A year after a spectacular spill into the Dan River, Duke Energy’s North Carolina ash ponds are apparently still leaking more than 3 million gallons a day near rivers and lakes.
In filings to state regulators in December, Duke reported 200 seeps at its 14 coal-fired power plants. Duke says it’s not clear whether all of them come from ash ponds.
Seeps at two power plants, Asheville and Lee in Wayne County, each leak nearly 1 million gallons a day, the reports show. Some release toxic elements at levels far higher than state standards view as safe.
The seeps are illegal, the state has said – but not for long.
Legislation that became law last September gives Duke two options. One is to stop the leaks. The second – which Duke and the Department of Environment and Natural Resources plan to choose – is to include the seeps in wastewater discharge permits.
The seeps will be incorporated into new or modified permits for each of the 14 plants this year, said DENR water-quality permitting chief Jeff Poupart. Duke is supposed to report new seeps as they’re found.
The Southern Environmental Law Center, which has sued Duke over ash pollution, says it will challenge the legality of such permits.
“Duke has been openly leaking for years. Now they’re asking DENR to give them amnesty,” said senior attorney Frank Holleman. “Can you imagine us allowing any municipality or county in the state to permit a wastewater treatment plant that leaks in multiple ways?”
State officials say the seeps are insignificant compared with the tens of millions of gallons a day that permits already allow Duke to discharge from its ash ponds.
Power plants sluice ash and water into the ponds, where the ash settles to the bottom and water drains to rivers or lakes.
The ash pond at Duke’s Allen power plant on Lake Wylie releases 18.6 million gallons of water a day. Seeps add an additional 15,100 gallons daily, Duke reported.
But seeps at the Asheville plant account for nearly 20 percent of the 4.6 million gallons a day it discharges. The February 2014 spill into the Dan River dumped an estimated 27 million gallons of water.
“Our objective is to include seeps in the permits so we can follow the appropriate monitoring protocol or next steps regulators prescribe,” Duke spokeswoman Erin Culbert said.
Arsenic, which at high concentrations can cause cancer, appeared in seeps at six power plants at levels up to 140 times the state safety standard. Elevated levels of selenium, an element that can kill or deform fish and birds, showed up in seeps at two plants.
Regulators assess power plant discharges, and will evaluate the seeps, by their “reasonable potential” to contaminate rivers or lakes. Discharge permits set limits on contaminants that might become problems.
Combined, the Duke seeps are “large, but when you compare them to the amount the plant is discharging, it wouldn’t trip any reasonable-potential analysis,” Poupart said.
DENR will apply special standards for four pollutants that pose potential risks: arsenic, mercury, selenium and nitrate. Duke would have to stop or capture the seepage that breaks those standards.
None of the seeps at the first three power plants analyzed – Riverbend, Allen or Marshall on Lake Norman – broke the limits, said state engineer Sergei Chernikov.
DENR consulted with the Environmental Protection Agency on the seeps, officials said. EPA asked the state to include a safety benchmark intended to flag high pollution levels.
Culbert said state analyses of Duke’s ash pond discharges have typically found minimal impacts to the rivers and lakes they flow into.
Holleman, the environmental lawyer, said that argument ignores the cumulative effects over time of low levels of pollutants.
Duke University scientists have found that arsenic from the Riverbend power plant sank into the sediment of Mountain Island Lake, Charlotte’s main water supply. But in some conditions, they learned, the toxic metal can be stirred back into the water.
Holleman said DENR and legislators are granting Duke a favor that other businesses don’t get.
“We don’t allow anybody else to get away with polluting our rivers because they say the rivers are so big it will just go away,” he said.