— Three environmental groups on Monday asked for an administrative hearing to challenge state permits that will allow Duke Energy to dump millions of tons of coal ash into open-pit clay mines in Chatham and Lee counties.

The state Department of Environment and Natural Resources last month issued the necessary permits for Duke to dump coal ash from several of its North Carolina power plants in clay mines near Moncure and Sanford as "engineered structural fill."

EnvironmentaLEE, Chatham Citizens Against Coal Ash Dump and Blue Ridge Environmental Defense League argue that the clay mines will be more akin to solid waste landfills than mine reclamation projects and should meet the stiffer design, construction and operational regulations of a landfill.

"Contrary to the permit applications for the proposed sites, nothing can be built on top of the finished 'reclamation' sites. The need to keep liners intact and projected height above grade would make these areas unsuitable for any future development," the groups state in their petition.

They also contend that the bonds required by the ash dump operators is inadequate in the event of a problem and that the DENR permits don't address potential health problems for nearby residents from coal ash dust.

Coal ash is the material left after coal is burned for fuel. While the bulk of it is inert, it does contain heavy metals and other toxins, including arsenic, chromium, selenium and mercury, that can harm fish, wildlife and people.

Despite containing those toxins, coal ash has been stored in unlined storage ponds for decades by Duke and other North Carolina power generators. Those ponds are perched along the same waterways from which the utilities have drawn water for their steam stations – and from which millions of North Carolinians draw their drinking water.

After a ruptured stormwater line under an ash pit in Eden dumped tons of sludge into the Dan River last year, North Carolina lawmakers ordered Duke to close all of its ash pits statewide by 2029 and created a state commission to oversee the process.