silver State Disposal Services Inc and the Clark County Commission will result in the collection and control of the landfill gas through flaring As the costs of the collection and flaring system are included in the settlement, there is no economic cost or benefit to the party with the methane mineral rights at the Sunrise Landfill The NPV of this option is $0 This case will serve as the basis for comparison with the following three landfill gas-to-energy projects

7.3 Case 2: Collect Gas and Sell to Southwest Gas for Use at Sunrise and Clark Power Stations To inject the landfill gas into the pipeline running between the Clark and Sunrise power stations, the gas must first be upgraded to meet the existing gas quality standards of Southwest Gas The process diagram for the gas enrichment and injection project is shown in Figure 7-1 Landfill gas is collected and flared in the same method as in Case 1 Under normal operation, the

Figure 7-1 Process diagram for gas enrichment and injection system

41 landfill gas would bypass the flare and go to a gas treatment stage where particulates and impurities that could damage combustion equipment are removed. Carbon dioxide and impurities would be removed in the enrichment stage where the landfill gas would be upgraded to 97% methane. This step is necessary so that the gas within the pipeline maintains its high level of purity. The upgraded gas would then be compressed for injection into the existing pipeline.

The E-PLUS model was used to evaluate the financial feasibility of upgrading the landfill gas for injection into the natural gas pipeline. The model uses the methane production projections developed in Section 5 and considers capital, operation, and maintenance costs of the project over a 50-year lifetime. The assumptions used in the model are summarized in Table 7-3. These costs were obtained from EPA (1996b) and SCS Engineers (1995) reports. Based on these assumptions, in year 2000, Sunrise Landfill would produce $2.9 million of methane. The E-PLUS model calculates the net present value (NPV) of this system to be $8.6 million. The gas-enrichment option has excellent environmental benefits. Since the landfill gas is offsetting the purchase of natural gas, there would be no net increase in local air pollution emissions from this option. All recovered landfill gas would be treated and burned as high Btu fuel for the nearby power stations.

Table 7-3. Capital and operating costs of gas enrichment and injection into pipeline. Gas Treatment System Capital Cost Basis Capital Operation and Operation and Costs Maintenance Maintenance Costs Cost Basis Per Year Scrubbers $15/cfm $32,100 ($1,010 /(106m3/yr)) Desiccators $10/cfm $21,400 ($670/(106m3/yr)) Filters (4) $3,200 each $12,800 Gas Treatment Variable O/M $2.50/mmcf7yr $2,800 ($88/(106 m3/yr)) Gas Treatment Fixed O/M $10,000 Gas Treatment Installation and $15/cfm $8,900 Other Costs ($1,010/(106m3/yr)) Total Gas Treatment Costs $75,200 $12,800

Gas Enrichment System Capital Costs $500/mcfd $1,510,000 ($6,442/(106m3/yr)) Gas Enrichment Fixed O/M $151,000*

Compression System 3 Compression Stages (478 HP) S1.350/HP $645,000 ($l,800/kW) Compression O/M (3 units) $12,000/unit $36,000

Pipeline System Pipeline (11,000 ft) $35/ft $370,000 ($112/m) Total $2,600,000 $200,000 ' = Estimated at 10% of capital costs.

42 7.4 Case 3: Collect Gas and Produce Power to Sell to a Power Company Such as Nevada Power

Under the Public Utilities Regulatory Policies Act (PURPA), public utilities must buy back electricity from non-fossil fuel power producers that generate less the 80 MW A project to produce power from landfill gas would qualify for this regulation Utilities are required to pay no more than their "avoided energy price" for the power supplied Nationally, this rate is typically 3 to 4 cents per kWh (EPA, 1996b) For the purposes of the economic analysis, the avoided energy price is assumed to be 3 5 cents per kWh

The process diagram for the energy production and sale project is shown in Figure 7-2 Gas must be treated prior to the electrical generation state to remove impurities that could harm the generators The choice of electrical generation equipment depends on the amount of gas produced Reciprocating internal combustion (1C) engines are the preferred alternative for projects with methane collection greater than 6 2 x 106 mVyr (600 mcf/day) Above 20 7 x 106 m3/yr (2,000 mcf/day), combustion turbines can become a profitable alternative Above 52 x 106 m3/yr (5,000 mcf/day), a boiler/steam turbine system should be considered Since Sunrise Landfill is estimated to collect approximately 25 x 106 mj/yr (2,400 mcf/day) of methane in 2000, calculations were run for both the 1C engine and the combustion turbine option The combustion turbine has the benefit of emitting less NCK than the 1C engine The modeled default efficiency of the 1C engine (28%) is greater than that of the combustion turbine (25%) Thus, more power is produced from the 1C engine than the combustion turbine The interconnect stage accounts for the transmission of power from the generator to the substation at Sunrise power station, 2,400 m The costs of each stage are presented in Table 7-4 and Table 7-5

Figure 7-2 Process diagram for energy production and sale.

43 Table 7.4. Capital and operating costs of power generation and sale using combustion turbine (Case 3a). Capital Cost Basis Capital Costs Operation and Operation and Maintenance Cost Maintenance Basis Costs Per Year Gas Treatment System Scrubbers $15/cfin $32,100 ($1,010 /(106 m3/yr)) Desiccators $10/cfrn $21,400 ($670/(106m3/yr)) Filters (4) $3,200 each $12,800 Gas Treatment Variable O/M $2.50/mmcf7yr $2,800 ($88/(106m3/yr)) Gas Treatment Fixed O/M $10,000 Gas Treatment Installation and $15/cfin $8,900 Other Costs ($1,010/(106 mV)) Total Gas Treatment Costs $75,200 $12,800

Power Generation System Combustion Turbine (6.64 MW) $450/kW capacity $2,980,000 Radiator $50/kW capacity $332,000 Control Systems $150/kW $996,000 Energy Generation Variable O/M $10/MWh/yr $532,000 Fixed O/M $75,000/MW $498,000 Installation $400/kW capacity $2,660,000 Power Generation Total $6,970,000 $1,020,000

Interconnect System Substation $60/kW $399,000 Engine Wiring (2,438 m) $45/ft $360,000 ($144/m) Intertie Wiring (61 m) $60/ft $12,000 ($192/m) Substation Telemetry $10,000 each $10,000 Protective Relays $10/kW $67,000 System Disconnect $20/kW $133,000 Interconnect Variable O/M $0.20/MWhr/yr $10,000 Interconnect Fixed O/M $2,000 $2,000 Installation and Other Costs $20/kW $133,000 Interconnect Total Costs $1,114,000 $12,000

Total $8,164,000 $1,044,000

44 Table 7.5. Capital and operating costs of power generation and sale using 1C engine (Case 3b). Capital Cost Basis Capital Costs Operation and Operation and Maintenance Cost Maintenance Basis Costs Per Year Gas Treatment System Scrubbers $15/cftn $32,100 ($1,010 /(106 m3/yr)) Desiccators $10/cfin $21,400 ($670/(106m3/yr)) Filters (4) $3,200 each $12,800 Gas Treatment Variable O/M $2.50/mmcfyyr $2,800 ($88/(106m3/yr)) Gas Treatment Fixed O/M $10,000 Gas Treatment Installation and $15/cfm $8,900 Other Costs ($1,010/(106 m3/yr)) Total Gas Treatment Costs $75,200 $12,800

Power Generation System 1C Engine (7.44 MW) $450/kW capacity $3,347,000 Radiator $50/kW capacity $371,000 Control Systems $150/kW $1,116,000 Energy Generation Variable O/M $10/MWh/yr $587,000 Fixed O/M $75,000/MW $557,000 Installation $400/kW capacity $2,976,000 Power Generation Total $7,811,000 $1,144,000

Interconnect System Substation $60/kW $446,000 Engine Wiring (2,438 m) $45/ft $360,000 ($144/m) Intertie Wiring (61 m) $60/ft $12,000 ($192/m) Substation Telemetry $10,000 each $10,000 Protective Relays $10/kW $74,000 System Disconnect $20/kW $149,000 Interconnect Variable O/M $0.20/MWhr/yr $12,000 Interconnect Fixed O/M $2,000 $2,000 Installation and Other Costs $20/kW $149,000 Interconnect Total Costs $1,200,000 $14,000

Total $9,086,000 $1,170,000

45 The combustion turbine and 1C engine would supply Nevada Power with 6.6 MW and 7.4 MW in 2000, respectively. The NPV of this project is calculated to be negative $631,000 for the combustion turbine and negative $662,000 for the internal combustion engine. These results indicate that this project would not make a profit at the current electrical buyback rates. Although the landfill gas used would decrease local dependence on outside energy sources, the emissions of nitrogen oxides would increase over using a flare only (Case 1). Emissions of CO from the combustion turbine would be less than CO emissions from the flare. The AP-42 NOX and CO emissions factors for a gas turbine operating with a steam emissions control system in place are shown hi Table 7-6. Similarly, the emissions factors for the four-stroke, clean burning 1C engine are shown in Table 7-7. 7.5 Case 4: Collect Gas and Produce Power to Sell to a Nearby User Such as the Clark County STP This option is almost equivalent to Case 3 with the exception that rather than selling gas back to Nevada Power at the buyback rate of 3.5 cents per kWh, the power would be sold to a nearby consumer (i.e., Clark County STP) at 5.7 cents per kWh. All other emissions and costs are identical. Using these assumptions, the net present value of the combustion turbine project is $6.7 million and the net present value for the internal combustion engine is $7.6 million. This example demonstrates the importance of energy prices on the profitability of the project.

Table 7.6. AP-42 emission factors and emissions from a 6.64 MW gas turbine operating on Sunrise Landfill gas (Case 3a). Emission factors assume a steam injection control system is in operation on the turbine. Emission Factor Estimated Emissions from Estimated Emissions from (kg/106 Btu) Sunrise Landfill Combustion Sunrise Landfill 1C Engine Turbine (tpy) (Mg/yr) Carbon Monoxide 0.073 57 52 Nitrogen Oxides 0.054 43 39

Table 7.7. AP-42 emission factors and emissions from a 7.44 MW natural gas fired reciprocating engine operating on Sunrise Landfill gas (Case 3b). Emission factors assume a four-stroke, clean burning engine is in operation at the landfill. Emission Factor Estimated Emissions from Estimated Emissions from (kg/kW-hr) Sunrise Landfill 1C Engine (tpy) Sunrise Landfill 1C Engine (Mg/yr) Carbon Monoxide 0.0048 344 313 Nitrogen Oxides 0.0012 86 78

46 7.6 Summary of Economic and Environmental Analysis of Methane Utilization The economic and environmental benefits of the four methane-use cases are summarized in Table 7-8. Case 2, in which gas is upgraded to pipeline quality offers the best economic and environmental benefit based on this analysis. Power generation and sale (Cases 3 and 4) is a financially viable option when energy prices are high enough to support the purchase of the capital equipment. While greater economic benefit is expected with the 1C engine, emissions of CO are expected to be a factor of six higher than that of the combustion turbine. Since the production of methane at the Sunrise Landfill is highly uncertain, the NPVs have been calculated for two bounding cases. The first case is for a low methane production and recovery scenario in which the methane production rate, k, is 0.01/yr rather than the default of 3 3 0.02/yr, and the methane production potential, L0, is 50 m /Mg rather than 100 m /Mg. The second case is a high methane production and recovery scenario using k = 0.03/yr and LO = 150 m3/Mg. The results of these cases are likely to bracket the actual NPV of each methane-use project. The ranges of NPV for each case are presented in Table 7-9. Based on these estimated ranges of gas production, Case 2 offers the most favorable range of NPV, $1.6 million to $15 million. The power production and sale to Nevada Power (Cases 3a and 3b) would lose money if power was sold at 3.5 cents/kW-hr. Case 4 would be profitable over the entire range of methane emissions.

Table 7.8. Summary of environmental and economic benefits of methane use options.

Case Project NPV NOX Emissions CO Emissions (Mg/yr) (Mg/yr)

1. Flare emissions $0 22 120

2. Upgrade landfill gas for injection in $8,600,000 0 0 natural gas pipeline 3a. Generate power with combustion -$631,000 39 52 turbine and sell back to Nevada Power at 3.5 cents/kWhr

3b. Generate power with 1C engine and sell -$661,000 78 313 back to Nevada Power at 3.5 cents/kWhr

4a. Generate power with combustion $6,700,000 39 52 turbine and sell to nearby customer at 5.7 cents/kWhr 4b. Generate power with 1C engine and sell to $7,600,000 78 313 nearby customer at 5.7 cents/kWhr

47 Table 7.9. Sensitivity of project NPV to changes in methane production rate and recovery.

Case Low Methane Production High Methane Production and Recovery and Recovery 3 3 (k = 0.01/yr, L0 = 50 m /Mg) (k = 0.03/yr, L0 = 150 m /Mg)

1. Flare emissions $0 $0

2. Upgrade landfill gas for $1,600,000 $15,100,000 injection in natural gas pipeline

3a. Generate power with -$143,000 -$2,320,000 combustion turbine and sell back to Nevada Power at 3.5 cents/kWhr

3b. Generate power with 1C engine $121,000 -$2,550,000 and sell back to Nevada Power at3.5cents/kWhr

4a. Generate power with $2,280,000 $10,500,000 combustion turbine and sell to nearby customer at 5.7 cents/kWhr

4b. Generate power with 1C engine $2,600,000 $11,800,000 and sell to nearby customer at 5.7 cents/kWhr

Although these analyses suggest that two of the methane-use options will be profitable over a broad range of methane production rates, these estimates are based on the E-PLUS model's default costs for the various processes. Real costs for the processes may be different from the values used. It is recommended that more accurate estimates of the methane production and process costs be obtained prior to designing a methane-use project. 8.0 CONCLUSIONS AND RECOMMENDATIONS Municipal solid waste landfills are notorious for emitting gas shortly after closure, even hi extremely arid environments like Clark County, Nevada. The LFG produced typically consists of about 50% methane and 45% carbon dioxide. The use of the LFG methane for energy production is a well-established industry. However, recent developments, such as low energy prices and elimination of the Section 29 tax credits, have significantly reduced the initiation of new projects. Sunrise Landfill was operated from the late 1950s to 1993 and closed with a Subtitle D cover in 1995. The landfill is one of the largest in the west, covering around 290 ha and is around 100 m thick at the deepest part. It has received media and regulatory attention due to concerns for surface runoff of waste, groundwater impacts and gas emissions. DRI was contracted by DOE/NV to study the potential of utilizing the gas emissions as an alternative energy source. A

48 critical component of such an evaluation is the determination of the gas production rate. Several options for determining the gas production rate were explored and a company and method selected. However, due to regulatory issues surrounding Sunrise Landfill, namely a Finding of Violation and Order by EPA Region 9, permission was not granted to conduct this component of the study. This report reviewed the state of knowledge on LFG-to-energy and methods of assessing the gas production rate. A recommendation of this report is to determine the gas production rate at Sunrise Landfill using the five-well dice-pattern method. Economic and environmental benefits of a potential LFG-to-energy project at Sunrise Landfill were investigated. Large energy users near the landfill were identified along with their specific energy needs. Four methane-use cases were chosen for detailed analysis. The cases were (1) flare the landfill gas emissions, (2) upgrade the landfill gas and inject it into a nearby natural gas pipeline, (3) produce power on site and sell electricity to a public utility, and (4) produce power on site and sell electricity to a nearby power consumer. Net present values (NPV) of each of these cases were estimated using EPA's E-PLUS program. The highest NPVs were calculated for Case 2 (upgrade and inject gas into pipeline) and Case 4 (sell locally generated power to nearby user) and were $8.6 million and $7.6 million, respectively. Case 3 (sell back power to a public utility) had a negative NPV of approximately -$650,000. The base case (Case 1, flare emissions) has a $0 NPV, since this system must be installed under federal regulation. Emissions of nitrogen oxides and carbon monoxide were also calculated for each case using AP-42 emissions factors. The lowest emissions case was Case 2, since injecting the methane into the natural gas pipeline would produce no emissions. The flare used to combust the landfill gas in Case 1 is estimated to emit 22 Mg/yr of NOX and 120 Mg/yr of CO. The combustion turbine used to produce electricity in Cases 3 and 4 would emit 39 Mg/yr of NOX and 52 Mg/yr of CO. An internal combustion engine used to produce electricity is estimated to emit 78 Mg/yr of NOX and 313 Mg/yr of CO. A sensitivity test on landfill production rates was performed to investigate how the profitability of each project would change if the gas collected at the site is found to be significantly different from the predicted values. Case 1 (flare emissions) retains an NPV of $0 over all ranges of methane production. Case 2 (upgrade and inject gas into pipeline) would remain profitable at all tested ranges of methane production. Case 3 (sell power to public utility) is never profitable for any tested range of methane production. Case 4 (sell power to nearby user) would be profitable over the tested range of methane emissions. The economic and environmental analyses should be considered as rough calculations to identify the feasibility of establishing an LFG-to-energy project at Sunrise Landfill. A great deal of uncertainty is associated with these estimates since the amount of methane to be recovered from the landfill is unknown. There is an additional uncertainty associated with the default costs for each project. Real costs to build and maintain an LFG-to-energy project are likely to vary from city to city. It is recommended that this analysis be repeated in the future when precise measurements of the methane production rate are available. At that time, process engineers specializing in LFG recovery should be consulted to develop specific cost estimates for each of the cases outlined in the report.

49 9.0 REFERENCES Augenstein, D. and J. Pacey, 1991. Landfill Methane Models. Proceedings of SWANA's 29th Annual International Solid Waste Exposition, Sliver Spring, MD. Solid Waste Association of North America, p. 1-25.

Bach, L.K., and K. Rogers, 1998. Methane gas leaking from landfill: The county disagrees with findings that say gas levels are at potentially explosive amounts. Las Vegas Review Journal, vol 93, no 316, p. 1A.

Balfour, W.D., C.E. Schmidt, and B.N. Eklund, 1987. Sampling approaches for the measurement of volatile compounds at hazardous waste sites. J. Hazard. Mater. 14:135. Barlaz, M.A., M.W. Milke, and R.K. Ham, 1987. Gas production parameters in sanitary landfill simulators. Waste Management and Research. 5:27-39.

Barlaz, M.A., R.K. Ham, and D.M. Schaefer, 1989. Mass balance analysis of anaerobically decomposed refuse. Journal of Environmental Engineering. 115:1088-1102. Berenyi, E., and R. Gould, 1991. 1990-1991 methane recovery from landfill yearbook. Government Advisory Association, New York. p. 386. Campbell, D.J.V, 1996. Explosion and fire hazards associated with landfill gas. In: Landfilling of Waste: Biogas. (Eds) T.H. Christensen, R.Cossu, and R. Stegmann. E&FN Spon., London, ISBN 0 419 19400 2.

CCJM, 1998. Reconnaissance investigation of the Sunrise Landfill, Las Vegas, NV. CCJM Environmental Consultants Inc., Lakewood, CO.

Christensen, T.H., P. Kjeldsen, and B. Lindhardt, 1996. Gas-generating processes hi landfills. In: Landfilling of Waste: Biogas. (Eds) T.H. Christensen, R.Cossu, and R. Stegmann. E&FN Spon., London, ISBN 0 419 19400 2. Constable, T.W., G.J. Farquar, and B.N. Clement, 1979. Gas migration and modeling. U.S. Environmental Protection Agency-600-9-79-023a, p. 396-412. Cossu, R., G. Andreottola, and A. Muntoni. 1996. Modeling landfill gas production. In: Landfilling of Waste: Biogas. (Eds) T.H. Christensen, R.Cossu, and R. Stegmann. E&FN Spon., London, ISBN 0 419 19400 2. Design News, 1985. Landfill gas fuels 5 MW eletric plant. January 1985, p. 46-48. Dwyer, S. F. 1997, Sunrise Mountain landfill final cover evaluation. Dynamac Corp. (TSA 97- 003). Eklund, B.M., M.R. Kienbusch, and D. Ranum.,1984. Development of a sampling method for measuring VOC emissions from surface impoundments. Radian Corp.

50 Eklund, B.M., E.P. Anderson, B.L. Walker, and D.B. Burrows, 1998. Characterization of landfill gas composition at Fresh Kills municipal solid waste landfill. Environmental Science and Technology, 32:2233-2237

EMCON Associates, 1986. Sunrise Mountain Landfill expansion. Clark County, Nevada. Project 833-01.01, San Jose, CA 95131.

EPA, 1996a. Standard of Performance for New Stationary Sources and Guidelines for Control of Existing Sources: Municipal Solid Waste Landfills. U.S. Environmental Protection Agency, Federal Register, pp. 9905-9944, March 12,1996. EPA, 1996b. Turning liability into and asset: A landfill gas-to-energy project development handbook. U.S. Environmental Protection Agency Landfill Methane Outreach Program, September 1996. EPA. 1997a. Compilation of air pollutant emissions factors, 5th ed., Supplement D, AP-42 Section 2.4, U.S. Environmental Protection Agency, Office of Air Quality Planning Standards: Research Triangle Park, NC, August 1997. EPA, 1997b. E-PLUS User's Manual. U.S. Environmental Protection Agency, Office of Air and Radiation, Atmospheric Pollution Prevention Division. EPA-430-B-97-006, January 1997. Farquar, G.L., and F.A. Rovers, 1973. Gas production during refuse decompositioa Water, Air, and Soil Pollution. 2:483-495. Federal Register, March 12,1996 (Vol. 61 No. 49), 40 CFR Parts 51, 52, and 60. Gholson, A.R., J.R. Albritton, R.K.M. Jayanty, J.E. Knoll, and M.R. Midgett, 1991. Evaluation of an enclosure method for measuring emissions of volatile organic compounds from quiescent liquid surfaces. Envrion. Sci. and Technol 25:519. Giovando, C.A. and C. Jones, 1998. Resourceful power producers turn to landfill gas for fuel. Power. 142:76-78. Gipe, P., 1988. Landfill gas capacity expected to double by 1990. Industry News, Waste-To- Energy. ASE, October 1988, p. 43-44. Ham, R.K., 1996. Field testing for evaluation of landfill gas yields. In: Landfilling of Waste: Biogas. (Eds) T.H. Christensen, R.Cossu, and R. Stegmann. E&FN Spon., London, ISBN 0 419 19400 2. Ham, R.K., and M.A. Barlaz, 1987. Measurement and prediction of landfill gas quality and quantity. In: Proceedings of International Symposium on Process, Technology, and Environmental Impact of Sanitary Landfill. CISA, Environmental Sanitary Engineering Centre, p. 1-24.

51 Hartz, K.E., R.E. Klink, and R.K. Ham, 1982. Temperature effects-Methane generation from landfill samples. J. Environ. Eng., ASCE, 108:629-638. Healy, R.W., R.G. Striegal, T.R. Russell, G.L. Hutchinson, and G.P. Livingston, 1996. Numerical evaluation of static-chamber measurements of soil-atmosphere gas exchange: Identification of physical processes. SoilSci. Soc. Am. J., 60:740-747. Hutchinson, P.J., 1990. Landfill gas-A significant resource (abs): American Association of Petroleum Geologist Bulletin, 39:680.

Hutchinson, P.J., 1993. An energy perspective on landfill gas. The Future of Energy Gases, U.S. Geological Survey Professional Paper 1570. Kjeldsen, P., 1996. Landfill gas migration in soil. In: Landfilling of Waste: Biogas. (Eds) T.H. Christensen, R.Cossu, and R. Stegmann. E&FN Spon., London, ISBN 0 419 19400 2.

Livingston, G.P., and G.L. Hutchinson, 1995. Enclosure-based measurement of trace gas exchange: Applications and sources of error. In: Biogenic Trace Gases: Measuring Emissions from Soil and Water. (Eds) P. Matson and R. Harriss. Blackwell Scientific. Oxford, England, p. 14-51. Lofy, R.J., 1983. The study of zones of vacuum influence surrounding landfill gas extraction wells. Argonne National Laboratory, Methane from Landfill Program. ANL/CNSV-TM- 113. Lofy, R.J., 1996. Zones of vacuum influence surrounding gas extraction wells. In: Landfilling of Waste: Biogas. (Eds) T.H. Christensen, R.Cossu, and R. Stegmann. E&FN Spon., London, ISBN 0 419 19400 2. Magnuson, S.O., S.J. Maheras, H.D. Nguyen, A.S. Rood, J.I. Sipos, M.J. Case, M.A. McKenzie- Carter, and M.E. Donahue, 1992. Radiological performance assessment for the Area 5 Radioactive Waste Management Site at the Nevada Test Site. Revision 1. Idaho National Laboratory, Idaho Falls, ID. Manning, M., 1998a. Landfill runoff pollutes LV Wash, Environmental group calls for quarantine. Las Vegas Sun, vol 49, no 93, p. ID. Manning, M., 1998b. Springs compound landfill concerns, Water found seeping from ground near Sunrise Mountain. Las Vegas Sun, vol 49, no 100, p. 8 A. Martin, J. and M. Fujii, 1985. Recovering Landfill Gas with Horizontal Trenches. Public Works, 116:59-61. Martinez, E.H., and W.C. Yeckes, 1994. Sunrise Mountain Landfill closure plan. Harding Lawson Assoc., Las Vegas, NV 89103. Pfeffer, J.T., 1974. Temperature effects on anaerobic fermentation of domestic refuse. Biotech. andBioeng., 16:771-781.

52 Pohland, F.G., Dertien, and S.B. Gosh, 1983. Leachate and gas quality during landfill stabilization of municipal refuse. In Proceedings of the 3rd International Symposium on Anaerobic digestion, Evans and Faulkner, Cambridge, Mass, p. 185-201.

Power Magazine. 1987. 50-MW steam powerplant burns landfill gas. February 1987, p.62- 63. Power Magazine. 1997. Hanes Mill Road Project: Extraction, collection, compression are keys to landfill gas project. March/April 1997, p.93-95. Rajagapolan, V. and L.L. Ertler, 1998. Sunrise Landfill monitoring, Clark County, Nevada. Kleinfelder, Inc., Las Vegas, NV. Ransom, R.C., and C.E. Parker, 1988. City turns landfill gas problem into cash. Public Works, July 1988, p. 60-62. Reason, J. 1987. 50 MW steam power plant burns landfill gas. Power Magazine, 131: 62-63. Rees, J.F., 1980. Optimization of methane production and refuse decomposition in landfill by temperature control. J. Chem. Technol. and Biotech. 30:458-465. Reinhart, D.R., D.C. Cooper, and B.L. Walker, 1992. Flux chamber design and operation for the measurement of municipal solid waste landfill gas. J. Air Waste Manage. Assoc. 42:1067- 1070. Rogers, K., 1998a. Landfill's toxin level high, The closed Sunrise dump has amounts of hazardous chemicals that are unusual for typical household refuse. Las Vegas Review Journal, March 24,1998, Section IB. Rogers, K., 1998b. Landfill draws fire from EPA, A federal agency says since a deadline to close a dump was missed, stronger requirements take effect. Las Vegas Review Journal, March 19, 1998, Section IB. Rolston, D.E., 1986. Gas Flux. In: Methods of Soil Analysis. Part 1, 2nd Ed., Agronomy Monograph 9. (Ed) A. Klute. Madison, WI, p. 1103-1120. SCS Engineers, 1995. Helping landfill owners achieve effective, low cost compliance with federal landfill gas regulations. Report prepared by SCS Engineers, Reston, VA, for U.S. Environmental Protection Agency, Washington, D.C.

VanDerPuy, M., 1984. Hydrologic and soil assessment of the Sunrise Landfill site and expansion. R&PP Nev-046208, Las Vegas District, U.S. Bureau of Land Management. Wallace, I.P., 1991. Landfill gas-fired power plant pays cost of operating landfill. Power Engineering, January 1991, p. 27-29. Walsh, J.L., 1999a. LFG-to-energy industry struggles to survive, Part 1: Why the industry faces its dilemma. Solid Waste Online, www.solidwasteonline.com.

53 Walsh, J.L., 1999b. LFG-to-energy industry struggles to survive, Part 2: Delivery from the industry's dilemma. Solid Waste Online, www.solidwasteonline.com.

Ward, R.F., 1988. Landfill gas production. Proceedings: GRCDA 11th International Landfill Gas Symposium. (Eds) M.J. Carolan, H.L. Martin, K.A. Flanagan, and L.W. Haley. Government Refuse Collection and Disposal Association, Silver Spring, MD, p.161-186. Westlake, K., 1990. Landfill microbiology. In: Landfill Gas-Energy and Environment. (Eds) G.E. Richards, and Y.R. Alston. Harwell Laboratories, Oxfordshire, England, p. 271-280.

Wild, H.S., Jr., 1990. Hydrogeology and hydrogeochemistry of the shallow alluvial aquifer zone, Las Vegas Valley, NV. M.S. Thesis, Univ. of Nevada, December 1990. Willumsen, H.C., 1996. Landfill gas utilization: Statistics of existing plants. In: Landfilling of Waste: Biogas. (Eds) T.H. Christensen, R.Cossu, and R. Stegmann. E&FN Spon., London, ISBN 0 419 19400 2. Wilson, G.V., B.R. Thiesse, and H.D. Scott, 1985. Relationships among oxygen flux, soil water tension, and aeration porosity hi a drying soil profile. Soil Sci. 139:30-36. Wilson, G.V., S. Hokett, D. Gillespie, and B. Ogan, 1998. Groundwater quality impacts of Sunrise Landfill. U.S. Bureau of Land Management. White paper report. Wilson, G.V., W.H. Albright, G. Gee, M.J. Payer, and B. Ogan, 1999. Alternative Cover Assessment Project: Phase I Report. U.S. Environmental Protection Agency, p. 1-218. Zehnder, A.J.B., 1978. Ecology of methane formation. In: Water Pollution Microbiology. (Ed) R. Mitchell, New York, Wiley-Interscience, p. 349-376. Zehnder, A.J.B., K. Ingvorsen, and T. Marti, 1982. Microbiology of methane bacteria. In: Anaerobic Digestion. (Eds) D.E. Hughs, D.A. Stafford, B.I. Wheatley, W. Baadar, G. Lettinga, E.J. Nyns, W. Verstraete, R.L. Wentworth. Elsevier Biomedical Press, New York, p. 45-68.

54 APPENDIX A LETTER TO BLM AND LETTERS OF SUPPORT

Letter submitted to BLM requesting permission to determine the gas emissions from Sunrise Landfill. Included are letters of support from NDEP, CCHD, and CCPW.

A-l University and Community College System of Nevada

Water Resources Center

TO: Rex Wells, Assistant Field Manager. Lands

FROM: Glenn Wilson, DRI

DATE: 3 May, 1999

RE: Sunrise Landfill Gas Emissions

DOE/NV has contracted to DRI lo study the potential for converting gas emissions from Sunrise landfill into energy production. DRI has proposed to install a series of gas collection wells on the landfill. Five wells will be installed and tied together for a composite analysis of gas production. The exact coordinates will be determined following a surface reconnaissance survey but we expect from past measurements that it'will be in the general vicinity of N 267537007ft, E829100ft. We are requesting permission form BLM for the installation of this well field.

We do not anticipate these wells will have any detrimental impacts on the hydrology of the cover as the upper portion will be grouted. Nor do we expect them to have detrimental impacts on air quality as they will be capped immediately following the gas production testing which will take a couple of days. The term of operation is uncertain. We do anticipate the project continuing next year but the project is funded one year at a time with no assurances of next year funding. During the life of the project, DRI will maintain these well as the responsible party or, if possible, transfer responsibility to another party prior to the termination of project. In the event that a party cannot be arranged, DRI will have these wells remediated, as necessary and funds permit, to prevent a preferred pathway for water or gas flow.

We have circulated our research plans to Clark County Public Works, Clark County Comprehensive Planning, Clark County Health District, Republic Silver State Disposal, and Nevada Department of Environmental Protection. We have letters of support from all of these parties except RSSD. We have received verbal concurrence from Mr. Alan Gaddy of RSSD and will be working closely with RSSD during these tests.

We look forward to working with the BLM in resolving the issue of gas generation.

Cc: Mike Moran, BLM PO.Boi 19040 Las VW3S.NV 89132-0040 702-8»W50 Fax702-SS5-0427

A-2 STATE OF NEVADA PETER C. MORROS. Director KENNY C. CUINN Governor ALLEN BIAGC1, MmialttrOor Waste ManagtmtM 1775) 687-46711 S5fc'S3&V Corrective Actions

AJminislraliiiri Water Pr.'Iutton Control Wfcf Water Quality PUnnlng Facsimile BH7-585B ^^gjjjS*^ Facsimile 687-6396 Mining Regulation and Reclamation F«o.-m.V» S84.5259 DEPARTMENT OK CONSERVATION AND NATURAL RESOURCES DIVISION OF ENVIRONMENTAL PROTECTION 333 W. Nye Lane. Room 138 Larson City. Nevada 897064851

April 2, 1999

Glenn V. Wilson Desert Research Institute 755 E. Flamingo Rd. Las Vegas, NV 891 19

Dear Dr. Wilson:

Thank you for providing the Division with an opportunity to review DRI's plans for studying potential use of landfill gas emitted at the Sunrise Landfill as a source of energy. It is our understanding that the scope of the work will include a review of literature and existing information, ambient air surveys, installation of a gas collection well at the landfill, gas generation modeling and preparation of a final report.

This work is timely, given that new Federal air quality emission guidelines (40 CFR Part 60 Subpart Ccj will eventually require control of landfill gas at the Sunrise Landfill site. While the Division is not the regulatory authority for these new requirements, we have been intimately involved with a range of issues associated with the Sunrise Landfill and we concur with the task plans proposed by DRI.

If I can provide further assistance, please contact me at (775) 687-4670, ext. 3001.

Sinc

David Emme, Chief Bureau of Waste Management

DE:nap

A-3 CLARK COUNTY HEALTH DISTRICT

P.O. BOX 3902 • 625 SHADOW LANE • LAS VEGAS. NEVADA 891 27 • 7O2-383-I276 • FAX 7OZ-383-1 443

April 1, 1999

Mr. Glenn V. Wilson Principal Investigator Desert Research Institute 755 E Flamingo Rd Las Vegas, NV 89119

Dear Mr. Wilson:

Re: Sunrise Mountain Landfill Gas Emissions

It is the Clark County Health District's understanding that the Department of Energy has contracted the Desert Research Institute (DRI) to study the potential for converting gas emissions from the Sunrise Mountain Landfill into energy production. DRI's task plan includes the following activities:

1. Literature review of gas-energy production from similar landfills, 2. Summarize existing data for Sunrise; 3. Conduct a surface air-quality survey at Sunrise; 4. Install a gas collection well(s) at Sunrise through subcontract with a yet-to- be-determined company; 5. Perform gas generation modeling; 6. Submit a draft report to DOE that summarizes this effort.

It is our understanding that the exact coordinates of the well will be determined following the surface reconnaissance survey. DRI has promised that the well will be installed in such a way that there will not be any detrimental impacts on the hydrology of the cover or on air quality of the area.

it is our further understanding that DRI will maintain the well as the responsible party during the life of the project and we will seek to transfer responsibility to another party prior to the termination of project. In the event that a party cannot be arranged, DRI will have the well closed, i.e., removed and remediated, as necessary, to prevent a preferred pathway for water or gas flow.

We have reviewed the DRI task plans and concur with the proposed activities.

Sincerely,

Donalcr-S. Kwalick, MD, MPH Chief Health Officer

CLARK COUNTY • LAS VEGAS • NORTH LAS VEGAS • BOULDER CITY . HENDERSON

A-4 Department of Comprehensive Planning

500 S Grand Central Pky • Ste 3012 • PO Box 551741 • Las Vegas NV 89155-1741 (702) 455-4181 • Fax (702) 385-8940

Richard 8 Holmes. Director • John Schlegel. Assistant Director • Lesa Coder, Assistant Director

April 1,1999

Glenn Wilson, Principal Investigator Desert Research Institute (DRI). WRC 755 E. Flamingo Road Las Vegas, NV 89119

Re: Sunrise Landfill Emissions Study

Dear Mr. Wilson:

It is our understanding that DOE/NV has contracted with DRI to study the potential for converting landfill gas emissions from Sunrise Landfill into potential energy production. We have reviewed the DRI task plans and believe that the study as proposed will provide useful information and data for our use. It is our understanding that you have made arrangements with the Bureau of Land Management and Republic Silver State Disposal for purposes of conducting the study.

Sv

JS:bh

BOARD OF COUNTY COMMISSIONERS YVONNE ATKINSON GATES Chair • LORRAINE T HUNT. Vice-Char ERIN KENNY • MARY J KING AID • LANCE M M ALONE » MYRNA WILLIAMS • BRUCE L WOOOBURY DALE W ASKEW. County Manager

A-5 APPENDIX B EMAIL RESPONSES FROM ALAN GADDY OF REPUBLIC SILVER STATE DISPOSAL

B-l Thu Sap 30 10:19:05 1999 1

Date: Thu, 20 May 1999 12:04:35 -0700 From: [email protected] To: [email protected] Cc: [email protected] Subject: Latest Plan for LFG at Sunrise

Hi Glenn,

I had a chance to review the latest revision to the LFG project you are working on. I still have problems with the methods which you are proposing to use for project. They are still unapproved as an EPA method. It looks like your combining methods using Landfill Gas Probes described in Method 2E as landfill gas wells will not benefit anyone. The design for a probe would yield poor data as a LFG well. Wells typically have a greater diameter bore as specified in Method 2E, section 3.2.

You are proposing to use only an 8 inch bore. Also, the five wells placed in a dice pattern only gives you one radius of influence data point. The probes are supposed to be staggered at 15', 30' and 45' away from the well at 120 degree spacing intervals in order to measure influence at different distances away from the vacuum point. I was also concerned about your sentence where Republic SSDS has agreed to perform subsurface characterization. We have not agreed to that. The last time we discussed your project, ^he quality control criteria was going to be a problem for DRI. Now that we are under the order from Region IX, we must maintain the proper protocol, or face penalties. I don't know how we can use non-EPA approved protocol anywhere in what we do. BLM, or course, is not a party to this agreement so they can approve anything they want. You need to pursue them. I still would like to be involved in your project to provide input on the procedures and methods. I v/ould like to see the best data available come from the site.

Thanks Alan

You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com/getjuno.html or call Juno at (800) 654-JUNO 1654-5866]

B-2 APPENDIX C LETTER SUBMITTED TO EPA REGION 9

University and Community Collage System of Nevada

Water Resources Center

Susanna Tujillo, Project Coordinator May 28,1999 Steve Wall, Technical Coordinator U.S. EPA Region 9, 75 Hawthorne St (WST-7) San Francisco, CA

DOE/NV has contracted to DRI to study the potential for converting gas emissions from Sunrise landfill into energy production. DRI has proposed to do a surface gas emission survey and install a series of gas collection wells on the landfill to determine the potential gas production rate. BLM originally requested that we get concurrence from all parties (CCPW, CCHD, CCCP, NDEP, and RSSD), stating that they had reviewed our work plans, in order for BLM to grant approval for our study. All panics responded in writing with concurrence except RSSD. Since the EPA citation, we have been informed by BLM that they can grant approval to DOE but not DRI. They also want DRI to get approval from EPA Region 9 and RSSD before they will grant approve to DOE. DOE has informed BLM that "their preference is for BLM to authorize DRI."

We discussed the impact of the citation on activity with CCCP who informed us that RSSD is the lead and for us to work with them. We contacted RSSD immediately after the citation and have had several discussions with them about incorporation of our study as part of their site assessment activities. RSSD has taken the stand that they cannot use our study because the wells we propose using do not comply with standard EPA approved methods. They have responded with review comments to our proposed work plans but not with a letter of concurrence. Instead. they have encouraged us to go directly to BLM for approval.

We are requesting approval from Region 9 for our work plans (attached documents). Then we will go back to BLM with a request that they grant DRI approval for this activity.

Thanks in advance for your consideration of this request.

Sincerely,

Glenn Wilson. Project Coordinator

D. Shafer. DRI E. Hodge. DOE

= 0 BWI9W1 .IsVeoas.NV 89132-OCM "2 89S-MK = 1.702 895 0«<:

C-l Sunrise Gas Production Rate Assessment Work Plans

In July, DRI will conduct a surface air-quality survey of the landfill cap (i) to determine if surface emissions have changed since a similar survey by in 1998 and (ii) to identify hot-spots as potential sites for subsurface assessment. The surface emissions survey will be conducted using a Landtec's GEM-500 Gas Analyzer to monitor methane concentrations, a National Draeger Toxic Gas Monitor to measure H2S concentrations, and a GPS to record the locations. The air-quality analysis will be made as close the soil surface as reasonable (within 10 cm) and the survey will be conducted on 30 m intervals.

DRI has been in discussion with a couple of companies for conducting the subsurface characterization of gas emissions. We have selected The Regenesis Group for subcontracting to for installation and testing of gas production wells. Well installation and testing is planned for July. Five-80 foot deep wells will be installed in a dice pattern, whereby four are in a square at 200 ft spacing and one in the center. The drilling will be performed with an Air Rotary Casing Hammer (ARCH) drill rig.

The wells will be connected by 2 inch PVC pipe above ground to provide a composite analysis of gas production. Each well. Fig. 1, will consist of an 8 inch diameter hole, completed with 4 inch schedule 80 PVC. Perforations will be kept at least 15 to 20 ft below ground surface and a bentonite seal will be placed in the annual region above the screened section to prevent air intrusion. Methane, and O;,, will be monitored along with the gas flow rate to determine the gas production rate. These will be natural gradient (passive flow) tests conducted shortly after well installation, and repeated to the degree that funds permit. These data will determine the rate of release which will ultimately determine the potential for energy production. These data will also enable verification/calibration of the gas generation modeling for making long-term estimates of gas production.

C-2 APPENDIX D MODEL INPUT AND RESULTS FOR GAS ENRICHMENT AND PIPELINE INJECTION

The following screen shots were taken using the E-PLUS model to evaluate the cost effectiveness of different landfill gas-use options.

D.I Universal assumptions applicable to all gas-use options.

Figure D-l. Project Financial Assumptions.

D-l Figure D-2. Landfill waste acceptance and methane emissions using parameters L0 = 100 mVMg and k = 0.02 yr'.

Figure D-3. Landfill gas collection stage parameters.

D-2 Jfemssws f rri*' s' >.->i Si*iS( «•

V '^S5' 5, , ^5 -{ J •* NI ' y, i'

Figure D-4. Landfill gas splitter parameters.

D.2 Case 2: Model input and results specific to methane enrichment and sale.

Figure D-5. Case 2: Landfill gas treatment stage. D-3 i.t'ii",,,,, iL^l^iJ^^S^^^^^^^^^^-?^^-- • >s S *#••> fx^^>^>V $-•'•'• * |1500?? ' x- -x. -"-S # -5* f

^ $S00054. ' -x^y i i ' ^ $10 ttvt, x---* '<'< -^ f < ff V*VA 43^0000^, «• ^ ^ # ^> < v ^/ v ...• ^2.50 r * ^ f '-A ' ""/> v •* --••

Sv^ / x- $1500 c *-**>.> ' ' ' s <••

Figure D-6. Case 2: Landfill gas treatment stage costs.

Figure D-7. Case 2: Landfill gas enrichment stage.

D-4 Figure D-8. Case 2: Landfill gas enrichment costs.

Figure D-9. Case 2: Landfill gas compression stage.

D-5 £ X4.-.4X"

Figure D-10. Case 2: Landfill gas compression stage costs.

Figure D-ll. Case 2: Landfill gas pipeline stage.

D-6 ain*

Figure D-12. Case 2: Landfill gas pipeline costs.

Figure D-13. Case 2: Landfill gas methane sale stage.

D-7 vy

Figure 0-14. Case 2: Financial analysis of gas sale option for L0 = 100 mVMg and k = 0.02 yr' (i.e., best estimate methane production).

3 Figure D-15. Case 2: Financial analysis of gas sale option for L0 = 50 m /Mg and k = 0.01 yr' (i.e., low methane production). D-8 Figure D-16. Case 2: Financial analysis of gas sale option for L0 = ISO m'/Mg and k = 0.03 yr' (i.e., high methane production).

D.3 Cases 3 and 4: Model input and results specific to power generation and sale.

Figure D-17. Cases 3 and 4: Landfill Gas Treatment Stage. D-9 Figure D-18. Cases 3 and 4 : Landfill gas treatment stage costs.

; ' lf'<&*&£?'<*&m><,'&&ft'.f'i'>&'f}*<&'frtg

Figure D-19. Cases 3 and 4: Landfill gas electricity generation stage.

D-10 D.3.1 Model input and results for power generation with combustion turbine.

I ' *»«< \'f '; ' ,f, '<• "j. r^~' _»K^_ _28] jr^ i°°® JOOOO' 25j 90, 6HI _L_ J_

Figure D-20. Cases 3 and 4: Landfill gas electricity generation for combustion turbine.

Figure D-21. Cases 3 and 4: Landfill gas electricity generation for combustion turbine costs.

D-ll Figure D-22. Cases 3 and 4: Landfill gas electricity generation for combustion turbine interconnect stage.

Figure D-23. Cases 3 and 4: Landfill gas electricity generation for combustion turbine interconnect stage costs.

D-12 Figure D-24. Cases 3 and 4: Landfill gas electricity generation for combustion turbine power sale stage.

Figure D-25. Cases 3 and 4: Financial analysis for combustion turbine power sale using two different power prices (best estimate methane production).

D-13 — -^*-^lSX< ^'f?f.^}!-*-r-rj+Jf*rfJ*!'^r V v£jM£j««">- -- •rrrrrrrrrrfffffffffafr^ VBQWCOX'-Jp-WrV^V^'t^ssv^^^^^aW^^'^S^— TrffffJX.-fi&X'fj?. U-^"^^ Figure D-26. Cases 3 and 4: Financial analysis for combustion turbine power sale using two different power prices (low estimate methane production).

!.}<•'?'ICt? 3 i4l.^'/* % i/' ,?;'; , Wt'%;;„/-'} $f,/i""> - -M '''/;$-'">, V'1 ' '<

Figure D-27. Cases 3 and 4: Financial analysis for combustion turbine power sale using two different power prices (high estimate methane production).

D-14 D.3.2. Model input and results for power generation with internal combustion (1C) engine.

Figure D-28. Cases 3 and 4: Landfill gas electricity generation for 1C engine.

Figure D-29. Cases 3 and 4: Landfill gas electricity generation for 1C engine costs.

D-15 Figure D-30. Cases 3 and 4: Landfill gas electricity generation for 1C engine interconnect stage.

Figure D-31. Cases 3 and 4: Landfill gas electricity generation for 1C engine interconnect stage costs.

D-16 Figure D-32. Cases 3 and 4: Landfill gas electricity generation for 1C engine power sale stage.

Figure D-33. Cases 3 and 4: Financial analysis for 1C engine power sale using two different power prices (best estimate methane production).

D-17 Figure D-34. Cases 3 and 4: Financial analysis for 1C engine power sale using two different power prices (low estimate methane production).

Figure D-35. Cases 3 and 4: Financial analysis for 1C engine power sale using two different power prices (high estimate methane production).

D-18 (7/2000)

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