Floodwaters have overwhelmed an ash basin at a Duke Energy Corp. power plant in North Carolina, spilling a byproduct of burning coal into the Cape Fear River.

The company said coal ash at the site “remains in place” but that tiny beads called cenospheres are flowing into the river. The hollow beads, left over from burning coal, are comprised of alumina and silica, Duke said in a statement Friday.

“Cenospheres are moving from the 1971 ash basin to the cooling lake and into the Cape Fear River,” the company said. “There is no visible ash in the cooling lake.”

Record floods cover much of eastern North Carolina in the wake of Hurricane Florence, and the waters are still rising. Emergency responders and companies like Duke will be dealing with the deluge for weeks after the storm made landfall in the state Sept. 14, according to the National Weather Service.

‘Major Escalation’

Friday’s developments mark a “major escalation” in the potential environmental damage at the plant that has been inundated with rain and floodwaters, according to Peter Harrison, a staff attorney for the environmental group Earthjustice. The 47-year-old coal ash basin is being excavated by Duke, which is moving the waste to a lined landfill that will eventually be capped with plastic and vegetation. The unlined ash basins are considered more vulnerable than the landfill, Harrison said.

Harrison added that it’s misleading for Duke to draw distinctions between cenospheres and toxic coal ash.

“To imply that cenoshperes are merely just these inert things that don’t carry with them the risk and toxic elements that other forms of coal ash have is completely false,” Harrison said in an interview Friday. “Cenospheres are coal ash.”

Coal ash, a byproduct from burning the fuel in power plants, can carry arsenic, mercury, lead and selenium, though its overall toxicity has long been debated.

‘Hardly Measurable’

“Cenospeheres are part of coal ash,” Avner Vengosh, a Duke University professor who specializes in geochemistry and water quality, said. “If we see them in the water, it means they’re mixed with coal ash.”

While coal ash is a hazardous, toxic material, the amounts that might have entered the Cape Fear River “would be hardly measurable” because of all the rainfall. Still, even small quantities can harm fish and aquatic life, he said by phone from Durham. “When the storm is over and everything goes back to normal, you still have a source of contamination at the bottom of the river.”

The company activated a high-level emergency alert Thursday at the site in Wilmington, North Carolina, where the Cape Fear River overtopped the facility’s cooling pond, also known as Lake Sutton. The facility also includes a coal-ash landfill, and Duke told state officials earlier this week that some material has spilled into the cooling pond, according to spokesman Bill Norton.

The company said Wednesday that initial tests show the coal ash spill “has not impacted water quality” in Sutton Lake.

Questions Remain

“What we know is the Cape Fear River has spilled into the Sutton Lake,” Michael Regan, head of the North Carolina Department of Environmental Quality, said a press briefing Friday morning, according to the News & Observer in Raleigh. “What we don’t know at this point is if any coal ash has filtered into the Cape Fear River.”

Flooding also reached the footprint of Duke’s 626-megawatt natural gas plant at the site, prompting the utility to shut down the generator.

Duke shares fell as much as 2.6 percent to $78.53 a share Friday. The stock was trading at $79.87 at 2:55 p.m. in New York.