Balancing Act: Creating the Right Regulation for Coal Combustion Waste

With the 22 December 2008 collapse of a Tennessee Valley Authority (TVA) ash pond in Kingston, Tennessee, and the arrival of the Obama administration the following month, the regulatory ground is shifting in regards to coal combustion waste (CCW), the millions of tons of waste left over each year from burning coal for electricity. The U.S. Environmental Protection Agency (EPA) is pursuing a host of initiatives that could directly or indirectly affect the disposition of CCW. States, too, are revisiting their regulations. The goal of these initiatives is to ensure public health; the challenge is to do so without compromising a recycling industry that the American Coal Ash Association (ACAA) says keeps about 56 million tons of CCW per year out of the landfilled waste stream.

power plants in the United States are located primarily in the East, but can be found in virtually every state. These plants generated roughly 131 million tons of CCW in 2007, according to the ACAA.
This waste takes the form of fly ash, bot tom ash, boiler slag, and flue gas desulfuriza tion (FGD) materials. Fly ash is captured in the chimneys of coalfired power plants, while the heavier bottom ash and boiler slag are collected from the bottom of the furnace. FGD materials are produced by emission control systems in which an alka line agent, primarily limestone, is sprayed into the smoke stream to remove acid gases and some heavy metals. The resulting FGD sludge is dried before reuse.
CCW contains varying levels of the same potentially toxic elements that are found in coal. These include arsenic, chromium, lead, cadmium, selenium, and mercury. Numerous studies, such as work published in the May 2006 issue of EHP by William Alexander Hopkins and colleagues, have documented adverse effects, including devel opmental and behavioral abnormalities, in fish and amphibians exposed to CCW con stituents that have been released to aquatic ecosystems.
About 43% of the CCW produced each year is recycled, primarily as a replacement for portland cement in concrete mix and, in the case of FGD gypsum, as a replacement for virgin gypsum in wallboard. These uses con serve landfill space, reduce the demand for virgin materials, and reduce carbon dioxide emissions caused by the extraction of virgin materials and the manufacture of finished products. A recent analysis by the Electric Power Research Institute (EPRI) and the Recycled Materials Resource Center at the University of New Hampshire suggests that such "beneficial uses" saved about 160 trillion BTUs of energy, 11 million tons of carbon dioxide equivalent, and 32 billion gallons of water in 2007. [For more information about constructionrelated uses of CCW, see "Trash or Treasure? Putting Coal Combustion Waste to Work," p. A490 this issue.] CCW that is not recycled typically is stored onsite in landfills or stored longterm in ponds (wet storage). Ash ponds, which are often built behind earthen dams or retain ing walls, can pose a direct threat to human health and the environment should their bounds fail. This was what happened at TVA's Kingston Fossil Plant in a spill that spread coal ash over 300 acres and damaged a dozen homes.

Questioning the Safety of CCW Storage
Following that event, the EPA requested information from electric utilities around the nation to assess the structural integrity of their ash ponds. The survey responses, published on the Special Wastes section of the EPA website, identified 584 impound ments, 49 of which were considered to have "high hazard potential" according to Federal Emergency Management Agency classifications for dams-that is, the vol ume and/or siting of the dam make it "probable" that human death and possibly major environmental damage will occur if the dam were to fail (this rating does not, however, speak to the potential toxicity of the dammed material or to the likelihood the dam will fail). Another 60 impound ments were rated as having "significant hazard potential." In this case, the concern is primarily economic and environmental loss; human deaths are not expected.
However, says John Suttles, a senior attorney at the Southern Environmental Law Center (SELC), "Many utilities in the Southeast U.S. refused to provide com plete data such as size and volume of waste ponds, citing confidential business infor mation. Most other utilities divulged this information and made no such claims of confidentiality." The EPA has followed up its survey with onsite assessments of all units having a potential rating of "high" or "significant" hazard. Reports on the first 17 units were published in September 2009; the EPA rated the structural integrity of 7 of these impoundments as "satisfactory," 9 as "fair," and 1 as "poor." All assessments are to be completed by the end of the year.
TVA, for its part, reported to the EPA that its Kingston Fossil Plant had been rated as having "low hazard potential" at its last assessment in October 2008. However, cleanup of the site, currently under way, will cost an estimated $1 billion.
A preliminary assessment of the eco logic consequences of the Kingston spill, published in the 1 August 2009 issue of Environmental Science & Technology by a consortium of Duke University scientists and engineers, identified elevated levels of arsenic, selenium, lithium, and boron in a tributary of the Emory River that had been dammed by the spilled ash. Concentrations of dissolved arsenic in this pond reached 86 µg/L, compared with upstream water concentrations of 0.1-0.4 µg/L. Mercury concentrations of 92-130 µg/kg in sedi ments downstream of the spill were almost as high as those in the CCW itself.
Concentrations of these elements were significantly lower at sampling sites downstream on the Emory and Clinch Rivers but still were above background concentrations. Levels of radioactivity were slightly higher than those in ambient soil at the site, although according to the U.S. Geological Survey, CCW radioactivity generally is comparable to that of natural sources including some shales and granitic and phosphate rocks.
Aside from the direct danger of fail ing dams, CCW disposal sites can pose a potential threat to human health and the environment by virtue of the leaching of toxic constituents into groundwater when appropriate protective measures are not in place. These chemicals may then be con veyed to nearby drinking water wells and surface waters. A 2007 EPA study, Coal Combustion Waste Damage Assessments, identified 24 cases of proven damage and 43 cases of potential damage to ground or surface water adjacent to CCW dis posal sites. Damage was "proven" when exceedances of healthbased standards were documented in water far enough from the disposal site "to indicate that hazardous constituents have migrated to the extent that they could cause human health con cerns," according to the report.
The year before, the EPA commis sioned Research Triangle Institute to per form an analysis of the health risks of land fills and storage ponds containing CCW. The authors assessed soil and aquifer data within a 5km radius of each of 181 selected coalfired power plants. In a draft report titled Human and Ecological Risk Assessment of Coal Combustion Wastes, the authors modeled elevated cancer risk from arsenic for people who drank water from wells near unlined or claylined surface impoundments. They also modeled ele vated noncancer risks from molyb denum, boron, lead, cadmium, and cobalt. The report has remained unpublished in final form for two years, but EPA spokeswoman Latisha Petteway says it has now been peer reviewed and that a final version is sched uled for publication in December 2009. Contaminated water is not the only problem associated with CCW storage. Fine ash particles also can be transported by wind and may be inhaled. Moreover, some scientists and advocacy groups believe cer tain "beneficial uses" of CCW, for instance as fill in unlined mines, may pose these same water and air quality threats.

Regulatory Options
As far back as 1980, the EPA has debated designating CC W a s a ha z a rdous waste under Subtitle C of the Resource Conservation and Recovery Act (RCRA). A Subtitle C designation would mean CCW must be managed as a hazardous waste "from cradle to grave." Under Subtitle C, federallevel regulations govern the gen eration, transportation, and treatment,  The EPA is now pushing forward on a number of policy fronts, including stricter regulation of CCW disposal sites, as well as another foray into possibly classifying CCW as a hazardous waste under RCRA. Matthew Hale, director of the EPA Office of Resource Conservation and Recovery, says, "EPA is considering a range of options, including regulation of coal combustion under Subtitle D authority, under Subtitle C authority, and combined options that involve a mixture of Subtitle C and Subtitle D authorities. EPA . . . will propose one option as the preferred approach, but will take comment on a full range of options." RCRA offers two main avenues by which a material can be classified as a haz ardous waste under Subtitle C. The first avenue is to specifically list CCW in the act, which assumes that all CCW is of a uniform nature as far as toxic constituents go. RCRA also has provisions that define a listed waste as hazardous but allow certain specified uses of the waste that are unlikely to pose a threat. The second is through a set of techni cal analyses known as the toxicity character istic leaching procedure. If, during testing, the material leaches more than a specified concentration of certain constituents, it is deemed "hazardous by characteristic." Very little CCW sampled has failed the toxicity characteristic leaching procedure. However, in an 8 September 2008 presen tation at the Global Waste Management Symposium, EPA scientist Susan Thornloe and colleagues reported that efforts are currently under way to incorporate more reliable CCW leach tests into the EPA's SW846, a compendium of accepted test methods for evaluating solid waste. Past CCW testing, they noted, has not always considered field conditions known to influ ence leaching. Furthermore, assessments have sometimes considered initial but not final site conditions, although changes at a site over time could change the propensity of a material to leach.

Hazardous or Not?
The distinction ultimately chosen for CCW will have tremendous implications for recy cling and disposal. Few would disagree that some of the constituents in CCW can be toxic under certain conditions (for instance, in drinking water). At the same time, many assert that classification of all CCW as "hazardous" under Subtitle C is unjustified and would severely constrain, if not alto gether end, recycling of the material. "The marketplace would not choose to use some thing designated hazardous waste when they have other options," says Tom Adams, ACAA executive director.
If classified as hazardous, utility com panies would be left with more than 50 million additional tons of CCW to dis pose of each year under strict regulations. This waste would have to be transported, in some cases long distances, to landfills specifically designed and permitted to han dle hazardous wastes. EPRI, using a cost estimate prepared for the Utilities Solid Waste Action Group of the Edison Electric Institute, modeled a tenfold increase in disposal costs, which are currently around $1 billion annually. In addition, existing facilities might have to be closed or, if pos sible, retrofitted.
For this reason, electric utility and coal industry officials are strongly opposed to Subtitle C classification. So, too, is the Association of State and Territorial Solid Waste Management Officials (ASTSWMO), which voiced its opinion in an April 2009 letter to Hale. "Coal combustion by products rarely if ever fail the criteria by which materials are determined to be hazard ous waste," the authors wrote. "To artificially classify them as hazardous waste will need lessly limit the management options for both [CCW] and other waste classified as hazard ous, which will be competing with [CCW] for limited hazardous waste disposal capac ity, while not providing any greater degree of environmental protection. . . . The prospect of adding a significant new waste stream to be managed by severely underfunded State hazardous waste programs is unconscionable unless a significant amount of new sustained funding is included." ASTSWMO is also opposed to a hybrid Subtitle C and D designation in which disposed material is classified as hazard ous whereas recycled material is classified as solid waste. "The uncertainty that a pre sumed hazardous waste material could be deemed hazardous as a result of a deter mination that a generator failed to follow Subtitle D requirements will create too much uncertainty and liability concerns for the beneficial user," the group wrote in its let ter. Instead, the organization encourages EPA to classify all CCW under Subtitle D, with implementation left to the states and enforcement by the federal government under RCRA.
Environmental groups do not want to end all genuinely beneficial uses of CCW, but they do want stiffer requirements for disposed waste than are called for under Subtitle D, and they also have serious con cerns about unconsolidated landbased uses such as structural fills and agricultural appli cations, says Chandra Taylor, a senior attor ney at the SELC. "There's no question that CCW has hazardous constituents, and the EPA should promulgate rules in consider ation of that fact," says Taylor. "Certainly, we want at least minimum federal standards for disposal-a dual liner for landfills, a leachate collection system, testing for contaminants in the groundwater supplies, and phaseout of wet storage." Industry spokespeople say the EPA is indeed likely to call for a phaseout of wet storage. TVA has already announced that it will phase out wet storage within eight years at an estimated cost of $1.5-2.0 billion to pay for new ashhandling equipment and storage facilities. But industry groups remain opposed to any mandatory closure of exist ing ponds.
"Mandatory pond closure is not neces sary to ensure safe management of [CCW]," says James Roewer, executive director of the Utilities Solid Waste Action Group. "The 'nonhazardous' regulations we are advocating would allow those ponds that are manag ing [CCW] without adverse environmental impact to continue to do so. Why should a disposal facility that is safely managing [CCW] be forced to close? The costs of con version of ponds to landfills are huge-as much as $39 billion across the industry." "Whatever EPA decides, it's going to require a lot of new landfill space," Adams says. "And new space is hard to identify and hard to permit."

A State Perspective
Irrespective of federal classification, states are moving toward stricter regulation of CCW used in various applications, most notably structural fills. This practice, a popular use of CCW in many states, involves depositing the waste at the core of earthen fills that are subsequently built upon as recreational, com mercial, or industrial sites. The key to the environmental safety of these structural fills is preventing water from leaching through the core and mobilizing toxic constituents of the CCW.
Most states do not require monitoring of groundwater around most structural fills, so there is little information on the potential for leaching from these facilities. But sev eral sites with environmental concerns have been cited, and at least one case of poten tially serious concern has been detected. In Chesapeake, Virginia, heavy metals have been detected in the groundwater surrounding a golf course built on 1.5 million tons of fly ash. Residents are suing Dominion Virginia Power Company to have the ash removed and public water and sewer brought to their neighborhoods. The EPA continues its study and monitoring in this case; the extent of the damage and a definitive link to the golf course have not been established, according to Petteway.
Virginia's Department of Environmental Quality has formed an advisory committee to look at strengthening the regulations for structural fills using CCW. "There are going to be some new requirements to limit the per meability of fills," says W. Lee Daniels, a pro fessor of crop and soil environmental sciences at Virginia Tech and a member of the com mittee. "New regulations would not allow a fill to be built in the 100year floodplain."

The Impact of Mercury Regulation
Other federallevel policy initiatives may impact the future of CCW by imposing pollution control technologies that affect the quality of fly ash. The EPA is currently in the process of developing standards under the Clean Air Act for reduction of mercury and other pollutants emitted by oil and coalfired power plants. The EPA's new rules would supplant a plan passed by the Bush administration in 2006 that would have allowed power companies to avoid controls by purchasing emission "credits" from power plants in other parts of the country. A trad ing system can make sense for greenhouse gases that are widely dispersed, but experts agree it is not appropriate for mercury, which deposits locally.
The EPA is currently acquiring data from utilities that have implemented various control technologies at their power plants to determine what levels of reduction are fea sible for mercury and other toxics included in the list of 187 hazardous air pollutants the agency is required to regulate under the Clean Air Act. The EPA has already found that coalburning power plants emit 67 of these pollutants, notes the SELC's Suttles. Some technologies, such as activated carbon injection, have proven highly effective in reducing mercury emission.
However, says Suttles, a great deal of pollution that is removed from power plant emissions-and thus goes into CCWends up being emitted into the air anyway from cement plants when these plants use CCW as a feedstock. This was the thinking behind a New York State announcement on 13 October 2009 that cement manufacturer Lafarge North America will no longer be allowed to use fly ash in its Ravena cement plant. The announcement follows the mea surement of elevated levels of mercury in the soil and wildlife surrounding the plant.
Moreover, depending on how activated carbon injection is incorporated, it can alter the airentrainment characteristics of fly ash, which are important to helping concrete resist the stress of freeze/thaw cycles. These alterations render the fly ash potentially less desirable for use as a concrete feedstock.
The latter "may not be a show stopper," says Ken Ladwig, EPRI senior program manager. EPRI and other groups are researching technologies for collecting fly ash separately from the injected carbon and for treating fly ash to minimize the effects of the injected carbon on concrete. "Any of these are going to raise the cost [of using fly ash in concrete]," says Ladwig. But because incorporation as a concrete component is the largest recycling use of CCW at more than 14 million tons per year, any practice that reduces this option would also increase CCW disposal costs and amounts.

Balance
EPA has yet to finalize any of its proposed rules, so it is too early to say what require ments will be placed on individual power plants and what technologies the utilities will use to achieve those requirements.
Suttles, a staunch advocate of strict con trols on power plant emissions, is cogni zant of the impacts that new regulations may have on disposal costs and recycling of CCW. But he does not believe such impacts are justification for compromising public health and safety.
"We are starting to see the true cost of using coal as an energy source," he says. "Yes, we may be taking pollution that would have gone into the air and creating a land disposal problem, [but] our position is that you have to account for all these risks. The result is that using coal is not cheap. We need to be pushing energy efficiency and renewable energy."