Duke Energy said Sunday that flooding of the Cape Fear River caused by Hurricane Florence has not resulted in coal ash contamination downstream, as environmentalists had feared.
The Charlotte-based utility company has received expedited lab results on water samples taken upstream and downstream of the Sutton power plant in Wilmington, where the company had deposited the pollutant in the ground for decades.
“Initial water tests from Duke Energy’s L.V. Sutton Plant in Wilmington confirm that discharges from the cooling lake to the Cape Fear River are not harming water quality downstream,” the company said. “Water samples captured on Friday (upstream) and downstream of the Sutton plant site show little to no impact to river water quality. All results are well within the rigorous state water quality standards in place to protect the environment.”
One of Duke’s coal ash impoundments at the Sutton power plant flooded Friday when rising water breached the dam, filling adjacent Sutton Lake and then flowed over the ash.
Cape Fear River Watch, an environmental group, and the N.C. Department of Environmental Quality have been monitoring the situation by boat. Both took their own water samples but have not yet received the lab results.
DEQ hopes to have results by mid-week. “It takes time to properly conduct the analysis of samples,” said Bridget Munger, a DEQ spokeswoman.
Kemp Burdette of Cape Fear River Watch, reached by phone Sunday, said he didn’t know when the group will get results back.
“Keep in mind, Duke sent their samples to their in-house lab,” said Burdette, the Cape Fear Riverkeeper. “Until you have a third-party analysis, any analysis should be taken with a grain of salt.”
The ash containment pit, built in 1974, held about 400,000 cubic yards of ash — the equivalent of 40,000 commercial dump trucks. That’s about half the volume that had been stored there for decades, because Duke has been excavating the site and moving the material to a lined landfill nearby.
The excavation created extra space for the ash pit to absorb a record 33 inches of rain that drenched the Sutton complex during Florence, ultimately flooding the area and forcing Duke to shut down a natural gas power plant and evacuate employees.
Coal ash is a byproduct of burning coal at power plants that contains toxic elements like mercury, arsenic and selenium. The ash is used as construction fill to build roads, but utilities produced more ash than was needed by the construction industry and stored the excess in open-air pits filled with water.
Duke permanently shut down the Sutton coal-burning plant in 2013 as part of a company-wide transition to cleaner-burning natural gas.
Duke released the lab results from Cape Fear River water samples it took 1 mile downstream from the Sutton plant, Sept. 18-21, showing levels of heavy metals and other contaminants, including arsenic, selenium, chromium, oil and grease. The results show a slight increase in contamination, but well below permitted regulatory limits, Duke said.
However, the volume of total suspended solids was nearly three times as high downstream of the Sutton plant, at 29 milligrams per liter, than upstream, at 11 milligrams per liter, in samples taken Friday. Duke said the permitted limit is 100 milligrams per liter.
Oil and gas presence was under 5 milligrams per liter on Tuesday and on Friday. The permitted limit is 20 milligrams.
It’s not clear if the readings will change in the coming days. Duke has not yet received test results from water samples taken on Saturday and Sunday, when the Cape Fear River was still cresting.
On Friday, River Watch warned that coal ash was washing out of the 47-year-old ash impoundment, was contaminating the river, and the environmental consequences would be felt for years to come. But the Department of Environmental Quality said the same day that it wasn’t clear if the flooding had dislodged the ash from the pit. The agency said it would conduct an investigation to determine whether Duke should be penalized or fined for any environmental violations.
Sutton Lake is a public fishing lake used as a source of cooling water for the coal-burning power plant that was shut down five years ago. As the Cape Fear River swelled in the wake of Hurricane Florence, Duke installed a steel barrier at the coal ash pond to block the waste from flowing out.
The Department of Environmental Quality said Friday that the dam that separates Sutton Lake and the Cape Fear River was overflowing in numerous places, the biggest breach measuring between 100 feet and 200 feet across.
The agency and Duke said the coal ash ponds are structurally sound.
Duke was excavating the two coal ash pits at the Sutton plant in accordance with a 2016 legal settlement with various environmental groups that had sued the company. The other ash pit, built in 1984, is not affected by the flooding, Duke said.
Duke is also bound by the 2014 Coal Ash Management Act to store coal ash in a way that doesn’t threaten public health, either by removing the ash to lined landfills, or by securing it in existing pits that are not known to be polluting groundwater. The 2014 legislation was the first in the nation to compel a power company to apply modern environmental standards to manage its coal ash waste, which was dumped into rivers or left in unsecured areas more than half-a-century ago.