Q&A: Examining The Tennessee Coal Ash Spill

A map showing the points where river water is being monitored. i

A map shows points where river water is being tested for contamination. Red circles indicate testing done by the Tennessee Valley Authority, and green stars indicate sampling points by the Tennessee Department of Environment and Conservation. Tennessee Department of Environment and Conservation hide caption

itoggle caption Tennessee Department of Environment and Conservation
A map showing the points where river water is being monitored.

A map shows points where river water is being tested for contamination. Red circles indicate testing done by the Tennessee Valley Authority, and green stars indicate sampling points by the Tennessee Department of Environment and Conservation.

Tennessee Department of Environment and Conservation

Officials from the Tennessee Valley Authority and state regulators appeared at a congressional hearing Thursday to answer questions about December 2008's devastating coal-ash spill in Kingston, Tenn. Some members of the Senate Environment and Public Works Committee called for coal-ash disposal to be more strictly regulated by the Environmental Protection Agency.

Here's a closer look at what happened and what the fallout may be:

What happened?

On Dec. 22, a dike at the TVA's Kingston Fossil Plant collapsed, spilling 1.1 billion gallons of wet coal ash. The sludge gushed out like a tidal wave, destroying three homes and blanketing nearly 300 acres with up to 9 feet of grayish muck.

Coal ash is the byproduct of electricity generated by the nation's coal-fired power plants, which together produce about 130 million tons of coal ash every year. The EPA has on record 24 spills. At the Kingston plant, the waste, channeled into ponds and contained by dikes, had been accumulating for 50 years.

What are the health risks?

Coal ash isn't classified by the EPA as a hazardous material, though it can contain trace amounts of such toxic metals as arsenic, mercury, lead, selenium and cadmium. These metals can cause cancer, kidney problems and nervous-system diseases in humans

Because the spill contaminated the Clinch River, tests are being done to make sure public drinking water is safe. Paul Sloan, deputy commissioner of the Tennessee Department of Environment and Conservation, says water is being tested daily at two reservoirs near the intake. It's also being tested after the water is treated. He says all drinking water samples so far had safe levels of all the contaminants tested.

To minimize airborne dust from the drying ash, which may contain toxic metal particles, TVA says it is treating areas of the spill with a liquid dust-suppression agent.

TVA also says it plans to spray seed and fertilizer on 213 acres of ash-fouled land to help keep dust particles out of the air and reduce erosion. Air samples taken in residential areas adjacent to the spill site showed concentrations of metals lower than the federal air-quality standard, according to TVA.

What's the potential environmental impact?

There are two main environmental concerns: water contamination from leeched metals or coal-ash sediment and the effects on fish and wildlife because of habitat loss. The sludge has gotten into the Emory River as well as the Clinch, and it is unclear how far the contamination might spread. TVA says it will use skimmers to trap lighter ash floating on the water's surface.

Although samples from drinking wells and from public drinking water have been found to be within safe levels, tests of surface and river water closer to the spill showed unsafe levels of some contaminants. On Jan. 6, the EPA found that two out of 16 water samples exceeded the Tennessee Water Quality Criteria for Domestic Supply.

Tests of ash taken from a road near the site indicated arsenic levels exceeding the EPA Removal Action Level.

Could another spill happen?

The federal government does not currently regulate coal-ash disposal, which views it as regular landfill waste. In 2000, the EPA said coal-ash disposal should be regulated, but as a non-hazardous waste. So far, the agency has not produced any rules.

There is disagreement over how coal ash should be regulated and disposed. TVA, the nation's largest public utility, has 11 coal-fired plants. Six of them use wet disposal systems, like at the Kingston plant, in which coal ash is stored in ponds.

TVA considered switching to a dry disposal system after the Tennessee Department of Environment and Conservation asked the Kingston plant to investigate two small leaks in 2003 and 2006. But TVA opted not to pay the estimated $25 million to convert its disposal system. Dry disposal eliminates the need for sedimentation ponds, but increases the risk that the ash becomes airborne.

TVA also has ash ponds or landfills in Kentucky and Alabama, but says it performs regular inspections at these sites and has not found any problems.

Additional reporting by Joanne Silberner and Elizabeth Shogren of NPR and The Associated Press.

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