RALEIGH, North Carolina — North Carolina environmental officials said Thursday that they have approved plans by Duke Energy to drain contaminated wastewater from a huge coal ash dump near Charlotte to repair a leaking pipe.
State Dam Safety Engineer Steve McEvoy told The Associated Press there is a small hole and a crack in a drainage pipe running under an earthen dam at the Marshall Steam Station, a coal-fired power plant located on the shores of Lake Norman.
McEvoy said the leaks at Marshall were identified about six months ago when a robotic camera was sent up the 30-inch-wide pipe, which is made out of corrugated metal with a plastic liner. He said the pipe is not in immediate danger of failure.
In February, the collapse of a corrugated metal pipe at a Duke plant in Eden triggered the massive spill that coated more than 70 miles of the Dan River with gray sludge. In response, state leaders passed a law requiring Duke to shut down all of its ash dumps by 2029. But precisely how the bulk of Duke's more than 100 million tons of ash in the state will be permanently disposed of remains to be determined.
McEvoy said his office has received similar requests from Duke for repairs on pipes at 18 of the company's 32 coal ash dumps scattered across the state.
"There are a number of repairs going on with the coal ash pond fleet," McEvoy said. "This is just one of them."
Duke spokeswoman Paige Sheehan said she didn't know the estimated flow of the leaks, but said the company's decades of monitoring of wastewater from Marshall had not identified any significant threat to the environment.
Division of Water Resources spokeswoman Susan Massengale said she couldn't immediately answer whether the agency has tested the flow rate or contamination levels in the water coming out of the pipe at Marshall since the leak was discovered.
The dump at Marshall covers about 450 acres and contains more than 22 million tons of waterlogged coal ash. State officials said Duke will be required to test the wastewater pouring into the lake periodically to ensure the levels of contamination don't exceed limits set under Duke's state wastewater permit.
Under that permit, issued in 2011, Duke is required to monitor for levels of arsenic and mercury, but there is no set limit on the levels of the toxic heavy metals the company is allowed to discharge into the lake. Under the permit, Duke is allowed to collect its own samples and have them tested at the company's own state-certified lab.
The permit includes no requirement that Duke test its wastewater for an array of other toxic chemicals often contained in coal ash, including lead, chromium or thallium.
"It is a chronic problem across the state that the permits for these disposal sites don't regulate the types of metals that we know to be a point of concern with coal ash pollution," said D.J. Gerken, a lawyer at the Southern Environmental Law Center.
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