Duke Energy said Monday that 50,000 to 82,000 tons of coal ash and up to 27 million gallons of water were released from a pond at its retired power plant in Eden into the Dan River, and were still flowing.
Duke said a 48-inch stormwater pipe beneath the unlined ash pond broke Sunday afternoon. Water and ash from the 27-acre pond drained into the pipe.
“We’ve had some temporary solutions that have intermittently worked at times during the day, but we are still working on a short-term solution and the long-term repair,” spokeswoman Erin Culbert said shortly after 9 p.m. Monday.
The pond has a liquid capacity of 155 million gallons when full, according to a recent inspection report, but was at a lower level because the Dan River power plant’s coal-fired units were retired in 2012. It’s not known how much ash was in the basin, but Culbert said most of it appears to still be in the pond.
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Duke said it notified local emergency managers and the N.C. Department of Environment and Natural Resources, which last year sued Duke over its ash handling, on Sunday afternoon. The first public notice of the spill came from Duke at 4:03 p.m. Monday.
Environmental groups that have filed lawsuits in an effort to force Duke and other utilities to remove ash stored near waterways quickly pointed out the lapse in time before public notification.
The Dan River plant is about 130 miles northeast of Charlotte near the Virginia line.
The North Carolina environmental agency said it notified downstream water districts of the spill. The nearest municipality that draws water from the Dan River, Danville, reported no problems with its water.
Duke and the North Carolina agency took water samples from the river but said results are not yet back. Coal ash contains metals that can be toxic in high concentrations.
The pond’s dam beside the river “remains secure,” Duke said. Some erosion has occurred on the side of a berm farthest from the river, it said, and engineers are working to stabilize it.
Independent engineers who inspected the pond’s dam in 2009 for the Environmental Protection Agency found it in good condition, but they noted some seepage and recommended a stability study on the structure’s river side. Built in 1956, it was divided into two ponds in the 1970s.
The report said the dam had “significant hazard potential” if it were breached, mainly for property and environmental damage.
A security guard spotted an unusually low water level in the ash pond about 2 p.m. Sunday, Culbert said, leading to the discovery of the pipe break.
Ash was visible on the banks of the Dan River on Monday, and the water was tinted gray.
“While it is early in the investigation and state officials do not yet know of any possible impacts to water quality, staff members have been notifying downstream communities with drinking water intakes,” the North Carolina environmental agency reported late Monday afternoon.
Danville, Va.’s water intake is about 6 miles downstream of the pond.
Barry Dunkley, the city’s water director, said in a release that “all water leaving our treatment facility has met public health standards. We do not anticipate any problems going forward in treating the water we draw from the Dan River.”
A 1-billion gallon spill of ash slurry at a Tennessee Valley Authority power plant in Tennessee in 2008 ignited national debate over coal ash.
Last week the EPA, which had been sued by two North Carolina environmental groups among others, said it would issue the first federal rules on ash-handling by December.
Duke has closed seven of its 14 North Carolina coal-fired power plants, including Dan River, and is evaluating ways to close the ash ponds at those sites. Groundwater contamination has been found around all 14 of its unlined ash ponds, although much of the contamination may occur naturally.
Ash ponds are at the Allen power plant in Gaston County near Belmont and at the Riverbend plant on Mountain Island Lake near Mount Holly.
North Carolina environmental officials, pressured by advocacy groups, sued Duke last year over ash handling at all its coal plants. Environmentalists say Duke should remove the ash from the retired ponds, as utilities in South Carolina have agreed to do.