Most of the Duke Energy coal ash that spilled into the Dan River in February will stay there, creating a rift between regulators and river advocates over the cleanup.
Duke said this week that contractors have finished dredging the largest of the deposits, 2,500 tons of ash and sediment behind a dam in Danville, Va. About 500 tons have been removed from four smaller deposits.
That leaves up to 36,000 tons of ash spread along 70 miles of river bottom from the spill site in Eden to Kerr Lake on the North Carolina-Virginia line. Ash contains metals that can be toxic.
“This stuff is not just going to go to the bottom and stay there and not harm the environment,” said Brian Williams of the Dan River Basin Association, which promotes the region’s natural assets. “It will be an issue for many, many years to come.”
Federal and state agencies say their work isn’t done. Duke and regulators, aided by computer models, will continue to patrol the river to find and test deposits of sediment and ash.
Nearly six months after the Feb. 2 spill, most of the ash is now covered by sediment. The upper layer of sediment is also where fish lay eggs and aquatic insects grow.
“Ecologically, you could do more damage trying to remove all the ash than leaving it in place,” said Dianne Reid, water sciences chief for the N.C. Division of Water Resources.
Disturbing the river bottom also risks stirring up the toxic mercury and cancer-causing chemicals called PCBs that already contaminate the Dan, Reid said.
A long-term monitoring plan being developed by Duke and state and federal agencies would look for places where deposits are likely to form. Computer models will help forecast water flows that would dislodge ash.
Factors such as how deeply ash is buried, whether sediment is contaminated and whether endangered species would be hurt by dredging guide decisions on whether to remove ash, said Kenneth Rhame, an Environmental Protection Agency official helping oversee the cleanup.
“If there’s ash out there that we know of, we’re not just walking away and leaving it,” Rhame said.
But that’s just how environmentalists interpreted Duke’s announcement this week that “there currently are no additional deposits to be removed from the river.”
Pete Harrison, an attorney with the Waterkeeper Alliance, said it’s far too soon for such a declaration when layers of ash deposits can still be readily found under sediment.
“They just seem to be sort of walking away from the job,” Harrison said. “To say it’s premature is an understatement.”
Metals buried under sediment can be released into the water under certain conditions, such as when oxygen levels drop during warm weather, researchers have found. Once in the water column, toxic metals may work their way up the food chain.
Williams, of the Dan River association, said the Dan’s nature changes from day to day, in part because of surges of water released from an upstream hydroelectric dam.
“The reason the river is red is because it’s disturbing the sediment,” he said, “and when it stirs up the sediment it stirs up coal ash.”
Metals in the river’s sediment “kind of seem to be diluting out as it moves downstream,” EPA’s Rhame said. Water samples now show only high levels of aluminum and iron, metals believed to come from natural sources.
The N.C. Department of Environment and Natural Resources, working with the EPA, said it continues to investigate the spill for enforcement actions such as fines. Separately, the department is working with Virginia, the U.S. Fish and Wildlife Service, and Duke on an agreement on damage to the river itself.
Duke and EPA reached a settlement in May that lets the federal agency fine Duke up to $8,000 a day if its cleanup work falls short. Duke would pay $500,000 if the EPA has to take over the cleanup.
Henderson: 704-358-5051; Twitter: @bhender
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