Florence Flooding Causes Dam Breach at Duke Energy North Carolina Power Plant, Possible Coal Ash Spill Into Cape Fear River

Rain and heavy winds brought to North Carolina by Hurricane Florence, now classified as a post-tropical cyclone, caused so much flooding that a dam near a Duke Energy power plant was breached, possibly spilling coal ash into the Cape Fear River.

Breaches in the dam at the south end of a cooling lake caused water to exit the lake. Sutton Lake is a 1,100-acre reservoir located at the L.V. Sutton Power Station in Wilmington, North Carolina.

There are two coal ash basins at the site and in a news release sent to Newsweek, Duke Energy said it believes ash in the 1971 basin remained in place. A steel wall separated the excavation area from the cooling lake, and although the wall was submerged by floodwater, the earthen portion of the basin dam was still about 2 feet above the water.

Cenospheres, lightweight, hollow beads made of alumina and silica that are a byproduct of coal combustion, were moving from the 1971 ash basin to the cooling lake and into the Cape Fear River. Duke spokeswoman Paige Sheehan told The Associated Press that the company could not rule out that coal ash was escaping and flowing into the river.

"Given the historic level of flooding on the river, there is little to no chance that cooling lake water will contribute to a measurable change to water levels in the area," the news release stated.

On Thursday, Duke Energy activated a high-level emergency alert for the plant in anticipation of the breach, according to the Chicago Tribune. Duke Energy officials used helicopters and drones to monitor the situation, and company employees notified state regulators on Thursday night of the alert.

The reservoir is a former cooling pond for the Sutton Power Plant and the Chicago Tribune reported it had been retired in 2013. It has since been replaced with a new generating station that runs off natural gas. Sutton Lake is used to supply cooling water to the power plant.

duke energy hurricane florence
Overnight flooding reached the Sutton combined cycle plant, which was safely shut down. Duke Energy

On Saturday, Duke Energy issued a statement informing residents that about 2,000 cubic yards of coal ash had flowed out of its landfill at the Sutton Power Plant. It was enough to fill two-thirds of an Olympic-size swimming pool, but the company told Bloomberg that contamination of nearby rivers was "highly unlikely."

"It's not hazardous," David Fountain, Duke's president for North Carolina, told Bloomberg about the previous spill. "We believe most of the material was contained on-site, and we certainly have confidence that there's no impact to the environment or public health and safety at this time."

Test results conducted before Friday's breach confirmed the presence of coal ash decreased as the water flowed toward Sutton Lake, according to a Duke Energy news release.

"Water quality remains well within state permit standards designed to protect people and the environment," the news release explained.

Duke spokeswoman Erin Culbert explained to The News & Observer that more information would become available as the floodwaters receded, but that its experience during Hurricane Matthew was that there were no "measurable environmental effects."

Coal ash is a byproduct of burning coal used to generate electricity, and it contained various metals, including arsenic, chromium and mercury. Although fine by itself, materials from coal ash can contaminate drinking water and fish that people consume.

The Sutton Power Plant received more than 30 inches of rain from Hurricane Florence, according to the Greensboro News & Record, and the Cape Fear River is expected to crest on Saturday. The plant was shut down following the breach.

Florence Flooding Causes Dam Breach at Duke Energy North Carolina Power Plant, Possible Coal Ash Spill Into Cape Fear River | U.S.