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1 Introduction O n August 14, 2003, more than 50 million people across the northeastern United States and Canada experienced an electrical blackout. While the blackout was caused not by a fuel shortage but by faulty controls in the grid, this event underscores the United States dependence on electricity. Munici- palities faced urgent challenges related to contaminated drinking water, fighting fires, looting, health care, and transportation services. Train and airline traffic was canceled, and thousands of passengers were trapped when more than 600 subway and commuter rail cars stopped in the middle of tunnels. Road travel was also affected as traffic lights stopped functioning, and many gas stations were unable to pump fuel because there was no electric power. Hundreds of people were trapped in elevators. Hospitals struggled to treat their most serious patients. Some areas lost water pressure because pumps did not have power, causing possible contamination of water supplies. Individuals quickly realized how diffi- cult simple daily tasks became without electricity, because they could not charge their cell phones, refrigerate or cook food, ride in elevators, or turn on air condi- tioning (Answers.com, 2005). It took New York City 29 hours to restore power, while other areas did not have electricity restored for up to four days. It is estimated that the economic cost to New York City alone due to the blackout was more than $500 million (Figure 1.1). Even though Americans depend on electric- ity for most everyday activities, the majority of people do not realize that electric- ity is provided primarily by coal-fired electric utilities. Coal-fired utilities represent the largest single source of electrical generation in the United States. In 2003, total U.S. coal consumption was nearly 1,095 13
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14 MANAGING COAL COMBUSTION RESIDUES IN MINES FIGURE 1.1 Pedestrians and vehicles clog New York's Brooklyn Bridge, August 14, 2003. SOURCE: AP, 2003. Courtesy of the Associated Press. million short tons,1 with the U.S. electric power industry consuming 1,004 mil- lion short tons of that total (USDOE, EIA, 2003a). The combustion of coal results in the formation of coal combustion residues (CCRs), the noncombustible portion of the coal itself and residues from various air pollution control technologies, such as sulfur dioxide scrubbers, installed at the combustion facility. Specific examples of CCRs include fly ash, bottom ash, boiler slag, and flue gas desulfu- rization sludge. During 2003, the combustion of coal resulted in at least 121 million short tons of CCRs (USDOE, EIA, 2003b) produced by utilities and an additional 5 million short tons produced by independent power producers firing coal refuse (PADEP, 2004). This mass is approximately 890 pounds per capita,2 which is roughly the amount of municipal solid waste disposed in landfills throughout the United States per capita each year (USEPA, 2005a). To paint a better picture, the 1 The U.S. ton is the short ton, which is equal to 2,000 pounds; the British ton is the long ton, which is equal to 2,240 pounds (see Glossary for more detail). 2Calculated from 126 million tons divided by the 2003 census population of 283 million.
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INTRODUCTION 15 amount of CCRs produced annually would fill about one million standard rail- road coal cars, which, if hitched together, would create a train about 9,600 miles long (Conrail Cyclopedia, 2005) that would span the United States from New York City, New York, to Los Angeles, California, 3.5 times. The management of large volumes of CCRs is a challenge for utilities, be- cause they must either place the CCRs in landfills, surface impoundments, or mines, or find alternative uses and markets for the material, such as the use of fly ash in concrete production. Each of these methods for disposing of CCRs has advantages and disadvantages pertaining to various factors including cost and environmental risk. To meet their CCR disposal needs, utilities often, as part of their contractual relationship with coal suppliers, require that a mine take the CCRs for use in reclamation, the process by which land-use capability is restored at a mine site. This report examines the management, benefits, and health and environmen- tal risks associated with the placement of CCRs in active and abandoned coal mines. To begin, this chapter provides an introduction to coal mining and CCRs to set the stage for the more in-depth discussion of CCRs and their placement in mines in the following chapters. This introduction briefly reviews coal produc- tion and use in the United States, including where and how coal is mined; man- agement of CCRs, including how they are produced and disposed of; and the purpose of this study. COAL PRODUCTION AND USE IN THE UNITED STATES Coal is the world's most abundant fossil fuel and the largest single source of fuel for electricity production in the United States (Sidebar 1.1). More than 90 percent (USDOE, EIA, 2003a) of the coal mined in the United States is used by SIDEBAR 1.1 Geological Origin of Coal Coal is a fossil fuel formed from the remains of organic plants that existed millions of years ago. The plant matter was buried by sediment, and the weight of these overlying deposits compacted the buried plant organic matter. Heat, pres- sure, and chemical and physical changes took place while the plant matter was buried, driving oxygen out of it and leaving rich hydrocarbon deposits. Through this process, the plant matter was gradually transformed into coal. Coal has a highly variable composition, affecting both its chemical and its physical properties. It may contain significant amounts of sulfur, arsenic, and other materials that can lead to environmental concerns as the coal residue is produced. SOURCES: Rice et al., 1979; Hoffman, 2002.
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16 MANAGING COAL COMBUSTION RESIDUES IN MINES Petroleum and Other Sources (4.7%) Nuclear (20.5%) Coal (52.5%) Natural Gas (15.3%) Hydroelectric (7.1%) FIGURE 1.2 Electricity generation in the United States, showing proportion generated by energy source, 2003. SOURCE: USDOE, EIA, 2004a. commercial power plants to generate electricity. In 2003, 1,004 million short tons of coal generated more than 50 percent of all the electric power produced in the United States (Figure 1.2; USDOE, EIA, 2004a). In 2003, coal consumption for electricity production increased by 2.7 percent (USDOE, EIA, 2003a, 2004a), and the percentage of electricity produced from coal is expected to increase through 2025 (Figure 1.3). Coal has a highly variable composition affecting both its physical and chemi- cal properties. Four types of coal and coal refuse (called culm when derived from anthracite mines and gob when derived from bituminous mines) with widely vary- ing characteristics are used in the production of electricity and heat (Table 1.1). The United States has approximately 25 percent of the world's coal reserves (USDOE, EIA, 2004b). More than 400 coalfields and small deposits cover a total of 458,600 square miles in 38 states, split nearly evenly between the eastern and western United States (Figure 1.4; Chircop, 1999). Although approximately 300 different coal deposits are mined each year, almost 47 percent of total production comes from just 10 of the largest deposits. In 2003, 51 percent of the country's total coal production of 1,071.8 million short tons came from western mines, 36 percent from the Appalachian area, 13 percent from Midwest area mines, and less than 1 percent from coal refuse recovery (USDOE, EIA, 2003a).
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INTRODUCTION 17 onsT Short Million FIGURE 1.3 Consumption of coal for electricity generation and other uses (million short tons), 1970-2025. SOURCE: USDOE, EIA, 2005a. TABLE 1.1 Types of Coal and Their Characteristics Moisture Average % Contenta Average Heat Content Sulfur by Average % Coal Type (percent) (Btu per pound) Weight Ash by Weight Lignite Up to 45 6,500b 0.91b 14.2b (or brown coal) Subbituminous 20-30 8,800b 0.35b 6.3b Bituminous <20 12,000b 1.45b 10.1b Anthracite <15 12,700d 0.7d 11d Coal refuse Not Available 6,000-9,500c Culm0.46c 32-72c (culm or gob) Gob2.3c NOTE: Btu = British thermal unit. aUSDOE, EIA, 2003a. bUSDOE, EIA, 2001. cARIPPA, 2000. dThe Pennsylvania Academy of Science, 1983.
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18 Anthracite States. Survey. United the of Geological areas U.S. Tewalt, Coal-bearing 1.4 Susan FIGURE SOURCE:
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INTRODUCTION 19 In 2003, 1,316 mines were actively operating in the United States. Of these, approximately 67 percent were surface mines and the remaining were under- ground mines (USDOE, EIA, 2003c). Surface mining is used when coal is found close to the surface and involves removing the topsoil, the subsoil, and other rock units, called overburden, and setting them aside. After the coal is removed, the area is reclaimed, refilled with the overburden, and covered with the soils that were saved; then the land is reshaped and reseeded. Underground mining is used to extract coal that lies deep beneath the surface; an underground mine's coal is removed mechanically and transferred by shuttle car or conveyor to the surface. Besides utilities, other industries and manufacturing plants use coal. Steel production accounts for the second largest use of coal; coal is placed in hot furnaces to produce coke, a form of coal that is used to smelt iron ore for making steel. Other industries use coal directly for the production of chemicals, cement, paper, ceramics, and various metal products. Coal is also an ingredient in prod- ucts such as plastics, tar, synthetic fibers, fertilizers, medicines, dyes, paint, dis- infectants, shampoo, soap, detergents, and cosmetics (University of Pittsburgh, 2000; Solid Energy, 2002; Cosmetics Programme, 2005; USDOE, EIA, 2005b). MANAGEMENT OF COAL COMBUSTION RESIDUES The combustion of coal produces heat. The heat is used to make steam that is then used to drive electrical generators or perform other types of steam-driven work. The combustion of coal also generates various forms of solid residues, including fly ash, bottom ash, boiler slag, and flue gas desulfurization sludge. These materials are known by a variety of terms including coal combustion waste, coal combustion product, fossil fuel combustion waste, coal combustion material, coal combustion ash, coal combustion by-product, and coal combustion residue. For the purpose of this report the committee chose to use the term "coal combustion residue." This term was chosen to avoid implying that these materi- als are destined for particular fates. The characteristics of CCRs are influenced by several factors such as the source coal, combustion technology, and power plant air pollution control technology. The characteristics of CCRs are discussed in more detail in Chapter 2. Burning coal and coal refuse to generate electricity produced more than 120 million short tons of CCRs in 2003 (USDOE, EIA, 2003c; PADEP, 2004). The amount will likely increase as the demand for coal-based energy in the United States grows and as air pollution control technology is more widely used for capturing residues. Utilities dispose of CCRs by placing them in landfills, surface impoundments, or mines (Sidebar 1.2 and Figure 1.5) or by finding alternative uses and markets for the material. Alternative uses for CCRs can include the production of concrete, wallboard, filler for paint and other products, and manu- facturing of mortars (ACAA, 2005b). Of the approximately 126 million short tons of CCRs reported to have been produced in 2003, 46 million short tons (37
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20 MANAGING COAL COMBUSTION RESIDUES IN MINES SIDEBAR 1.2 Placement Options In 1999, it was estimated that approximately 600 fossil fuel combustion waste management units, defined by the Environmental Protection Agency (EPA) as landfills and surface impoundments, were in operation at approximately 450 coal- fired utility power plants. At the time, the 600 units included equal proportions of landfills and surface impoundments, although the trends in 1999 suggested an increasing preference for landfills (USEPA, 1999a). Surface impoundments are natural depressions, excavated ponds, or diked basins that usually contain a mixture of liquids and solids. CCRs managed in sur- face impoundments typically are sluiced with water from the point of generation to the impoundment. The solid CCRs gradually settle out of this slurry, accumulating at the bottom of the impoundment. This process leaves a standing layer of relative- ly clear water at the surface, which is commonly termed head. Solids that accumu- late at the bottom of a surface impoundment may be left in place as a method of disposal. The impoundment also may be dewatered periodically and the solids removed for disposal elsewhere, such as a landfill (USEPA, 1999a). Landfills are facilities usually constructed in sections called cells, in which residues are placed for disposal on land. Residues are placed in the active cell and compacted until the predetermined cell area is filled. Completed cells are covered with soil or other material, and then the next cell is opened. Cells constructed on top of previously completed cells are called lifts. Landfills are usually natural de- pressions or excavations that are gradually filled with residue, although the con- struction of lifts may continue to a level well above the natural grade. Coal com- bustion residues managed in landfills may be transported dry from the point of generation, or they may be placed after dredging from a surface impoundment. Residual liquids may be placed along with the dredged solids. Also, liquids may be added during the construction of the landfill for dust control purposes (USEPA, 1999a). Minefills involve the placement of CCRs in surface or underground mine voids (USEPA, 1999a). When used in surface mines, the CCRs are incorporated into the mine reclamation plan and generally are deposited in the mine as backfill combined with the overburden or as a monofill. They can be used in mine reclamation to achieve the approximate original contour. CCRs can also be used to form a grout to fill underground mines in order to prevent subsidence (USEPA, 2002a). Because the transportation of CCRs to the disposal site can be costly, disposal in mines is commonly done when the utility and the mine are located near one another. percent) went to alternative uses (AACA, 2005a); 73 million short tons (58 percent) were placed by utilities into surface impoundments, landfills, and other on-site locations (USDOE, EIA, 2003b); and approximately 7 million short tons (5 percent)--2 million short tons from traditional utilities and 5 million short tons from independent power producers fueled by coal refuse--were used in mine applications. According to the American Coal Ash Association Coal Combustion
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INTRODUCTION 21 FIGURE 1.5 Coal combustion residue mine placement sites in the United States. SOURCE: National Research Council; data collected through individual state surveys. Product Production and Use Survey (2005a), such mine applications may include use in surface mine reclamation, underground mining projects, and use in other mining industries such as sand and gravel pits. The available data are likely to underestimate the actual tonnage of CCRs being placed in coal mines due to deficiencies and inconsistencies in the current reporting framework (see Chapter 2, Sidebar 2.4).
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22 MANAGING COAL COMBUSTION RESIDUES IN MINES SIDEBAR 1.3 Statement of Task In response to a request from Congress, the National Research Council con- ducted a study that examined the health, safety, and environmental risks associat- ed with using coal combustion wastes (CCWs)a for reclamation in active and aban- doned coal mines. The study looked at the placement in abandoned and active, surface and underground coal mines in all major coal basins. The study consid- ered coal mines receiving large quantities of coal combustion wastes. The commit- tee focused its efforts on coal combustion wastes from utility power plants and independent power producers, rather than small business, industries, and institu- tions. A profile of the utility industry was taken into consideration in designing the study to focus on the sources producing the greatest quantities of coal combustion wastes. Specifically, the committee addressed the following points: 1. The adequacy of data collection from surface-water and groundwater monitoring points established at CCW sites in mines. 2. The impacts of aquatic life in streams draining CCW placement areas and the wetlands, lakes, and rivers receiving this drainage. 3. The responses of mine operators and regulators to adverse or unintend- ed impacts such as the contamination of groundwater and pollution of surface waters. 4. Whether CCWs and the mines they are being put in are adequately char- acterized for such placement to ensure that monitoring programs are effective and groundwater and surface waters are not degraded. 5. Whether there are clear performances standards set and regularly as- sessed for projects that use CCW for "beneficial purposes" in mines. PURPOSE OF THE STUDY Whether CCRs should be placed in coal mines and, if so, under what condi- tions, are important policy issues. Many CCRs can be recycled for use in engi- neering applications or products such as cement or wallboard--uses that avoid other environmental impacts and the consumption of other natural resources. The remainder must be disposed. Using CCRs in mine reclamation avoids having to dispose of them in landfills and/or surface impoundments, limiting the environ- mental disturbance of other land. Concerns have been raised about public health and environmental risks posed by mine placement of CCRs, especially when they come in contact with water. Burning coal concentrates metals and metalloids, such as arsenic, cadmium, chromium, and lead, in the CCRs, compared to the original coal, and alters the leachability of the contaminants by changing the mineralogy of the material (USGS, 2002). As an example of the risks to be
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INTRODUCTION 23 6. The status of isolation requirements and whether they are needed. 7. The adequacy of monitoring programs including: a. The status of long-term monitoring and the need for this monitoring after CCW is placed in abandoned mines and active mines when placement is com- pleted and bonds released; b. Whether monitoring is occurring from enough locations; c. Whether monitoring occurs for relevant constituents in CCW as deter- mined by characterization of the CCW; and d. Whether there are clear, enforceable corrective actions standards regu- larly required in the monitoring. 8. The ability of mines receiving large amounts of CCW to achieve economically- productive post-mine land uses. 9. The need for upgraded bonding or other mechanisms to assure that ade- quate resources area available for adequate periods to perform monitoring and address impacts after CCW placement or disposal operations are completed in coal mines. 10. The provisions for public involvement in these questions at the permitting and policy-making levels and any results of that involvement. 11. Evaluation of the risks associated with contamination of water supplies and the environment from the disposal or placement of coal combustion wastes in coal mines in the context of the requirements for protection of those resources by the Resource Conservation and Recovery Act (RCRA) and the Surface Mining Control and Reclamation Act (SMCRA). aAlthough the term "coal combustion wastes" (CCWs) was used in the statement of task, after much discussion the committee chose to use the term "coal com- bustion residue" (CCR) for the purpose of this report. This term was chosen to avoid implying that these materials are destined for particular fates. considered, the Safe Drinking Water Act places limits on the presence of some of these constituents in public water supplies. The placement of CCRs in coal mines is a complex issue that involves consideration of possible human health and environmental impacts, as well as a comparison of the economic, health, and environmental impacts from other disposal options or uses (see Chapter 4). CCR mine placement is indirectly regulated under the Surface Mining Con- trol and Reclamation Act (SMCRA). This act gives states the option of develop- ing and implementing their own programs, subject to national standards and federal oversight (see Chapter 5). Thus, at present, regulation of CCR mine placement is primarily a state issue. Concern about the potential public health and environmental risks associated with using CCRs for reclamation in active and abandoned coal mines led Con- gress to direct the Environmental Protection Agency (EPA) to commission an independent study to examine this topic. As a result, the National Research
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24 MANAGING COAL COMBUSTION RESIDUES IN MINES Council (NRC) established the Committee on Mine Placement of Coal Combus- tion Wastes to undertake a study to address issues outlined in the statement of task (Sidebar 1.3). The committee consists of 14 experts from academia, industry, and state government with expertise in hydrogeology, geology, geochemistry, nuclear chemistry, biology, ecology, toxicology, epidemiology, occupational and environmental medicine, natural resource economics, environmental policy, en- vironmental law, mining regulations, environmental engineering, mining engi- neering, geotechnical engineering, and coal mining. Brief biographies of the committee members appear in Appendix A. This report is intended for multiple audiences including the general public. It contains advice for EPA and the Office of Surface Mining (OSM), other federal agencies, and state regulatory agencies, as well as policy makers, the coal indus- try, and its consultants, scientists, and engineers. THE COMMITTEE'S APPROACH To address the statement of task, the committee reviewed relevant govern- ment documents and materials, pertinent National Research Council reports, in- formation submitted to the committee by various sources (see Appendix B), and other technical reports and literature published through July 2005. In addition, the committee held seven meetings, six of which included information-gathering sessions that were open to the public, between October 2004 and August 2005. The information-gathering sessions included presentations by and discussions with personnel from EPA, OSM, and other federal, state, and local government agencies and representatives of industry, academia, environmental organizations, and citizens' groups (Appendix B). To obtain input from the public, the commit- tee also held six public testimony sessions, in conjunction with the information- gathering meetings, in Washington, D.C.; Farmington, New Mexico; the Navajo Nation, New Mexico; Austin, Texas; Evansville, Indiana; and Harrisburg, Penn- sylvania. During the information-gathering meetings the committee, subgroups of the committee, and individual committee members also visited several mine sites that were currently using or had previously used CCRs for minefilling. In addition to published technical reports, the committee considered numer- ous letters and reports (in both final and draft form), data compilations (both formal and informal materials), and other materials from citizens' groups, indus- try groups, and state and federal regulatory agencies. The information ranged from materials dealing with individual mining and CCR disposal sites (a few that the committee visited, as well as other sites) to compilations of monitoring data and interpretive reports of monitoring data. Further, at the information-gathering meetings the committee received public testimony pertaining to more than a dozen sites where CCR has been placed in mines, including sites where CCR has
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INTRODUCTION 25 been implicated in the degradation of environmental quality. In total, the commit- tee heard presentations or received testimony from more than 120 individuals. The committee considered all of this information during its deliberations. The information helped to identify data needs, as discussed in more detail later in this report. The reports and presentations often communicated conflicting views and interpretations of the environmental impacts of particular sites. Citizens' groups presented information on environmental degradation (e.g., water quality contamination) that may be related to CCR placement in mines and/or overall mining operations. This information was contrary to industry information that was presented, and many of these presentations were questioned or the interpre- tations were challenged by state agency personnel. In the committee's review of these data, it noted not only differences in their interpretation, but in several cases clear discrepancies in the data themselves. Although these discrepancies were quite informative, it is well beyond the committee's charge to review and resolve these local disputes. Hence, these local issues are not discussed in this report. To the extent possible, the committee has attempted to use and cite independently peer-reviewed reports and other information and government agency reports that are typically independently reviewed and available to the scientific community for review and comment. In addition, during public testimony, citizens raised concerns about various public health and environmental issues related to CCRs and mining operations, such as traffic hazards, fugitive dust, and respiratory problems related to trans- porting CCRs to mine sites. Although these issues may be important health and safety concerns for the affected communities, they are beyond the charge and capability of this committee to address in this report. Although CCRs have also been placed in other mine settings, including sand and gravel mines and base metal mines, the committee restricted its consider- ations to the placement of coal combustion residues in coal mines. Also, some coal-burning facilities add other combustible materials with coal (e.g., municipal wastes, old tires, waste oil), and a few mines accept other materials, such as dredge spoils, for minefill. To stay within its charge, the committee decided to include only materials derived directly from coal. Related to its statement of task, the committee also limited its consideration to the impacts of placing large quantities of CCR in coal mines. With the limited data directly applicable, the committee did not attempt to evaluate or comment on possible impacts from relatively small-scale applications of CCRs such as their use on mine roads. The committee also did not consider occupational safety issues. The committee's analysis focuses on the use of CCRs in surface mine recla- mation, the largest use of CCRs for minefilling. The principles and standards presented in this report apply to placement of CCRs in underground mines as well, although such applications are relatively minor. While the statement of task may not have specified that the committee evalu-
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26 MANAGING COAL COMBUSTION RESIDUES IN MINES ate impacts from the disposal of CCRs in landfills and surface impoundments, or the recycling of CCRs for other purposes, it was not feasible to address the impacts of CCR use in minefilling without comparison to other disposal and use options. Particularly, limitations in data available on the practice necessitated the review of environmental impact data from landfills and surface impoundments because these case studies illustrate how CCRs may affect human and environ- mental health (see Chapter 4). REPORT ROADMAP The chapters that follow address the statement of task and present the committee's findings and recommendations. Chapter 2 describes coal combus- tion residue production, characteristics, reuse, and placement technologies. Chap- ter 3 examines the behavior of coal combustion residues in the environment. Chapter 4 looks at the potential environmental impacts, considerations for human health, and reasons for concern regarding placement of CCRs in mines (statement of task numbers 2 and 3). Chapter 5 provides an overview of the regulatory framework governing the placement of CCRs in mines (statement of task number 5). Chapter 6 discusses the risk management framework for CCR disposal, as well as material and site characterization and prediction (statement of task num- ber 4). Chapter 7 addresses site management strategies including reclamation and monitoring practices (statement of task numbers 1, 6, 7, and 8). Chapter 8 sum- marizes the committee's overall management approach and other overarching issues (statement of task numbers 9, 10, and 11). Technical terms and acronyms are defined in Appendixes C and D.
Representative terms from entire chapter: