Skip to Navigation
Skip to Content
Share this page


Welcome to PSR's Environmental Health Policy Institute, where we ask questions -- then we ask the experts to answer them. Join us as physicians, health professionals, and environmental health experts share their ideas, inspiration, and analysis about toxic chemicals and environmental health policy.


More Topics »

Coal Ash: the toxic legacy of the nation’s dependence on coal burning

Posted on March 2, 2012

By Lisa Widawsky Hallowell

This essay is in response to: How toxic is coal ash, the waste material left after coal is burned? How does it come to poison the waters and dust the land in communities across the nation? And what can be done to prevent further toxic contamination?

The myriad potential dangers of coal combustion waste, or “coal ash,” have been highlighted in the news in the three years since the fateful collapse of a coal ash impoundment dam at TVA’s Kingston Plant. But what exactly is coal ash? What are the exposure pathways by which its pollutants pose risks to human health and the environment? Has it actually done serious harm yet?   

What Is Coal Ash, and How Is It Disposed of in the United States?

Coal ash is the by-product of burning coal for electricity, and every year an additional 140 million tons of coal ash are generated by coal-burning power plants.[1] This waste material is dangerous to human health and the environment, containing a toxic soup of pollutants, especially heavy metals, often at extremely high concentrations.

Once generated, much of this waste gets disposed.[2] Unfortunately, although the law that governs waste disposal was passed over 30 years ago, coal ash regulation was exempted from that regulation. So, there are NO federal regulations for disposal of coal ash.

Consequently, power plants have dumped coal ash into three main types of sites: 1) landfills, which are dry sites; 2) surface impoundments, which are wet ponds; and 3) minefills, the extremely dangerous practice of dumping coal ash into abandoned coal mines. In the absence of composite liners, groundwater monitoring systems, leachate collection systems, covers, and other rudimentary environmental controls, all of these disposal units can be perilous to nearby communities and ecosystems. The toxic constituents of coal ash can leach into groundwater, discharge into surface waters, or blow as fugitive dust into the air, making living near a coal ash site dangerous to anyone who drinks well water, fishes, drinks stream water, or simply breathes. An EPA risk assessment found that drinking groundwater near an unlined coal ash surface impoundment can pose as high as a 1 in 50 cancer risk (2,000 times the safety threshold of 1 in 100,000), but further found that converting to a dry landfill and including a composite liner could reduce that risk almost to zero.[3]

Documented Evidence of Damage: what constitutes a damage case? 

The scope of this environmental problem is vast, as coal ash is located almost everywhere where there is or ever has been a facility that has burned coal. Documented evidence of harm to human health or the environment (or both) has been found in at least 35 states to date.[4]  

EPA was ordered by Congress to study “proven” and “potential” coal ash damage cases. According to EPA, proven damage cases are those where contaminants at levels exceeding the “maximum contaminant levels” for drinking water are found in ground water at a sufficient distance from the waste management unit to indicate that hazardous constituents had migrated to the extent that “they could cause human health concerns.” Potential damage cases were those with “documented MCL exceedances that were measured in ground water beneath or close to the waste source.”[5] In addition, exceedances of standard high enough to cause “large scale, system level ecological disruptions” (as opposed to just human health threats) also constitute damage.[6] To date, there are a total of 157 damage cases – 90 identified by the Environmental Integrity Project and its partners, and 67 identified by EPA.[7]

What Does It Mean if a Coal Ash Site Has a High Hazard Dam?

Following the 2008 breach of a dam at the TVA Kingston Fossil Plant in Tennessee that spilled over one billion gallons of coal ash, the EPA asked utilities to self-rank each of their coal ash surface impoundments[8] based on the U.S. Army Corps of Engineers’ criteria for the potential impacts of a dam collapse. Dams at an alarming forty-nine coal ash impoundments were ranked “high hazard” – meaning that a breach of any of these dams would result in probable loss of human life.[9]

Have Any Coal Ash Sites Been Deemed Superfund Sites?

Several sites have been cleaned up pursuant to the Superfund program guidelines (including the Kingston disaster), but two coal ash sites have actually been listed as Superfund sites.

Industrial Excess Landfill Superfund Site, Uniontown, Ohio: At this former sand and gravel quarry, there were exceedances of Maximum Contaminant Levels (MCLs) for at least 10 pollutants—antimony, arsenic, barium, beryllium, cadmium, chromium, lead, mercury, nickel, and thallium—in off-site residential wells. Dozens of residential wells were contaminated by the dumping of at least one million tons of industrial coal ash in the 1960s and ‘70s before the site was closed and eventually became a Superfund National Priorities List site in 1986. Court documents establish that coal ash was the only metal-laden waste dumped at this site that could have caused the exceedances.[10]

Town of Pines, Indiana. The use of coal ash for construction projects throughout the Town of Pines, Indiana, including as uncovered roads, led to the entire town being declared a Superfund Site after health-threatening or environment-threatening levels of boron, molybdenum, arsenic, and other metals were found in residential wells.   


Given the many grave risks posed by irresponsible coal ash disposal, the only prudent path forward is for EPA to ban the riskiest disposal practices and require federally enforceable, common-sense safeguards at all sites where coal ash is disposed.

PSR invites concerned readers to sign our petition urging President Obama to direct the EPA to issue strong coal ash protections.

[1] Linda Luther, “Managing Coal Combustion Waste (CCW): Issues with Disposal and Use,”  Congressional Research Service 1 (Jan. 12, 2010);  U.S. Environmental Protection Agency (EPA), Human and Ecological Risk Assessment of Coal Combustion Wastes (Aug. 6, 2007) (draft), available at  (hereinafter EPA, 2007 CCW Risk Assessment).

[2] Some coal ash gets recycled into various uses (some of which are deemed safe, some of which have been more controversial due to the potential for toxic pollutants to leach from the products and into the surrounding environment, and all of which warrant more close scrutiny).

[3] Office of Solid Waste & Emergency Response, EPA, Human and Ecological Risk Assessment of Coal

Combustion Wastes (draft) (Apr. 2010).

[4] The states are: Alabama, Arkansas, Arizona, Connecticut, Delaware, Florida, Georgia, Illinois, Indiana, Iowa, Kentucky, Louisiana, Massachusetts, Maryland, Michigan, Minnesota, Montana, North Carolina, North Dakota, Nebraska, New Mexico, Nevada, New York, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Virginia, Wisconsin, West Virginia, and Wyoming.

[5] EPA, Notice of Regulatory Determination on Wastes From the Combustion of Fossil Fuels, 65 Fed. Reg. 32,214, 32,224 (May 22, 2000).

[6] Id.

[7] Environmental Integrity Project (EIP), NEW REPORT: 20 Additional Toxic Coal Ash Contamination Sites Found in 10 States (Dec. 13, 2011),

[8] Unfortunately for the public, other disposal units such as landfills were not surveyed.

[10] Earthjustice, et al, Comments on EPA’s Proposed Coal Combustion Waste Regulatory Proposal (Nov.19, 2010).


Comments closed.