State environmental officials have ordered Duke Energy to fix more leaking pipes in its coal ash dams, including one at the Dan River power plant that spilled ash in February.
Letters to Duke on Thursday addressed six ash pond dams in eastern and central North Carolina. The N.C. Department of Environment and Natural Resources issued 14 such letters last week.
DENR, in warnings called notices of deficiency, ordered Duke to get engineering evaluations at four dams at the Dan River, Cape Fear and Roxboro power plants. The problems were uncovered by internal video Duke took at the state’s direction.
The video found leaks in risers that carry overflow water and in the dams’ spillway systems. The Dan River plant is in Rockingham County, Cape Fear in Chatham County and Roxboro in Person County.
Three of the four dams are classified as high hazard, meaning a failure could cause significant environmental damage. None of the leaks pose imminent threats, the state said.
The Dan River pipes are in its secondary ash pond, which sits next to the pond that dumped up to 39,000 tons of ash into the river on Feb. 2. The spill happened when a metal stormwater pipe under the pond broke.
Concrete piping in the secondary dam showed drips, numerous holes, tree roots growing through joints and displaced joints, the state said in its letter to Duke.
“The condition of the decant structure appears serious enough to justify further engineering study in order to determine appropriate remedial measures,” DENR wrote.
Video of piping at other dams found fractures, roots and cracks.
In addition to the four notices of deficiency, the department told Duke to have engineers evaluate smaller leaks at the Lee plant in Wayne County, the Mayo plant in Person County, Cape Fear plant in Chatham County and Belews Creek plant in Stokes County.
Duke spokesman Jeff Brooks said the company will make repairs where needed. The inspections that uncovered the leaks, he said, “just demonstrates that we’re following through on our commitment” to address the problems.
Last week DENR issued a notice of deficiency for leaks at the Weatherspoon plant in Lumberton, where the state said it found “numerous gushers, drips and stains” in the pipes. Notices also went to the Riverbend and Allen plants near Charlotte, the Buck plant in Rowan County and Cliffside plant in Rutherford and Cleveland counties.