RALEIGH, N.C. (AP) — Sludge washed from buried coal-ash pits by Hurricane Florence's floodwaters hasn't polluted a neighboring North Carolina river with heavy metals at levels concerning to human health, state environmental officials said.
Three old coal-ash dumps capped with soil and trees at Duke Energy Corp.'s closed H.F. Lee power plant in Goldsboro plant were submerged when the river flooded last month. The country's No. 2 electricity company has said that any coal ash released from the Goldsboro site appeared "minimal."
The environmental group Waterkeeper Alliance disputed that, saying samples collected and had tested by a private laboratory found arsenic levels many times higher than the state standard for drinking water as well as lead and other heavy metals in the water.
But a Duke University coal-ash expert cautioned Tuesday the initial tests for contamination of the Neuse River don't tell the full story. That's because neither is measuring pollutants that may have dropped to the river bottom and are likely to linger in the sediment, said Avner Vengosh, a professor of geochemistry and water quality.
"The bottom line: we are still missing information of how much coal ash was released," he said in an email.
Both the state Department of Environmental Quality and Duke Energy said they will continue to test the river. A company spokeswoman said Tuesday the company would do more if necessary.
"We're pleased that additional water testing performed by the state demonstrates that the environment remained well protected from our operations in the wake of historic flooding," Duke Energy spokeswoman Paige Sheehan said in an email.
Duke Energy's ash waste management has faced intense scrutiny since a drainage pipe collapsed under a waste pit at an old plant in Eden in 2014, triggering a massive spill that coated miles (kilometers) of the Dan River in gray sludge. The utility later agreed to plead guilty to nine Clean Water Act violations and pay $102 million in fines and restitution for illegally discharging pollution from ash dumps at five North Carolina power plants. It plans to close all its ash dumps by 2029.
State officials said water samples taken from three sites near the Lee plant on Sept. 23, more than a week after Florence hit the state, found arsenic, mercury and three other metals within acceptable levels.
Waterkeeper Alliance members sampled the river four days earlier, took photographs and collected samples of sludge washing into the floodwaters.
An environmental attorney working with the Waterkeepers Alliance said the extra days made all the difference in the results.
"They buried their heads in the sand until the problem washed downstream," said Peter Harrison of the group Earthjustice. "Duke and DEQ must analyze river sediments where the spill occurred before making a credible determination that there were no environmental impacts from the release."
State officials and environmentalists have yet to release their findings from a separate Duke Energy power plant near Wilmington. A dam breached at a the company's L.V. Sutton power plant where an old coal ash dump had been covered over by Florence's floodwaters.
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Biesecker reported from Washington, D.C.