Under a new settlement with state regulators, communities and environmental groups, Duke Energy will spend $3.5 billion to close its last nine coal-ash storage impoundments in North Carolina, bringing the company’s cost of closing all of its coal-ash sites in North and South Carolina to between $8 billion and $9 billion.

The agreement, announced Jan. 2, calls for waste in seven of the basins to be excavated and moved to lined landfills. At the other two sites, the company will add protections and monitoring. The new cleanup actions will shave about $1.5 billion from the previous estimated total cleanup cost at the nine basins, Duke Energy says.

The North Carolina Dept. of Environmental Quality described the nearly 80-million-ton removal at the nine basins as the nation’s largest. Including earlier settlements and court orders, 126 million tons are being removed from state coal-ash basins, with projected completion in 10 to 15 years under expedited state permits.

The agreement “achieved all our goals to protect North Carolina waterways and communities,” Frank Holleman, Southern Environmental Law Center senior attorney, tells ENR. The settlement by the largest U.S. electric utility “broadly underscores the fact that excavation of ash is the industry standard,” he says, with capping in place no longer an acceptable approach. The action also undermines federal attempts to weaken Obama-era coal ash rules, said Holleman.

South Carolina utilities also are removing all coal ash from basins to lined landfills, and Dominion Virginia is considering lined landfills and recycling for coal ash after a law passed in that state in 2019 requires closure of unlined facilities. “It’s a trend,” Holleman says, noting laws approved in Illinois and Puerto Rico and an administrative action in Tennessee that restricts coal-ash disposal.

Under the new pact, Duke Energy will excavate 76 million tons of coal ash from seven unlined impoundments at six sites and three million tons of non-impounded ash. The utility submitted closure plans for the excavations by the Dec. 31 deadline required by the state’s Coal Ash Management Act.

North Carolina regulators last April ordered Duke to excavate nine large coal-ash pits, which previously had been deemed low-risk. Duke appealed the decision, saying the requirement was the “most expensive and disruptive” option possible. The company said at the time that state did not fully consider the science and engineering, but a North Carolina Office of Administrative Hearings judge on Oct. 29 said the DEQ acted appropriately when ordering Duke Energy to excavate 100 million tons of ash from the nine impoundments at six plants.

Duke said in a statement that the settlement is a reasonable and prudent plan for basin closure that requires ash from seven of the nine basins to be excavated and moved to lined landfills. At the Marshall Steam Station and Roxboro plant, uncapped basin ash will be excavated and moved to lined landfills, but waste located under existing lined landfills will be stabilized, monitored and closed under other state regulations, according to Duke’s statement.

Duke also has 19 basins in Indiana holding more than 92 million tons of coal ash. The company has submitted plans to regulators that blend capping in place and excavation, Duke spokeswoman Paige Sheehan told ENR.

Holleman said that in other southeast U.S. areas, Georgia Power is about one year behind Duke in cleaning up coal-ash basins, with public hearings set in 2020 to determine whether the utility will be allowed to cap some in place.

Alabama Power, said Holleman, is the only utility in the region that has not agreed to remove coal waste from unlined pits in coastal areas subject to hurricanes. The utility plans to dewater and cap in place its coal-ash basins, including one at the Barry plant 20 miles north of Mobile, the company says. The 600-acre ash pond holds 21 million tons of coal waste.