Green Parking Lot Resource Guide TABLE OF CONTENTS

INTRODUCTION ...... 1 CHAPTER 1: IMPACTS OF PARKING LOTS ...... 2 Environmental Impacts of Parking Lots ...... 2 Costs of Parking Lots ...... 5

CHAPTER 2: “GREEN” PARKING LOT TECHNIQUES ...... 7 Planning Aspects ...... 7 On-Site Stormwater Management ...... 8 Parking Surface Material Selection ...... 9 Landscaping and Irrigation ...... 9

CHAPTER 3: PLANNING ASPECTS ...... 10 Municipal Parking Requirements ...... 10 Parking Lot Placement and Aesthetics ...... 12 Linking Parking to Smart Growth ...... 13

CHAPTER 4: STORMWATER MANAGEMENT ...... 14 Green Parking Lot Stormwater Management Techniques ...... 14 BMP Pollutant Removal and Eff ectiveness ...... 17 BMP Cost Considerations ...... 18 Case Study 1: Stormwater Best Management (BMP) —Bloedel Donovan Park, Bellingham, Washington ...... 20

CHAPTER 5: ALTERNATIVE PARKING SURFACE MATERIALS ...... 22 Porous Pavement ...... 22 Alternative Pavers ...... 23 Design and Installation Considerations ...... 24 Maintenance of Permeable Pavement ...... 25 Infiltration & Pollutant Removal Eff ectiveness of Permeable Pavements ...... 27 Cost Considerations ...... 29 Case Study 2: Parking Surface Alternatives—Heifer International, Little Rock, Arkansas 31 Case Study 3: Parking Surface Alternatives—University of Rhode Island, Kingston, Rhode Island ...... 33

Green Parking Lot Resource Guide—February 2008 i CHAPTER 6: LANDSCAPING AND IRRIGATION ...... 35 Overview of Natural Landscaping and Irrigation ...... 35 Environmental Benefits of Using Natural Landscaping and Associated Irrigation ...... 38 Cost Effectiveness of Using Natural Landscaping ...... 40 Case Study 4: Landscaping and Irrigation—Heifer International, Little Rock, Arkansas .. 42

CHAPTER 7: REDUCED INFRASTRUCTURE BURDEN...... 44 Regional Stormwater and Wastewater Impacts ...... 45 Cost Eff ectiveness ...... 45 Case Study 5: Reduced Infrastructure Burden —Green Streets Program, Portland, Oregon ...... 47

KEY RESOURCES ...... 49

United States Environmental Protection Agency Office of Solid Waste and Emergenc Response (5101T) EPA-510-B-08-001 February 2008 http://epa.gov/oswer/iwg/

Recycled/Recyclable—Printed with vegetable oil based inks on 100% postconsumer, process chlorine free recycled paper.

Table of Contents ii INTRODUCTION

“ reen” parking lot is a term increas­ ■ Chapter 2 provides an overview of the ingly used to describe parking lots benefits of green parking lot development Gthat may incorporate a variety of techniques, briefly describing major plan­ environmentally preferable features, includ­ ning, design, and material considerations. ing a minimized footprint and/or impervi­ ■ Chapters 3 through 6 provide detailed ous surfaces, stormwater best management information on specific elements of sus­ practices (BMPs), and alternative parking tainable parking lot approaches including surface materials. To date, however, informa­ planning and design approaches (Chapter tion on green parking lots has been scattered 3), sustainable stormwater management across planning, construction, stormwater, techniques (Chapter 4), alternatives to engineering, and landscaping resources. The asphalt parking surfaces (Chapter 5), and goal of this resource guide is to present the water effi cient landscaping and irrigation fundamental planning and design concepts (Chapter 6). of a green parking lot and connect readers to existing resources on the environmental ben­ ■ Chapter 7 discusses how green parking efits and cost eff ectiveness of green parking lots can help municipalities reduce future approaches. This document is expected to be stormwater infrastructure and utility particularly useful for local government of­ maintenance costs. ficials involved in planning and development Case studies are included throughout the activities, as well as construction industry guide to provide real world examples of professionals (developers, project managers, green parking lot techniques. facility managers and other decision makers) interested in green parking lot technologies. Key resources consulted in developing this guide are listed in the back of the document. The guide is organized into seven chapters:

■ Chapter 1 describes the environmental and cost impacts associated with conven­ tional parking lots.

Green Parking Lot Resource Guide—February 2008 1 CHAPTER 1

IMPACTS OF PARKING LOTS

arking lots are a ubiquitous feature high rate and volume, negatively impacting of the American landscape. Perhaps the surrounding ecosystem. Hence, parking Pbecause they are so commonplace, lots degrade water quality, strain stormwa­ the significant environmental and cost im­ ter management systems, consume large pacts associated with parking lots are often amounts of land and resources, and enable overlooked. In this chapter, we provide an urban sprawl. Furthermore, materials used overview of these impacts. to construct parking lots have a variety of impacts on air, water, and biodiversity ENVIRONMENTAL IMPACTS OF throughout their life cycle. Some of the major PARKING LOTS environmental impacts of traditional parking The prevailing low-density American devel­ lots are described below. opment pattern (i.e., urban sprawl) necessi­ Water Quality Impacts tates reliance on automobiles, along with the construction of parking lots to accommodate, Parking lot runoff is a major contributor to and many times overaccomodate, demand non-point source pollution of our waterways. for parking. As parking lots have become a Conventional parking lots quickly move dominant feature of urban and suburban stormwater into receiving water bodies. As landscapes, their environmental impacts it flows across pavement, the water picks up have also become increasingly apparent. pollutants from the surface. This results in large volumes of polluted runoff entering Most parking lots are made of pavement—a surface water and groundwater resources, combination of asphalt concrete, the most negatively aff ecting water quality. widely used paving material in the United States, and aggregates such as sand, gravel, Contaminants in parking lot runoff can or crushed stone. Pavement is an impervi­ originate from a variety of sources, includ­ ous, heat absorbing material that collects ing the paving materials used to build them. stormwater on its surface and does not allow Recently, the U.S. Geological Survey (USGS) it to filter into the soil, inhibiting the natural pinpointed parking lot sealants as a signifi­ water cycle. With this in mind, parking lots cant source of non-point source pollution, have traditionally been built with the primary specifically polycyclic aromatic hydrocarbons goal of channeling stormwater into receiving (PAHs), a known carcinogen that can be toxic water bodies as quickly as possible, via means to fish and wildlife.1 Automobiles are also a such as gutters, drains, and pipes. As a result, major source of pollutants in parking lot run­ runoff that is contaminated with many types off , including antifreeze, oil, hydrocarbons, of petroleum residues, fertilizers, pesticides, metals from wearing brake linings, rubber and other pollutants from parking surfaces particles from tires, nitrous oxide from car enters receiving waters at an unnaturally exhausts, and grease.

CHAPTER 1—Impacts of Parking Lots 2 Water Supply Impacts ide (CO), volatile organic compound (VOCs), polycyclic aromatic hydrocarbons (PAHs), and Conventional parking lots consist of large ar­ carbon dioxide (CO ) during the manufactur­ eas of impervious surfaces that do not permit 2 ing process. The activities associated with the infiltration of water into the soil. Unlike the construction and maintenance of park­ natural conditions where rainwater filters ing lots also generate emissions, typically in into the ground, impervious surfaces halt the form of dust, fumes, and equipment and this process, inhibiting a watershed’s natural vehicle exhaust. For example, the use of hot hydrological cycle and preventing ground­ mix asphalt, a common process where the water recharge. As a result, water tables are asphalt is heated to extremely high tempera­ lowered, reducing streamflow during dry tures prior to application, can cause health periods, depleting water supplies, and exac­ problems for workers including headache, erbating the negative impacts of droughts. skin rash, fatigue, throat and eye irritation, Stormwater Management breathing problems, and coughing. Diesel Impacts emissions from on-site equipment can also cause similar health eff ects.2 In addition, the According to the USGS, an impervious, typical after effects of parking lot construc­ man-made surface will generate two to six tion, such as fewer trees and less vegetation times more runoff than a natural surface. In due to clearing, as well as heat island eff ect addition to the direct impact of paving, con­ (see below), also lead to higher amounts of ventional parking lots also typically include CO in the air. pipes, curbing, gutters, and drains to help 2 speed water off of parking surfaces. These Heat Island Effect systems cause runoff to move even faster Heat island effect (HIE) occurs in urban areas downstream, increasing the risk of stream where materials that have heat-absorbing flooding. Sewer systems often become over­ properties, such as asphalt, are prevalent. whelmed by the rapid runoff of stormwater, In urban areas, the combined effect of such causing them to overflow and, in the case of surfaces can cause a change in the energy combined sewer and stormwater systems, (temperature) balance, leading to hotter air discharge raw sewage into receiving water­ and surface temperatures. Recent research ways. In addition to the human health risks indicates that urban areas are 2 to 8ºF hotter related to combined sewer overflows, these in summer due to this increased absorbed discharges can cause algal blooms to form, heat.3 depleting aquatic oxygen levels and altering a waterbody’s habitat. Parking lots contribute significantly to HIE. Asphalt, one of the most common paving Air Emission Impacts materials used in parking lots, is a dark, heat Pollutant air emissions occur throughout absorbing material.4 When asphalt cools at the lifecycle of a parking lot. Asphalt cement night, all the heat it has absorbed during plants emit particulate matter, nitrogen ox­ the day is released into the air, slowing the rate of nighttime cooling. This hot surface, ides (NOX), sulfur oxides (SOX), carbon monox­

Green Parking Lot Resource Guide—February 2008 3 combined with stormwater runoff from the fauna. The velocity and volume of runoff from parking lot also aff ects surrounding water- parking lots can damage plant, fish and inver­ bodies. When water is forced to flow quickly tebrate habitat. During storm events, runoff off the lot’s surface, not enough time is al­ can erode stream banks and alter the natural lowed for evaporation to occur, again limiting shape of a waterway. Stream edge habitat natural cooling of the air. In addition, the land and stream channel protection removed clearing needed to create space for parking during the construction of the parking lot lots diminishes tree cover and other natural increases the potential for erosion. Sediments vegetation that can help shade land and entering the waterway as a result of erosion moderate temperatures. can smother habitat and stress aquatic organ­ isms. The turbidity created from the sedi­ The environmental impacts of the HIE are mentation can disrupt an aquatic ecosystem varied. Hotter temperatures can lead to by diminishing light transmission, reducing more CO emissions due to increased energy 2 plant growth, altering food supplies, interfer­ demand to cool neighboring buildings.5 HIE ing with navigation, decreasing spawning can also increase smog, and subsequently habitat, and reducing shelter. exacerbate pulmonary and cardiovascular health problems. During rain events, paved The contaminants in parking lot runoff also surfaces can transfer heat to runoff , increas­ pose a risk to wildlife. Toxic substances from ing the temperature of receiving waters. This contaminated ground and surface water sup­ warmer water can be detrimental to the natu­ plies have the potential to bioaccumulate in ral habitats of fish and other aquatic life. the tissue of fish and other organisms in the wildlife food chain. They can also accumulate Waste Impacts in sediments, posing risks to bottom feeding The traditional production and application organisms and their predators. of asphalt relies heavily on the use of virgin The impact of parking lots on water supplies stone and aggregate and non-renewable, aff ects local ecology. Unnaturally low stream petroleum-based materials. Use of fresh flows as a result of decreased infiltration asphalt in parking lot construction creates a can negatively impact deep water and swift lost opportunity for reusing waste products, flowing habitats. Impaired water quality, and such as recycled asphalt, which would reduce increased volume and velocity of runoff , can the amount of material sent to landfills lead to habitat loss, stress aquatic species, and increase the amount of virgin materi­ and have an overall negative eff ect on bio­ als conserved. The use of recycled asphalt is logical diversity in abutting areas. common in the construction of roads, but has yet to become prevalent in parking lot Decrease In Greenspace construction. Greenspace is a finite resource with a wide Disturbance of Habitat and Local range of intrinsic values, including conserva­ Ecology tion, recreation, and agricultural purposes, as well as its scenic qualities and contribution to Traditional parking lots can have a host of the overall character of a city or town. Proper negative impacts on adjacent habitat and

CHAPTER 1—Impacts of Parking Lots 4 management of greenspace is essential to ing walking and bicycling, and encourages achieving and maintaining sustainable com­ automobile travel, disconnecting communi­ munities. Nevertheless, greenspace areas are ties and decreasing the habitability of cities commonly paved to accommodate demand and towns. The resulting increase in vehicle for parking. For example, it is estimated that miles traveled and the associated high levels 30 to 40 percent of a typical American down­ of mobile source air emissions exacerbate town is used for parking spaces.6 air quality issues, and contribute to global climate change. Ineff ective local government zoning restric­ tions also result in the creation of larger areas COSTS OF PARKING LOTS of paved surface than necessary to meet the parking demand. Many municipalities require Beyond their environmental impacts, parking a minimum number of parking spaces per lots have economic and social costs related development project, often forcing devel­ to their construction—costs that are often opers to build more spaces than needed much higher than consumers realize. More­ to meet actual demand. For instance, com­ over, parking costs are shouldered by many mercial parking lots frequently have 60 to stakeholders, including developers, local 70 percent vacancy rates.7 Parking stall sizes governments, parking users, and community required by zoning can also be larger than members. Below we describe the types of necessary, eliminating opportunities to alter costs related to parking lot construction, as parking lot configuration designs to achieve well as who pays. higher car capacity and minimize impervious On-site Costs surface area. On-site costs include the construction, opera­ Conventional parking lots are often viewed as tion, maintenance, and disposal of materials unattractive, hostile, and sometimes unsafe needed to develop and maintain parking lots, areas. In contrast, green parking lots with including paving materials and infrastructure urban greenscaping provide aesthetic ben­ such as gutters and curb cuts. In addition, efits, including privacy and noise reduction, on-site costs include the cost of parking lot to landowners and to communities. These landscaping that, depending on the shrubs, benefits are lost when conventional parking trees, and turf chosen, vary in their need for lot construction and paving techniques are mowing, pruning, and irrigation. These costs used. are typically paid by developers, although Urban Sprawl local governments sometimes subsidize infrastructure costs. HIE can add to parking Urban sprawl and prevailing low-density lot user costs, by decreasing an automobile’s development patterns characterized by free, value by quickening the deterioration of the plentiful parking reinforce dependence on vehicle’s paint, plastics, and tires while on automobiles for commuting to work, shop­ the lot. HIE can also shorten the life of the ping, and social activities. Thus, conven­ pavement, causing it to become brittle and tionally designed parking is an enabler of weak (a cost to parking lot owners); and can urban sprawl. Conventional parking creates increase the energy costs of adjacent build- barriers to alternative transportation, includ­ Green Parking Lot Resource Guide—February 2008 5 ings due to the hotter air temperatures (a Distributional Issues cost to the building owner and potentially to Parking lots provide a value to consumers third parties). who use them, but result in negative im­ Infrastructure Costs pacts for neighbors and other community members who do not use them. Community Local governments bear the brunt of infra­ members would be better served by almost structure costs related to parking. The high any other land use, particularly in cases of volume and velocity of polluted run-off from excessive sizing of paved areas, which can parking lots can stress stormwater man­ reduce adjacent property values. agement systems and hasten the need for repairs, upgrades, and expansions to handle Community Development Costs water flow and treat runoff . Flooding caused Parking lots and associated sprawl decrease a by runoff can also degrade bridges, roads, community’s habitability, livability, and sense and other parts of a city’s infrastructure. of identity, a cost to all community members. Additionally, groundwater shortages due to Unattractive expanses of pavement placed disruption of the water cycle can increase in front of buildings create voids and discon­ the frequency, and thus cost, of pumping nectedness, discouraging pedestrian-friendly groundwater. communities and alternative methods of Opportunity Costs transport. The presence of multiple conven­ tional parking lots can also signal develop­ Parking lots consume large areas of open ers that a community accepts urban sprawl space that could otherwise be used for development. This signal can create a cyclical alternative, higher value purposes, such as eff ect on a community’s future development parks, wildlife habitat, recreation, agriculture, patterns. Subsequent developments in these housing or other businesses. Building park­ areas are far more likely to have a similar pat­ ing instead of other types of development tern of urban sprawl, further disconnecting could reduce the property tax base, a cost the link with any older non-sprawl develop­ to local governments and local taxpayers. ment, and eroding or precluding unique Enforced minimum parking requirements characteristics that establish a community’s do not benefit developers either. They limit sense of place. the development potential of land; the more parking spaces that are required, the less land available for more profitable uses. This can be costly because parking is relatively expensive to construct and yields little return, or no return where parking is free.

CHAPTER 1—Impacts of Parking Lots 6 CHAPTER 2

“GREEN” PARKING LOT TECHNIQUES

nnovative approaches to planning and of transport, through company support or design can greatly mitigate many of the subsidies. Another alternative is for mu­ Inegative impacts of parking lots, includ­ nicipalities to institute an optional fee that ing diminished recharge of groundwater, developers can pay towards an appropriate high rates of stormwater runoff , and non- municipal fund, such as a traffi c mitigation point source pollution, by decreasing imper­ fund, in lieu of meeting minimum parking vious surface area, protecting water quality, requirements.8 reducing stormwater management and Depending on the site, developers may not maintenance costs, and increasing aesthetic opt for constructing less parking because it value. Below, we introduce green parking lot may make a site less marketable. A technique techniques, many of which are described in applicable in this case would be to set park­ detail in subsequent chapters. ing maximums and/or area wide parking restrictions, which would limit the number PLANNING ASPECTS of spaces allowed across a larger area, eve­ Local planners regularly reinforce car depen­ ning the playing field for the marketability of dence through zoning bylaws that, although sites in the area. meant to meet a community’s parking needs, can result in an oversupply of parking. As a Beyond reducing the number of parking result, cities and towns are increasingly trying spaces required, municipalities and develop­ new approaches to parking management ers can also encourage practices that reduce that allow for greater flexibility and adapt­ stall dimensions by creating more compact ability by determining parking space num­ car spaces and realistic stall size require­ bers on a project-specific basis, rather than ments. Some local zoning laws currently through a one-size-fits-all regulation. require unnecessarily large stall dimensions that are bigger than even the largest SUV.9 One such technique is to reduce minimum In many cases smaller, more realistic, stall parking requirements based on project sizes would be suffi cient while reducing the location or demographics. For example, local amount of disturbed land and impervious governments can encourage projects that are surface associated with a project. located near public transportation to reduce the demand for parking spaces. Adaptations Improving the aesthetic of the parking lot is of this technique include municipalities also a central technique in green parking lots. allowing a reduction in the minimum park­ For instance, placing a parking lot behind a ing requirements in return for a developer/ building rather than in front of it creates a employer agreeing to implement a transpor­ more inviting and pedestrian-friendly envi­ tation demand management program to en­ ronment. Reducing the number of curb cuts courage employees to use alternative modes also decreases the frequency of pedestrian/

Green Parking Lot Resource Guide—February 2008 7 traffi c interaction, thus making for a more pedestrian-accessible area. These practices aim to improve the character of the develop­ ment while maintaining accessibility to the lot. Additionally, parking lots can be divided into two or more parking areas, again project­ ing a more visually welcoming appearance. Strategically sloped vegetated strips are a better option than conventional grassy parking islands for collecting and fi ltering runoff . The impact of locating a parking lot at the front of a building can be mitigated by by 25-30 percent compared to conventional providing ample space between the lot and approaches.10 the road, and then creating a buff er with Stormwater BMPs include structural controls landscaping, fencing, or a wall. Landscaping and bioengineering techniques designed to inside the parking lot is also an important facilitate natural water cycling processes (i.e. technique. Beyond making the parking lot evaporation, transpiration, and groundwater more visually pleasing, vegetation and land­ recharge) by capturing, filtering, infiltrating, scaping (including trees) around and inside and/or storing stormwater. Components the parking lot reduce HIE and help to absorb of these soil- and plant-based systems can CO emissions. Landscaping is discussed 2 carry out one or more of the aforementioned below. functions, including some that store water for Chapter 3 provides detailed information on various durations (from 24 hours to perma­ green parking planning. nent storage). Examples of BMPs include swales, vegetated buff er strips, and bioreten­ ON-SITE STORMWATER tion areas. MANAGEMENT Unlike traditional stormwater management Innovative stormwater management strate­ systems designed only for effi ciency in storm- gies are increasingly being incorporated into water removal, which can lead to negative parking lot design as part of the overarching downstream eff ects, BMPs represent a shift concept of Low Impact Development (LID). towards a sustainable approach to storm- LID stormwater techniques (also known as water management. Thus, in the context of Best Management Practices, or BMPs) man­ parking lots, BMPs add value by minimizing age stormwater on-site, reducing negative environmental impacts of runoff , and often impacts on receiving waters and municipal lower site development costs while improv­ stormwater management systems, and ing aesthetics. decreasing the need for costly infrastruc­ ture such as pipes, gutters, and curbs. Done Chapter 4 provides detailed information on on a small-scale, these controls attempt to greener stormwater management and BMPs. mimic the pre-development ecological and hydrological processes of an area and can reduce stormwater and site development design, construction, and maintenance costs

CHAPTER 2—”Green” Parking Lot Techniques 8 PARKING SURFACE MATERIAL economical for developers than incurring SELECTION the rising costs in some states for disposal of construction, demolition, and clearing debris The negative impacts associated with large in landfills. impervious surface areas in parking lots can be reduced through the use of new perme­ Chapter 5 provides detailed information on able materials as substitutes for pavement. greener choices for parking surface materials. A number of paving substitutions have been developed to reduce the range of environ­ LANDSCAPING AND IRRIGATION mental impacts associated with the use of Green parking lot techniques work to mini­ pavement. Types of permeable and semi­ mize the amount of land cleared for construc­ permeable alternative pavers include gravel, tion, conserving as much of a site’s natural cobble, concrete, wood mulch, brick, open vegetation and open space as possible, jointed pavers filled with turf or aggregate, and retaining habit for local wildlife. When turf blocks, natural stone, and pervious designing a parking lot area, landscapers concrete. can use native trees and shrubs rather than Based on a site’s characteristics (i.e. traffic non-indigenous species, which are more suit­ volume, soil type, climate etc.), alternative able to local climates and, therefore, require pavers may not be an option for the entire less irrigation. The benefits of increasing the surface of primary parking areas.11 However, amount of greenscape in and around park­ ing areas include reduction of CO in the air; in many cases, the aisles and driveways can 2 be constructed using conventional pave­ improved stormwater runoff management ment, while alternative pavers can be used in including water storage; increases aquifer parking stalls, crosswalks, and overflow lots. recharge and flood protection; and increased Alternative pavers slow the flow of runoff , human comfort through mitigation of HIEs. allowing it to filter into the soil, sustaining an Wetlands preservation or creation is particu­ area’s natural hydrological cycle, and in some larly beneficial, as they can act as natural cases, allowing microbes to break down con­ bioretention basins, providing water quality taminants before entering the soil layer. improvements, flood protection, and ero­ sion control. Wetlands also provide excellent Opportunities for materials recycling ex­ habitat for local avian and fish species, and ist in the management and construction of are invaluable for water storage; one acre of parking lots. For example, the use of recycled wetlands can store over million gallons of asphalt in parking lot construction is not only water.12 environmentally beneficial, but can make economic sense. Other environmentally pref­ Chapter 6 provides detailed information on erable materials, such as recycled rubberized green parking lot landscaping and irrigation. asphalt, may also be used in parking lot con­ struction. Recycling materials can be more

Green Parking Lot Resource Guide—February 2008 9 CHAPTER 3

PLANNING ASPECTS

arking lot design and parking avail­ quantity of spaces in a parking lot. It is these ability are vital to transportation regulations that manage a community’s park­ Pmanagement throughout the United ing capacity, and thus a large amount of its States. Parking availability may determine a impervious surface area. customer’s willingness to visit a business, and Zoning requirements for developers to it is often a sought after feature in urban resi­ provide off-street parking first began in the dential areas. However, parking lots should 1930s as a solution to an on-street parking be designed effi ciently so that spaces are shortage. Over the years, off -street parking used frequently and not left empty a majority requirements expanded in response to the of the time. When developing a parking lot, a population’s dependence on automobiles. number of factors combine to determine the Today, according to the U.S. Department of lot’s size, layout, and design. These decisions, Transportation, 87 percent of trips of less made during the planning stages of a devel­ than 50 miles are made by personal motor opment, can transform a parking lot from a vehicles.13 Americans have become accus­ sparsely landscaped expanse of impervious tomed to the availability of free parking and paving to a space that is more aesthetically automobile travel, rather than public transit pleasing, land effi cient, and community and or other alternative methods, even for very environmentally friendly. short distance trips. Increased parking avail­ Local governments can use better park­ ability encourages more driving, more driving ing planning as a tool to promote infill and requires more parking, and so on. smart growth developments while reducing One of the most important local parking the direct environmental impact of park­ ordinances addresses minimum space re­ ing. In many cases, revisions to zoning and quirements, or parking ratios. Typically, local other parking ordinances may be needed to governments require developers to construct achieve better parking planning. This chap­ the minimum number of parking spaces ter provides a summary of parking planning needed to satisfy peak demand. These mini­ considerations that have environmental mum parking regulations often result in an implications, including municipal parking oversupply of parking. One study found that lot regulations, parking lot aesthetics and the average parking supply at worksites is 30 design, and the connection between parking percent greater than peak parking demand.14 and smart growth. In many instances, minimum parking require­ ments are inflexible to adaptation or vari­ MUNICIPAL PARKING ances. Also, the methods to determine these REQUIREMENTS minimum parking requirements are often In most urban and suburban areas, a num­ excessive and over-generalized, leading to an ber of zoning laws govern the layout and oversupply of parking.15 In addition, although

CHAPTER 3—Planning Aspects 10 municipalities regulate the minimum number City of San Francisco, where city planners of parking spaces, they typically do not put eliminated minimum parking require­ a cap on the maximum. Thus, developers ments for development within a half mile can frequently construct even more than the of train stations and one-quarter mile of required minimum, which is often the case major public transit routes.17 at large retail developments, leading to a Municipalities can also consider the land further surplus in supply. uses in the surrounding area. For instance, In addition to requirements for the number it is possible that existing nearby develop­ of spaces in a parking lot, regulations for the ment and parking may already provide size of each space are also common. Some some of the parking necessary to sup­ local zoning laws require unnecessarily large port a new development. Mixed used stall dimensions that are bigger than even developments often have natural parking the largest SUV.16 In many cases, smaller flexibility; an offi ce where peak parking stall sizes would satisfy parking needs while demand occurs during the day can share reducing impervious surface, and the entire the same parking spaces with restaurants, footprint, of the parking lot. entertainment venues, or residential units that have peak parking demands at night Re-thinking Municipal Parking and on weekends. Shared parking is also Requirements an option for single use developments in There are a number of planning alternatives mixed-use areas.18 to minimum parking requirements that lead­ • Maximum Limits on Parking—The ing local governments throughout the United opposite of parking minimums, parking States are implementing to minimize land maximums limit the number of spaces dedicated to parking. These include reducing that a developer can construct, which is minimum parking requirements; assessing often determined by the development’s parking needs on an individual project basis square footage. Portland, Oregon is one rather than using a generic formula; en­ city that has successfully implemented couraging shared parking; and establishing the use of parking maximums. Benefits parking maximums, area wide parking caps, of such a policy include open space in-lieu parking fees, and reduced parking preservation, reduction in impervious space dimensions. surface area, traffi c congestion reduction, • Reduced minimum parking require­ promotion of alternative transport, and ments—Parking requirements should the development of pedestrian-friendly be determined on a project-by-project urban design. For developers, such limits basis instead of by formula, taking into mean lower parking lot construction consideration how a project’s location can costs.19 Similar policies include setting shape parking needs. This approach may both a parking minimum and maximum, decrease the required parking capac­ or determining a median parking ratio. ity where there is accessibility to public • Area wide parking caps—Municipalities transportation and/or a high level of foot can control the amount of parking by and bike traffi c. Such was the case for the Green Parking Lot Resource Guide—February 2008 11 setting limits on the total amount of park­ stalls to achieve the greatest car capacity, ing spaces allowed in a certain area. This again reducing the amount of land neces­ strategy is being used in major U.S. cities sary for the lot. including Boston and San Francisco. Such regulations require greater research and PARKING LOT PLACEMENT AND planning efforts by the city or town to AESTHETICS ensure that the parking cap is appropriate Parking lots have been described as “sterile, and reasonable, but if done properly, it unattractive environments that deaden city can be very successful in minimizing the and suburban streets alike, further isolate land area used for parking and encourag­ users and preclude lively pedestrian-friendly ing use of public transportation. This op­ streets.”24 Although all parking lots do not tion is appropriate for areas with adequate match this description, many are eyesores access to public and alternative transpor­ that inhibit the usability and walkability of tation, as well as desirable location that an area. Several techniques can be incorpo­ would outweigh the perceived drawbacks rated into the design and layout of a parking 20 of more limited parking. lot to improve aesthetics and help connect • In-Lieu Parking Fees—Towns such as parking lots to community design. This not Berkeley, California, Lake Forest, Illinois only benefits the user, but also the organi­ and Orlando, Florida incorporated systems zation or business adjacent to the lot, as a of in-lieu parking fees. This optional fee more pleasing atmosphere will help draw in is offered to developers by municipalities the public. Plantings around the perimeter, in-lieu of meeting minimum parking re­ especially trees and shrubs, can screen the lot quirements. This fee is typically allocated from passer-bys and break-up the otherwise to an appropriate municipal fund, such as continuous strip of asphalt and cars from a traffi c mitigation fund.21 An alternative the street to the parking lot. This can also be under the in-lieu system is that in return achieved through the use of fencing or a wall. for the developer’s fee, the city provides Vegetation can also be used to divide one existing centralized, off -site parking to the large lot into two or more smaller lots, again new development’s tenants and visitors.22 increasing the site’s visual appeal. Equally important, landscaping within the lot pro­ • Reduced stall size requirements— vides an environmental benefit by decreasing Adjusting a local government’s stall size dust, wind, noise, glare and air pollution; and requirements may reduce impervious sur­ minimizing heat island eff ect.25 face coverage as well. Alternatives include creating a certain number of compact The placement of a parking lot is a simple, car spaces and/or limiting stall dimen­ yet fundamental feature that can improve a sions to feasible sizes. For example, in the development’s attractiveness. A majority of town of Needham, Massachusetts, up to parking lots are placed in the front of build­ 50 percent of off -street parking can be ings, between buildings and streets, requiring reduced dimension spaces designed for pedestrians and bicyclists to cross expanses compact cars.23 If possible, developers can of parking in order to enter a building. Alter­ also adapt the layout and angle of parking natively, parking lots could be placed at the

CHAPTER 3—Planning Aspects 12 rear of a building, increasing the intercon- States, and promoting sustainable land use nectedness between pedestrians and the patterns. With many cities designed around built environment. This simple zoning change use of the automobile, planners are often is incredibly eff ective in shifting the orienta­ presented with the conflicting challenge of tion of a streetscape from cars to pedestrians. promoting smart growth development while This also helps give the community a greater supporting the parking needs of a popula­ sense of place and interconnectedness. In tion. Green parking planning approaches recognition of such benefits, the City of Fort support smart growth by creating more Collins, Colorado requires that no more than sustainable land use patterns and decreasing 50 percent of the parking for a retail devel­ the environmental impacts of conventional opment be located between the principle parking lot development. By promoting and building and the primary abutting street.26 supporting alternative transport and com­ Limiting the number of curb cuts also makes muting, local governments may reduce the a parking lot more pedestrian friendly and parking needs. inviting. Furthermore, by minimizing the A concept linked to smart growth is “transit­ number of vehicular entries to parking areas, oriented development,” defined as develop­ pedestrian mobility is improved, and pedes­ ment placed within close proximity of public trian/traffi c is minimized. transportation, designed to create walkable communities and alleviate traffi c conges­ LINKING PARKING TO tion and environmental impacts caused by SMART GROWTH urban sprawl. When building parking lots, Smart Growth is a state and local government local governments can encourage or require planning movement aimed at improving the developers to incorporate features that help long-term habitability and sustainability of reduce automobile reliance, such as bicycle cities and towns by minimizing environmen­ racks. Employers can support use of alterna­ tal impacts, improving human health, build­ tive transport options by subsidizing the cost ing a sense of community, creating walkable of public transit, encouraging participation neighborhoods, promoting traditional and in a commuting program, and/or providing alternative transport, and preserving open shower facilities on-site so that staff can bike space. Most fundamentally, smart growth to work. entails moving away from the urban sprawl development pattern common in the United

Green Parking Lot Resource Guide—February 2008 13 CHAPTER 4

STORMWATER MANAGEMENT

pivotal component of green park­ project alone can be minimal, but multiplied ing lots is the inclusion of innova­ by the current, and growing, number of A tive stormwater management commercial and residential parking lots, the techniques, often referred to as stormwater combined eff ect of stormwater runoff has be­ “best management practices” (BMPs). BMPs come the leading cause of non-point source are practices, techniques, and measures pollution to our waterbodies.29 that prevent or reduce water pollution from As discussed in Chapter 2, the environmen­ non-point sources (i.e. runoff ) using the most tal effects of increased volume and velocity eff ective and practicable means available.27 of stormwater include not only diminished Stormwater management BMPs often include water quality in surrounding waterbodies, engineered, on-site systems that, when but also: coupled with reduction of impervious surface area, can help significantly reduce detrimen­ • Degradation of stream channels resulting tal environmental effects and infrastructure erosion and sedimentation; burden from stormwater runoff . • Minimized groundwater recharge, which Increased development and conventional can diminish water flow in the dry weath­ stormwater systems have significantly er, and lead to poorer water quality during changed the characteristics of stormwater low flows; flow from land into receiving waters. Accord­ • Higher water temperatures, which ing to the Natural Resources Defense Council, negatively impact aquatic organisms and the amount of rain converted to runoff under plants; and natural conditions is less than ten percent of the rainfall volume.28 However as more devel­ • More frequent and severe flooding. 30 opment occurs, rainwater or snow melt that This chapter provides an overview of green would have infiltrated into the soil, evapo­ parking lot stormwater management BMPs rated into the air, or been absorbed by plants, that can help mitigate these impacts, in­ instead flows quickly off of the pavement as cluding information on pollutant removal stormwater runoff . Moreover, conventional effi ciency and cost considerations. stormwater management exacerbates this problem. Conventional parking lot stormwa­ GREEN PARKING LOT STORMWATER ter management typically consists of costly MANAGEMENT TECHNIQUES systems of man-made drains, pipes, gutters, storm ponds, and paved channels that direct Green parking lots off set environmental im­ runoff from impervious lots into storm drains pacts of parking by using on-site stormwater and neighboring waterbodies. The environ­ infrastructure that more closely mimics the mental ramifications of one development natural water cycle, and manages stormwater

CHAPTER 4—Stormwater Management 14 through eff ective rainfall retention, pollutant ter runoff , and often are incorporated to removal, and water infiltration. Although still pre-treat and remove sediment before in the early stages of wide-spread implemen­ water enters infiltration devices such as tation, cities and towns are recognizing the bioretention areas.34 Other benefits in­ benefits of stormwater BMPs, and many have clude protection of riparian areas, habitat introduced both voluntary and mandatory creation, and streambank stability. policies for their inclusion in development Vegetated filter strips are frequently used projects.31 in combination with riparian buff ers, an­ Some of the most commonly used structural other common BMP, to increase pollutant BMPs are described below. It also should be removal eff ectiveness. Riparian buff ers noted that incorporating BMPs is not lim­ are vegetated strips along waterways that ited to new development. As illustrated by trap and filter contaminants, encourage the case study of building a rain garden at infiltration, and slow stormwater flow. Bloedel Donovan Park in this chapter, exist­ They also help to preserve streambank ing parking lots can be retrofitted to include stability. them. • Bioretention Areas (Rain Gardens) • Swales One of the more well-know BMPs, biore­ Swales are open channels or depressions tention treatment areas (a.k.a., rain with dense vegetation used to transport, gardens) consist of a grass buff er strip, decelerate, and treat runoff . In parking shallow ponding area, organic layer, plant­ lots, they are designed to help direct ing soil, and vegetation. These areas are water into bioretention areas. Swales can typically used in parking lot islands. Unlike come in the form of a grassed channel, dry swales, bioretention areas are well-suited swale, or wet swale. They can be used in for parking lots in denser, urban areas most climatic regions of the United States, with less available open space. but may be unsuitable for densely urban • Dry Detention Basins areas as they require a large amount of pervious surface area.32 A dry detention basin is a vegetated basin with controlled outlets, designed to • Vegetated Filter Strips/Riparian detain runoff (lowering flows and reduc­ Buff ers ing velocity) for a short amount of time Vegetated filter strips are flat pieces of (e.g. 24 hours or less), partially removing land with low slopes, which are designed pollutants before the water is discharged. to encourage natural sheet flow of storm- This helps limit flooding and other storm- water as opposed to channeled runoff . water impacts, such as stream channel Vegetated filter strips are well suited for erosion and wildlife habitat destruction. low-density development or areas with Dry extended detention basins are better less concentrated amounts of runoff .33 suited for pollutant removal than standard They function by using soil and vegeta­ dry detention basins because they retain tion to remove pollutants from stormwa­ the water for an “extended” period of time

Green Parking Lot Resource Guide—February 2008 15 (i.e., up to 48 hours). They are eff ective and filled with stone to form a subsurface at treating certain runoff contaminants, basin, where water is stored until it infil­ particularly those contained in spring trates into the soil. This system greatly re­ and winter runoff in colder climate areas. duces the volume of runoff, and is particu­ However, because water temperature larly good for groundwater recharge as it increases while in this type of system, dry allows a significant amount of rainwater to detention basins discharge warmer than infiltrate. Both of these BMPs are consid­ natural water into waterbodies, which ered eff ective for pollutant removal when should be taking into consideration. Both used in conjunction with a pre-treatment dry detention and dry extended detention BMP such as a swale. However, potential basins are normally dry between storm drawbacks include higher failure rates events, thus giving them their name.35 due to improper design and maintenance, limited site applicability, and increased • Wet Retention Basins sediment clogging.38 Wet retention basins are designed to cap­ Porous pavement is another type of infil­ ture, filter, store, and infiltrate storwmater, tration technique used in green parking and have storage capacity adequate for lots; as it is also an asphalt alternative, it flood volumes of water. Because they have is discussed in Chapter 5: Parking Surface the capacity to store a permanent pool of Materials. water, wet basins can be very eff ective for water control, and can provide the bene­ • Constructed Wetlands fits of aesthetic value and wildlife habitat, Constructed wetlands are designed to both terrestrial and aquatic. Although not capture, filter, and store stormwater simi­ suitable for smaller areas because of their lar to a wet retention basin. However, they size, when applicable, retention basins are also contain a large quantity of wetland a very eff ective BMP.36 vegetation and have wetland channels. • Infi ltration Systems Although they are not built to replicate all of the ecological functions of wetlands, Infiltration systems are designed to constructed wetlands help simulate the capture and retain stormwater runoff , natural water cycle, recharge groundwa­ allowing water to gradually infiltrate into ter, remove pollutants, reduce erosion, the ground over a period of hours or days, and provide wildlife habitat. They are depending on the design.37 Two common considered to be a very eff ective pollutant infiltration systems used in green parking removal option.39 Constructed wetlands lots are infiltration basins and infiltration have a few limitations; they are not ap­ trenches. An infiltration basin is an open plicable in arid climates and, due to their depression that covers a relatively large large size, they are not suitable for dense area. It is constructed to work in conjunc­ urban areas. tion with filter strips or swales, which help direct runoff from a parking surface into It is not necessary for developers to in­ the basin. Infiltration trenches are shallow corporate all available green stormwater excavated ditches lined with filter strips techniques into a project; rather, they should

CHAPTER 4—Stormwater Management 16 determine those useful for specific site condi­ source of pollutants in parking lot runoff , in­ tions. Considerations should include all fac­ cluding antifreeze, oil, hydrocarbons, metals tors that aff ect the amount, speed, and pol­ from wearing break linings, rubber particles lutant loadings of runoff : soil type, the slope from tires, nitrous oxide from car exhausts, and landscape of the site, amount of impervi­ and grease. Other polluting materials include ous surface, local precipitation patterns, and pesticides, fertilizers, litter, pet waste, dirt, rainfall surface retention.40 Carefully choos­ and sand.45 ing the appropriate BMP(s) is important to One of the main goals of a green parking lot avoid any secondary environmental impacts is to decrease pollutant levels in stormwater caused by the use of an inappropriate BMP. runoff as much as possible before it enters a BMPs should address peak discharge, runoff waterbody. Exhibit 1 shows a range of pol­ volume, infiltration capacity, base flow levels, lutant removal effi ciencies for selected BMPs. ground water recharge, and maintenance of Understanding the effectiveness of each BMP water quality, so that they are ideally man­ for pollutant removal is a complex undertak­ aged in the pre-development stormwater ing because pollutant removal is aff ected by filtration conditions of the site.41 a large number of variables. Fundamentally, It should be noted that BMPs are helping to removal eff ectiveness depends on: 1) BMP meet the Clean Water Act’s mandate to “re­ type, 2) the quantity of runoff treated, and store and maintain the chemical, physical and 3) the type of pollutant being removed.46 biological integrity of the Nation’s waters”.42 Variation in one of these factors can aff ect By 2025 the U.S. population is predicted to a BMP’s effi ciency. For example, infiltration grow 22 percent, which could mean an ad­ trenches show a high pollutant removal ef­ ditional 68 million acres of development, a ficiency for pathogens, but much lower for good fraction of which will be dedicated to phosphorus. However, these eff ectiveness parking.43 Thus, BMPs may play a larger role ranges can vary based on the climate, soil, in the future to mitigate non-point water and land type of a particular site. Infiltra­ pollution. tion trenches may be less effective in colder climates when surface waters freeze and can­ BMP POLLUTANT REMOVAL AND not allow runoff to flow into them, a limita­ EFFECTIVENESS tion that can be partially remedied through Stormwater can carry a number of harmful proper design and maintenance, but may still 47 pollutants, and is the prime contributor to reduce pollutant removal eff ectiveness. non-point source pollution. Runoff contami­ As seen in Exhibit 1, not all BMPs have a high nants can originate from a variety of sources, level of pollutant removal eff ectiveness. including the paving materials used to build Instead, they serve other roles in control­ the parking lots. Recently, the USGS pin­ ling the impacts of runoff. This is the case for pointed parking lot sealants as a large source dry detention basins, which serve to reduce of non-point source pollution, specifically peak discharges of stormwater to neighbor­ polycyclic aromatic hydrocarbons (PAHs), a ing waterbodies, as well as limit erosion and known carcinogen that can be toxic to fish downstream flooding. and wildlife.44 Automobiles are also a major

Green Parking Lot Resource Guide—February 2008 17 EXHIBIT 1: BMP EFFECTIVENESS

Typical Pollutant Removal Effi ciency (percentage) BMP Type Suspended Nitrogen Phosphorus Pathogens Metals Solids Dry Detention Basins 30-65 13-45 15-45 <30 15-45 Retention Basins 50-80 30-65 30-65 <30 50-80 Constructed Wetlands 50-80 <30 15-45 <30 50-80 Infi ltration Basins 50-80 50-80 50-80 65-100 50-80 Infi ltration Trenches/ 50-80 50-80 15-45 65-100 50-80 Dry Wells Grassed Swales 30-65 15-45 15-45 <30 15-45 Vegetated Filter Strips 50-80 50-80 50-80 <30 30-65

Source: U.S. EPA, 1993, Handbook Urban Runoff and Pollution Prevention Planning, EPA-625-R-93-004, taken from Purdue Uni­ versity Engineering Department’s Long-Term Hydrologic Impact Assessment (L-THIA): http://cobweb.ecn.purdue.edu/~sprawl/ LTHIA7/lthia/lthia_index.htm.

BMP COST CONSIDERATIONS constructing a BMP considerably because of excavation costs. Innovative structural stormwater BMPs are more eff ective than conventional storm- Another significant variable in the compara­ water management in removing pollutants tive cost of BMPs is the value of land; in areas and maintaining the environmental quality where real estate prices are high, construct­ of a site. However, because some of these ing a BMP may take up too much space to be techniques are relatively new and have not cost eff ective.49 BMPs operation and mainte­ achieved market penetration, it is not clear nance costs can also be significant. The long- their costs compare to conventional storm- term cost to maintain certain, more complex, water management approaches.48 Calculating stormwater BMPs over a 20-25 year period the cost-eff ectiveness of a stormwater BMP can be close to its initial construction cost.50 is a very site-specific endeavor, and current However, some BMPs, such as swales and cost information is limited and inconsistent. bioretention areas, are less expensive to build The main factors affecting the relative costs than their conventional counterparts of pipe of BMPs include the cost of land, engineering and gutter systems. These BMPs can decrease and design, permitting, construction, and development costs by reducing or eliminat­ operation and maintenance. These costs can ing the high cost of conventional stormwater vary greatly due to individual site characteris­ infrastructure such as piping, gutters, and tics such as climate, topography, government drains, as well as reduced long-term mainte­ regulations, soil type, time of year of con­ nance costs for such systems. Furthermore, struction, drainage, accessibility of equip­ some BMPs, such as constructed wetlands, ment, and economics of scale. For instance, may increase the property value by creat­ very rocky soils may increase the cost of ing a water feature and vegetation that has

CHAPTER 4—Stormwater Management 18 high aesthetic value. Developers may also protect the health of waterbodies, but also gain from local government incentives that because they can avoid long-term costs. encourage incorporating structural stormwa­ Without stormwater BMPs, many waterbod­ ter BMPs. For instance, the City of Portland, ies and water infrastructure may deteriorate. Oregon will give up to a 35 percent discount Taxpayers bear the cost burden to slow off its stormwater utility fee to properties or repair damage caused by downstream with on-site stormwater management.51 In flooding, stream and aquatic habitat dete­ addition, some costs are tax deductible, and rioration, and repairs and upgrades to worn operating costs may be fully deductible as town stormwater infrastructure systems, all expenses in the year they are incurred.52 of which are very expensive and time-con­ suming.53 Infrastructure costs associated with Although the costs of BMPs vary by site and stormwater management and how green type, they are almost always a good invest­ parking can help mitigate these costs are ment from the perspective of local govern­ discussed further in Chapter 7. ments and taxpayers, not only because they

Green Parking Lot Resource Guide—February 2008 19 CASE STUDY 1: STORMWATER BEST MANAGEMENT PRACTICES (BMP) BLOEDEL DONOVAN PARK, BELLINGHAM, WASHINGTON54

Stormwater runoff in Bellingham, Washing­ ton, like much of the U.S., is a foremost water quality issue. The Washington Department of Ecology estimates that roughly one-third of the state water bodies with pollution related problems are impaired because of stormwa­ ter runoff impacts. In an effort to protect the receiving waters of nearby Lake Whitcom from such impacts, City of Bellingham of­ ficials chose to retrofit stormwater manage­ ment at the heavily used Bloedel Donovan Park parking lot. Rather than choosing a conventional technique, they elected to build an innovative rain garden to manage storm- The raingarden in Bloedel Donovan Park helps protect the water quality in nearby Lake Whatcom, and recharge groundwater supplies. water on-site. of drain rock, and topped with a layer of DESIGN AND CONSTRUCTION fabric to constrain the sand and restrict Designed on a 550 square-foot section of the any plants from growing through. An parking lot near the catch basin, the park’s 18- to 24-inch layer of sand composed of rain garden supports runoff from 80 parking twenty percent organic materials is the spaces and two parking lanes. To meet water top layer . quality guidelines, the rain garden was also • Landscaping—For landscaping, the city designed to treat 91 percent of the runoff chose native plants that could survive the from a 50-year storm event. Aspects of its year-round climatic conditions of the site. construction included: This included plants that prefer wet soil, • Site excavation—From site topography but could also tolerate drought. and soils logs, the city determined the maximum allowable depth for water to EXHIBIT 2: CASE STUDY INITIAL pond in the rain garden. Under a 50-year COST COMPARISON storm event, the depth should be no more Conventional stormwater than six-feet. Thus, the site was excavated technique $52,800 three to four feet. (4,400 ft3 wet vault) • Layering of materials—The rain garden Rain Garden $12,820 is composed of three layers of non-woven Cost Savings $39,980 geotextile fabric alternated with six inches

CHAPTER 4—Stormwater Management 20 COST AND POLLUTANTS REMOVAL in-ground storage and treatment stormwa­ EFFECTIVENESS ter system (see Exhibits 2 and 3). This was achieved through reduced construction and The benefits from incorporating this rain equipment costs, as well as reduced labor garden are numerous. It adds aesthetic value costs from the relative ease of installation, to the site, increases wildlife habitat, and is a some of which was accomplished by volun­ highly eff ective BMP for treating stormwater teer landscaping help. These costs savings do runoff. According to offi cials at the Belling­ not include future regular maintenance costs. ham Public Works Department’s, monitoring shows that approximately 80 percent of total A more detailed case study of the city of runoff is captured by the rain garden, with Bellingham’s rain garden can be found overflows running through media filtration on the Puget Sound Action Team’s Web and then another infiltration bed. Further­ site at www.psat.wa.gov/Publications/ more, Bellingham saved 70 percent in initial Rain_Garden_book.pdf. costs compared to installing a conventional

EXHIBIT 3: COST FOR BLOEDEL DONOVAN PARK RAINGARDEN

Labor $3,600 Vehicle use 1,900 Amended soil 1,650 Concrete 1,200 Asphalt 1,200 PVC/grates/catch basins/fabric/other misc. 1,000 Washed rock 805 Excavator rental (1.5 days) 500 Plants 400 Debris Removal 300 WCC crew planting time 265 Total Cost $12,820

Green Parking Lot Resource Guide—February 2008 21 CHAPTER 5

ALTERNATIVE PARKING SURFACE MATERIALS

he majority of parking lots are made Permeable pavements provide a sustainable of a combination of asphalt concrete, alternative to the conventional asphalt and Tthe most widely used paving material concrete parking materials widely used today. in the United States, and aggregates such as Permeable pavements are a broadly defined sand, gravel, or crushed stone. Conventional group of pervious paving options that allow pavement is an impervious, heat absorb­ natural infiltration rates of stormwater into ing material that collects stormwater on its the soil through certain design techniques surface, and does not allow it to filter into the and material substitutions.58 For this reason, soil, inhibiting the natural water cycle. As a re­ like many of the techniques mentioned in sult, parking lots must be designed to quickly Chapter 4, permeable pavements are consid­ remove the water that gathers during storms ered a best management practice (BMP) for by channeling it off the lot via means such stormwater management. However, perme­ as gutters, drains, and pipes. The stormwater able pavement should be used in combina­ is directed into receiving water bodies at tion with other BMP techniques to magnify unnaturally high rates, causing a number of benefits and provide back-up systems in case adverse impacts including increased down­ of BMP failure.59 Two basic types of perme­ stream flooding, combined sewer overflow able paving designs exist: 1) porous pave­ events, diminished groundwater supplies, ment and 2) alternative pavers. This chapter streambank erosion, and non-point source describes these permeable pavement alterna­ water pollution from runoff contaminated by tives, considering their functionality, infiltra­ vehicular residues and other pollutants. tion and pollutant removal eff ectiveness, and cost implications. To combat several of the negative impacts of conventional parking lot paving, develop­ POROUS PAVEMENT ers are increasingly incorporating modest changes, such as using light colored concrete Porous pavement is a permeable pavement instead of asphalt to reduce heat-island surface, often built with an underlying stone eff ect, or using recycled rather than virgin reservoir, which temporarily stores storm- asphalt to reduce emissions and natural re­ water before it infiltrates into the underlying source consumption. For example, 80 percent soil.60 Porous pavement works by eliminating of asphalt pavement removed each year the finer aggregates typically used in con­ during widening and resurfacing projects is ventional paving, and binding the remain­ reused, with contractors typically incorpo­ ing aggregates together with an asphalt or rating up to 20 percent recycled material in Portland cement binder. By eliminating finer concrete mixes.55, 56 However, these changes aggregates, a less dense material is created do not address the fundamental problem of that allows stormwater to seep through. The parking lot impermeability.57 underlying stone bed is designed with an overflow control structure, helping to ensure

CHAPTER 5—Alternative Parking Surface Materials 22 that water does not rise to the pavement significant downstream benefits. 66 Although level. Stormwater settles in the empty spaces porous pavement looks very similar to con­ of the storage bed, infiltrating over time into ventional pavement, it is a far more sustain­ the subgrade soils—a process similar to an able alternative, considered by experts to be infi ltration basin.61 the most effective and aff ordable technique for addressing stormwater management The most common types of porous pavement from development.67 are porous asphalt and pervious concrete, which are very similar in their design and Porous pavements typically have a greater applicability. spectrum of uses than alternative pavers (discussed below), as porous pavement • Porous Asphalt—Developed by the can be applied to both low vehicular traffic Franklin Institute in the 1970s, porous areas and some medium traffi c areas. Porous asphalt consists of an open-grade coarse pavements also have been used in a few high aggregate, bonded together by a typical traffi c areas, including some highway applica­ asphalt cement in which fine aggregates tions, because the product can provide better have been reduced or eliminated, allow­ traction than conventional pavement and ing water to move through the small voids reduce hydroplaning.68 Ongoing research is created.62 Porous asphalt can be used in working to improve its highway applicability all climates where conventional asphalt is through the use of additives and binders.69 suitable.63 In addition, porous asphalt may help reduce • Pervious Concrete—Pervious concrete noise levels from tires on pavement. In a was developed by the Florida Concrete study measuring acoustical properties of Association. It typically contains a mixture pavement types, porous asphalt was shown of Portland cement; uniform, open-graded to have lower noise levels than conventional coarse aggregate; and water. There is at hot mix asphalt.70 least 15 percent more void space in pervi­ ous concrete compared to conventional ALTERNATIVE PAVERS 64 pavements. Pervious concrete can be Alternative pavers, also known as perme­ more durable than porous asphalt, par­ able pavers or unit pavers, are interlocking ticularly in hot weather. However, the State concrete blocks or synthetic fibrous grids of Pennsylvania’s Department of Environ­ with open areas filled with grass, sand, or mental Protection has noted that in colder gravel. Unlike concrete or asphalt poured-in­ northern and mid-Atlantic climates, porous place paving surfaces, alternative pavers are concrete parking lots should always be separate units laid out on a prepared base.71 designed with a stone subbase for storm- When built with a storage bed infiltration water management, and should not be system, alternative pavers function similarly 65 placed directly onto a soil subbase. to porous paving systems. The voids between The manufacturing process for porous pave­ the interlocked pavers allow stormwater from ment has the same environmental and health a parking lot’s surface to collect and then impacts as the process for conventional pav­ seep into the storage bed, which is made of ing materials, but porous pavement exhibits sand or crushed stone. The water then gradu-

Green Parking Lot Resource Guide—February 2008 23 ally infiltrates over time into the subgrade last 15 to 20 years, a length similar to con­ soils. In addition to stormwater management, ventional asphalt concrete pavement, which the storage bed also provides added struc­ requires resurfacing after 20 years on aver­ tural support to the pavers.72 As with porous age.78 However, a number of factors need to pavements, the most beneficial element of be assessed when determining whether a site alternative pavers is the reduction or elimina­ is suitable for a permeable paving system, in­ tion of stormwater impacts.73 cluding: slope, traffic volume, subgrade, land use, soil, infiltration and drainage characteris­ A number of alternative paver options are on tics, and groundwater conditions.79 the market, including but not limited to: Turf- stone®, UNI Eco-Stone®, Checkerbox®, Grass­ Compared to conventional asphalt surface pave2®, and Gravelpave2®. Of the alternative installation and design, features such as sub- paver options, grass paving systems are the grade, soil type, and installation requirements most permeable. However, they have more are more complicated for permeable paving limited applicability because grass cannot systems.80 For example, soil, including its survive daily traffi c; thus, grass-based systems type, porosity, and stability, is considered one are typically used for emergency fire lanes or of the most important factors to determine temporary overflow parking areas.74 Pavers site suitability. According to the New York should be filled with fine gravel or other per­ State Stormwater Design Manual, developers meable materials when more frequent park­ must ensure that soils are permeable enough ing is expected.75 It should also be noted that to carry out adequate infiltration by consider­ certain types of alternative pavers, including ing the natural qualities of a soil type as well block, grid pavers, and gravel, are not always as past land uses, because previous grading, suitable for handicap accessible areas.76 filling, compaction, and other disturbances of the land can alter soil infiltration qualities. DESIGN AND INSTALLATION Underlying soils should have a minimum infil­ CONSIDERATIONS tration rate of 0.5 inches per hour to accom­ A number of uses for permeable pavement modate stormwater volumes, and knowledge exist beyond new, whole parking lot con­ of the organic matter content of the soil is struction projects. One option for high traffic also important in determining its pollutant 81 parking lots is to design a hybrid parking lot removal capabilities. combining permeable pavement parking Permeable pavement is meant to treat small spots with more conventional paving in the storm events, which can range from 0.5 to 1.5 aisles.77 In addition, permeable pavements inches. A site must be designed with an ad­ can be used during parking lot retrofits and equate ratio of infiltration area to impervious replacements. area, and the soil should have a permeability According to the U.S. Department of Trans­ of between 0.5 and 3.0 inches per hour in 82 portation, permeable pavements must be order to adequately handle stormwater. Oc­ properly sited, designed, and installed in casionally, exceptions can be made to allow order to function fully over their life span. If for permeable paving when sites do not meet planned correctly, permeable pavements can certain criteria. For instance, permeable pave-

CHAPTER 5—Alternative Parking Surface Materials 24 ment can be used in soils with low porosity that if properly installed, success rates for a if a discharge pipe is installed to run from a permeable paving system, particularly po­ storage area to a conventional stormwater rous asphalt, can be much higher than earlier system. This modified system will still treat installations using these materials.88 stormwater from small and medium storms, but also will prevent flooding during large MAINTENANCE OF PERMEABLE storm events.83 PAVEMENT

Porous pavement and alternative pavers In the past, studies indicated that permeable alone are not an appropriate BMP to combat pavement applications had a high failure extreme flooding events in channels and rate, due not only to improper siting, but riverbanks. It is recommended that a BMP de­ also poor maintenance. Failure of a perme­ signed specifically to control high waterflows, able paving system means that the surface such as a dry detention pond, should be used becomes impervious and behaves like con­ in conjunction with porous pavement. This ventional asphalt, yet typically without the approach is required by some local govern­ fully developed system of piping and gutters ments as part of flood protection design used to manage runoff on conventional park­ criteria.84 ing surfaces. However, with correct mainte­ nance, permeable pavement can retain its Permeable pavement should not be used permeability, and be a successful stormwater in parking lot areas with high volumes of management option.89 sediment-laden runoff , high traffi c volume, high dust areas, and/or heavy equipment The level of maintenance necessary to traffi c.85 Clogging is the main cause of a maintain permeable pavement lots varies. system malfunction that can result from poor Alternative pavers such as concrete grid pav­ siting of the permeable pavement system. ers and plastic modular blocks will require During construction, developers can prepare less maintenance because they do not clog for possible clogging by installing a perim­ as easily as porous asphalt and permeable eter trench connected to the stone reservoir concrete. Location also impacts the amount to treat overflow should the surface clog.86 of maintenance, as areas receiving more Other common problems to avoid include: sediment will require more maintenance. For example, a parking lot with higher traffi c vol­ • Compaction of underlying soil, such as umes will tend to require more maintenance through the use of heavy equipment. because of the resulting increased quantities • Contamination of stone sub-base with of soil and particulates brought onto the lot. sediment. Although the new soil alone will not neces­ sarily clog the pavement’s voids, if ground in 87 • Tracking of sediment onto pavement. repeatedly by tires, clogging can occur.90,91

Like other best management practices, when Regular maintenance can avoid clogging of permeable paving systems fail, it is frequently permeable paving systems. Facilities manag­ due to mistakes made during the design and ers are generally advised to high pressure construction process. Recent studies note hose and then vacuum porous pavement a

Green Parking Lot Resource Guide—February 2008 25 minimum of two to four times a year, de- may lead to contamination of the ground- pending on the system. This should remove water. This includes prohibiting construction any dislodged sediment and particulate vehicles or hazardous material carriers from matter from the site.92 Exhibit 4 provides an using the lot.95 Finally, because these types of example of typical permeable pavement parking lots have unique maintenance needs, maintenance activities. land owners must ensure that individuals

EXHIBIT 4: MAINTENANCE ACTIVITIES FOR PERMEABLE PAVEMENT PARKING LOTS

Maintenance Activity Scheduling Ensure paved area is clear of sediments As needed Mow upland and adjacent areas, and seed bare areas Monthly Ensure paved area is clear of debris Monthly Monthly and after Monitor that paved area dewaters between storms storms >0.5 inches Vacuum sweep routinely to keep surface free of sediments 3 to 4 times a year Clean inlets draining to the subsurface bed Biannually Inspect the paved surface for deterioration Annually

Source: Adapted from New York State Department of Environmental Conservation, (2007), New York State Stormwater Design Manual—Chapter 9, : www.dec.ny.gov/chemical/29072.html.

Clogging can also be avoided through responsible for parking lot maintenance, such monitoring activities on and around the lot, as the facilities manager, are properly trained including: and prepared to handle the lot’s maintenance • Never using sand or gravel to address needs. icy conditions on porous pavements, although salt may be used on porous Cold Climate Considerations asphalt, and commercial deicers may be In cold weather regions, specific activities 93 used on porous concrete. are necessary to properly maintain a perme­ • Ensuring that the surface is not sealed or able pavement parking lot. The underlying repaved with a non-porous material. stone bed of permeable paving systems often absorbs and retains heat, causing faster snow • Maintaining planted areas adjacent to melt which leads to less snow accumulation. porous pavement to prevent soil washout However, snow may still accumulate, espe­ 94 onto the pavement. cially during heavier storms. When treating Signs should also be posted around the lot to it, abrasive materials such as sand should not prevent harmful activities such as resurfacing, be used on or near the pavement, as it will the use of abrasives, and any activities that quickly clog the surface. As noted above, salt

CHAPTER 5—Alternative Parking Surface Materials 26 can be used as a deicer on the porous pave­ INFILTRATION & POLLUTANT ment, though nontoxic, organic deicers are REMOVAL EFFECTIVENESS OF preferable because the chlorides in salt can PERMEABLE PAVEMENTS migrate into the groundwater.96 With porous pavement, some sites have found that light Permeable paving coupled with a subsurface plowing reduces the need for salt, as the storage bed can capture and manage storm- remaining snow quickly drains into the mate­ water from small, frequent rainfall events, which accounts for between 30 and 50 rial.97 When plowing snow, operators should 102 set the blade slightly higher than usual (i.e., percent of annual precipitation on average. one inch), as to not damage the material. This In addition, this combination can be very ef­ will avoid the blade catching the edge of a fective at removing stormwater pollutants. block or paving and damaging its surface. Infi ltration Effectiveness Signs should be posted to reinforce plowing requirements.98 Finally, frost heave can occur Permeable pavement, when properly de­ if infiltrating runoff freezes below the surface, signed and maintained, can eliminate almost however porous pavement can be designed all surface runoff from low intensity storms.103 to avoid this issue.99 As mentioned before, proper siting and maintenance of permeable parking areas are Repairs critical to maintaining high surface infiltra­ 104 According to Cahill Associates, a leading tion rates. Data on infiltration rates vary sustainable stormwater management design widely according to design characteristics firm, potholes in porous pavement are very and underlying soils, however, research indi­ rare. However, settling might occur if any soft cates that an average of 50 percent of annual spots in the subgrade are not addressed dur­ rainfall on porous pavement infiltrates, with ing construction. Even after 20 years, a well- reported infiltration rates reaching as high as 105 maintained porous surface can show little if 80 percent. Infiltration rates can decline to a certain extent over time, again depending any cracking or potholes.100 Many alternatives are available for repairing damaged porous on design, installation, maintenance, and site 106 pavement and alternative pavers. In general, characteristics such as sediment loads. areas less than 50 square feet can be patched Pollutant Removal Effectiveness by using either a porous mix or standard pavement because the loss of porosity to Limited data indicate that permeable pave­ a small spot is insignificant to the overall ment systems have high removal rates for stormwater management function. If an area many pollutants, including total suspended greater than 50 square feet is damaged, an solids, metals, oils, and grease.107 However, engineer should be consulted to design an pollutant removal is not eff ective for larger appropriate patch.101 storms with rainfall greater than one-inch, or with high rainfall intensity.108

Green Parking Lot Resource Guide—February 2008 27 Porous Pavement lower. Also, motor oil was detected in 89 per­ Studies of porous pavement performance cent of the runoff samples from conventional show that they can eff ectively trap soluble asphalt, while no motor oil was detected in pollutants, which are then absorbed or any samples that infiltrated through sections broken down in the underlying soil layers. Ex­ of alternative pavers.111 hibit 5 depicts the range of pollutant removal Another study researched driveways con­ eff ectiveness for porous pavement, showing structed of conventional asphalt versus a removal eff ectiveness of at least 65 percent permeable pavers to compare their runoff for suspended solids, nitrogen, pathogens, depths, infiltration rates, and pollutant con­ and metals; and at least 30 percent of phos­ centrations over two years. The study found phorus.109 that the mean weekly runoff rate for conven-

EXHIBIT 5: POROUS PAVEMENT POLLUTANT REMOVAL EFFICACY

Typical Pollutant Removal (percentage) BMP Type Suspended Nitrogen Phosphorus Pathogens Metals Solids Porous Pavement 65-100 65-100 30-65 65-100 65-100

Source: U.S. EPA, 1993, Handbook Urban Runoff and Pollution Prevention Planning, EPA-625-R-93-004, taken from Purdue Uni­ versity Engineering Department’s Long-Term Hydrologic Impact Assessment (L-THIA): http://cobweb.ecn.purdue.edu/~sprawl/ LTHIA7/lthia/lthia_index.htm.

Alternative Pavers Alternative paver systems have been shown tional asphalt was over three times that of to be just as eff ective as porous pavement the permeable pavers. In addition, they found in removing pollutants. A study from the that pollutant concentrations in runoff from University of Washington conducted to the permeable pavers were substantially less determine the long-term eff ectiveness of than from the conventional asphalt, as shown 112 permeable pavements as a stormwater in Exhibit 6. management strategy showed significant As with other stormwater infiltration BMPs, pollutant removal rates. Researchers com­ developers must take measures to mitigate pared the effectiveness of four permeable any possible groundwater contamination at pavement types and conventional asphalt a permeable pavement site. Permeable pav­ over six-years.110 They found that runoff from ing should not be used to treat stormwater the conventional asphalt had significantly “hotspots,” areas where land uses or activities higher concentrations of measured pollutants have the potential to generate highly con­ (i.e. motor oil, copper, zinc) compared to the taminated runoff. These areas include: com­ alternative paver surfaces. Concentrations of mercial nurseries, auto recycling and repair copper in runoff from alternative pavers were facilities, vehicle service and maintenance roughly 80 percent lower than those found areas, fueling stations, high-use commercial in the runoff from conventional asphalt, and parking lots, and marinas.113 zinc concentrations were at least 40 percent

CHAPTER 5—Alternative Parking Surface Materials 28 EXHIBIT 6: STUDY EXAMPLE: STORMWATER RUNOFF COMPARISON IN JORDAN COVE, CT Conventional Asphalt Permeable Pavement Pollutant (mg/l) (mg/l) TSS 47.8 15.8

NO2-N 0.6 0.2

NH3-N 0.18 0.05 TP 0.244 0.162 Cu 18 6 Pb 6 2 Zn 87 25

Source: Hinman, C., (2005), Low Impact Development Technical Guidance Manual for Puget Sound, Puget Sound Action Team, publication number PSAT 05-03: www.psat.wa.gov/Publications/LID_tech_manual05/lid_index.htm.

COST CONSIDERATIONS percent more than conventional asphalt pav­ ing.114 Finally, Cahill Associates maintains that The costs for permeable pavement systems the cost of a porous pavement installation is vary depending on site specifications and the roughly the same as the cost of a convention- type of system being used. In general, the al asphalt parking lot.115 The costs for alterna­ cost to install alternative pavers or porous tive pavers are more difficult to estimate, as pavements alone are higher than conven­ they fluctuate widely depending on type and tional asphalt paving, which costs between manufacturer.116 In general, larger parking $0.50 to $1.00 per square-foot. Sources dis- lots utilizing alternative pavers will incur a agree on the average initial costs for perme­ lower overall unit cost per space. able pavement. Exhibit 7 provides an initial cost comparison of pavement options from The overall cost-eff ectiveness of perme­ the NY State Stormwater Design Manual. able pavement can only be fully assessed by However, another source notes that porous considering its typical use in concert with asphalt, with additives, costs from 10 to 20 other stormwater BMPs. Specifically, the cost- EXHIBIT 7: PARKING SURFACE INITIAL COST COMPARISON CHART

Pavement Type Cost per Ft2 (Installed) Conventional Asphalt $0.50 to $1.00 Permeable Concrete $1.50 to $5.75 Grass/Gravel Pavers $2.00 to $6.50 Interlocking Concrete Blocks $5.00 to $10.00

Source adapted from New York State, New York State Stormwater Design Manual: www.rpi.edu/~kilduff /Stormwater/ permpaving1.pdf.

Green Parking Lot Resource Guide—February 2008 29 competitive nature of permeable pavement the need for land-intensive BMPs such as dry systems lies in their success when combined extended detention or wet retention ponds. with other BMPs or subsurface drainage This fact produces additional cost advantages to create a well-designed and sustainable for permeable pavement over conventional stormwater management system. Prop­ asphalt in locations with high land prices.118 erly designing and installing such a system Maintenance costs should also be factored in requires a high level of labor and expertise, when considering the costs of a permeable as well as material costs, including excavation paving system. If not designed and main­ for deep underlying stone bed and the use of tained properly, porous pavement’s eff ective geotextile fabric. However, these higher ini­ lifespan may be shortened due to potentially tial costs are offset by reductions in the need high risks of clogging.119 Some studies sug­ for expensive traditional “hard” stormwater gest that the cost of vacuum sweeping on a management of pipes, gutters, and drains new permeable lot may be considerable if the relative to parking lots made of conventional landowner does not already perform vacuum asphalt pavement. When these savings are sweeping operations. However, one study incorporated, overall project costs are often estimates the annual maintenance cost for a reduced.117 Also, when used in combination porous pavement parking lot at $200 per acre with other smaller techniques, such as biore­ annually, which includes regular inspections, tention cells, vegetated swales, or vegetated as well as jet hosing and vacuum sweeping.120 filter strips, permeable pavement reduces

CHAPTER 5—Alternative Parking Surface Materials 30 CASE STUDY 2: PARKING SURFACE ALTERNATIVES HEIFER INTERNATIONAL, LITTLE ROCK, ARKANSAS

In 2006, Heifer International, a non-profit sus­ tainable community development organiza­ tion located in Little Rock, Arkansas, designed an environmentally-friendly parking plaza to complement their new green building head­ quarters. A first of its kind in Arkansas, this project serves as a model for other organiza­ tions considering a green parking lot. Heifer’s parking plaza encompasses numerous green parking lot techniques including the use of more sustainable materials to minimize im­ pervious surface, reduce runoff , reduce virgin Heifer International’s World Headquarters: a green building with a green water use, and incorporate recycled content. parking lot. Heifer evaluated a variety of paving options • Gravel Pave system—Used for the park­ when selecting materials for their green ing stalls, thirty thousand square feet of parking lot. Unlike a conventional lot, which Heifer’s parking plaza are covered by a most likely would be constructed primarily gravel pave system. The stalls are construct- of asphalt, Heifer chose three types of paving ed using 100 percent recycled material materials that provide environmental ben­ (90 percent post-industrial and 10 percent efits over asphalt. post-consumer). At a unit cost of $4.75 per square foot, this gravel pave portion of the • Concrete—The high traffi c aisles and lot cost a total of $142,500. Maintenance driveway of the Heifer lot are paved with is minimal, requiring roughly eight hours a concrete rather than asphalt. Overall, it month at a cost of $160 per month. covers an 86,000 square-foot area, at a cost of $5.75 per square foot, or $494,500. • Brick pavers—Recycled brick pavers The concrete base contains 90 percent were used to form a decorative driveway recycled cement and its top layer is made centerpiece, and cover the smallest part of 2 of locally produced concrete.121 Because it the lot (2,500 ft ) at a total cost of $34,418. is a light colored and highly reflective sur- Heifer minimized the cost for the pav­ face, concrete helps minimize heat island ers by reusing bricks from buildings that effect (HIE) at the Heifer site. Coupled with previously occupied the site. Heifer em- the extreme humidity in the Little Rock ployees also volunteered to help clean a region where Heifer is located, this HIE can number of the bricks so they could be re- be stifling. However the use of concrete used. The total cost for the pavers includes for paving has been shown to produce a additional labor, beyond the volunteer 20ºF reduction in surface temperatures hours, to clean bricks and construct the compared to asphalt.122 centerpiece. Heifer has yet to incur any maintenance costs for this area. Green Parking Lot Resource Guide—February 2008 31 All of the parking lot materials used in the net increase in emissions or resource use. For Heifer lot were purchased from local deal­ instance, Heifer’s green parking lot used more ers within 500 miles of the site, supporting water than an asphalt parking lot would have the local economy and reducing emissions because of the greater water inputs required associated with transportation of purchased in the recycling of concrete pavement com­ materials. pared to the production of asphalt pavement.

By applying estimates of the economic value UPSTREAM BENEFITS of reduced human health and ecological Upstream environmental benefits were real­ impacts from avoiding emissions, these ized through Heifer’s use of recycled concrete upstream benefits were then monetized. and other recycled materials, instead of using Reliable estimates of economic value are not virgin asphalt, in the construction of their lot. available for carbon dioxide (CO2) emissions. These benefits include reduced air emissions However, by applying estimates for the value (associated with the production of asphalt), of reducing sulfur dioxide (SO2) and particu­ reduced transportation emissions (from pur- late matter (PM10) emissions, a range of mon- EXHIBIT 8: UPSTREAM BENEFITS OF THE HEIFER PARKING LOT124

Energy Water Use Tons Hazardous Waste (MMBtu) (gallons) CO NO PM SO 2 X 10 2 Generated 668.3 -116 20.9 -0.89 0.72 25.3 20.7 chasing locally produced materials), reduced etary values related to Heifer’s reductions can energy use, and reduced hazardous waste be shown (see Exhibit 9).125 generation related to the production of virgin materials. Heifer’s goal in building its parking plaza was to minimize impacts to the environment Modeling was used to estimate any upstream while handling a large volume of site traffi c. benefits from the construction of Heifer’s lot.123 The resulting analysis (see Exhibit 8) A more detailed case study of Heifer Inter­ shows a clear overall positive net benefit national’s green parking lot can be found from the construction of Heifer’s lot, although on the U.S. EPA’s Web site at www.epa.gov/ results for some individual metrics indicate a earth1r6/6sf/bfpages/bfheifer.html.

EXHIBIT 9: VALUE OF UPSTREAM AIR EMISSIONS BENEFITS FOR HEIFER LOT

Monetized Upstream Benefi t Air Emission Low High

SO2 $43,044 $455,760

PM10 $7,170 $71,700

CHAPTER 5—Alternative Parking Surface Materials 32 CASE STUDY 3: PARKING SURFACE ALTERNATIVES UNIVERSITY OF RHODE ISLAND, KINGSTON, RHODE ISLAND126

OVERVIEW In 2002 and 2003, the University of Rhode (URI) constructed two parking lots at their Kingston, Rhode Island campus to meet parking demands from new University development and commuting students. The parking lots were located within the town’s groundwater protection overlay district, the University’s wellhead protection area, and also within the Pawcatuck sole source aquifer. These lots would increase parking capacity by 1,000 spaces, spread over seven acres of land (see areas highlighted in red in Photo 1). Rainwater infiltrates the porous asphalt (left), but accumulates on adjacent However, because the lots were located in an road paved with conventional material (right). ecologically sensitive area already covered by In addition, project managers were also an estimated thirty percent impervious sur­ interested in avoiding any potential impacts face, the University desired an environmen­ to groundwater supplies.127 The University tally protective option than would combat determined that a permeable asphalt surface stormwater issues more eff ectively than con­ would help control runoff quantities as well ventional paving surfaces. The University’s as potentially limit pollutants entering sur­ main stormwater concern was to decrease face and groundwater supplies. runoff quantities to protect a nearby stream In addition to using permeable asphalt, considered impaired due to low water flows. landscaped islands were designed as biofil­ tration areas to provide a secondary route of infiltration during large storm events or pavement clogging. Also, the University took precautions to avoid clogging the permeable pavement by planting trees and grass around the parking lot perimeter, which limits wind­ blown dust from nearby agricultural areas and controls soil erosion. An emergency spill­ way was also constructed to direct overflow to recharge beds in the extremely unlikely event that the permeable asphalt and biofil­ tration areas both clog.

URI’s permeable parking lots - The two original permeable asphalt parking lots built in 2002 and 2003 are outlined in red. The 2005 parking lot exten­ sion is outlined in green. Green Parking Lot Resource Guide—February 2008 33 COST CONSIDERATIONS meable asphalt layer was not infiltrating properly because the binder had become The total construction costs for the two park­ separated from the asphalt. Project ing lots was just over $3 million, or $3,000 per consultants recommended an improved parking space, which is considered compara­ polymer mixture, new to the market, that ble to conventional parking lots of equal size. would prevent the separation and elimi­ Costs included site preparation, barn demoli­ nate the infiltration problem. tion, materials, lighting, drainage, landscap­ ing, monitoring wells, post-construction in­ • Pollutant removal spections, and design fees that were roughly The University is currently monitoring the ten percent of the total cost. URI’s costs pollutant removal and runoff level from included non-typical items such as removal the lots. They found a 90 percent retention of stone masonry walls, and installation of of zinc and copper. However, the perme­ security cameras and emergency telephones. able asphalt was not as eff ective in captur­ Without these additions, installation would ing other pollutants, including organic have been cheaper. On average, installation pollutant such as PAHs, and inorganic runs between $2,200 and $2,750 for porous pollutant such as nitrate and phosphate. pavements such as permeable asphalt. This is due to clogging, as well as the type of geotextile fabric used in the project, INCORPORATING LESSONS LEARNED which was found to prevent an even flow In the few year since they constructed the of water into the subsurface. two permeable asphalt parking lots, URI has In the summer of 2005, the larger of the two been monitoring their success in managing permeable asphalt parking lots was expand­ and filtering stormwater. As a new technolo­ ed by another 800 spaces. When planning gy, they noted several areas for improvement. this expansion, the University was able to • Clogging incorporate improvements to their design based on lessons learned from the original Overall, these parking lots were successful two parking lots. Design changes included from a hydrological perspective. However, use of the polymer mixture to prevent sepa­ some clogging was observed in the higher ration of the binder, fewer and wider biofiltra­ traffi c areas of the lot. Clogging also tion islands, and curb cuts for water entry to occurred in one corner of the lot where the biofiltration islands. Maintenance issues plowed snow was stockpiled during the regarding snow removal were also addressed. winter, which reduced infiltration due to sediment build-up. This is an indication Further information on the University of that plow blades were not raised to the Rhode Island’s permeable asphalt parking required height, an issue that also caused lots can be found at www.uri.edu/ce/wq/ surface defects to the lot. NEMO/Publications. Excavation of the lot during construction of a sidewalk also revealed that the per-

CHAPTER 5—Alternative Parking Surface Materials 34 CHAPTER 6

LANDSCAPING AND IRRIGATION

n the majority of parking lots across • Reduce damage from stormwater, and the country, landscaping does not vary • Improve habitat and increase according to geographic location. It is I biodiversity.130 typically designed using conventional turf grass, such as Kentucky Bluegrass, and com­ This chapter provides an overview of natural mon popular ornamental plantings. However, landscaping and irrigation techniques suitable because these plants are often not native for green parking lots. It describes the diff er­ to areas where they are being used, regu­ ence in irrigation and maintenance require­ lar maintenance is required to keep them ments for natural landscaping compared to healthy. Sustaining this greenery requires conventional landscaping, the benefi ts of irrigation systems and potable water use to natural landscaping, and cost considerations. supplement rainfall, chemical applications of pesticides and fertilizers, and ongoing lawn OVERVIEW OF NATURAL maintenance (e.g., mowing).128 Irrigation and LANDSCAPING AND IRRIGATION chemical use contribute to degradation of Natural Landscaping water quality and aquatic habitat in receiving Considerations and Vegetation waters, decreased water supplies, increased Conservation stormwater runoff , declining biodiversity, and air pollution. Mowing and other maintenance Natural landscape design, sometimes activities are a significant air pollution con­ referred to as native or sustainable landscap­ cern; for example, in one hour a lawn mower ing, uses plant species indigenous to a region emits as much pollution as a car driving 350 pre-European settlement. Because these miles.129 With proper planning, landowners native plant species have evolved in the local can avoid these impacts by utilizing “natural environment, maintaining them is relatively landscaping” approaches. easy—they are more resistant to local pests, they are better suited to survive on natural Natural landscaping involves creating a low- rainfall, and they are adapted to live in local maintenance landscape in and around a park­ soil types. These heartier plants also provide ing lot using native plants and water-efficient habitat for local native wildlife species that irrigation techniques. A vital component of they co-evolved with—a symbiotic relation­ green parking lots, natural landscaping can: ship that is the foundation for our native • Reduce landscape installation and main­ ecosystems and biodiversity.131 tenance costs, A feasible and intelligent approach for most • Limit harmful chemical pollution (i.e. development sites, natural landscaping also pesticides, fertilizers), supports sustainable development strategies such as Low Impact Development (LID) and • Reduce potable water use and pollutant Smart Growth, and is a vital component to air emissions, Green Parking Lot Resource Guide—February 2008 35 many stormwater Best Management Practic­ amount of turf to only those areas necessary es (BMPs). For example, some of the bioreten­ for practical purposes. tion approaches described in Chapter 4, such as vegetated swales and rain gardens, are Irrigation Requirements for based on natural systems and intended to Natural Landscaping function as they would have in absence of de­ As mentioned above, a key diff erence be­ velopment.132 BMPs rely on native plants for tween conventional and natural landscaping added effi ciency in retention, infiltration and is water use requirements. Conventional land­ transpiration, and cleansing.133 See Chapter 4 scaping consumes large quantities of water for more information on BMPs. to sustain non-native species, which typically Developers must take a number of factors cannot withstand local conditions as well as into consideration when planning and de­ native varieties. For instance, the popular turf signing natural landscaping. Natural land­ species Kentucky Bluegrass typically requires scaping involves more than new plantings of in excess of 40 inches a year of precipitation 136 native species; an important step to consider to thrive. This is above annual rainfall levels before construction even begins is retaining for many states, particularly in Western parts as much of the existing native landscaping as of the country. According to the U.S. Depart­ possible at a site. By preserving existing vege­ ment of Energy, native and other climate tation, developers can minimize the need for appropriate landscaping can reduce irriga­ 137 new landscaping, and limit site disturbance. tion water use by at least 50 percent. This If the location of existing vegetation is not was the case for Heifer International’s green suitable, it is preferable to relocate it on-site parking lot (see case study at the end of the rather than dispose of it during construction. chapter), where the landscaping requires no Another option is to remove native plants additional irrigation under normal conditions. from sites scheduled for construction; some Typically, native plants require irrigation only 138 volunteer organizations will retrieve plants when they first take root. from construction sites to later replant at In most cases the water source for conven­ other locations.134 tional irrigation is the same potable drinking Landscaping choices should be compatible water used inside buildings, applied gener­ with individual site characteristics including ously by ineffi cient spray irrigation systems. topography, soil, drainage patterns, and sun In many developments, these irrigation exposure.135 It is important to select site- systems are programmed to turn on auto­ appropriate plants when bringing native matically, and do not take fluctuating rainfall landscaping in from off -site; as such, consult­ amounts or soil moisture into account. In ing a local landscape designer with native contrast, natural landscaping fosters smarter plant knowledge is recommended. irrigation practices, through water-efficient planting, mulching, rainwater harvesting, and Although native landscaping is feasible for water-effi cient irrigation technology. most sites, in cases where it is not feasible or is otherwise not utilized, developers should Efficient Irrigation Technology139 choose low-water use plants and limit the Effi cient irrigation technology is essential to

CHAPTER 6—Landscaping and Irrigation 36 conserving water, and a number of options properly schedule sprinkler use; and zoning are available to help landowners save money systems that focus on the water needs of through less wasteful practices. A fundamental each plant grouping.143 problem of conventional irrigation is over- watering. Not only does over-watering reduce Efficient Irrigation Procedures water supplies and increase runoff amounts, The basic practices of landscaping, including but it also can result in plant diseases such as plant layout and irrigation scheduling, are fungus, and in the excessive growth of weeds also vital to natural landscaping. and pests. Over-watering also results in weak plant growth that in turn precipitates the need • Seasonal infl uences—When scheduling for additional maintenance.140 irrigation, it is important to understand the seasonal variations and changing If landscaping is watered at a less frequent weather conditions. In some regions of and more appropriate rate, plants will the country, water requirements can vary develop deeper roots and become healthier considerably depending on the season. overall.141 Recommended alternatives to the traditional sprinkler method, which often • Time of day—It is also important to over-waters landscaping, include soaker consider the time of day when irrigation hose, drip, or subsurface irrigation. is taking place. Watering is more eff ective during early morning hours or early in Drip irrigation in particular is a water conser­ the evening, when temperature and wind vation technology that is gaining popularity. speeds are typically lower, thus reducing Used in the past to conserve water in arid evaporation water loss.144 areas, its use has expanded with heightened awareness of resource conservation and • Weather conditions—Weather condi­ environmental sustainability. Drip irrigation tions and weather forecasts should be is a system of tubing with small holes that incorporated into irrigation planning. Use allows water to drip out onto the root zone of system override devices when it is raining, plants, providing more targeted and uniform and try to program irrigation to avoid days irrigation. Such systems can run on recycled when rain is forecast. In addition, watering water, and can be an option for temporary on windy days means that the water may use to establish native plants. Should a sprin­ not reach targeted areas or may be blown kler system be selected, low-flow sprinkler onto paved areas. systems that release water slowly and close Mulching helps keep moisture in the soil and to the ground are preferable to sprinklers allows rainfall and irrigation water to better 142 that emit mist, which easily evaporates. penetrate the root system. Landscapers rec­ Other examples of effi cient irrigation tech­ ommend that roughly three inches of organic nology include soil tensiometers, which de­ mulch be applied over trees and shrubs roots, termine when the soil is dry and gauge water and in plant beds. This also helps moderate needs; rain or moisture sensors that can shut soil temperature, minimize evaporation, and off automated irrigation systems during rain; reduce erosion and weeds. In addition, when irrigation timers with manual overrides to mulch decomposes, it increases the organic

Green Parking Lot Resource Guide—February 2008 37 content of the soil.145 Lastly, the layout of are established. The primary environmental natural landscaping is important to efficient benefits of incorporating natural landscaping irrigation. By grouping plants with similar wa­ into parking lots are described below. ter needs together, a dedicated irrigation line or valve can be used to apply the appropriate Decreased Non-Point Source amount of water at the correct frequency.146 Pollution The U.S. EPA’s 2004 Conference on Landscap­ Rainwater Harvesting and ing with Native Plants found that landscaping Recycled Water147 with native plants may help reduce non-point To conserve water, natural landscaping also source pollution reduction in the following includes the use of collected rainwater or ways: recycled wastewater for irrigation. These are • The need for fertilizers and pesticides to both preferred alternatives to using potable maintain conventional landscapes (i.e. turf water, which is a finite natural resource. grass) can often be eliminated with native Moreover, potable water treatment man­ vegetation. agement requires energy use for desalting, pumping, pressurizing, groundwater extrac­ • Through direct uptake of nutrients, native tion, conveyance, and treatment.148 plants may reduce the impact of fertilizer elements (i.e. nitrogen and phosphorous) Reuse of rainwater is a good option because it that would otherwise contaminate water is “not chlorinated and is mildly acidic, which sources.152 Fertilizer contributes to ap­ helps plants take up important minerals.”149 proximately 80 percent of nutrient loads Containers, such as cisterns or rain barrels, can in the springtime.153 be used to collect and store water from roof catchment areas. Rainwater can also be har­ • Native plants may create sub-soil condi­ vested from an underground storage system, tions that help reduce levels of nitrate which is then pumped to the irrigation system. entering water supplies via facilitation.154 In addition to rainwater harvesting, certain • Native plants are capable of filtering other types of non-potable water, if treated properly, impurities from stormwater runoff , such as can be used as well for irrigation. For instance, salt and automobile deposits (i.e., oil). water recycled from wastewater, also known as irrigation quality or reclaimed water, can be The over-application of fertilizers and treated and, although not suitable for drinking, pesticides can lead to other detrimental is very useful for irrigation. environmental impacts beyond non-point source pollution. Less than 10 percent of ENVIRONMENTAL BENEFITS OF insects actually harm plants, yet inappropri­ USING NATURAL LANDSCAPING AND ate pesticide use harms non-target insects ASSOCIATED IRRIGATION that are beneficial to the environment, it can 155 Compared to conventional landscaping de­ also harm wildlife. Overuse of fertilizers can sign, natural landscaping can off er substan­ exacerbate insect diseases as well as promote tial environmental benefits by minimizing ir­ unnecessary plant growth, which in turn 156 rigation and maintenance needs once plants increases maintenance needs.

CHAPTER 6—Landscaping and Irrigation 38 An innovative natural landscaping approach industrial developments. Xeriscaping is a to pest management, called “integrated pest collection of sustainable landscaping design management,” is a low chemical approach principles incorporating the use of native to landscape maintenance. Rather than or other water effi cient plants.160 Another emphasizing the use of harsh chemicals, it example is Las Vegas, Nevada, where a city incorporates materials composed of natu­ ordinance limits the amount of turf on new rally occurring compounds, and promotes landscapes to no more than 50 percent.161 natural landscaping design and maintenance practices. According to the U.S. Department Reduced Air Pollution of Energy, integrated past management Reduced maintenance from native landscap­ “demonstrably creates a better environment ing can improve air quality: for plants as time passes.”157 • Locally, through reduced smog and air Water Conservation toxics; Water conservation is one of the primary • Regionally, through the reduction of acid benefits of a natural landscaping approach. rain caused by nitrogen oxide (NOX) and

Using native plants in landscaping helps con­ sulfur dioxide (SO2) emissions; and serve water because once established, native • Globally, by combating greenhouse gas plants often do not need supplemental wa­ emissions.162 tering beyond local rainfall amounts.158 This is not the case for conventional landscaping It is estimated that for every 10 days of where, for instance, the watering schedule maintenance required for a traditional turf for turf landscaping is estimated at 1 inch of landscape area, a natural designed area only water over the entire area, for 30 applications requires one day.163 This greatly minimizes per year.159 The water conservation ben­ the need to run maintenance equipment efits become even greater when harvested such as lawn mowers, leaf blowers, and weed rainwater or recycled wastewater are used for wackers, which typically run on gasoline and irrigation rather than potable water. emit carbon dioxide (CO2) and other air pol­ lutants. For example, the use of lawn equip­ With water shortages seen in many commu­ ment in just the Chicago region produces 50 nities throughout the country, native land­ tons of volatile organic compounds (VOCs) scaping is a sensible approach to preserving every day in the summertime.164 water. Local governments in states such as North Carolina, Texas, and California have Reduced Erosion and adopted natural landscaping ordinances, Sedimentation innovative rate structures, and wastewater reuse plans to address water shortages. For Natural landscaping in parking lots also helps example, Santa Monica, California requires minimize the erosion and sedimentation the use of a particular water-effi cient land­ impacts of development. The deep root sys­ scaping strategy called “xeriscaping” for all tems of native plants stabilize soils and help landscapes installed in new commercial and prevent wind and water erosion along deten-

Green Parking Lot Resource Guide—February 2008 39 tion basin edges and streambanks.165 This is the variety of life. Defined as “the variability particularly true of plants that were on-site among living organisms from all sources in­ pre-construction and preserved. Native plant­ cluding…terrestrial, marine and other aquat­ ings can also help remove sediments from ic ecosystems, and the ecological complexes runoff through filtration, again helping to of which they are part,” biodiversity is the preserve water quality and aquatic habitat.166 diversity within species, between species and of ecosystems.170 Conventional landscaping Reduced Heat Island Effect can negatively affect biodiversity of species at As discussed in Chapter 1, heat island eff ect various levels when native plants species are (HIE) occurs in urban areas when the com­ replaced with homogenous, exotic, ornamen­ bined eff ect of heat-absorbing surfaces, such tal species. This “monoculture” limits genetic, as asphalt, leads to higher air and surface species, and ecosystem diversity. temperatures. HIE can increase temperatures The diversity of our flora and fauna is an in­ between 2 to 8ºF on average during the sum­ valuable resource from an environmental and 167 mer. The greatest temperature increases are human health perspective. Ecosystems that typically seen in areas with less vegetation contain a diversity of native plant and animal and high amounts of urban development. species better provide “ecosystem services” Vegetation, especially trees, can help reduce to humans, such as water and air purifica­ HIE, by providing shading to paved areas. For tion.171 Native plants also support a healthier example, a NASA study on the Madison Square environment by providing food and shelter Mall in Huntsville, Alabama found that the for wildlife. In addition, some exotic plants temperature in the middle of the parking lot can become invasive species, smothering na­ on a summer day was 120ºF, while the temper­ tive plants or overrunning their habitat, again ature at a small tree island in the parking lot aff ecting the plant population and the chain was only 89ºF. For every additional tree canopy of species dependent upon it. cover temperatures can often be reduced by 1º F. Vegetation can also indirectly cool parking COST EFFECTIVENESS OF USING areas though transpiration, and soil also cools NATURAL LANDSCAPING through water evaporation.168 A common perception is that natural land­ Because of its cooling capabilities, landscap­ scaping is more costly than conventional ing also plays a role in reducing building landscaping. However, cost/benefit modeling energy use and associated CO2 air emissions. and case studies have shown that natural Hotter temperatures from HIE can lead to landscaping can be more cost-eff ective in the increased energy demand to cool buildings long term—for both communities and land located near heat absorbing surfaces such as owners.172 Reduced costs result from de­ parking lots. By reducing HIE, it is estimated creased energy use, forestalled infrastructure that plantings close to buildings can reduce upgrades, and lower land maintenance costs. air conditioning costs by 5 to 20 percent.169 For example, one study found that landown­ ers can save between $270 and $640 dollars Enhanced Biodiversity per acre by preserving the native landscape Biological diversity, or biodiversity, is literally of their open land instead of creating a

CHAPTER 6—Landscaping and Irrigation 40 conventional, tuft-based, landscape. Savings sustainable landscaping versus conventional can also be realized during the installation landscaping. of natural landscaping. It can be between By using a simple payback calculation, the $4,400 and $8,850 less expensive per acre for above example demonstrates that the costs the installation of natural landscaping than for the native landscaping are recovered for turf grass.173 within the first year because of significantly Of all the potential sources of costs savings lower maintenance costs.174 As a general from natural landscaping, reduced main­ rule, annual maintenance costs for natural tenance leads to the greatest savings. As landscaping are approximately 10 percent of discussed throughout this chapter, natural conventional landscaping.175 landscaping requires less maintenance and Other economic benefits of natural landscap­ labor expenditures, such as less irrigation, ing include local government and commu­ mowing, weeding, and fertilizer/pesticide ap­ nity cost-savings from avoided infrastructure plication. Decreased irrigation is a major part and/or water supply upgrades associated of these savings, as is seen in the case of Heifer with stormwater runoff , which can lead to International (see following case study). flooding, pollution, groundwater recharge

EXHIBIT 10: INSTALLATION, MAINTENANCE, AND INCREMENTAL COSTS OF SUSTAINABLE VS. CONVENTIONAL LANDSCAPE AREA (LANDSCAPE AREA = 8,000 SQUARE FEET)

Site Design and Total Maintenance Installation Implementation ($/year) Native Planting $3,673 $184 $272 Traditional Turf $1,224 $61 $3,318 Cost Diff erence (Native $2,449 $123 -$3,046 minus Traditional)

Source: Estimate of landscape area includes 1-acre (43,560 ft2) lot with 25,200 square foot parking area and 10,082 ft2 building footprint. For more information see U.S. Department of Energy, (2003), The Business Case for Sustainable Design in Federal Facilities—Appendix D, http://www1.eere.energy.gov/femp/sustainable/sustainable_federalfacilities.html.

An example of the overall maintenance sav- deficits, and damage to stream ecology.176 ings, including water savings, is presented in Reduced infrastructure burden is discussed the following comparison produced by the in Chapter 7. In addition, communities often U.S. Department of Energy. In this example, pay to eradicate algae blooms caused by ex- costs are compared for a one-acre site (in- cess fertilizing, a cost avoided by widespread cluding a 50 to 75 space parking area) using use of native landscaping.177

Green Parking Lot Resource Guide—February 2008 41 CASE STUDY 4: LANDSCAPING AND IRRIGATION HEIFER INTERNATIONAL, LITTLE ROCK, ARKANSAS

In 2006, Heifer International, a non-profit sus­ tainable community development organiza­ tion located in Little Rock, Arkansas, designed an environmentally-friendly parking plaza to complement their new green building head­ quarters. A first of its kind in Arkansas, this project serves as a model for other organiza­ tions considering utilizing green parking lot techniques. One highlight is Heifer’s use of native landscaping and irrigation methods, which reduce potable water use and provide habitat for local species. By using native landscaping around its parking lot, Heifer International supports The innovative landscaping and irrigation the local ecosystem and conserves water. surrounding Heifer International’s parking lot thirds reduction in water demand compared provides a variety of environmental benefits. to a conventional parking lot scenario with The grasses, plants, trees, and wildflowers standard landscaping. By using recycled wa­ used throughout much of the site are indig­ ter, native plants, and water conserving irriga­ enous, and do not require pesticides. They tion, Heifer is conserving 520,000 gallons of also offer food and shelter to native wildlife, potable water, and saving $65,343, annually. and help create a more visually pleasing aesthetic. Under natural rainfall events, the Currently Heifer has six irrigation zones, four species planted in the lot should be able to that use drip irrigation and two that use con- sustain themselves with little irrigation. In ventional sprinkler irrigation. fact, in a normal rainfall year, the landscape • Drip Irrigation—Heifer has four drip- will require irrigation only once a week. zones for irrigating native trees and shrubs Because Heifer used a combination of native on the site. Each releases 0.9 gallons per seeding and sod, their parking lot requires hour, using a total of approximately 2,000 less irrigation than a conventional lot using gallons of water per week. The total cost all sod and non-native landscaping. In a typi­ for the drip irrigation system was $79,000. cal, non-drought year, Heifer’s closed loop • Sprinkler Irrigation—Heifer has two stormwater system will provide 100 percent spray-zones for irrigating the sod portions of the water necessary to irrigate vegeta­ of the lot. These conventional pop-up tion throughout the lot, eliminating use of spray heads produce approximately 25 municipal water for this purpose. Heifer uses gallons of water per minute per zone, us- approximately 5,000 gallons of irrigation ing a total of approximately 3,000 gallons water per week, or 260,000 gallons annually, of water per week. The total cost for the to irrigate its grounds. According to their sprinkler irrigation system was $42,000. landscape architect, this represents a two- CHAPTER 6—Landscaping and Irrigation 42 Heifer supported this sustainable landscap- aesthetics of the parking lot, reduced heat ing by amending the soil with compost, island effect, and supported wildlife habitat. which helps increase nutrient retention, For more information on Heifer Internation­ decrease irrigation needs, and improve soil al’s green parking lot, including their sustain­ and plant health. They went beyond the City able landscaping techniques, please vist the of Little Rock’s parking ordinance by planting U.S. EPA’s green building Web site at: www. 80 trees (63 more than the city requires) and epa.gov/earth1r6/6sf/bfpages/bfheifer.html. landscaped a far larger area within the lot than required. These actions improved the

Green Parking Lot Resource Guide—February 2008 43 CHAPTER 7

REDUCED INFRASTRUCTURE BURDEN

his resource guide has explored • The Environmental Council of States how components of a green park­ (ECOS) ing lot, including stormwater best T In 2007, ECOS’ Green Infrastructure management practices, innovative planning Resolution (07-10) encouraged the use policies, and native landscaping, can be of green infrastructure to mitigate sewer used in combination to sustainably manage overflows and protect public health and stormwater at individual sites. The ultimate the environment.179 potential of these practices, however, lies in scaling them up to the neighborhood, town, • The U.S. Conference of Mayors or regional level, to reduce burden on the A 2006 Green Infrastructure Resolution current stormwater management infrastruc­ from the U.S. Conference of Mayors recog­ ture, and plan for sustainable future growth. nized that “green infrastructure naturally This “green infrastructure” approach encom­ manages stormwater, reduces flooding passes planning for parking lots, housing risk and improves air and water quality, developments, roads, and other stormwater thus performing many of the same func­ related infrastructure. Defined by the EPA tions as traditional building infrastructure, as techniques that “utilize natural systems, often at a fraction of the cost.”180 or engineered systems that mimic natural landscapes, to capture, cleanse, and reduce The need for scaling up green infrastructure stormwater runoff using plants, soils, and is pressing. It is estimated that nearly 25 microbes,” green infrastructure is an approach million acres of impervious surface cover the that is being endorsed by U.S. federal, state continental United States, and that approxi­ and local government entities, including: mately 70 million acres of land will be newly developed in the United States by the year • The U.S. Environmental Protection 2025. By 2030, 50 percent of the built envi­ Agency (EPA) and national stakeholders ronment will have been constructed since In 2007, EPA and four major national 2000.181 Such growth will increase strain on groups (National Association of Clean Wa­ existing municipal stormwater management ter Agencies, Natural Resources Defense systems by adding more impervious surface Council, Low Impact Development Center, area and higher volumes of runoff. In many and Association of State and Interstate areas of the country, these systems are al­ Water Pollution Control Administrators) ready critically strained and are saddled with signed an agreement to promote the use a backlog of deferred maintenance. A green of green infrastructure to reduce stormwa­ infrastructure approach can minimize runoff ter runoff and sewer overflows. 178 volumes, and reduce the combined burden on municipal stormwater and wastewater infrastructures.182

CHAPTER 7—Reduced Infrastructure Burden 44 186 REGIONAL STORMWATER AND major component. For example, Portland, WASTEWATER IMPACTS Oregon is a leader in integrating innovative environmental technology into its city plan­ As outlined in previous chapters, stormwater ning and policies. The city’s building codes runoff can cause a number of serious prob­ require on-site stormwater management lems including water pollution, flooding, for all new construction projects, and their groundwater recharge deficits, and damage stormwater manual encourages the use of to stream ecology.183 These impacts translate best management practices.187 A number of into high costs to municipalities, and using smaller cities and towns have also started conventional methods alone to control them to embrace green infrastructure planning. can be an expensive use of public funds. This In Kansas City, Missouri, planners are imple­ is particularly true in regions of the country menting the 10,000 Rain Garden Initiative, with older infrastructure, including the Pacific which will create 10,000 such gardens to Northwest, Northeast, and Great Lakes. In help the city achieve its 20-year Wet Weather these regions, stormwater is often channeled Solutions Program. This is one of the largest into the same pipes as sewage (i.e., combined infrastructure projects in the city’s history.188 sewers). With large areas of impervious sur­ face and development, heavy rain events can COST EFFECTIVENESS push these combined pipes beyond capacity, causing them to overflow. These “combined Looking at stormwater management from sewer overflows,” or CSOs, result in large a regional or watershed scale is important amounts of untreated waste overflowing into when considering costs. The piping, channels, waterways, making them a primary source of and treatment plants of a traditional storm- pollution for many water bodies. The Clean water infrastructure are expensive to build, Water Act requires that combined sewer sys­ operate, and maintain, and are not the most 189 tems be updated to prevent CSOs, however, eff ective way of controlling stormwater. these upgrades are cost prohibitive for many The EPA’s Assistant Administrator for Water cities and towns.184 The EPA’s 2000 Clean has stated that: Watersheds Needs Survey estimates that $56 “Green infrastructure may save capital billion in capital investment nationally was costs associated with digging big tun­ needed for CSO controls.185 nels and centralized stormwater ponds, The regional impact of stormwater runoff operations and maintenance expenses for and CSOs cannot be properly controlled by treatment plants, pipes, and other hard sporadic site-by-site controls, or large end­ infrastructure; energy costs for pumping of-pipe conventional stormwater treatment water; and costs of wet weather treatment alone. A coordinated, area-wide planning and repairing of stormwater and sewage eff ort is required. Major cities throughout the pollution impacts, such as stream bank 190 country, including Portland (Oregon), Seattle, restoration.” Chicago, and Philadelphia, have started to Potential cost savings are important to com­ invest in land use planning and infrastructure munities throughout the United States that development with green infrastructure as a are working to comply with federal storm-

Green Parking Lot Resource Guide—February 2008 45 water management regulations. According the water body, rather than piping it directly to an 2007 report evaluating the potential into the river. They found that, at a cost of of a major storm water minimization pro­ less than $50,000 per year, the wetlands not gram, “the use of green infrastructure can only diminished stormwater flows, but also help communities meet their overall water successfully removed pollutants from runoff , resource management goals and reduce the including 80 percent of suspended solids, costs (or free up funding for other uses such 70 percent of phosphorus, and 60 percent as land purchases) of constructing and main­ of oxygen depleting compounds and heavy taining engineered infrastructure including metals. The high efficacy of the wetlands pipes and treatment systems.”191 For example, made them a cost-effective strategy for in Kane County, Illinois, researchers estimated improving the river’s water quality.194 In Port­ economic benefits of downstream stormwa­ land, Oregon, the City has found that adopt­ ter management through green infrastruc­ ing a variety of green infrastructure tech­ ture practices implemented upstream would niques over the course of a 10 year period has save approximately $4 million, money that avoided over 1.2 billion gallons of runoff and would otherwise have been spent on culvert has reduced CSO events by 10 percent.195 replacement or upgrades for stormwater It is clear that stormwater management must diversion. When both flood reduction and in­ be elevated to a key urban planning and frastructure savings are considered, the green policy issue as local governments seek to infrastructure practices were found to be ap­ reduce stormwater impacts cost-eff ectively. proximately $300-$700 less expensive per de­ Promoting green infrastructure regionally or veloped acre.192 Portland, Oregon estimates watershed-wide will help control the cumula­ its Green Streets stormwater infrastructure tive impact that stormwater from multiple design saves 40 percent in costs compared to sources has on stormwater infrastructure. conventional stormwater infrastructure (also Even in cases where green infrastructure see Green Streets case study at the end of this investments are not more cost-eff ective in chapter).193 the short-term, the long-term environmental Green infrastructure can be a cost eff ective and social benefits can be quite significant replacement or complement for other water to livability and sustainability on a regional quality improvement strategies. For example, scale. These benefits have been explored for 10 years, a demonstration project in the throughout this guide, and include enhanced Rouge River area of Michigan has been utiliz­ groundwater recharge, pollution prevention, ing 14 acres of wetlands (two thirds of which increased carbon sequestration, HIE mitiga­ are constructed) along the river’s banks to tion, improved air quality, and increased naturally treat stormwater before it enters green space and wildlife habitat.196

CHAPTER 7—Reduced Infrastructure Burden 46 CASE STUDY 5: REDUCED INFRASTRUCTURE BURDEN GREEN STREETS PROGRAM—PORTLAND, OREGON

For over a decade, the City of Portland, Oregon has been pursuing new approaches to stormwater management. Known for its wet weather with the third highest number of rainy days annually in the U.S., Portland typically averages 37 inches of rain a year.197 Approximately 66 percent of the resulting stormwater runoff comes from streets and rights of way.198 For this reason, the City created “Green Streets,” a city-wide land use planning eff ort for stormwater management focused on transportation-related develop­ ment (i.e. parking lots, streets). Defining a Green Street as “one that uses vegetated facilities to manage stormwater runoff as its One of many rain gardens being built throughout Portland as part of the city’s Green Streets program. source,” this program is part of a concert of initiatives that the city is undertaking to help surface runoff through the use of infiltration them reach their goal of removing 60 million basins. In 2006, this project was recognized gallons of stormwater annually by 2011.199, 200 with the national American Society of Land- scape Architects Design Award.201 By starting Although city officials have been promoting with demonstration projects, the City was a green streets theme for a number of years, able to monitor results and incorporate les­ in 2005 an interdisciplinary team of area sons learned into more eff ective stormwater experts, including government offi cials, en- designs that could be replicated on a city­ gineers, planners, landscape architects, and wide scale.202 watershed managers refocused the program by taking a fresh look at opportunities for its In April 2007, the Portland City Council of- implementation. This multi-disciplinary ap­ ficially endorsed the enhanced Green Streets proach provided the breadth of knowledge program by approving an innovative storm­ necessary to properly address comprehensive water management plan comprised of a reso­ stormwater management, and was invalu­ lution, report, and policy. The overarching able to successfully implementing the Green goal of this program is to “comprehensively Streets program. address numerous city goals for neighbor- hood livability, sustainable development, In revamping the Green Streets program, increased green spaces, stormwater manage- Portland focused on learning through dem­ ment, and groundwater protection.”203 The onstration projects. This includes a project on city council articulated several objectives for the Portland State University campus built achieving this goal, including a neighbor- in 2005 to treat 8,000 square-feet of street hood planning initiative, further stakeholder

Green Parking Lot Resource Guide—February 2008 47 outreach, the pursuit of more funding mecha- For more information on the Portland, nisms, and ultimately the establishment of Oregon Green Streets program, please visit even more Green Streets. As a short term the Green Streets Web site at: objective, the City is planning on developing www.portlandonline.com/BES/index. 500 additional Green Street projects to ad- cfm?c=44407&. dress combined sewer overflow issues.204

CHAPTER 7—Reduced Infrastructure Burden 48 KEY RESOURCES

PLANNING RESOURCES U.S. EPA, (2006), Parking Spaces/Community Places: Finding the Balance through Smart American Rivers and SmartGrowth America, Growth Solutions, EPA 231-K-06-001: (2002), Paving Our Way to Water Short­ www.epa.gov/dced/pdf/ ages: www.smartgrowthamerica.org/ EPAParkingSpaces06.pdf. DroughtSprawlReport09.pdf. U.S. EPA, (2005), Using Smart Growth Tech­ Boston Metropolitan Area Planning Council, niques as Stormwater Best Management (2006), Sustainable Transportation Toolkit: Practices, EPA 231-B-05-002: Parking: http://transtoolkit.mapc.org/. www.epa.gov/livability/pdf/ Center for Neighborhood Technology, (2006), sg_stormwater_BMP.pdf Paved Over: Surface Parking Lots or Op­ U.S. EPA, (1999), Parking Alternatives: Mak­ portunities for Tax—Generating Sustain­ ing Way for Urban Infill and Brownfield able Development, November 2006: Redevelopment, EPA231-K-99-001. www.cnt.org/repository/PavedOver-Final.pdf.

Gibbons, J. (1999), Parking Lots—Technical STORMWATER MANAGEMENT BMP Paper #5, University of Connecticut RESOURCES Nonpoint Education for Municipal Officials Chester County, Pennsylvania Water (NEMO) program: http://nemo.uconn.edu/ Resources Compendium, (2005), Water­ tools/publications/tech_papers/ shed Primer: http://dsf.chesco.org/water/ tech_paper_5.pdf. cwp/view.asp?a=3&q=607722.

Litman, T., (2006), Parking Management: Community Design and Architecture, (2005), Strategies, Evaluation and Planning, Stormwater Guidelines for Green Dense Victoria Transport Policy Institute, April 25, Redevelopment, U.S. EPA: www.epa.gov/ 2006: www.vtpi.org/park_man.pdf. dced/pdf/Stormwater_Guidelines.pdf.

Maryland Governor’s Offi ce of Smart Growth, Kloss, C. and Calarusse, C. (2006), Rooftops (2005), Driving Urban Environments: to Rivers: Green Strategies for Controlling Smart Growth Parking Best Practices: Stormwater and Combined Sewer Over­ www.smartgrowth.state.md.us. flows, Natural Resources Defense Council: Shoup, D., (2005), The High Cost of Free Park­ www.nrdc.org/water/pollution/rooftops/ ing, APA Planners Press. contents.asp.

Shoup, D., (1999), The Trouble with Minimum Minnesota Pollution Control Agency, (2000), Parking Requirements, Transportation Protecting Water Quality in Urban Areas: Research Part A, Vol. 33, pgs. 549-574: www.pca.state.mn.us/water/pubs/ www.vtpi.org/shoup.pdf. sw-bmpmanual.html.

Green Parking Lot Resource Guide—February 2008 49 Muthukrishnan, S. and Selvakumar, A., (2004), Wossink, A. and Hunt, B., (2003), An Evalua­ The Use of Best Management Practices tion of the Costs and Benefits of Structural (BMPs) in Urban Watersheds, U.S. En­ Stormwater Best Management Practices vironmental Protection Agency, EPA­ in North Carolina, North Carolina State 600-R-04-184. University: www.stormwaterauthority.org/ assets/Stormwater_BMP_Factsheet%20 NAHB Research Center, Inc., (2003), The -%20NC.pdf. Practice of Low Impact Development, U.S. Department of Housing and Urban Devel­ NATURAL LANDSCAPING AND opment: www.huduser.org/publications/ IRRIGATION PDF/practlowimpctdevel.pdf. City of Chicago, (2003), A Guide to Storm- U.S. EPA, (2007), National Pollutant Discharge water Best Management Practices: www. Elimination (NPDES) Fact Sheets: cdfi nc.com/CDF_Resources/Chicago%20 http://cfpub.epa.gov/npdes/ GuideTo%20Stormwater%20BMP.pdf. stormwater/menuofbmps/ index.cfm?action=factsheet_ Florida Department of Environmental Protec­ results&view=specifi c&bmp=75. tion, (2006), Water Best Management Practices, Florida Green Lodging Program: U.S. EPA, (2007), Polluted Runoff (Nonpoint www.treeo.ufl .edu/greenlodging/content/ Source Pollution) Web site: gr_h2o.htm. www.epa.gov/owow/nps/whatis.html. Illinois Conservation Foundation and Chi­ U.S. EPA, (1999), Preliminary Data Summary cago Wilderness, (2005), Changing Cost of Urban Stormwater Best Management Perceptions: An Analysis of Conserva­ Practices, EPA-821-R-99-012, August 1999: tion Development: www.cdfinc. com/ www.epa.gov/waterscience/guide/ CDF_Resources/Cost%20Analysis%20 stormwater. -%20Part%201%20-%20Report%20-%20 U.S. EPA, (1999), Storm Water Municipal Tech­ with%20Exec%20 nologies, EPA-832-F-99-019: Summary.pdf. www.epa.gov/owm/mtb/mtbfact.htm. North Carolina Department of Environment Washington State Department of Ecology, and Natural Resources, (2005), Water (2004), Stormwater and Economic Devel­ Effi ciency: Water Management Options, opment, 04-10-001: www.ecy.wa.gov/ Division of Pollution Prevention and Envi­ pubs/0410001.pdf. ronmental Assistance: www.p2pays.org/ ref/04/03102.pdf. Weiss, P., Gulliver, J., and Erickson, A., (2007), Cost and Pollutant Removal of Storm-Wa­ Pennsylvania Department of Environmental ter Treatment Practices, Journal of Water Protection, (2006), Pennsylvania Stormwa­ Resources Planning and Management, ter Best Management Practices Manual: Volume 133, Issue 3, pp. 218-229, May/ Chapter 5, 363-0300-002: www.dep.state. June 2007. pa.us/dep/deputate/watermgt/wc/sub- jects/stormwatermanagement/BMP%20 Manual/05_Chapter_Final_Draft.pdf. Key Resources 50 State of California Energy Commission, (2005), Cahill, T. et al, (2005), Stormwater Manage­ California’s Water-Energy Relationship, ment with Porous Pavements, Govern­ CEC-700-2005-011-SF: www.energy. ment Engineering, March-April 2005, pp. ca.gov/2005publications/CEC-700-2005-011/ 14-19: www.govengr.com/ArticlesMar05/ CEC-700-2005-011-SF.PDF. porous.pdf.

U.S. Department of Energy, (2006), Federal Diyagama, T., et al., (2004), Permeable Pave­ Energy Management Program—Water ment Design Guidelines - Draft, prepared Effi ciency: http://www1.eere.energy.gov/ for North Shore City, EcoWater Solutions, femp/water/water_bmp3.html. and Rodney District: www.northshorecity. govt.nz/IDSM/IDSM2006/downloads/ U.S. Department of Energy, (2001), Greening PDFs/Permeable_Pavement_Design_ Federal Facilities, second edition: Guidelines_Draft_092004.pdf. www.nrel.gov/docs/fy01osti/29267.pdf. Hinman, C., (2005), Low Impact Development U.S. EPA, (2004), Conference Summary, Technical Guidance Manual for Puget Landscaping with Native Plants: Exploring Sound, Puget Sound Action Team, publi­ the Environmental, Social and Economic cation number PSAT 05-03, p. 121: Benefits Conference December 6 - 7, 2004: www.psat.wa.gov/Publications/LID_tech_ www.epa.gov/greenacres/conf12_04/ manual05/lid_index.htm. conf_knwldge.html. Idaho Department of Environmental Quality, U.S. EPA, GreenScapes Web site Resource: (2005), Storm Water Best Management www.epa.gov/greenscapes/. Practices Catalog: www.deq.idaho.gov/ U.S. EPA, Landscaping with Native Plants— water/data_reports/storm_water/catalog/ Greenacres Web site Resource: www.epa. sec_3/bmps/11.pdf. gov/greenacres//index.html#Benefi ts. Knox County, Tennessee, (2007), Stormwater U.S. EPA, (2003), Water-Effi cient Landscaping: Management Ordinance, Volume 1 and 2: www.epa.gov/npdes/pubs/ http://knoxcounty.org/stormwater/. watereffi ciency.pdf. New Jersey Department of Environmental Wolf, K., (2004), Trees, Parking, and Green Protection, (2004), New Jersey Stormwa­ Law: Strategies for Sustainability: www.ur­ ter Best Management Practices Manual: banforestrysouth.org/Resources/Library/ www.njstormwater.org/tier_A/pdf/ Citation.2004-07-14.1757/fi le_name. NJ_SWBMP_9.7.pdf.

New York State Department of Environmen­ ALTERNATIVE PARKING SURFACE tal Conservation, (2003), New York State MATERIALS Stormwater Management Design Manual, Brattebo, B. and Booth, D., (2003), Long-term with updated sections from 2007: stormwater quantity and quality perfor­ www.dec.ny.gov/chemical/29072.html. mance of permeable pavement systems, Water Research, 37, 4368-4376, November Pennsylvania Department of Environmental 2003. Protection, (2005), Draft Pennsylvania

Green Parking Lot Resource Guide—February 2008 51 Stormwater Best Management Manual: Administrator on Water, to USEPA Regional www.dep.state.pa.us/dep/deputate/ Administrators regarding Using Green watermgt/wc/subjects/ Infrastructure to Protect Water Quality in stormwatermanagement/BMP%20 Storm Water, CSO, Non-point Source and Manual/BMP%20Manual.htm. Other Water Programs, March 5, 2007.

U.S. Department of Transportation, (2007), Kloss, C. and Calarusse, C., (2006), Rooftops Stormwater Best Management Practices to Rivers: Green Strategies for Controlling in an Ultra Urban Setting: www.fhwa.dot. Stormwater and Combined Sewer Over­ gov/environment/ultraurb/uubmp3p6.htm. flows, Natural Resources Defense Council: www.nrdc.org/water/pollution/rooftops/ U.S. EPA, National Pollutant Discharge Elimi­ contents.asp. nation System (NPDES)—National Menu of Stormwater Best Management Practices U.S. EPA, (2007), Green Infrastructure Pro­ (i.e. Porous Pavement Fact Sheet, Alterna­ gram—A report evaluating the concept of tive Pavers Fact Sheet): http://cfpub.epa. a major storm water minimization pro­ gov/npdes/stormwater/menuofbmps/. gram, utilizing green infrastructure and related methods, prepared by Prepared REDUCED INFRASTRUCTURE BURDEN by Metropolitan Sewer District of Greater Center for Neighborhood Technology, (2007), Cincinnati et al: www.msdgc.org/ Green Infrastructure Performance: www. downloads/wetweather/greenreport/ cnt.org/repository/BMP-Performance.pdf. Files/Green_Report.pdf.

City of Portland, Oregon Green Streets Program: U.S. EPA, (2007), National Pollutant Discharge Elimination System (NPDES): Environmen­ Green Streets Program Web site accessed tal Benefits of Green Infrastructure: at: www.portlandonline.com/BES/index. http://cfpub.epa.gov/npdes/ cfm?c=eeeah greeninfrastructure/information. Green Street Cross-Bureau Team Report – cfm#enviroben. Phase I, March 2006: www.portlandonline. U.S. EPA, (2007), National Pollutant Discharge com/shared/cfm/image.cfm?id=123793 Elimination Systems (NPDES): Green In­ Green Street Cross-Bureau Team Report— frastructure: http://cfpub.epa.gov/npdes/ Phase 2: www.portlandonline.com/ home.cfm?program_id=298. shared/cfm/image.cfm?id=153974. U.S. EPA, Report to Congress: Impacts and Dunn, A. and Stoner, N., (2007), Green Light Control of CSOs and SSOs, Offi ce of Water, for Green Infrastructure, The Environ­ EPA-833-R-04-001, August 2004. mental Forum, May/June 2007, reprinted Water Environment Research Foundation, by the Environmental Law Institute and (2007), Portland Oregon: Building a accessed at: www.epa.gov/npdes/pubs/ Nationally Recognized Program Through green_light_gi.pdf. Innovation and Research, accessed as: Grumbles, B.H., (2007), Memorandum from www.werf.org/livablecommunitires/stud­ Benjamin H. Grumbles, USEPA Assistant ies_port_or.html. Key Resources 52 Requirements, Transportation Research Part A, Vol. 33, pgs. ENDNOTES 549-574. 1 Van Metre, P. et al, (2006), Parking Lot Sealcoat: A Major 16 Ibid. Source of Polycyclic Aromatic Hydrocarbons (PAHs) in Urban 17 and Suburban Environments, USGS Fact Sheet 2005-3147, Halifax Regional Municipality, (2003), Parking Supply Man­ January 2006. agement Strategies, accessed at: www.halifax.ca/regional­ planning/publications/ParkingStrategies.pdf. 2 N.Y. State Department of Transportation, (2003), Safety 18 Bulletin: Paving with Hot Mix Asphalt, SB-03-3, accessed U.S. EPA, (1999), Parking Alternatives: Making Way for Urban at: www.dot.state.ny.us/progs/safety/files /pavinghma. Infill and Brownfield Redevelopment, EPA231-K-99-001. pdf#search=%22fumes%20from%20hot%20mix%20as­ 19 Ibid. phalt%22. 20 Maryland Governor’s Offi ce of Smart Growth, (2005), 3 U.S. EPA, (1992), Cooling Our Communities, Driving Urban Environments: Smart Growth Parking Best GPO#055-000-00371-8, January 1992, accessed at: www. Practices, page 4, accessed at: www.smartgrowth.state. epa.gov, as cited in Pavement Busters Guide (2002), page md.us. 10, Victoria Transport Policy Institute. 21 Ibid. 4 Gibbons, J., (1999), Pavements and Surface Materials, Tech­ 22 nical Paper #8, pg. 2, University of Connecticut Nonpoint U.S. EPA, (1999,) Parking Alternatives: Making Way for Urban Education for Municipal Offi cials (NEMO) program, accessed Infill and Brownfield Redevelopment, EPA231-K-99-001. at: http://nemo.uconn.edu/tools/publications/tech_papers/ 23 Boston Metropolitan Area Planning Council, (2006), Sustain­ tech_paper_8.pdf. able Transportation Toolkit: Parking, accessed at: 5 Pomeranz, Melvin, Lawrence Berkeley National Laboratory, http://transtoolkit.mapc.org/ in June 2007. Benefits of Cooler Pavements, http://eetd.lbl.gov/HeatIs­ 24 Maryland Governor’s Offi ce of Smart Growth, (2005), land/Pavements/Overview/index.html, Driving Urban Environments: Smart Growth Parking Best 6 Miramontes, E.M. University of California at Berkeley, (1997), Practices, page 4, accessed at: www.smartgrowth.state. The Bay Area’s Love-Hate Relationship With The Motorcar, md.us. San Francisco Examiner, October 20, 1997, as cited in Gib­ 25 Gibbons, J., (1999), Parking Lots, Technical Paper #5, bons, J. (1999), Parking Lots, Technical Paper #5, page 2, University of Connecticut Nonpoint Education for Municipal University of Connecticut Nonpoint Education for Municipal Offi cials (NEMO) program, accessed at: http://nemo.uconn. Offi cials (NEMO) program, accessed at: http://nemo.uconn. edu/tools/publications/tech_papers/tech_paper_5.pdf. edu/tools/publications/tech_papers/tech_paper_5.pdf. 26 University of Connecticut Nonpoint Education for Municipal 7 Benfield, F.K. et al, (1999), Once There Were Greenfields: Offi cials (NEMO) program, (1999), Parking Lots - Technical How Urban Sprawl is Undermining America’s Environment, Paper #5, accessed at: http://nemo.uconn.edu/tools/publi­ Economy, and Social Fabric, Natural Resources Defense cations/tech_papers/tech_paper_5.pdf. Council (NRDC), as cited in Paving Our Way to Water Short­ 27 ages, NRDC, American Rivers, Smart Growth America, 2002, Minnesota Pollution Control Agency, (2000), Protecting page 6. Water Quality in Urban Areas, accessed at: www.pca.state. mn.us/water/pubs/sw-bmpmanual.html. 8 Maryland Governor’s Offi ce of Smart Growth (2005) Driving 28 Urban Environments: Smart Growth Parking Best Practices, Kloss, C. and Calarusse, C., (2006), Rooftops to Rivers: Green page 4, accessed at: www.smartgrowth.state.md.us. Strategies for Controlling Stormwater and Combined Sewer Overflows, Natural Resources Defense Council, accessed at: 9 Ibid. www.nrdc.org/water/pollution/rooftops/contents.asp. 10 Maryland Governor’s Offi ce of Smart Growth, (2005), 29 Muthukrishnan, S. and Selvakumar, A., (2004), The Use of Driving Urban Environments: Smart Growth Parking Best Best Management Practices (BMPs) in Urban Watersheds, Practices, page 23, accessed at: www.smartgrowth.state. U.S. Environmental Protection Agency, EPA-600-R-04-184. md.us. 30 Ibid. 11 Permeable pavers should not be used for the aisles and 31 main (primary) vehicle travel areas in high traffi c lots Ibid. because they are not strong enough to withstand constant 32 U.S. EPA, (2007), National Pollutant Discharge Elimination weight and use, however in most cases they would be ideal (NPDES)—Grassed Swales Fact Sheet, accessed at: http:// for use in parking stalls, crosswalks, or overflow (i.e. second­ cfpub.epa.gov/npdes/stormwater/menuofbmps/index. ary) parking areas. cfm?action=factsheet_results&view=specifi c&bmp=75. 12 U.S. EPA, (2001), Functions and Values of Wetlands, EPA 33 Muthukrishnan, S. and Selvakumar, A., (2004), The Use of 843-F-01-002c, September 2001, accessed at: www.epa. Best Management Practices (BMPs) in Urban Watersheds, gov/owow/wetlands/pdf/fun_val.pdf. U.S. Environmental Protection Agency, EPA-600-R-04-184. 13 Shoup, D., (2005), The High Cost of Free Parking, APA Plan­ 34 NAHB Research Center, Inc., (2003), The Practice of Low Im­ ners Press, pages 2-3. pact Development, U.S. Department of Housing and Urban 14 Litman, T., (2002), Pavement Busters guide, Victoria Trans­ Development, accessed at: www.huduser.org/publications/ port Policy Institute, accessed at: www.vtpi.org/pavbust.pdf PDF/practlowimpctdevel.pdf. in June 2007. 35 Muthukrishnan, S. and Selvakumar, A., (2004), The Use of 15 Standards are typically determined by referring to the Best Management Practices (BMPs) in Urban Watersheds, Institute of Transportation Engineers guidance documents U.S. Environmental Protection Agency, EPA-600-R-04-184. or by researching the requirements of surrounding towns. 36 ibid. Shoup, D., (1999), The Trouble with Minimum Parking

Green Parking Lot Resource Guide—February 2008 53 37 ibid. 54 Information for this case study was obtained from: LaCroix, R., et al, (2004), Reining in the Rain: A case study of the city 38 U.S. EPA, (2007), National Pollutant Discharge Elimination of Bellingham’s use of rain gardens to manage stormwater, (NPDES) - Grassed Swales Fact Sheet, accessed at: http:// accessed at: www.psat.wa.gov/Publications/Rain_Garden_ cfpub.epa.gov/npdes/stormwater/menuofbmps/index. book.pdf and personal communication with Bill Reilly, City cfm?action=factsheet_results&view=specifi c&bmp=75. of Bellingham Public Works Department. 39 Muthukrishnan, S. and Selvakumar, A., (2004), The Use of 55 King County Environmental Purchasing Program, (2007), Best Management Practices (BMPs) in Urban Watersheds, Recycled Asphalt Fact Sheet, King County, Washington, ac­ U.S. Environmental Protection Agency, EPA-600-R-04-184. cessed at: www.metrokc.gov/procure/green/asphalt.htm#1. 40 Community Design and Architecture, (2005), Stormwater 56 U.S. EPA, (2005), EPA Lessons Learned Paper – Heifer Inter­ Guidelines for Green Dense Redevelopment, U.S. EPA, ac­ national, page 5. cessed at: www.epa.gov/dced/pdf/Stormwater_Guidelines. pdf. 57 Similarly, the new paving product RESINPAVE™ is manu­ factured from renewable resources, contains no petroleum 41 Minnesota Pollution Control Agency, (2000), Protection ingredients, and is highly reflective. However, it too is Water Quality in Urban Areas, March 1, 2000, accessed at: impervious, and is also still in experimental stages. www.pca.state.mn.us/water/pubs/sw~bmpmanual.html. 58 New York State Department of Environmental Conservation, 42 Washington State Department of Ecology, (2004), Storm- (2007), New York State Stormwater Design Manual - Chapter water and Economic Development, 04-10-001, accessed at: 9, accessed at: www.dec.ny.gov/chemical/29072.html. www.ecy.wa.gov/pubs/0410001.pdf. 59 U.S. EPA, (2007), National Pollutant Discharge Elimination 43 Kloss, C. and Calarusse, C., (2006), Rooftops to Rivers: Green System (NPDES) – Porous Pavement Fact Sheet, accessed at: Strategies for Controlling Stormwater and Combined Sewer http://cfpub.epa.gov/npdes/stormwater/menuofbmps/in­ Overflows, Natural Resources Defense Council, accessed at: dex.cfm?action=factsheet_results&view=specifi c&bmp=71. www.nrdc.org/water/pollution/rooftops/contents.asp. 60 Ibid. 44 Van Metre, P. et al, (2006), Parking Lot Sealcoat: A Major Source of Polycyclic Aromatic Hydrocarbons (PAHs) in Urban 61 New Jersey Department of Environmental Protection, and Suburban Environments, USGS Fact Sheet 2005-3147, (2004), New Jersey Stormwater Best Management Practices January 2006. Manual, accessed at: www.njstormwater.org/tier_A/pdf/ NJ_SWBMP_9.7.pdf. 45 U.S. EPA, (2007), Polluted Runoff (Nonpoint Source Pollu­ tion) website, accessed at: www.epa.gov/owow/nps/whatis. 62 U.S. EPA, (2007), National Pollutant Discharge Elimination html. System (NPDES) – Porous Pavement Fact Sheet, accessed at: http://cfpub.epa.gov/npdes/stormwater/menuofbmps/in­ 46 Muthukrishnan, S. and Selvakumar, A., (2004), The Use of dex.cfm?action=factsheet_results&view=specifi c&bmp=71. Best Management Practices (BMPs) in Urban Watersheds, U.S. Environmental Protection Agency, EPA-600-R-04-184. 63 Pennsylvania Department of Environmental Protection, (2005), Draft Pennsylvania Stormwater Best Management 47 U.S. EPA, (1999), Storm Water Technology Fact Sheet Infiltra­ Manual, Section 6 - Comprehensive Stormwater Manage­ tion Trench, EPA-832-F-99-019, accessed at: www.epa.gov/ ment: Structural BMPs, accessed at: www.dep.state.pa.us/ owm/mtb/infl trenc.pdf. dep/subject/advcoun/stormwater/Manual_DraftJan05/ 48 Wossink, A. and Hunt, B., (2003), An Evaluation of the Costs Section06-StructuralBMPs-part1.pdf and Benefits of Structural Stormwater Best Management 64 Knox County, Tennessee, (2007), Stormwater Management Practices in North Carolina, North Carolina State University, Ordinance, Volume 2 (technical guidance), accessed at: accessed at: www.stormwaterauthority.org/assets/Storm- http://knoxcounty.org/stormwater/volume2.php. water_BMP_Factsheet%20-%20NC.pdf. 65 Pennsylvania Department of Environmental Protection, 49 U.S. EPA, (1999), Preliminary Data Summary of Urban (2005), Draft Pennsylvania Stormwater Best Management Stormwater Best Management Practices, EPA-821-R-99-012, Manual, Section 6 - Comprehensive Stormwater Manage­ August 1999, accessed at: www.epa.gov/waterscience/ ment: Structural BMPs, accessed at: www.dep.state.pa.us/ guide/stormwater. dep/subject/advcoun/stormwater/Manual_DraftJan05/ 50 Muthukrishnan, S. and Selvakumar, A., (2004), The Use of Section06-StructuralBMPs-part1.pdf Best Management Practices (BMPs) in Urban Watersheds, 66 Frazer, L., (2006), Paving Paradise: The Peril of Impervious U.S. Environmental Protection Agency, EPA-600-R-04-184. Surfaces, Environ Health Perspect. 2006 Jan;114(1):A21. 51 Kloss, C. and Calarusse, C., (2006), Rooftops to Rivers: Green 67 Cahill, T. et al, (2005), Stormwater Management with Porous Strategies for Controlling Stormwater and Combined Sewer Pavements, Government Engineering, March-April 2005, Overflows, Natural Resources Defense Council, accessed at: pp. 14-19, accessed at: www.govengr.com/ArticlesMar05/ www.nrdc.org/water/pollution/rooftops/contents.asp. porous.pdf. 52 Wossink, A. and Hunt, B., (2003), An Evaluation of the Costs 68 U.S. EPA, (2007), National Pollutant Discharge Elimination and Benefits of Structural Stormwater Best Management System (NPDES) – Porous Pavement Fact Sheet, accessed at: Practices in North Carolina, North Carolina State University, http://cfpub.epa.gov/npdes/stormwater/menuofbmps/in­ accessed at: www.stormwaterauthority.org/assets/Storm- dex.cfm?action=factsheet_results&view=specifi c&bmp=71. water_BMP_Factsheet%20-%20NC.pdf. 69 Pennsylvania Department of Environmental Protection, 53 Chester County, Pennsylvania Water Resources Compen­ (2005), Draft Pennsylvania Stormwater Best Management dium, (2005), Watershed Primer Part 4: Land Use impacts Manual, Section 6 - Comprehensive Stormwater Manage­ and Watershed Economics, accessed at: http://dsf.chesco. ment: Structural BMPs, accessed at: www.dep.state.pa.us/ org/water/cwp/view.asp?a=3&q=607722. dep/subject/advcoun/stormwater/Manual_DraftJan05/ Section06-StructuralBMPs-part1.pdf.

Key Resources 54 70 McDaniel, R., (2004), Field Evaluation of Porous Asphalt dex.cfm?action=factsheet_results&view=specifi c&bmp=71. Pavement – Research Summary, Purdue University, 84 Knox County, Tennessee, (2007), Stormwater Management accessed at: http://meweb.ecn.purdue.edu/~sqdh/ Ordinance, Volume 2 (technical guidance), accessed at: SQDH2004_3/RS%20McDaniel%20Porous%20Asphalt.pdf. http://knoxcounty.org/stormwater/volume2.php. 71 Idaho Department of Environmental Quality, (2005), Storm 85 New York State Department of Environmental Conservation, Water Best Management Practices Catalog, accessed at: (2007), New York State Stormwater Design Manual - Chap­ www.deq.idaho.gov/water/data_reports/storm_water/ ter 9, accessed at: www.dec.ny.gov/chemical/29072.html. catalog/sec_3/bmps/11.pdf. 86 Ibid. 72 New Jersey Department of Environmental Protection, (2004), New Jersey Stormwater Best Management Practices 87 Pennsylvania Department of Environmental Protection, Manual, accessed at: www.njstormwater.org/tier_A/pdf/ (2005), Draft Pennsylvania Stormwater Best Management NJ_SWBMP_9.7.pdf. Manual, Section 6 - Comprehensive Stormwater Manage­ ment: Structural BMPs, accessed at: www.dep.state.pa.us/ 73 U.S. EPA, (2007), National Pollutant Discharge Elimina­ dep/subject/advcoun/stormwater/Manual_DraftJan05/ tion System (NPDES) – Alternative Pavers Fact Sheet, Section06-StructuralBMPs-part1.pdf. accessed at: http://cfpub.epa.gov/npdes/storm­ water/menuofbmps/index.cfm?action=factsheet_ Cahill, T. et al, (2005), Stormwater Management with Porous results&view=specifi c&bmp=134. Pavements, Government Engineering, March-April 2005, pp. 14-19, accessed at: www.govengr.com/ArticlesMar05/ 74 Idaho Department of Environmental Quality, (2005), Storm porous.pdf. Water Best Management Practices Catalog, accessed at: www.deq.idaho.gov/water/data_reports/storm_water/ 88 U.S. EPA, (2007), National Pollutant Discharge Elimination catalog/sec_3/bmps/11.pdf. System (NPDES) – Porous Pavement Fact Sheet, accessed at: http://cfpub.epa.gov/npdes/stormwater/menuofbmps/in­ 75 Idaho Department of Environmental Quality, (2005), Storm dex.cfm?action=factsheet_results&view=specifi c&bmp=71. Water Best Management Practices Catalog, accessed at: www.deq.idaho.gov/water/data_reports/storm_water/ 89 Ibid. catalog/sec_3/bmps/11.pdf. 90 New York State Department of Environmental Conservation, 76 New York State Department of Environmental Conservation, (2007), New York State Stormwater Design Manual - Chap­ (2007), New York State Stormwater Design Manual - Chap­ ter 9, accessed at: www.dec.ny.gov/chemical/29072.html. ter 9, accessed at: www.dec.ny.gov/chemical/29072.html. 91 Pennsylvania Department of Environmental Protection, 77 Idaho Department of Environmental Quality, (2005), Storm (2005), Draft Pennsylvania Stormwater Best Management Water Best Management Practices Catalog, accessed at: Manual, Section 6 - Comprehensive Stormwater Manage­ www.deq.idaho.gov/water/data_reports/storm_water/ ment: Structural BMPs, accessed at: www.dep.state.pa.us/ catalog/sec_3/bmps/11.pdf. dep/subject/advcoun/stormwater/Manual_DraftJan05/ Section06-StructuralBMPs-part1.pdf. 78 US Department of Transportation, (2007), Stormwater Best Management Practices in an Ultra Urban Setting, accessed 92 New Jersey Department of Environmental Protection, at: www.fhwa.dot.gov/environment/ultraurb/uubmp3p6. (2004), New Jersey Stormwater Best Management Practices htm. Manual, accessed at: www.njstormwater.org/tier_A/pdf/ NJ_SWBMP_9.7.pdf. 79 Diyagama, T., et al. ,(2004), Permeable Pavement Design Guidelines - Draft, prepared for North Shore City, EcoWater 93 Pennsylvania Department of Environmental Protection, Solutions, and Rodney District, accessed at: www.northsho­ (2005), Draft Pennsylvania Stormwater Best Management recity.govt.nz/IDSM/IDSM2006/downloads/PDFs/Perme­ Manual, Section 6 - Comprehensive Stormwater Manage­ able_Pavement_Design_Guidelines_Draft_092004.pdf. ment: Structural BMPs, accessed at: www.dep.state.pa.us/ dep/subject/advcoun/stormwater/Manual_DraftJan05/ 80 US Department of Transportation, (2007), Stormwater Best Section06-StructuralBMPs-part1.pdf. Management Practices in an Ultra Urban Setting, accessed at: www.fhwa.dot.gov/environment/ultraurb/uubmp3p6. 94 Ibid. htm. 95 Ibid. 81 New York State Department of Environmental Conservation, 96 Pennsylvania Department of Environmental Protection, (2007), New York State Stormwater Design Manual - Chap­ (2005), Draft Pennsylvania Stormwater Best Management ter 9, accessed at: www.dec.ny.gov/chemical/29072.html. Manual, Section 6 - Comprehensive Stormwater Manage­ 82 Cahill, T. et al, (2005), Stormwater Management with Porous ment: Structural BMPs, accessed at: www.dep.state.pa.us/ Pavements, Government Engineering, March-April 2005, dep/subject/advcoun/stormwater/Manual_DraftJan05/ pp. 14-19, accessed at: www.govengr.com/ArticlesMar05/ Section06-StructuralBMPs-part1.pdf. porous.pdf. New York State Department of Environmental Conservation, U.S. EPA, (2007), National Pollutant Discharge Elimination (2007), New York State Stormwater Design Manual - Chap­ System (NPDES) – Porous Pavement Fact Sheet, accessed at: ter 9, accessed at: www.dec.ny.gov/chemical/29072.html. http://cfpub.epa.gov/npdes/stormwater/menuofbmps/in­ 97 Cahill, T. et al, (2005), Stormwater Management with Porous dex.cfm?action=factsheet_results&view=specifi c&bmp=71. Pavements, Government Engineering, March-April 2005, New York State Department of Environmental Conservation, pp. 14-19, accessed at: www.govengr.com/ArticlesMar05/ (2007), New York State Stormwater Design Manual - Chap­ porous.pdf. ter 9, accessed at: www.dec.ny.gov/chemical/29072.html. 98 New York State Department of Environmental Conservation, 83 U.S. EPA, (2007), National Pollutant Discharge Elimination (2007), New York State Stormwater Design Manual - Chap­ System (NPDES) – Porous Pavement Fact Sheet, accessed at: ter 9, accessed at: www.dec.ny.gov/chemical/29072.html. http://cfpub.epa.gov/npdes/stormwater/menuofbmps/in­

Green Parking Lot Resource Guide—February 2008 55 99 U.S. EPA, (2007), National Pollutant Discharge Elimination dex.cfm?action=factsheet_results&view=specifi c&bmp=71. System (NPDES) – Porous Pavement Fact Sheet, accessed at: 114 Pennsylvania Department of Environmental Protection, http://cfpub.epa.gov/npdes/stormwater/menuofbmps/in­ (2005), Draft Pennsylvania Stormwater Best Management dex.cfm?action=factsheet_results&view=specifi c&bmp=71. Manual, Section 6 - Comprehensive Stormwater Manage­ 100 Cahill, T. et al, (2005), Stormwater Management with Porous ment: Structural BMPs, accessed at: www.dep.state.pa.us/ Pavements, Government Engineering, March-April 2005, dep/subject/advcoun/stormwater/Manual_DraftJan05/ pp. 14-19, accessed at: www.govengr.com/ArticlesMar05/ Section06-StructuralBMPs-part1.pdf. porous.pdf. 115 Cahill, T. et al, (2005), Stormwater Management with Porous 101 Pennsylvania Department of Environmental Protection, Pavements, Government Engineering, March-April 2005, (2005), Draft Pennsylvania Stormwater Best Management pp. 14-19, accessed at: www.govengr.com/ArticlesMar05/ Manual, Section 6 - Comprehensive Stormwater Manage­ porous.pdf. ment: Structural BMPs, accessed at: www.dep.state.pa.us/ 116 Pennsylvania Department of Environmental Protection, dep/subject/advcoun/stormwater/Manual_DraftJan05/ (2005), Draft Pennsylvania Stormwater Best Management Section06-StructuralBMPs-part1.pdf. Manual, Section 6 - Comprehensive Stormwater Manage­ 102 New York State Department of Environmental Conservation, ment: Structural BMPs, accessed at: www.dep.state.pa.us/ (2007), New York State Stormwater Design Manual - Chapter dep/subject/advcoun/stormwater/Manual_DraftJan05/ 9, accessed at: www.dec.ny.gov/chemical/29072.html. Section06-StructuralBMPs-part1.pdf. 103 Hinman, C., (2005), Low Impact Development Technical 117 New York State Department of Environmental Conservation, Guidance Manual for Puget Sound, Puget Sound Action (2007), New York State Stormwater Design Manual - Chapter Team, publication number PSAT 05-03, accessed at: www. 9, accessed at: www.dec.ny.gov/chemical/29072.html. psat.wa.gov/Publications/LID_tech_manual05/lid_index. 118 Pennsylvania Department of Environmental Protection, htm. (2005), Draft Pennsylvania Stormwater Best Management 104 Bean, E., et al, (2007), Field Survey of Permeable Pavement Manual, Section 6 - Comprehensive Stormwater Manage­ Surface Infiltration Rates, J. Irrig. and Drain. Engrg., Volume ment: Structural BMPs, accessed at: www.dep.state.pa.us/ 133, Issue 3, pp. 249-255, May/June 2007. dep/subject/advcoun/stormwater/Manual_DraftJan05/ Section06-StructuralBMPs-part1.pdf. 105 U.S. EPA, (2007), National Pollutant Discharge Elimination System (NPDES) – Porous Pavement Fact Sheet, accessed at: 119 U.S. EPA, (2007), National Pollutant Discharge Elimina­ http://cfpub.epa.gov/npdes/stormwater/menuofbmps/in­ tion System (NPDES) – Alternative Pavers Fact Sheet, dex.cfm?action=factsheet_results&view=specifi c&bmp=71 accessed at: http://cfpub.epa.gov/npdes/storm­ water/menuofbmps/index.cfm?action=factsheet_ Hinman, C., (2005), Low Impact Development Technical results&view=specifi c&bmp=134 Guidance Manual for Puget Sound, Puget Sound Action Team, publication number PSAT 05-03, p. 121, accessed at: 120 New York State Department of Environmental Conservation, www.psat.wa.gov/Publications/LID_tech_manual05/lid_in­ (2007), New York State Stormwater Design Manual - Chapter dex.htm. 9, accessed at: www.dec.ny.gov/chemical/29072.html. 106 Hinman, C., (2005), Low Impact Development Technical 121 Another option is to also include coal ash in the concrete, Guidance Manual for Puget Sound, Puget Sound Action which improve its strength and durability while using a Team, publication number PSAT 05-03, accessed at: www. recycled material. Heifer explored this, but chose other psat.wa.gov/Publications/LID_tech_manual05/lid_index. sustainable options for their lot based on preference and htm. budget. 107 Cahill, T. et al, (2005), Stormwater Management with Porous 122 Wade, B., (2000), Putting the freeze on heat islands, Ameri­ Pavements, Government Engineering, March-April 2005, can City & County, 115, 2, 30, page 2, Feb 2000. pp. 14-19, accessed at: www.govengr.com/ArticlesMar05/ 123 Calculated using the PaLATE model, a lifecycle assessment porous.pdf. tool created to derive the environmental and economic 108 New York State Department of Environmental Conservation, effects of paved surfaces. Information on the PaLATE model (2007), New York State Stormwater Design Manual - Chapter can be found at: www.ce.berkeley.edu/~horvath/palate. 9, accessed at: www.dec.ny.gov/chemical/29072.html. html. 109 Knox County, Tennessee, (2007), Stormwater Management 124 Mercury (Hg) emissions were modeled by PaLATE, but were Ordinance, Volume 2 (technical guidance), accessed at: not mentioned here because the emissions diff erence was http://knoxcounty.org/stormwater/volume2.php. negligible. 110 Turfstone®, UNI Eco-Stone®, Grasspave2®, and Gravelpave2® 125 U.S. Offi ce of Management and Budget, (2005), Draft 2005 Report to Congress on the Costs and Benefits of Federal 111 Brattebo, B. and Booth, D., (2003), Long-term stormwater Regulations, Appendix B and U.S. Offi ce of Management quantity and quality performance of permeable pavement and Budget, Circular A-94: Guidelines and Discount Rates systems, Water Research, 37, 4368-4376, November 2003. for Benefit-Cost Analysis of Federal Programs, accessed at: 112 Hinman, C., (2005), Low Impact Development Technical www.whitehouse.gov/omb/circulars/a094/a094.pdf on Guidance Manual for Puget Sound, Puget Sound Action January 10, 2007. Team, publication number PSAT 05-03, accessed at: www. It should be noted that the values shown here are based on psat.wa.gov/Publications/LID_tech_manual05/lid_index. national averages. htm. The high end of this range represents values associated 113 U.S. EPA, (2007), National Pollutant Discharge Elimination with avoided emissions in areas with severe air quality System (NPDES) – Porous Pavement Fact Sheet, accessed at: impairment, and are likely too high to apply to the Little http://cfpub.epa.gov/npdes/stormwater/menuofbmps/in­ Rock area, which is in attainment with federal PM10 and SO2

Key Resources 56 standards, as well as all other air quality standards. Query Building Sciences, (2007), Whole Building Design Guide, of EPA Air Data, January 21, 2006: www.epa.gov/air/data/ accessed at: www.wbdg.org/tools. nonat.html?st~AR~Arkansas. 140 Florida Department of Environmental Protection, (2006), 126 Sources for this case study include: McNally, C., et al, Water Best Management Practices, Florida Green Lodging (2003), The University of Rhode Island’s Permeable Parking Program, accessed at: www.treeo.ufl .edu/greenlodging/ Lots: A case Study of Alternative Pavement Materials, ac­ content/gr_h2o.htm. cessed at: www.uri.edu/ce/wq/NEMO/Publications/PDFs/ 141 Ibid. PP.URICaseStudy.pdf; and the 2005 update to this docu­ ment located at www.uri.edu/ce/wq/NEMO/Publications/ 142 U.S. Department of Energy, (2006), Federal Energy Manage­ index.htm. ment Program – Water Effi ciency, accessed at: http://www1. eere.energy.gov/femp/water/water_bmp3.html. 127 URI also does not permit commercial and industrial vehicles on this lot because of groundwater contamination con­ 143 Ibid. cerns, and to avoid compaction of the pourous bituminous 144 Florida Department of Environmental Protection, (2006), asphalt. Water Best Management Practices, Florida Green Lodging 128 Potable water is defined by the US EPA as water suit­ Program, accessed at: www.treeo.ufl .edu/greenlodging/ able for drinking or cooking purposes from both health content/gr_h2o.htm. and aesthetic considerations. (Offi ce of Environmental 145 Ibid. Information, (2007), Ecoview Glossary, accessed at: http:// iaspub.epa.gov/trs/trs_proc_qry.navigate_term?p_term_ 146 San Mateo County, (2007), Recycle Works – Landscape id=291323&p_term_cd=TERMDIS). Plantings, accessed at: www.recycleworks.org/greenbuild­ ing/sus_plantings.html. 129 Romero, M. and Hostetler, M., (2007), Policies that Address Sustainable Landscaping Practices, Circular 1519, University 147 As with high-efficiency irrigation technology, developers of Florida, accessed at: http://edis.ifas.ufl .edu/UW253. can also acquire LEED WE Credit-1.1 by recycling rainwater or using recycled wastewater to reduce potable water 130 U.S. EPA, (2005), The Natural Landscaping Alternative: consumption by fifty percent over conventional means; An Annotated Slide Collection, from Green Landscaping: or through LEED WE Credit-1.2 by using only captured Greenacres Natural Landscaping Tool Kit, accessed at: www. rainwater or recycled water to eliminate all potable water epa.gov/greenacres/tooltestkit/gallary/index.html. use for site irrigation (except for initial watering of plants). 131 San Mateo County, (2007), Recycle Works – Landscape National Institute of Building Sciences, (2007), Whole Build­ Plantings, accessed at: www.recycleworks.org/greenbuild­ ing Design Guide, accessed at www.wbdg.org/tools. ing/sus_plantings.html. 148 State of California Energy Commission, (2005), Califor­ 132 Pennsylvania Department of Environmental Protection, nia’s Water-Energy Relationship, CEC-700-2005-011-SF, (2006), Pennsylvania Stormwater Best Management accessed at: www.energy.ca.gov/2005publications/ Practices Manual: Chapter 5 - Non Structural BMPs, CEC-700-2005-011/CEC-700-2005-011-SF.PDF. 363-0300-002, accessed at: www.dep.state.pa.us/dep/ 149 Milwaukee Metropolitan Sewerage District, (2007), State deputate/watermgt/wc/subjects/stormwatermanagement/ of the Art Report Draft, accessed at: www.mmsd.com/ BMP%20Manual/05_Chapter_Final_Draft.pdf. wqi/2020Plan/SR_04.pdf. 133 Illinois Conservation Foundation and Chicago Wilderness, 150 U.S. EPA, (2004), Conference Summary, Landscaping with (2005), Change Cost Perceptions: An Analysis of Conserva­ Native Plants: Exploring the Environmental, Social and Eco­ tion Development, accessed at: www.cdfinc.com/CDF_Re­ nomic Benefits Conference December 6 - 7, 2004, accessed sources/Cost%20Analysis%20-%20Part%201%20-%20 at: www.epa.gov/greenacres/conf12_04/conf_knwldge. Report%20-%20with%20Exec%20Summary.pdf. html. 134 King County Department of Natural Resources (2007) Na­ 151 Ibid. tive Plant Salvage Program, accessed at: http://dnr.metrokc. gov/wlr/pi/salopps.htm. 152 Ibid. 135 City of Chicago, (2003), A Guide to Stormwater Best Man­ 153 Muthukrishnan, S. et al, (2004), The Use of Best Manage­ agement Practices, accessed at: www.cdfinc. com/CDF_Re- ment Practices (BMPs) in Urban Watersheds, U.S. EPA, sources/Chicago%20GuideTo%20Stormwater%20BMPs.pdf. EPA/600/R-04/184, accessed at: www.epa.gov/ORD/ NRMRL/pubs/600r04184/600r04184.pdf. 136 U.S. Department of Energy, (2006), Federal Energy Manage­ ment Program – Water Effi ciency, accessed at: http://www1. 154 Ibid. eere.energy.gov/femp/water/water_bmp3.html. 155 U.S. EPA, (2004), Conference Summary, Landscaping with 137 Ibid. Native Plants: Exploring the Environmental, Social and Eco­ nomic Benefits Conference December 6 - 7, 2004, accessed 138 San Mateo County, (2007), Recycle Works – Landscape at: www.epa.gov/greenacres/conf12_04/conf_knwldge. Plantings, accessed at: www.recycleworks.org/greenbuild­ html. ing/sus_plantings.html. 156 Florida Department of Environmental Protection, (2006), 139 By using high efficiency irrigation technology, developers Water Best Management Practices, Florida Green Lodging can acquire LEED Water-Effi ciency (WE) Credit 1.1 if they Program, accessed at: www.treeo.ufl .edu/greenlodging/ reduce potable water consumption for irrigation by fifty content/gr_h2o.htm. percent over conventional means. In addition, they can also achieve LEED WE Credit 1.2 by not installing a permanent 157 U.S. Department of Energy, (2001), Greening Federal landscape irrigation system, which is the highest goal of Facilities, second edition, accessed at: www.nrel.gov/docs/ water effi cient natural landscaping. National Institute of fy01osti/29267.pdf.

Green Parking Lot Resource Guide—February 2008 57 158 U.S. EPA, (2004), Conference Summary, Landscaping with 176 U.S. EPA, (2004), Conference Summary, Landscaping with Native Plants: Exploring the Environmental, Social and Eco­ Native Plants: Exploring the Environmental, Social and Eco­ nomic Benefits Conference December 6 - 7, 2004, accessed nomic Benefits Conference December 6 - 7, 2004, accessed at: www.epa.gov/greenacres/conf12_04/conf_knwldge. at: www.epa.gov/greenacres/conf12_04/conf_knwldge. html. html. 159 U.S. Department of Energy, (2001), Greening Federal 177 Ibid. Facilities, second edition, accessed at: www.nrel.gov/docs/ 178 Dunn, A. and Stoner, N., (2007), Green Light for Green fy01osti/29267.pdf. Infrastructure, The Environmental Forum, May/June 2007, 160 North Carolina Department of Environment and Natural reprinted by the Environmental Law Institute and accessed Resources, (2005), Water Effi ciency: Water Management at: www. Epa.gov/npdes/pubs/green_light_gi.pdf. Options, Division of Pollution Prevention and Environmental 179 U.S. EPA, (2007), National Pollutant Discharge Elimination Assistance, accessed at: www.p2pays.org/ref/04/03102.pdf. Systems (NPDES): Green Infrastructure, accessed at: http:// 161 U.S. EPA, (2003), Water-Effi cient Landscaping, accessed at: cfpub.epa.gov/npdes/home.cfm?program_id=298. www.epa.gov/npdes/pubs/watereffi ciency.pdf. 180 U.S. EPA, (2007), National Pollutant Discharge Elimination 162 U.S. EPA, (2007), Landscaping with Native Plants, accessed System (NPDES): Green Infrastructure – General Informa­ at: www.epa.gov/greenacres//index.html#Benefits. tion, accessed at: http://cfpub.epa.gov/npdes/greeninfra­ structure/information.cfm 163 U.S. Department of Energy, (2003), The Business Case for Sustainable Design in Federal Facilities – Appendix D, ac­ 181 Ibid. cessed at: http://www1.eere.energy.gov/femp/sustainable/ 182 Kloss, C. and Calarusse, C., (2006), Rooftops to Rivers: Green sustainable_federalfacilities.html. Strategies for Controlling Stormwater and Combined Sewer 164 U.S. EPA, (2004), Conference Summary, Landscaping with Overflows, Natural Resources Defense Council, accessed at: Native Plants: Exploring the Environmental, Social and Eco­ www.nrdc.org/water/pollution/rooftops/contents.asp. nomic Benefits Conference December 6 - 7, 2004, accessed 183 U.S. EPA, (2004), Conference Summary, Landscaping with at: www.epa.gov/greenacres/conf12_04/conf_knwldge. Native Plants: Exploring the Environmental, Social and Eco­ html. nomic Benefits Conference December 6 - 7, 2004, accessed 165 City of Chicago, (2003), A Guide to Stormwater Best Man­ at: www.epa.gov/greenacres/conf12_04/conf_knwldge. agement Practices, accessed at: www.cdfinc. com/CDF_Re- html. sources/Chicago%20GuideTo%20Stormwater%20BMPs.pdf. 184 Kloss, C. and Calarusse, C., (2006), Rooftops to Rivers: Green 166 U.S. EPA, (2004), Conference Summary, Landscaping with Strategies for Controlling Stormwater and Combined Sewer Native Plants: Exploring the Environmental, Social and Eco­ Overflows, Natural Resources Defense Council, accessed at: nomic Benefits Conference December 6 - 7, 2004, accessed www.nrdc.org/water/pollution/rooftops/contents.asp. at: www.epa.gov/greenacres/conf12_04/conf_knwldge. 185 U.S. EPA, Report to Congress: Impacts and Control of CSOs html. and SSOs, Office of Water, EPA-833-R-04-001, August 2004 167 U.S. EPA, (1992), Cooling Our Communities, as cited in Kloss, C. and Calarusse, C., (2006), Rooftops to GPO#055-000-00371-8, January 1992, accessed at: www. Rivers: Green Strategies for Controlling Stormwater and epa.gov, as cited in Pavement Busters Guide (2002), page Combined Sewer Overflows, Natural Resources Defense 10, Victoria Transport Policy Institute. Council, accessed at: www.nrdc.org/water/pollution/ rooftops/contents.asp. 168 Wolf, K., (2004), Trees, Parking, and Green Law: Strategies for Sustainability, accessed at: www.urbanforestrysouth.org/ 186 U.S. EPA, (2007), Green Infrastructure Program - A report Resources/Library/Citation.2004-07-14.1757/fi le_name. evaluating the concept of a major storm water minimiza­ tion program, utilizing green infrastructure and related 169 U.S. Department of Energy, (2001), Greening Federal methods, prepared by Prepared by Metropolitan Sewer Facilities, second edition, accessed at: www.nrel.gov/docs/ District of Greater Cincinnati et al, accessed at: www.msdgc. fy01osti/29267.pdf. org/downloads/wetweather/greenreport/Files/ 170 United Nations, (1993), Text of the Convention on Biological Green_Report.pdf. Diversity, Article 2: Use of Terms, accessed at: www.cbd.int/ 187 U.S. EPA, (2007), National Pollutant Discharge Elimination convention/convention.shtml. System: Green infrastructure—Case Studies, accessed at: 171 U.S. EPA, (2004), Conference Summary, Landscaping with http://cfpub.epa.gov/npdes/greeninfrastructure/ Native Plants: Exploring the Environmental, Social and Eco­ casestudies.cfm#portland. nomic Benefits Conference December 6 - 7, 2004, accessed 188 Dunn, A. and Stoner, N., (2007), Green Light for Green at: www.epa.gov/greenacres/conf12_04/conf_knwldge. Infrastructure, The Environmental Forum, May/June 2007, html. reprinted by the Environmental Law Institute and accessed 172 Ibid. at: www. Epa.gov/npdes/pubs/green_light_gi.pdf. 173 Illinois Conservation Foundation and Chicago Wilderness, 189 U.S. EPA, et al, (2007), Green Infrastructure Statement of (2005), Change Cost Perceptions: An Analysis of Conserva­ Intent, Stakeholder Statement of Support for Green Infra­ tion Development, accessed at: www.cdfinc. com/CDF_Re­ structure, accessed at: www.epa.gov/npdes/pubs/ sources/Cost%20Analysis%20-%20Part%201%20-%20 gi_supportstatement.pdf. Report%20-%20with%20Exec%20Summary.pdf. 190 Grumbles, B.H., (2007), Memorandum from Benjamin H. 174 Ibid. Grumbles, USEPA Assistant Administrator on Water, to USEPA Regional Administrators regarding Using Green 175 Ibid. Infrastructure to Protect Water Quality in Storm Water, CSO, Non-point Source and Other Water Programs, March 5, 2007. Key Resources 58 191 U.S. EPA, (2007), Green Infrastructure Program—A report 197 Arvidson, A.R., (2006), A Green Demonstration, Landscape evaluating the concept of a major storm water minimiza­ Architecture Magazine, September 2006. tion program, utilizing green infrastructure and related 198 City of Portland, Oregon, (2006), Green Streets Cross-Bureau methods, prepared by Metropolitan Sewer District of Team Report – Phase I, March 2006, accessed at: www. Greater Cincinnati et al, accessed at: www.msdgc.org/ portlandonline.com/shared/cfm/image.cfm?id=123793. downloads/wetweather/greenreport/Files/Green_Report. pdf. 199 City of Portland, Oregon, (2006), Green Streets Resolution, accessed at: www.portlandonline.com/shared/cfm/image. 192 U.S. EPA, (2004), Conference Summary, Landscaping with cfm?id=154232. Native Plants: Exploring the Environmental, Social and Eco­ nomic Benefits Conference December 6–7, 2004, accessed 200 City of Portland, Oregon, (2006), Green Streets Cross-Bureau at: www.epa.gov/greenacres/conf12_04/conf_knwldge. Team Report—Phase I, March 2006, accessed at: www. html. portlandonline.com/shared/cfm/image.cfm?id=123793. 193 Center for Neighborhood Technology, (2007), Green Infra­ 201 Water Environment Research Foundation, (2007), Portland structure Performance, accessed at: www.cnt.org/ Oregon: Building a Nationally Recognized Program Through repository/BMP-Performance.pdf. Innovation and Research, accessed as: www.werf.org/ livablecommunitires/studies_port_or.html. 194 Dunn, A. and Stoner, N., (2007), Green Light for Green Infrastructure, The Environmental Forum, May/June 2007, 202 Ibid. reprinted by the Environmental Law Institute and accessed 203 City of Portland, Oregon, (2006), Green Streets Cross-Bureau at: www. Epa.gov/npdes/pubs/green_light_gi.pdf. Team Report—Phase I, March 2006, accessed at: www. 195 Center for Neighborhood Technology, (2007), Green Infra­ portlandonline.com/shared/cfm/image.cfm?id=123793. structure Performance, accessed at: www.cnt.org/ 204 Water Environment Research Foundation, (2007), Portland repository/BMP-Performance.pdf. Oregon: Building a Nationally Recognized Program Through 196 U.S. EPA, (2007), National Pollutant Discharge Elimina­ Innovation and Research, accessed as: www.werf.org/ tion System (NPDES): Environmental Benefits of Green livablecommunitires/studies_port_or.html. Infrastructure, accessed at: http://cfpub.epa.gov/npdes/ greeninfrastructure/information.cfm#enviroben.

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