Remember the massive Tennessee coal ash disaster?
While the EPA continues to put off its decision on coal ash regulation—and Congress considers blocking the EPA from regulating it at all—the story of coal ash contamination continues around the country.
In North Carolina, after stepping up their monitoring efforts at 14 coal-fired power plants, state regulators have found elevated levels of metals in the groundwater near the power plants' coal ash dump sites.
Duke Energy and Progress Energy sank test wells around their ash ponds several years ago and found tainted groundwater. N.C. officials told them in 2010 to sink more wells, farther from the ponds.
That led to results the N.C. Division of Water Quality is now reporting.
Iron, manganese and low pH, all in excess of what the state says is allowable, were found at all 14 plants. Duke and Progress each own seven.
Sulfate, dissolved solids and chromium were found at seven plants. Boron was found at six, arsenic at three, and selenium, thallium and antimony at two. Chloride and nickel were each detected at one plant.
Both companies said the results were similar to earlier samples and to "background" groundwater unaffected by the ash basins. And while the state plans to compare the monitoring results with unaffected groundwater, an official also said that the power plants have been operating for so long and their sites are so large that it can be hard to pinpoint contaminants' origins.
Techniques exist to "fingerprint" the source of elements that occur both in ash and naturally, said Avner Vengosh, a Duke University geochemist. While iron and manganese are commonly detected, he said, elements such as boron and strontium are more closely associated with ash.
Power plant ash ponds also drain into the rivers and lakes the power plants use for cooling water. The three Duke power plants closest to Charlotte, Riverbend overlooking Mountain Island Lake, Allen on Lake Wylie and Marshall on Lake Norman, discharge 23 million gallons a day from their ponds.