Duke University researchers issued a study Monday warning that tons of ash from coal-burning power plants are polluting North Carolina's drinking water with arsenic, selenium, cadmium and other toxins.
The report is part of the fallout from the December 2008 dam spill in Tennessee that focused public attention on the risks associated with storing coal ash in impoundments and retaining ponds. Environmental groups since then have been urging federal and state agencies to regulate coal ash pits as hazardous waste.
Duke researchers wrote that coal ash residues "represent one of the largest industrial waste streams in the U.S. and are not classified as hazardous waste."
"Our data clearly show high contaminant levels that suggest the need for enhanced removal/wastewater treatment," Duke researchers wrote. "The results of this study have significant implications for hundreds of similar sites across the US given that CCR [coal combustion residue] storage facilities continuously generate contaminants via leaching and transport to nearby hydrological systems."
The report, titled "The Impact of Coal Combustion Residue Effluent on Water Resources: A North Carolina Example," looked at surface water and sediment accumulation around nine coal ash sites in North Carolina, and compared the toxic buildup to a body of water that is not near a coal ash pit, Jordan Lake.
Duke Energy and Progress Energy, which own and operate the coal-burning power plants and the ash pits, challenged the report's conclusions. Charlotte-based Duke acquired Raleigh-based Progress in July to form the nation's largest electric utility.
Duke spokeswoman Erin Culbert said the power companies conduct extensive monitoring, which shows that fish are healthy and local drinking water supplies are safe. The utilities said that critics are focusing on minute trace elements very close to the power plants, a measure that distorts the overall state of water quality.
"Water quality sampling demonstrates that the vast majority of samples are well within state surface water quality standards in lake and rivers near our power plants," Culbert said in a prepared statement.
The Duke University report was published in the most recent issue of Environmental Science & Technology, a journal issued by the American Chemical Society. The study was co-authored by five researchers from Duke University and one each from University of Arkansas and N.C. Department of Environment and Natural Resources.
The Duke study did not look at groundwater contamination. But it came on the heels of an environemntalist action that did. A coalition of environmental groups last week petitioned N.C. authorities by state environmental groups to clean up groundwater contaminants from leaking toxins released by ash pits at 14 coal-burning power plants in the state.
That request was based on two years of groundwater monitoring at ash pits. The monitoring was implemented by the N.C. Department of Environment and Natural Resources in the wake of the Tennessee coal ash pit spill.