# Municipal Solid Waste Landfills Industry Profile

U.S. Environmental Protection Agency Office of Air and Radiation Office of Air Quality Pl anning and Standards Research Triangle Park, NC 27711

June 2014ii CONTACT INFORMATION

This document has been prepared by staff from the Office of Air and Radiation, U.S. Environmental Protection Agency. Questions related to this docu ment should be addressed to Alexander Macpherson, U.S. Environmental Pr otection Agency, Office of Air and Radiation, Office of Air Quality Planning and Standards, C439-02, Research Triangle Park, North Carolina 27711 (email: macpherson.alex@epa.gov).

ACKNOWLEDGEMENTS

In addition to EPA staff from the Office of Air Quality Planning and Standards and the Office of Atmospheric Programs with the U.S. EPA Office of Air and Radiation, Eastern Research Group, Inc. (ERG) contributed da ta and analysis to this document.iii TABLE OF CONTENTS

T ABLE OF C ONTENTS .................................................................................................................... III L IST OF T ABLES ............................................................................................................................. IV L IST OF F IGURES ............................................................................................................................ V I NDUSTRY P ROFILE ........................................................................................................................ 1
1 I NTRODUCTION

.............................................................................................................................. .................. 1 2 W ASTE S TREAM B ACKGROUND ....................................................................................................................... 3 2.1 Municipal Waste ............................................................................................................... .......................... 3 2.1.1 Generation of Munici pal Solid Waste ........................................................................................... .... 3 2.1.2 Landfills Covered Un der the NS PS/EG ........................................................................................... . 4 2.1.3 Trends in Per Capita Wa ste Sent to Landfills .................................................................................. . 4 2.1.4 Composition of MSW Se nt to La ndfills .......................................................................................... .. 5 2.2 Consolidation of Waste Streams ................................................................................................ ................. 7 3 D ISPOSAL F ACILITY B ACKGROUND ................................................................................................................. 8 3.1 Technical Background on Land fills as a Sour ce Category ........................................................................ . 8 3.1.1 Landfill Siting an d Permitting ................................................................................................ ........... 8 3.1.2 Landfill Oper ations ........................................................................................................... ................ 9 3.1.3 Landfill Cl osure .............................................................................................................. ................ 10 3.1.4 Management of Liqu ids ......................................................................................................... ......... 10 3.2 Ownership and Character istics of La ndfills .................................................................................... .......... 11 4 C OSTS AND R EVENUE S TREAMS FOR L ANDFILLS ........................................................................................... 15 4.1 Major Cost Component s for Landfills ........................................................................................... ........... 15 4.2 Landfill Revenu e Sour ces ...................................................................................................... ................... 18 5 A IR P OLLUTANT E MISSIONS FROM L ANDFILLS .............................................................................................. 21 5.1 NMOC in LFG ................................................................................................................... ...................... 21 5.2 Methane in LFG ................................................................................................................ ....................... 22 5.3 Criteria Pollutants from Combustion of LFG .................................................................................... ....... 23 6 T ECHNIQUES FOR C ONTROLLING E MISSIONS FROM L ANDFILLS ..................................................................... 24 6.1 Introduc tion

.................................................................................................................. ............................ 24 6.2 Gas Collectio n Systems ........................................................................................................ .................... 24 6.3 Destruc tion ................................................................................................................... ............................ 26 6.4 Utiliza tion ................................................................................................................... .............................. 27 6.4.1 Technologies .................................................................................................................. ................. 27 6.4.2 Revenues and Incentives ....................................................................................................... .......... 32 7 R EFERENCES

.............................................................................................................................. .................... 35iv LIST OF TABLES

Table 1 Generation and Discards of MSW, 1960 to 2010 (in pounds per person per day) ......................................... 5 Table 2 Materials Discarded a In the MSW Stream, 1960 to 2 010 (in thousands of tons) ........................................... 7 Table 3 Top 5 Waste Management Companies Th at Own or Operate MSW Landfills in 2011 ............................... 13 Table 4 Typical Costs Per Acre for Compon ents of Landfill Constr uction (Duffy, 2005a) ...................................... 16 Table 5 Average Regional and Nationa l Per-Ton Tip Fees (Rounded): 1995-2 012 ................................................. . 19 Table 6 Average LFG Power Production Techno logy Costs ....................................................................... .............. 29 Table 7 Average LFG Direct-u se Project Com ponents Costs ..................................................................... .............. 31v LIST OF FIGURES

Figure 1 Material Compos ition of the MSW Stream, 2010 ....................................................................... .................. 6 Figure 2 Landfill Cost Life Cycle ........................................................................................... ................................... 18 Figure 3 Typical LFG Generation Curve ....................................................................................... ............................ 23 Figure 4 Vertical Well LFG Co llectio n ....................................................................................... .............................. 25 Figure 5 Hori zontal Trench LFG Coll ecti on ................................................................................... .......................... 251 INDUSTRY PROFILE 1 Introduction
Municipal solid waste (MSW) is the stream of garbage collected by sanitation services from homes, businesses, and in stitutions. MSW typically consists of metals, glass, plastics, paper, wood, organics, mixed categories, and co mposite products. The ma jority of collected MSW that is not recycled is typically sent to landfills—engineered areas of land where waste is deposited, compacted, and covered. The New So urce Performance Standards (NSPS) and the state and federal plans implementing the emi ssion guidelines for MSW landfills regulate air emissions from landfills that receive househol d waste as defined in 40 CFR 60.751. Hereinafter these regulations are collectively referred to as the NSPS/EG. These MSW landfills can also receive other types of waste, su ch as construction and demoliti on debris, industrial wastes, or nonhazardous sludge. MSW landfills are designed to protect the environment from contaminants which may be present in the solid waste stream and as such are required to comply with federal Resource Conservation and Recovery Act (RCRA) regulations or equivalent state regulations, which include standards related to location rest rictions, composite liners requirements, leachate collection and removal systems, operating pr actices, groundwater mon itoring requirements, closure and post-closure care requi rements, corrective action provisi ons, and financial assurance (EPA, 2012a). EPA estimates the total amount of MSW ge nerated in the United States in 2010 was approximately 250 million tons, a 20 percent increase from 1990. Despite increased waste generation, the amount of MSW deposited in land fills decreased from about 145.3 million tons in 1990 to 135.5 million tons in 2010. This decline is due to a significant increase in the amount of waste recovered for recycling a nd composting as well as that combusted for energy recovery (EPA, 2011). The number of active MSW landfills in the United States has decreased from approximately 7,900 in 1988 to 1,900 in 2009 (EPA, 2010a). Landfills are different than many other traditionally regulated emissions source categories. Typically, entities regulated for ai r emissions are involved in manufacturing or production and their emissions are directly rela ted to processes involved in creating products (e.g., vehicles, bricks) or commodities (e.g., natura l gas, oil). When manu facturing or production facilities cease to operate, thei r emissions typically cease. Landfills are a service industry—a repository for waste that needs to be properly disposed—and their emissi ons are a by-product of2 the deposition of that waste. Landf ills continue to emit air polluti on for many years after the last waste is deposited. Landfill gas (LFG) is a by-product of the deco mposition of organic material in MSW in anaerobic conditions in landfills. LFG contains roughly 50 percent methane and 50 percent carbon dioxide, with less than 1 percent non- methane organic compounds and trace amounts of inorganic compounds. The amount of LFG created primarily depends on the quantity of waste and its composition and moisture content as well as the design and management practices at the site. LFG can be collected and combusted in fl ares or energy recove ry devices to reduce emissions. MSW landfills receive approximately 69 percent of the total waste generated in the United States and produce 94 percent of landfill em issions. The remainder of the emissions is generated by industrial wa ste landfills (EPA, 2012b). Entities potentially regulated under Standards of Performance for Municipal Solid Waste Landfills include owners of MSW landfills and owners of combustion devices that burn untreated LFG. At its core, firms engaged in the collection and disposal of refuse in a landfill operation are classified under the North Ameri can Industry Classification System (NAICS) codes Solid Waste Landfill (562212) and Administ ration of Air and Water Resource and Solid Waste Management Programs (924110). Landfills are owned by private companies, gove rnment (local, state, or federal), or individuals. In 2004, 64 percent of MSW la ndfills were owned by public entities while 36 percent were privately owned (O’Brien, 2006). Affected entit ies comprise establishments primarily engaged in operating la ndfills for the disposal of non- hazardous solid waste; or the combined activity of collecting and/or hauling no n-hazardous waste materials within a local area and operating landfills for the disposal of non-haza rdous solid waste. This industry also includes government establishments primarily engaged in the administration and regulation of solid waste management programs. Private companies that own landfills range in size from very small businesses to large businesses with billions in annual revenue. Public landf ill owners include cities, counties/parishes, regional auth orities, state governments, and the federal government (including military branches, Bureau of Land Management, De partment of Agriculture, Forest Service, and Department of the Interior - National Park Service).3 2 Waste Stream Background

2.1 Municipal Waste

2.1.1 Generation of Municipal Solid Waste
Municipal solid waste (MSW) is genera lly defined as nonhazardous waste from household, commercial, and institu tional sources. These three br oad categories of primary MSW generators are described as:

 Household – solid waste from single-and multiple-family homes, hotels and motels, bunkhouses, ranger stations, crew quarte rs, campgrounds, picnic grounds, and dayuse recreation areas.

 Commercial – solid waste from stores, o ffices, restaurants, warehouses, and other nonmanufacturing activities.

 Institutional – solid waste from public work s (such as street sweepings and tree and brush trimmings), schools and colleges, hos pitals, prisons, and similar public or quasi-public buildings. Infectious and h azardous waste from these generators are managed separately from MSW. Households are the primary source of MS W, accounting for 55 to 65 percent of total MSW generated, followed by the commercial sector (EPA, 2011). Waste from commercial and institutional locations amounts to 35 to 45 per cent of total MSW (EPA, 2011). The industrial sector manages most of its own solid residuals by recycling, reuse, or se lf-disposal in industrial waste landfills. For this reason i ndustry directly contri butes a very small sh are of the MSW flow, although some industrial waste does end up in MSW landfills. Various underlying factors infl uence the trends in the qua ntity of MSW generated over time. These factors include changes in populatio n, individual purchasi ng power and disposal patterns, trends in product packaging, and techno logical changes that aff ect disposal habits and the nature of materials dispose d. Generators of MSW provide mo st of the demand for services that collect, treat, or dispose of MSW. Fluctuations in the quantity of MSW generated and changes in the cost and pricing st ructure of disposal services resu lt in varying demand for landfill services. Most MSW generators are charged a flat fee for disposal services, which can be paid through taxes for household garbage collection. Th is structure may provide little economic4 incentive to lower waste disposal or to divert waste through re cycling because generators are charged the same price regardless of the quantity of waste disposed. Le ss common are unit price programs, such as “pay-as-you-throw” (PAYT). In PAYT programs, each unit of waste disposed has an explicit price, such that the total fee paid for MSW services increas es with the quantity of waste discarded. Hence, the unit pr ice can act as a disincentive to dispose of excess waste and also encourages recycling (Callan, 2006).

2.1.2 Landfills Covered Under the NSPS/EG
The Landfills NSPS/EG applies onl y to landfills that accept “household waste” as defined in 40 CFR 60.751, which states “household waste means any solid waste (including garbage, trash, and sanitary waste in septic tanks) deri ved from households (inc luding, but not limited to, single and multiple residences, hotels and mote ls, bunkhouses, ranger stations, crew quarters, campgrounds, picnic grounds, and day-use recr eation areas).” Some of the MSW landfills subject to the Landfills NSPS/EG may also receive other types of wastes, such as commercial, industrial, and institutional solid waste, nonhazardous sludge, and construction and demolition debris.

2.1.3 Trends in Per Capita Waste Sent to Landfills
In 2010, Americans generated a bout 250 million tons of tras h, and recycled nearly 65 million tons of this material, equivalent to a 26 percent recycling rate (EPA 2011). Composting recovered more than 20 million tons of waste (~8 percent of total waste) and about 29 million tons of waste were combusted for en ergy recovery (~12 percent) (EPA 2011). After recycling, composting, and combustion with energy recovery, the net per cap ita discard rate to landfills was 2.40 pounds per person per day in 2010 (EPA 2011). This is a 4 percent decrease from the 2.51 per capita discard rate in 1960, when minimal recycling occurred in the United States (see Table 1). Since 1990, the total amount of MSW going to landfills has dropped by almost 10 million tons, from 145.3 million to 135.5 million tons in 2010 (EPA 2011). While the number of U.S. landfills has steadily declined over the years, the average landfill size has increased. At the national level, landfill capacity a ppears to be sufficient, although it is limited in some areas (EPA 2011).5 Table 1 Generation and Discards of MSW, 1960 to 2010 (in pounds per person per day) 1 Activity 1960 1970 1980 1990 2000 2005 2007 2008 2009 2010
Generation 2.68 3.25 3.66 4.57 4.72 4.67 4.64 4.53 4.35 4.43
Discards to landfill a 2.51 3.02 3.24 3.19 2.71 2.61 2.52 2.45 2.36 2.40
Discards to landfill (% of total generation) 94% 93% 89% 70% 57% 56% 54% 54% 54% 54%

a Discards after recovery minus combustion with energy recovery. Discards include combustion without energy

recovery
. 2.1.4 Composition of MSW Sent to Landfills
Organic materials continued to be the largest component of MSW in 2010. Yard trimmings and food scraps account for 29.1 perc ent and paper and paperboard account for another 16.2 percent. Plastics comprise 17.3 perc ent while metals and wood make up 8.8 percent and 8.2 percent, respectively. Textiles account for 6.8 percent and glass accounts for 5.1 percent. Rubber and leather follow at 4.0 percent. Other miscellaneous wastes make up approximately 4.4 percent of the MSW generated in 2010 (EPA 2011). Figure 1 displays material composition percentages of the MSW stream in 2010, and Tabl e 2 shows the amounts of different materials discarded in the MSW stream from 1960 to 2010.

1 Table adapted from U.S. Environmental Protection Agency. 2011. “Municipal Solid Waste Generation, Recycling, and Disposal in the United States Tables and Figures for 2010.” Table 4. EPA-530-F-11-005. Washington, DC: U.S. EPA. Available at < http://www.epa.gov/osw/nonhaz/municipal/pubs/2010_ MSW_Tables_and_Figures_508.pdf>. As obtained on October 30, 2011.6 Figure 1 Material Composition of the MSW Stream, 2010 2

2 Figure adapted from U.S. Environmental Protection Agency. 2011. “Municipal Solid Waste Generation, Recycling, and Disposal in the United States Tables and Figures for 2010.” Table 3. EPA-530-F-11-005. Washington, DC: U.S. EPA. Available at < http://www.epa.gov/osw/nonhaz/municipal/pubs/2010_ MSW_Tables_and_Figures_508.pdf>. As obtained on October 30, 2011.7 Table 2 Materials Discarded a In the MSW Stream, 1960 to 2010 (in thousands of tons) 3

Wastes 1960 1970 1980 1990 2000 2005 2010 Paper and Paperboard 24,916 37,540 43,420 52,500 50,180 42,880 26,740 Glass 6,620 12,580 14,380 10,470 9,890 9,950 8,400 Metals 10,770 13,350 14,290 12,580 12,340 13,400 14,540 Plastics 390 2,900 6,810 16,760 24,050 27,470 28,490 Rubber and Leather 1,510 2,720 4,070 5,420 5,850 6,200 6,610 Textiles 1,710 1,980 2,370 5,150 8,160 9,670 11,150 Wood 3,030 3,720 7,010 12,080 12,200 12,960 13,580
Other Materials b 70 470 2,020 2,510 3,020 3,080 3,380 Food Scraps 12,200 12,800 13,000 23,860 29,130 31,300 33,790 Yard Trimmings 20,000 23,200 27,500 30,800 14,760 12,210 14,200 Miscellaneous Inorganic Wastes 1,300 1,780 2,250 2,900 3,500 3,690 3,840 Total MSW Discarded 82,516 113, 040 137,120 175,030 173,080 172,810 164,720

a Discards after materials and compost recovery. In this table, discards include combustion with energy recovery.

Does not include construction and demolition debris, industrial process wastes , or certain other wastes

. b Includes electrolytes in batteries and fluff pul p, feces, and urine in disposable diapers.

Details may not add to totals due to rounding.

2.2 Consolidation of Waste Streams
Collection and transportation are necessa ry components of all MSW management systems regardless of the specific disposal options. Collections of MSW vary by service arrangements between local gove rnments and collectors and by level of service provided to households. Depending on the arrangement type and other considerations for particular jurisdictions, MSW being sent to landfills may be deposited in a local landfill or routed to a regional landfill through a transfer process. Local landfills are gene rally located in the

3 Table adapted from U.S. Environmental Protection Agency. 2011. “Municipal Solid Waste Generation, Recycling, and Disposal in the United States Tables and Figures for 2010.” Table 3. EPA-530-F-11-005. Washington, DC: U.S. EPA. Available at < http://www.epa.gov/osw/nonhaz/municipal/pubs/2010_ MSW_Tables_and_Figures_508.pdf>. As obtained on October 30, 2011.8 communities in which they serve whereas regional landfills are often located outside of the communities they serve and receive wa ste from several cities and towns. Solid waste transfer is the process in whic h collection vehicles unload their waste at centrally located transfer stati ons. Transfer stations can minimi ze hauling costs by decreasing the number of drivers and vehicles hauling waste to disposal sites and re ducing the turn-around time of vehicles because they do not ha ve to haul waste to distant regional landfills. Smaller loads are consolidated into larger vehicles , usually tractor-trailer trucks, tr ains, or barges, which are better suited for the long-distance hauls often required to reach the final disposal site, often a regional landfill. As public opposition to local MSW disposal facilities increases and the cost of disposal at locations near generators rise, long-distan ce hauls to regional landfills are becoming more

common.

3 Disposal Facility Background

3.1 Technical Background on Landfills as a Source Category

An MSW landfill refers to an area of land or an excavation where MSW is placed for permanent disposal. MSW landfills do not includ e land application units, surface impoundments, injection wells, or waste piles. Modern MSW landf ills are well-engineered disposal facilities that are sited, designed, operated, and monitored to pr otect human health and the environment from pollutants that may be present in the solid waste stream (EPA, 2012c).

3.1.1 Landfill Siting and Permitting
MSW landfills are required to comply with federal regulations contained in Subtitle D of the Resource Conservation and Recovery Act (R CRA) [40 CFR Part 258], or equivalent state regulations. RCRA requirements include location rest rictions that ensure landfills are constructed away from environmentally-sensitive areas, incl uding fault zones, wetlands, flood plains, or other restricted areas (EPA, 2012c). Site selection for landfills is an integral part of the design
process.
Construction and operating permit applications for new landfills must be submitted to and approved by state and local regulatory agencies as part of the siting a nd design process. Often, states require a registered professional engi neer to design the landf ill (Guyer, 2009). Additional9 permits must be issued for each expansion of the landfill from its originally permitted waste design capacity and footprint area. New or modifi ed landfills may also require air permits under the New Source Review (NSR) permitting program, which includes Prevention of Significant Deterioration (PSD) requirements for landfills si ted in attainment areas, or areas where the air quality meets the National Ambient Air Qualit y Standards (NAAQS), a nd more stringent NSR requirements for landfills loca ted in non-attainment areas.

Developing a new landfill or expanding an existing landfill has become increasingly difficult, especially in metropolitan areas, due to the urbanization of suitable sites, permitting barriers, elevated land costs, and other factors. If a new landfill is proposed or when expansion plans for existing landfills are announced, adja cent communities may mount opposition that can hinder issuance of required permits and thus development of the landfill (Alva, 2010).

3.1.2 Landfill Operations
The two most common methods for active disposal of waste into landf ills are the area fill method and the trench method. The area fill me thod involves waste placement in a large open section of a lined landfill and then spreading and compacting wa ste in uniform layers using heavy equipment. The trench method of filling wa ste in a modern landfill involves placing and compacting waste into a trench and then using material from the trench excavation as daily cover. Local conditions often determine the most appropriate method for a particular landfill, and a combination of the two methods can be utili zed. The trench method is less commonly used than the area fill method, mostly due to the expense of lining side slopes of the landfill (Guyer, 2009). As required by Subtitle D of RC RA, cover material is applied on top of the waste mass at the end of each day to prevent odors and fires an d reduce litter, insects, and rodents. Materials used as daily cover include soil, compost, incinerator ash, foam, and tarps (NSWMA, 2008). Similarly, intermediate cover is used when an area of the landfill is not expected to receive waste or a cap for an extended period of time. Intermediate covers have traditiona lly consisted of layers of soil, geotextiles, or other materials. The r easons for using intermediate cover are similar to those for using daily cover and ma y also include erosion control. It is important to maintain anaerobic condi tions within the landf ill waste mass to avoid excess air infiltration that can cause fires. Landf ill fires can be avoided by closely monitoring10 landfill conditions and maintaining the landfill as a controlled facility. If active LFG collection systems are installed, then gas wells are monitore d to ensure oxygen is no t being pulled into the landfill due to excessive vacuum levels.

3.1.3 Landfill Closure
Once an area of the landfill, or cell, has re ached its permitted height, that cell is closed and a low permeability cap made of compacted clay or synthetic material is installed to prevent infiltration of precipitation. To divert water off of the top of the landfill, a granular drainage layer is placed on top of the low-permeability barrier la yer. A protective cover is placed on top of the filter blanket and topsoil is placed as the fina l layer to support vege tation. The final cap and cover inhibit soil erosion and provide odor and LFG control (NSWMA, 2008). If an LFG collection and control system is in place, then ex pansion of the collection system into filled cells or areas of the landfill may require additional gas wells to be installed soon after these cells are closed and capped. Gas collection system de sign is discussed further in Section 6. RCRA Subtitle D regulations contain clos ure and post-closure care requirements, including written closure and post-closure care pl ans and maintaining the final cover, leachate collection system, and groundwater and LFG monitoring systems. The required post-closure care period is 30 years from site clos ure, but this can be shortened or extended if approved by state regulatory agencies (EPA, 2012d).

3.1.4 Management of Liquids
Leachate is the liquid that passes through the landfilled waste and strips contaminants from the waste as it percolates . Precipitation is the primary s ource of this liquid. To prevent water pollution and protect soil beneath, RCRA Subtit le D requires liners for landfills as well as leachate collection and removal and groundwater monitoring systems. Composite liner systems are used along the bottom and sides of landfills as impermeable barriers and are typically constructed with layers of natu ral materials with low permeabili ty (e.g., compacted clay) and/or synthetic materials (e.g., high-density polyeth ylene) (NSWMA, 2008). Landfill liner systems also help prevent off-s ite migration of LFG. Leachate collection systems remove leachate from the landfill as it collects on the liner using a perforated collection pipe placed in a drainage layer (e.g., gravel). Waste is placed11 directly above the leachate collection system in layers. Collected leachate can be treated on-site or transported off-site to treatment facilities . For landfills with LFG collection systems, LFG condensate can be combined with leachate prior to treatment. Although traditional landfills tend to minimize th e infiltration of liquids into a landfill using liners, covers, and caps (sometimes referred to as “dry tombs”), some landfills recirculate all or a portion of leachate collected to increase the amount of moisture within the waste mass. This practice of leachate recircul ation results in a faster anae robic biodegradation process and increased rate of LFG generation. Similarly, land fills may introduce liquids other than leachate, such as sludge and industrial wastewater. Conven tional landfills typically have in-situ moisture contents of approximately 20 percent, whereas landfills recirculating leachate or other liquids may maintain moisture contents ranging from 35 to 65 percent (EPA, 2012e). Often, landfills injecting or recirculating liquids are termed bi oreactors, but bioreactor landfills are defined differently amongst industry and regulatory agen cies. In addition, bioreactor landfills may have air injected in a controlled ma nner to further accelerate biodegr adation of the waste, which occurs for aerobic and hybrid bioreactor configurations.

3.2 Ownership and Characteristics of Landfills
Since the 1980’s, the number of active MSW landfills in the United States has decreased by approximately 75 percent (from ~7,900 in 1988 to ~1,900 in 2009) and the share of sites that are publicly owned has also d ecreased—from 83 percen t in 1984 to 64 perc ent in 2004 (EPA, 2010b; O’Brien, 2006). However, the overall volume of disposal capacity has remained fairly constant, indicating a trend of growing indi vidual landfill capacity (SWANA, 2007). In 2004, privately owned sites represented 83 percent of the permitted MSW landfill capacity and 77 percent of the MSW landfilled in that year, an indication that private landfills are likely to be significantly larger than public ones (O’Brien, 2006). In 2004, the average daily amount of MSW disposed at public sites was just under 200 short tons, whereas the average private site landfilled nearly 1,200 short tons of MSW per day—furth er evidence that publicly owned landfills are generally much smaller than their private counterparts (O’Brien, 2006). EPA recognized as early as 2002 that a nationwid e trend in solid waste disposal is toward the construction of larger, more remote, regiona l landfills. Economic cons iderations, influenced by regulatory and social forces, are compelling factors that likel y led to the closure of many12 existing sites and to the idea of regional landfills (EPA, 2002b). Th e passage of federal environmental regulations that affected la ndfills (e.g., RCRA in 1976, Subtitle D of RCRA in 1991), established requirements which made it more expensive to properly construct, operate, maintain, and close landfills (O’Brien, 2006; EPA 2012f; EPA, 2002b). Large, private companies are better able to accommodate the in creased costs of owning a landfill, since owning multiple sites, many of which have large capaci ties, provides an econom y of scale for cost expenditures (O’Brien, 2006). To offset the high cost of constr ucting and maintaining a modern landfill, facility owners construct large facilities that attract high volumes of waste from a large geographic area. By maintaining a high volume of incoming waste, landfill owners can keep tipping fees relatively low, which subseque ntly attracts more business (EPA, 2002b). As older, public landfills near their cap acities, communities must decide whether to construct new landfills or seek other options. Ma ny find the cost of upgrading existing facilities or constructing new landfills to be prohibitively high, and opt to close existing facilities. Also, public opposition often makes siting new landfills near population centers difficult and adequate land may not be available near densely populated or urban areas. Many communities are finding that the most economically viable solution to thei r waste disposal needs is shipping their waste to regional landfills. In these circumstances, a transfer station serves as the critical link in making the shipment of waste to distant facilities cost-e ffective (EPA, 2002b). Waste transfer stations are facilities where MSW is unloaded from collection vehicles and reloaded into long-distance transport vehicles for delivery to landfills or other treatment/disposal facilities. By combining the lo ads of several waste collection trucks into a single shipment, communities and waste manage ment companies can save money on the labor and operating costs of transporting waste to a distant disposal site. They can also reduce the total number of vehicular miles traveled to and fr om the disposal site(s) (EPA, 2012g). Given the dramatic decrease in the number of active landfills in the past 20 years, transfer stations play an important part in facilitating the movement of soli d waste from the areas in which it originates to its end location, often a large, cen trally located landfill. The role of transfer stations in waste management has become even more prominent with the increase in the number of “regional” landfills—sites with very large capacities, often located in remote areas, and usually privately owned. As more and more publicly owned landfills reach capacity and close, the waste must go somewhere, and often that is to a regiona l landfill by way of a transfer station.13 There are more than 200 private companies that own and/or operate landfills, ranging from large companies with numerous landfills th roughout the country to local businesses that own a single landfill (EPA, 2012b). The handling of MSW in the United States generated $55 billion of revenue in 2011 (E BI, 2012). In terms of 2011 revenue , the top two companies that own and/or operate MSW landfills in the United States were Waste Mana gement ($13.38 billion) and Republic Services ($8.19 billion), which toge ther accounted for 39 percent of the revenue share in 2011 (Bloomberg, 2012WM; Bloomber g, 2012RSG). The next tier of companies involved in landfill management includes Veolia Environmental Services North America Corp. ($1.88 billion), Progressive Wa ste Solutions ($1.84 billion) , and Waste Connections ($1.51 billion) (Gerlat, 2012; Bl oomberg, 2012BIN; Bloomberg, 2012 WCN). Table 3 contains a summary of the 2011 revenue for the top five co mpanies, as well as information about their MSW landfills and transfer stations. Table 3 Top 5 Waste Management Compan ies That Own or Operate MSW Landfills in 2011

Company 2011 Revenue (billion $) No. of MSW Landfills Owned and/or Operated MSW Received at

Landfills (million tons) No. of Transfer Stations Owned and/or Operated

Waste Management (Bloomberg, 2012WM) 13.38 266 91.2 287

Republic Services (Bloomberg, 2012RSG) 8.19 191 active/ 130 closed NA 194

Veolia Environmental Services North America Corp. (Gerlat, 2012) a 1.88 29 NA 4314 Table 3 Top 5 Waste Management Compan ies That Own or Operate MSW Landfills in 2011

Company 2011 Revenue (billion $) No. of MSW Landfills Owned and/or Operated MSW Received at

Landfills (million tons) No. of Transfer Stations Owned and/or Operated
Progressive Waste Solutions (Bloomberg, 2012BIN) 1.84 NA NA NA

Waste Connections (Bloomberg, 2012WCN) 1.51 46 14.9 58

a In 2012, VESNA agreed to sell its U.S. solid waste operations , Veolia ES Solid Waste, Inc., to Star Atlantic Waste Holdings LP, a unit of Highstar Capital; the sale is to be completed by end of 2012. Highstar also owns Advanced Disposal Services Inc. and Interstate Waste Services Inc. NA = Not available.

The industry that deposits MSW in landfills encompasses a wide range of job types, including garbage collectors, truck drivers, h eavy equipment operators, engineers of various disciplines, specialized technicians, executives, MSW department directors, administrative staff, weigh scale operators, salespersons, and la ndfill operations managers. In 2007, 1,501 private establishments had 21,766 employees in the continental United States under NAICS 562212 (Solid Waste Landfill) (Census, 2012). In 2011, so lid waste management departments of local governments reported 98,957 full-time employees and 14,679 part-time employees (Census, 2011); however, statistics are not readily availabl e solely for landfill-related aspects of these departments. As the population continues to grow in the United States the amount of waste generated will continue to increase, but the am ount of waste landfilled may remain the same or decrease (EPA, 2012h). Employment within the waste management industry overall will likely remain strong, perhaps with an increased shift of employees from the public sector to the private

sector.15 4 Costs and Revenue Streams for Landfills

4.1 Major Cost Components for Landfills
EPA promulgated Criteria for Municipal Solid Waste Landfills (40 CFR Part 258) under the RCRA on October 9, 1991 (EPA, 2012i). Th e law requires that non-hazardous MSW be disposed of in specially designed sanitary landf ills. The criteria includ e location restrictions, design and operating standards, groundwater monitoring requirements, corrective actions, financial assurance requirements, landfill gas (L FG) migration controls, closure requirements, and post-closure requirements (EPA, 2012j). It can cost more than $1 million per acre to construct, operate, and close a landfill in compliance with thes e regulations (F itzwater, 2012). Landfill costs are site specific and vary based on factors such as terrain, soil type, climate, site restrictions, regulatory issues, type and amount of waste disposed, preprocessing, and potential for groundwater contamination. La ndfill costs fall into the following categories: site development, construction, equipment pur chases, operation, closur e, and post-closure. Site development includes site surveys, engineering and design studies, and permit package fees. Surveys are necessary to determin e if a potential site is feasible. Permits are required from local, state, and federal government s. As an example, engineering design and a permit application for an MSW landfill in Kentucky can cost approximately $750,000 to $1.2 million (KY SWB, 2012). Construction costs encompass building the landfill cells as well as development of permanent on-site structures needed to ope rate the landfill. Cortland County, New York estimated that the cost for site development a nd cell construction (not including on-site building construction) for a 224.5-acre site would be approximately $500,000 per acre (EnSol, 2010). In 2005, a series of articles was written that estim ated costs for a hypothetical landfill based on known market conditions and cost data. The th eoretical landfill had a design capacity of 4 million cubic yards and a footprint of 33 acr es. The study determined that the cost of constructing a landfill of this size woul d be between $300,000 and $800,000 per acre. Table 4 summarizes typical construction cost s per acre by individual task for this example site (Duffy, 2005a).16 Table 4 Typical Costs Per Acre for Components of Landfill Construction (Duffy, 2005a)

Task Low End High End Clear and Grub $1,000 $3,000

Site Survey $5,000 $8,000 Excavation $100,000 $330,000 Perimeter Berm $10,000 $16,000 Clay Liner $32,000 $162,000 Geomembrane $24,000 $35,000 Geocomposite $33,000 $44,000 Granular Soil $48,000 $64,000 Leachate System $8,000 $12,000 QA/QC $75,000 $100,000 TOTAL $336,000 $774,000

Excavation of the landfill site comprises a notable portion of the construction costs. Installation of a landfill liner can vary greatly in cost depending on the site’s geology. Most states require only a single liner and leachate co llection system for MSW, but requirements vary for the minimum thickness of clay liners. Landfil l sites may have good quality clay located onsite that would significantly lower the cost of a clay liner. The QA/QC task in Table 4 refers to management and quality oversight which is usually performed by independent third-party consultants. For the hypothetical landfill in the study, to tal building and additional structure costs could total between $1.165 million and $1.77 million. Op eration of the landfill requires a truck scale, scale house, wheel wash facility, and bui ldings to accommodate an office and provide space for maintenance. The cost of each building structure varies depending on its functions and could range from $10 to $100 per square foot. O ffice buildings cost more while maintenance buildings and tool sheds cost less. In addition, fencing around th e facility and roadways are required and add to the costs (Duffy, 2005a). Operating costs of the example landfill include staffing, equipment (payments and maintenance), leachate treatment, and facilities and general maintenance. Landfill operations and maintenance activities are perf ormed using a variety of hea vy construction equipment with17 operating costs dependent on fuel, repairs, and main tenance. Operating costs are relatively small when compared to the capital co sts; estimated annual operating costs from this study are (Duffy, 2005a):

 Operations (equipment, staff, fac ilities and general maintenance): $500,000.

 Leachate collection and treatment (assumes sewer connection and discharge cost of $0.02/gallon): $10,000.

 Environmental sampling and monitoring (g roundwater, surface water, air gas, leachate): $30,000.

 Engineering services (consulti ng firms and in-house staff): $60,000. Once a landfill no longer accepts waste, the clos ure process includes the installation of a final cover and cap. Capital costs for installati on of a cap can run between $80,000 and $500,000 per acre. For example, at a Maryland sanitary landfill costs were $150,000 per acre (MDE, 2012). The capping costs for a 249.4-acr e site in Cortland County, New York were estimated to be approximately $134,000 per acre. Factors influencing these cost s include the materials used for the cap, site topography, and the availability of clay or soil su itable for use as the cover. Similar to the costs of the clay liner during the c onstruction of the landfill, availability of nearby clay would significantly redu ce this cost (EnSol, 2010). The closure process can include the installa tion of an LFG collec tion system which is necessary to collect and destroy or beneficially use the methane gas that is generated. (However, many landfills install gas collection and control system s as the landfill is being filled, or as areas within the landfill reach final grade, rather th an waiting until closure to begin gas collection system installation.) The costs as sociated with an LFG collection and flare system are minimal as compared to the capital costs for landfill cons truction, annual landfill opera ting costs, and other closure costs. Section 6 discusse s average installation costs for ga s collection systems and flares. Post-closure care requires main tenance to ensure the integrity and effectiveness of the final cover system, leachate collection system, groundwater monitoring system, and methane gas monitoring system. These activities prevent wate r and air pollution from escaping into the surrounding environment. The required post-closure care period is 30 years from site closure, and can be shortened or extended by the director of an approved state program as necessary to ensure protection of human health and the enviro nment. Over a 30-year period, post-closure care and maintenance can cost from $64,0 00 to $88,000 per acre (Duffy, 2005b).18 Figure 2 shows that landfill costs peak prior to the landfill opening and again following the landfill closing (EPA, 1997).

Figure 2 Landfill Cost Life Cycle

4.2 Landfill Revenue Sources
The cost to dispose of MSW at a landfill is commonly known as a “tip fee” or “gate fee”. Typically, reported tip fees repres ent the “spot market” price for MSW disposal, i.e., the drive-up cost to dispose of a ton of waste (NSWMA, 2011 ). Other tip fees exist at MSW facilities (e.g., waste accepted under a long-term contract, volume discounts, and special wastes); these fees may be higher or lower than the spot market price (Repa, 2005). In September 2012, the average national spot market price to dispose of one ton of waste in a U.S. landfill was roughly $45, up 3.5 percent over 2011 (WBJ, 2012). This compares to average national tip fees of approximately $32 in 1998 (EPA, 2002) and $8 in 1985 (NSWMA, 2011). Average tip fees vary by re gion of the country, as show n in Table 5. Tip fees in northeastern states have hi storically been and continue to be higher than those in other regions.19 The next most expensive areas, on average, are the Mid-Atlantic and western states. Tip fees tend to be higher near large population centers (W right, 2012); this is likely influenced by the fact that metropolitan areas have less land area for waste disposal and therefore, fewer landfills. There is variation in tip fees within states as well, depending on landfill ownership (public or private) and proximity of other landfills.

Table 5 Average Regional and Nation al Per-Ton Tip Fees (Rounded): 1995-2012

U.S. Region 1995 a 1998 a 2000 a 2002 a 2004 a 2008 b 2010 c 2012 d Northeast $73 $67 $70 $69 $71 $67 NA $73 Mid-Atlantic $46 $44 $46 $45 $46 $56 NA NA South $29 $31 $31 $30 $31 $32 NA NA Midwest $31 $31 $33 $34 $35 $39 NA NA South Central $20 $21 $22 $23 $24 $34 NA NA West Central $23 $23 $22 $23 $24 $39 NA NA West $38 $36 $35 $39 $38 $44 NA NA
National $32 $32 $32 $34 $34 $42 $44 $45

Northeast: CT, ME, MA, NH, NY, RI, VT Mid-Atlantic: DE, MD , NJ, PA, VA, WV South: AL, FL, GA, KY, MS, NC, SC, TN Midwest: IL, IN, IA, MI, MN, MO, OH, WI South Central: AZ, AR, LA, NM, OK, TX West Central: CO, KS, MT, NE, ND, SD, UT, WY West: AK, CA, HI, ID, NV, OR, WA

a Source: Repa, 2005. b Source: Data from Biocycle, 2010. Data were not available for all states. For nine states, 2006 or 2009 data were substituted for missing year 2008 data.
c Source: WBJ, 2010. d Source: WBJ, 2012.
Publicly owned landfills set tip fees based on the need to cover landfill and other waste management-related costs, while privately owned landfills’ tip fees are set based on competition or the lack thereof (Wright, 2012). For municipa lities that depend on landfill tip fees to fund programs and services, more waste disposed in the local community-owned landfill means more money generated to fund their solid waste sy stems, including non-disposal services like recycling. Conversely, if more wa ste starts going to private la ndfills instead, less revenue is generated for community programs. An increasing presence of private facilities that can set20 competitive tip fees has caused some communities to reduce their own tip fees in an effort to attract enough disposal volume to keep revenues at a sufficient level (Burgiel, 2003). Historically, the construction and operating costs of public MSW landfills have been funded by tip fees, tax revenues (e .g., county/city property tax reve nue that goes into a general fund), or a combination of these. Factors influencing tip fee valu es have included population and economic growth, recycling rates, operating and tran sportation costs, land values, and legislation. Traditionally, 30 percent of landfills receive all revenue from tip fees, 35 percent receive all revenue from taxes, and 35 percent cover the co sts of waste disposal through a combination of tip fees and taxes. The use of taxes as a revenu e source rather than tip fees has implications on waste disposal services. When di sposal costs are included in taxe s, most people are not aware of the actual costs involved and there is little in centive to reduce waste generation rates. Also, tax-supported facilities are typi cally underfunded relative to actual disposal costs, resulting in poorer operation than fully funded landfills suppor ted by tip fees. Factors that influence the choice of revenue sources include landfill size and ownership. Landfills receiving small quantities of waste are likely to rely heavily on taxes for their revenue while larger landfills rely on both taxes and tip fees (EPA, 2002a). Private owners of landfills re ly heavily on tip fees relative to other landfill owners. It remains unclear whether private landfills rely on tip fees because they are larger, or larger landfills rely heavily on tip fees because they are private (EPA, 2002a). As shown in Table 5, average tip fees by re gion remained fairly steady between 1995 and 2004, with minor declines in some years but with a gradual upward trend. The greatest increases in average tip fees occurred between 1985 and 1995, with the national aver age tip fee increasing by $24 (293 percent) or an average of $2.40 pe r year. By contrast, between 1995 and 2004, the national average tip fee increased by only 7 percent, or an average of 23 cents per year. Tip fees are expected to continue to increase gradually, based on recent data and given rising fuel costs, insurance costs, and other operating costs (Wright, 2012). A landfill can also generate revenue by entering an agreement to sell carbon credits for voluntary destruction of methane, entering a gas sa les agreement to sell LFG for beneficial use, or entering a power purchase agreement to sell el ectricity generated from LFG and/or renewable energy credits from the generation of that electric ity. These types of revenue are small relative to tip fees and total landfill revenues, but can help offset some landfill expenses, for example, the21 cost of installing a gas collection system or ener gy recovery equipment. More information about these potential revenue sources is available in Section 6.

5 Air Pollutant Emissions from Landfills
Municipal solid waste (MSW) landfills are a source of non-methane organic compounds (NMOC) which include volatile organic com pounds (VOC) , methane, a potent greenhouse gas (GHG), and hazardous air pollutants. LFG is fo rmed during the decom position of landfilled waste and, if not controlled, can emit numerous pollu tants into the air. Several factors affect the amount of LFG generated and its components, in cluding the age and composition of the waste, the amount of organic compounds in the waste, a nd the moisture content and temperature of the waste (EPA, 2012k). LFG generated from established waste (waste that has been in place for at least a year) is typical ly composed of roughly 50 percent methane (CH 4 ) and 50 percent carbon dioxide (CO 2 ) by volume, with trace amounts of non-NMOC and inorganic compounds (e.g., hydrogen sulfide) (EPA, 2010c; EPA, 2012k).

5.1 NMOC in LFG
The NMOC portion of LFG, while a small am ount of LFG by volume, can contain a variety of significant air polluta nts. NMOC include various or ganic hazardous air pollutants (HAPs) and VOC. If left uncontrolled, VOC can contribute to the formation of ground-level ozone, a common pollutant with adverse health impacts. Near ly 30 organic hazardous air pollutants have been identified in uncontrolled LF G, including benzene, toluene, ethyl benzene, and vinyl chloride (EPA, 2012k). NMOC in LFG results mainly from the volati lization of organic compounds contained in the landfilled waste, while some NMOC may be formed by biological processes and chemical reactions within the waste (EPA , 1998). Waste materials that c ontribute to the formation of NMOC include items such as household cleani ng products and materials coated with or containing paints and adhesive s; during decomposition, NMOC can be stripped from these materials by other gases (e.g., CH 4 or CO 2 ) and become part of the LFG (EPA, 2012k). The concentration of NMOC in uncontrolled LFG depends on several factors, including waste types in the landfill and the local climate. EPA’s Compilation of Air Pollutant Emission Factors (AP–42) provides a default NMOC con centration of 595 parts per million by volume22 (ppmv), of which 110 ppmv are considered HAP compounds. The tota l uncontrolled organic HAPs volume in LFG from MSW landfills is typical ly less than 0.02 percent of the total LFG (EPA, 2012k).

5.2 Methane in LFG

Methane is 25 times more effective at retain ing heat in the earth’s atmosphere than CO 2 and therefore is considered a potent GHG (IPCC 2007). The CO 2 generated from MSW landfills is deemed biogenic because the CO 2 would have been generated a nyway as a result of natural decomposition of the organic waste materials if th ey had not been deposited in the landfill (EPA, 2010c). When waste is first placed in a landfill, it enters an aerobic decomposition stage during which little CH 4 is produced. However, within a year or less, the waste environment becomes anaerobic, CH 4 generation increases, and the amount of CO 2 produced begins to level out (EPA, 2010c). Figure 3 presents a sample LFG generation curve over time for a typical MSW landfill. Significant CH 4 generation can continue for 10 to 60 years after initial waste placement (EPA, 2012k).23 Figure 3 Typical LFG Generation Curve

In 2012, landfills were the third-la rgest anthropogenic source of CH 4 emissions in the United States, accounting for approximately 18 percent (EPA, 2014). Increasing attention is being given to mitigation of CH 4 , given its global warming poten tial 25 times greater than CO 2 and its relatively short atmospheric lifetime of about 12 years (as compared to 50-200 years for CO 2 ) (EPA, 2014).

5.3 Criteria Pollutants from Combustion of LFG

While collection and combustion of LFG in a flare or energy project equipment (e.g., reciprocating engine, boiler, turbine) greatly reduces emissions of methane and NMOC (including VOC and organic HAP), the combus tion process generate s criteria pollutants including carbon monoxide (CO), nitrogen oxides (NO X ), sulfur dioxide (SO 2 ), and particulate matter (PM) (EPA, 1998). NO X formation is strongly tied to the combustion temperature in the equipment, while CO and PM emissions are primar ily the result of incomplete combustion of the24 gas. SO 2 production depends upon the amount of sulfur in the LF G (EPA, 2000). More information about LFG combustion devi ces is available in Section 6. 6 Techniques for Controlling Emissions from Landfills

6.1 Introduction
Emissions from landfills can be controlled by installing gas collection systems and either flaring the LFG or utilizing it as an energy sour ce. Large landfills with emissions exceeding 50 megagrams per year (Mg/yr) of nonmethane organic compounds (NMOC) are required by the MSW landfills NSPS to control and/or treat LFG to significantly reduce the amount of toxic air pollutants released. However, many landfills voluntarily choose to control emissions, in part because of the economic benef its of LFG energy projects. This section describes the equipment and co sts associated with LFG emission controls. The control technologies are divi ded into three categories: gas collection systems, destruction, and utilization. Much of the information in th is section was obtained from the U.S. EPA’s Landfill Methane Outreach Program (LMOP) Landfill Gas Energy Project Development Handbook (EPA 2010d).

6.2 Gas Collection Systems
LFG collection typically begins after a portion of the landf ill (known as a “cell”) is closed to additional waste placement. Gas vents are installed to collect LFG from the closed cell. The gas vents may be configured as vertical wells or horizontal trenches, and some collection systems involve a combination of the two. Vert ical wells (Figure 4) are the most common method of LFG collection and invol ve drilling wells vertically in the waste to collect gas. Horizontal trenches (Figure 5) us e piping laid horizontally in trenches in the waste; these systems are useful in deeper landfills and in areas of active filling. Both types of collection systems connect the wellheads to lateral piping that transports the gas to a collection header.25 Source: EPA, 2010d
Figure 4 Vertical Well LFG Collection

Source: EPA, 2010d
Figure 5 Horizontal Trench LFG Collection

Collection from the gas vents may be either pa ssive or active. Passive systems rely on the natural pressure gradient between the waste mass and the atmosphe re to move gas to collection systems. Most passive systems intercept LFG migr ation and the collected gas is vented to the atmosphere. Active systems use mechanical blowers or compressors to create a vacuum that optimizes LFG collection (ATSDR, 2001).26 Collection efficiency is a measure of the ab ility of a gas collection system to capture generated LFG. Although rates of LFG capture can be measured, rates of actual generation in a landfill cannot be measured; therefore, considerable uncertainty exists regarding actual collection efficiencies achieved at landfills. Collection effi ciencies at landfills with comprehensive gas collection systems typically range from 60 to 85 percent, with an average of 75 percent most commonly assumed (EPA, 1998). Total collection system costs vary widely, ba sed on a number of site-specific factors. For example, if the landfill is deep, collection costs tend to be higher because well depths will need to be increased. Collection costs also increase with the number of wells installed. Based on data from the LMOP’s Landfill Gas Energy Cost Model (LFGcost), the estimated capital cost (in 2008 $’s) required for a 40-acre co llection system designed for 600 cubic feet per minute (cfm) of LFG is $784,000, assuming one well is instal led per acre. Typical annual operation and maintenance (O&M) costs (in 2008 $’s) for coll ection systems are $2,250 per well. If an LFG energy project generates electricity, a landfill will often use a portion of the electricity generated to operate the system and sell the rest to the gr id in order to offset these operational costs.

6.3 Destruction
Collected LFG is typically combusted in fl ares or combustion devices that recover energy, such as boilers, internal combustion engi nes, and gas turbines. Properly designed and operated combustion equipment generally reduces NMOC by 98 percent or to a 20 ppmv outlet concentration, as specified in the current MSW landfill NSPS (40 CFR 60.752). Combustion also destroys over 98 percent of the methane. Flares are the most common control device used at landfills. Flares are also a component of each energy recovery option because they ma y be needed to control LFG emissions during energy recovery system startup a nd downtime and to control any ga s that exceeds the capacity of the energy conversion equipment. In addition, a flar e is a cost-effective way to gradually increase the size of the energy recovery system at an ac tive landfill. As more waste is placed in the landfill and the gas collection system is expanded, the flare is used to control excess gas between energy conversion system upgrades (e.g., be fore addition of a nother engine). Flare designs include open (or candlestick) flar es and enclosed flares. Open flares employ simple technology where the collected gas is combusted in an elevated open burner. A27 continuous or intermittent pilot light is genera lly used to maintain the combustion. Enclosed flares typically employ multiple burners within fire-resistant walls, which allow them to maintain a relatively constant and limited peak temperat ure by regulating the supply of combustion air (ATSDR, 2001b). Enclosed flares are more expensive but may be preferable (or required by state regulations) because they provide greater cont rol of combustion conditions, allow for stack testing, and might achieve slightly higher combus tion efficiencies than open flares. They can also reduce noise a nd light nuisances. Flare costs vary based on the gas flow of th e system. LFGcost estimates for flares include condensate collection and blower s. Condensate collection (also called knockout devices) is necessary because condensate forms when warm gas from the landfill cool s as it travels through the collection system. If condens ate is not removed, it can block the collection system. Blowers are needed to ensure a steady flow of gas to th e flare. The size, type, and number of blowers needed depend on the gas flow rate a nd distance to downstream processes. Based on data from LFGcost (in 2008 $’s), a flare for a system with an average of 600 cfm of LFG will cost $207,000 (including condensate collec tion and blowers). Typical annual O&M costs are approximately $4,500 per flare. Electricity costs to operate the blower for a 600 cfm active gas collection system average $44,500 per year.

6.4 Utilization
After collection, LFG may be used in an ener gy recovery system to combust the methane and other trace contaminants. LMOP’s Landfill and LFG Energy Project Database, which tracks the development of U.S. LFG energy projects an d landfills with project development potential, indicates that approximately 600 LFG energy pr ojects are currently operating in 48 states. Roughly three-fourths of these projects generate electricity, while one-f ourth are direct-use projects in which LFG is used fo r its thermal capacity (EPA, 2012m). This section summarizes LFG utilization techno logies in four general categories: power production, cogeneration, direct use, and alternative fuel. This s ection also provides a discussion of the economic benefits of LFG utilization projects.

6.4.1 Technologies It is important to note that all of the technologies disc ussed below typically require treatment of LFG prior to entering the control de vice to remove moisture, particulates, and other28 impurities. (While “treatment” has a specific mean ing within the MSW landfill NSPS, the term is used more generally in common usage and as disc ussed here.) The level of treatment can vary depending on the type of control and the types an d amounts of contaminants in the gas. LFG is typically dehumidified, filtered, and compressed be fore being sent to energy recovery devices. For most boilers and internal combustion engines, no additional treatment is used. Some internal combustion engines and many gas turbine and micr oturbine projects apply siloxane removal using adsorption beds after the dehumidification step.

Power Production
Producing electricity from LFG continues to be the most common beneficial-use application, accounting for about three-fourths of all U.S. LF G energy projects (EPA, 2012m). Electricity can be produced by burning LFG in an in ternal combustion engine , a gas turbine, or a microturbine. The majority (more than 70 percent) of LFG en ergy projects that gene rate electricity do so by combusting LFG in internal combustion engines. Advantages of this technology include: low capital cost, high efficiency, and adaptability to variations in the gas output of landfills. Internal combustion engines are well-suited for 80 0 kilowatt (kW) to 3 megawatt (MW) projects, but multiple units can be used together for projects larger than 3 MW. Internal combustion engines are relatively efficient at converting LFG into electricit y, achieving efficiencies in the range of 25 to 35 percent. Gas turbines are more likely to be used for large projects, where LFG volumes are sufficient to generate a minimum of 3 MW and t ypically more than 5 MW. Unlike most internal combustion engine systems, gas turbine systems have significant economie s of scale. The cost per kW of generating capacity dr ops as gas turbine size increase s, and the electric generation efficiency generally improves as well. Microturbines, as their name suggests, are mu ch smaller than turbin es, with a single unit having between 30 and 250 kW in capacity, and thus are generally used for projects smaller than 1 MW. Small internal combustion en gines are also available for pr ojects in this size range and are generally less costly. Microturbi nes may be selected for certain projects (rather than internal combustion engines) because they can operate with as little as 35 percen t methane and less than 300 cfm, and also produce low nitrogen oxide emissions.29 An LFG energy project may use multiple uni ts to accommodate a landfill’s specific gas flow over time. For example, a project might ha ve three internal combustion engines, two gas turbines, or an array of 10 microturbines, depending on gas flow and energy needs. The costs of energy generation using LFG vary greatly; they depend on many factors including the type and size of electricity generation equipment, the necessary compression and treatment system, and the interconnect equipment. Table 6 presents examples of typical costs for several technologies, including cost s for a basic gas treatment system typically used with each technology. Table 6 Average LFG Power Production Technology Costs

Technology Typical Capital Costs ($/kW) a Typical Annual O&M Costs ($/kW) a
Internal combustion engine (>800 kW) $1,700 $180 Small internal combustion engine (<1 MW) $2,300 $210 Gas turbine (>3 MW) $1,400 $130 Microturbine (<1 MW) $5,500 $380
Source: EPA 2010d
a 2010 $’s

Cogeneration
LFG energy cogeneration applic ations, also known as combined heat and power (CHP) projects, provide greater overall energy efficiency and are grow ing in number. In addition to producing electricity, these proj ects recover and beneficially use the heat from the unit combusting LFG. LFG cogeneration projects can use internal com bustion engine, gas turbine, or microturbine technologies. Less common LFG electricity generation techno logies include a few boiler/steam turbine applications in which LFG is combusted in a larg e boiler to generate steam which is then used by a steam turbine to create electricity. A few co mbined cycle applications have also been implemented. These combine a gas turbine that co mbusts LFG with a steam turbine that uses steam generated from the gas turbine’s exhaust to create electricity. Boiler/steam turbine and combined cycle applications tend to be larger in scale than the majority of LFG electricity projects that use internal combustion engines.30 Direct Use
The simplest and often most cost-effective use of LFG is direct use as a fuel for boilers and other direct thermal applications to produce us eful heat or steam. However, this is only an option if there is an end user located near the la ndfill who is willing and ab le to use the LFG. An end user’s energy requirements are an important consideration when eval uating the sale of LFG for direct use. Because no economical way to stor e LFG exists, all gas that is recovered must be used as available; gas that ca nnot be immediately used in energy recovery equipment is flared and the associated revenue opportuni ties are lost. The ideal gas cust omer, therefore, will have a steady annual gas demand compatible with the landfill’s gas flow. When a landfill does not have adequate gas flow to support the entire needs of a facility, LFG can stil l be used to supply a portion of the needs. The number and diversity of direct-use LFG applica tions is continuing to
grow. Boilers are the most common type of direct use, and LFG is used in boilers at a wide variety of industrial manufacturing facilities as well as commercial and institutional buildings. Boilers can often be easily converted to use LFG alone or in comb ination with fossil fuels. Equipment modifications or adjustments may be necessary to accommodate the lower Btu value of LFG, and the costs of modifications will vary. If retuning the boiler burner is the only modification required, costs will be minimal. Howe ver, retrofitting an existing natural gas boiler to include LFG may cost between $100,000 and $400,000, depending on the extent of the
retrofit. Direct thermal applications include kilns (e.g., cement, pottery, and brick), tunnel furnaces, process heaters, and blacksmithing forges . In addition, infrared heaters can use LFG to fulfill space heating needs. Greenhouses can combust LFG in boilers to provide heat for the greenhouse and to heat water us ed in hydroponic plant culture. LF G can be used to heat the boilers in plants that produce biof uels including biodi esel and ethanol. Table 7 presents typical cost ranges for the components of a direct-use project. The costs shown below for the gas compression and trea tment system include compression, moisture removal, and filtration equipment typically requir ed to prepare the gas for transport through the pipeline and for use in a boiler or process heat er. If more extensive treatment is required to remove other impurities, costs will be higher. The gas pipeline costs also assume typical construction conditions and pipeli ne design. Pipelines can range from less than a mile to more31 than 30 miles long, although most are shorter than 10 miles because length has a major effect on costs. In addition, the cost s of direct-use pipelines are often a ffected by obstacles along the route, such as highway, railroad, or water crossings. End users will likely need to modify their equipment to make it suitable fo r combusting LFG, but these costs are usually borne by the end user and are site-specific to their combustion device. Table 7 Average LFG Direct-use Project Components Costs Component Typical Capital Costs a Typical Annual O&M Costs a
Gas compression and treatment $960/scfm $90/scfm Gas pipeline and condensate management system $330,000/mile Negligible

Source: EPA 2010d

a 2010 $’s, based on a 1,000 scfm system scfm: standard cubic feet per minute

Alternative Fuel

Production of alternative fuels from LF G, by upgrading the gas using high-Btu conversion technologies, is becoming more pr evalent. LFG can be used to produce the equivalent of pipeline-quality gas (natural gas), compressed na tural gas (CNG), or liquefied natural gas (LNG). Pipeline-quality gas can be inj ected into a natural gas pipeline and used by residential, commercial, or industrial end users along the pipe line. CNG and LNG can be used to fuel vehicles at the landfill (e .g., water trucks, earthmoving equipment, light trucks, autos), fuel refuse-hauling tucks (long-haul re fuse transfer traile rs and route collectio n trucks), and supply the general commercial market. Although only a handful of these pr ojects are currently operational, several more are in th e construction or planning stages. LFG can be converted into a high-Btu gas by increasing its methane content and, conversely, reducing its carbon dioxid e, nitrogen, and oxygen content. In the United States, three methods have been commercially employed (i.e., beyond pilot testing) to remove carbon dioxide from LFG, including membrane separation, mol ecular sieve (also known as pressure swing adsorption or PSA), and amine scrubbing. Recent capital costs of high-Btu proce ssing equipment have ranged from $2,600 to $4,300 per standard cubic foot per minute (scfm) of LFG. The annua l cost to provide electricity32 to, operate, and maintain these systems ranges from $875,000 to $3.5 million (EPA 2010d). Costs will depend on the purity of the high-Btu gas required by the receiving pipeline or energy end user as well as the size of the project, sin ce some economies of scale can be achieved when producing larger quantit ies of high-Btu gas.

6.4.2 Revenues and Incentives

Landfill owners can receive revenue from the sale of carbon credits, the sale of electricity generated from LFG to the local power grid, or fro m the sale of LFG to a direct end user or pipeline. However, the revenue received repres ents only a small percen tage of the operating costs of a landfill.

Greenhouse Gas Credits
Voluntary greenhouse gas trading programs purch ase credits from la ndfills that capture LFG to destroy or convert methane contained in the gas and obtain credit for the reduction of greenhouse gas in terms of carbon equivalents. In order to qualify for these programs, the emission reductions must be in addition to regu lated actions and have re cent project installation. Examples of companies operating on the vol untary carbon market include Climate Action Reserve, EcoSecurities, Evolution Markets, AgCe rt, Blue Source, GE/AES, and Chicago Climate Exchange (EPA 2012a). Bilateral trading and greenhouse gas credit sa les are other voluntary sources of revenue. Bilateral trades are project-spec ific and are negotiated direc tly between a buyer and seller of greenhouse gas credits. In these cases, corporat e entities or public institutions, such as universities, may wish to reduce their “carbon footprint” or meet internal sustainability goals, but do not have direct access to developing their own project. Therefore, a buyer may help finance a specific project in exchange for the credit of offsetting greenhouse gas emissions from their organization. Many state and regional government entities are establishing their own greenhouse gas initiatives to cap or minimize greenhouse gas em issions within their jurisdictions. Examples include the Regional Greenhouse Gas Initiative (RGGI), the Washington carbon dioxide offset program, and the Massachusetts carbon dioxide reduction from new plants. Some of these programs establish a cap-and-trade program on car bon dioxide emissions, while others require33 new fossil-fueled boilers and power plants to either implement or co ntribute to funding of offset projects, including LFG. Certain LFG energy projects may qualify for pa rticipation in nitr ogen oxides cap-andtrade programs, such as the nitrogen oxides Stat e Implementation Plan (SIP). The revenues for these incentives vary by state and will depend on fact ors such as the allowances allocated to each project, the price of allowances on the market, and if the project is a CHP project (typically CHP projects receive more revenue due to credit for avoided boiler fuel use).
Electricity Project Revenue
The primary revenue component of the typical el ectricity project is th e sale of electricity to the local utility. This revenue stream is affect ed by the electricity buy-b ack rates (i.e., the rate at which the local utility purchas es electricity generated by the LFG energy project). Electricity buy-back rates for new projects depend on several fact ors specific to the local electric utility and the type of contract available to the project, but typically ra nge between 2.5 and 7 cents per kilowatt-hour (kWh) (EPA, 2010d). When assessing the economics of an electricit y project, it is also im portant to consider the avoided cost of the electricity used on-site. Electricity generate d by the project that is used in other operations at the landfill is, in effect, electri city that the landfill does not have to purchase from a utility. This electricity is not valued at the buy-back rate, but at the rate the landfill is charged to purchase electricity (i .e., retail rate). The retail rate is often significantly higher than the buy-back rate. LFG energy projects can potentially use a va riety of additional environmental revenue streams, which typically take advantage of the f act that LFG is recognized as a renewable, or “green,” energy resource. These additional revenues can come from premium pricing, tax credits, greenhouse gas credit trading, or incentive payments. They can be reflected in an economic analysis in various ways, but typically, convert ing to a cents/kWh format is most useful. LFGcost accommodates four common types of el ectric project credits: a direct cash grant, a renewable energy tax credit expressed in dolla rs per kWh, a direct greenhouse gas (carbon) credit expressed in dollars per metric ton of carbon dioxide equi valent (discussed in Section 6.3.2.1), and a direct electricity tax cred it expressed in dollars per kWh. This section34 includes discussion of the availa ble environmental revenue str eams that an LFG electricity project could possibly use. Premium pricing is often available for rene wable electricity (inc luding LFG) that is included in a green power program, through a Rene wable Portfolio Standard (RPS), a Renewable Portfolio Goal (RPG), or a voluntary utility green pricing program. These programs could provide additional revenue above the standard buy-back rate because LFG electricity is generated from a renewable resource. Renewable energy certificates (RECs) are sold through voluntary markets to consumers seeking to reduce their environm ental footprint. They are typically offered in 1 megawatt-hour (MWh) units, and are sold by LFG electricity gene rators to industries, commercial businesses, institutions, and even private citizens who wi sh to achieve a corporate renewable energy portfolio goal or to encourage renewable ener gy. If the electricity produced by an LFG energy project is not being sold as part of a utility green power program or green pricing program, the project owner may be able to sell RECs th rough voluntary markets to generate additional

revenue. Tax credits, tax exemptions, and other tax incen tives, as well as federal and state grants, low-cost bonds, and loan programs are availa ble to potentially provide funding for an LFG energy project. For example, Section 45 of th e Internal Revenue Code provides a per-kWh federal production tax credit for el ectricity generated at privately owned LFG electricity projects. To qualify for the credit, which was 1.1 cent per kWh for the 2009 taxable year, all electricity produced must be sold to an unrelated person du ring the taxable year. Unde r legislation passed in February 2009, the placed-in-servi ce date deadline for LFG energy proj ects to be eligible for the first 10 years of production is December 31, 2013. Another popular funding option is the Clean Renewable Energy Bond (CREB) program, which allows electric cooperatives, government entities, and public power producers to issue bonds to finance renewable energy projects including LFG electricity projects. The borrower pays back the principal of the CREB, and the bondholder receives federal tax credits in lieu of the traditional bond interest.
Direct-use Project Revenues
The primary source of revenue for direct-use pr ojects is the sale of LFG to the end user; the price of LFG, therefore, dictates a project’ s revenue. Often LFG sales prices are indexed to35 the price of natural gas, but prices will vary depending on site-specific negotiations, the type of contract, and other factors. In recent years, typical LFG prices have ranged from $4.00 to $8.00 per million British thermal units (MMBtu) or 0.38¢ to 0.75¢ per megaj oule. In general, the price paid by the end user must provide an energy cost savings that outweighs the cost of required modifications to boilers, process heaters, ki lns, and furnaces in order to burn LFG. Federal and state tax incentives, loans, a nd grants are available that may provide additional revenue for direct-use projects. Greenhouse gas emissi ons trading programs are also potential revenue streams fo r direct-use projects.

7 References

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