By Neal Lineback and Mandy Lineback Gritzner, Geography in the NewsTM
Coal Ash Problems from Coal-fired Power Plants
In December 2008, an environmental disaster unfolded in Kingston, Tenn., when a TVA-owned earthen dike meant to contain wet coal ash breached. A wave of 1.1 billion gallons (4.2 million cubic meters) of sludge spread across the landscape. It destroyed three homes and covered nearly 300 acres (121 hectares) with as much as nine feet (2.7 m) of grayish muck.
The catastrophe in Tennessee points to more potential problems, one of which recently surfaced in the news concerning Duke Energy’s Belews Creek coal-fired steam plant in North Carolina. Hundreds of similar threats exist in across the country. More than 1,300 coal-ash waste sites dot the United States. Only half of them are actively used. Some of them are landfills, while others are storage lagoons. These surface impoundments, as the lagoons are often called, hold ash mixed with water, similar to the one in Tennessee.
Coal ash is one of the residues of the combustion of coal and is the by-product of electricity generated by coal-fired power plants. Coal ash is actually comprised of two types of ash: fly ash and bottom ash. Fly ash is generally the ash captured from the chimneys of coal-fired power plants, while bottom ash is removed from the bottoms of coal furnaces. Together, the plants in the United States produce about 130 million tons (116 million metric tons) of coal ash every year.
The components of coal ash can vary considerably depending upon the source and composition of the coal being combusted. All coal ash, however, includes substantial amounts of silicon dioxide (SiO2) and calcium oxide (CaO). Toxic metals such as arsenic, mercury, lead, selenium and cadmium often are found in trace amounts in coal ash. These metals can cause cancer, kidney problems and nervous-system diseases in humans. Nonetheless, the Environmental Protection Agency (EPA) only recently proposed to classify coal ash as a “special” or “non-hazardous” material.
Before the last few decades, coal fly ash was generally released into the atmosphere. Pollution control standards now mandate that it is captured prior to release. While most ash is placed in landfills or storage lagoons, some 43 percent is recycled, most often mixed with concrete to make roads.
The dangers of coal-ash waste sites finally are being recognized. The EPA has found that at least 67 coal-ash sites are damaging drinking water supplies in communities across 23 states. Environmentalists say those EPA-identified sites grossly underestimate the threat posed by the substance.
The EPA reviewed another 155 landfill and surface impoundment sites in 36 states in 2007. While an impermeable liner is necessary to prevent toxic metals from leaching from the ash into groundwater, only 13 had appropriate and effective liners. Moreover, of those 155 waste sites, more than one-third were close or very close to significant human populations and two-thirds were near or very near key water sources. About half of those sites were coal-ash storage lagoons. A lawyer who crosschecked the EPA data, Kevin Madonna, surmised that toxic wastes probably were leaking into water bodies from every one of those lagoons.
The public knows very little about coal-ash waste sites because they are not heavily regulated by the states and are not subject to federal hazardous-waste regulations. The companies and agencies that own the lagoons are the main stewards of the sites. Many of those sites are decades old, increasing the potential for leakage or failure of the containment systems. At the TVA plant in Tennessee, the waste, channeled into ponds and contained by dikes, had been accumulating for 50 years.
While the pond in Tennessee was relatively small at 40 acres (16 hectares), some surface impoundments are 1,500 acres (607 hectares) in size. At that size, a lagoon holds perhaps 55 million cubic yards (42 million cubic meters) of coal ash.
Though the problem of coal-ash storage is truly national in scope, environmentalists say the solution is obvious. First, all wet storage of toxic coal ash should be phased out and all coal ash should be stored in dry, specially lined landfills. Second, the states should immediately inspect and begin monitoring coal-ash storage and disposal sites. Third, the federal government should begin to regulate all coal-ash storage and disposal facilities.
Changing practices with regard to coal ash will be cost effective in the end. Lisa Evans, an attorney for the environmental group Earthjustice, says that the cost to clean up the spill in Tennessee may be 10 times what it would have cost to dry and ship the ash to a proper landfill.
More importantly than the bottom line, however, changing the storage practices will help protect groundwater resources lying below the lagoons from toxic coal ash. No other communities should have to suffer through the environmental disaster endured by that Kingston, Tenn., residents.
And that is Geography in the NewsTM.
Sources: GITN 977 Looming Coal-Ash Threats, Feb. 20, 2009; http://www.npr.org/templates/story/story.php?storyId=99134153; Clayton, Mark. “Coal-ash danger rises,” The Christian Science Monitor, January 14, 2009; and http://www.epa.gov/solidwaste/nonhaz/industrial/special/fossil/ccr-rule/index.htm.
Co-authors are Neal Lineback, Appalachian State University Professor Emeritus of Geography, and Geographer Mandy Lineback Gritzner. University News Director Jane Nicholson serves as technical editor. Geography in the NewsTM is solely owned and operated by Neal Lineback for the purpose of providing geographic education to readers worldwide.