State environmental officials are investigating a pipe that is leaking groundwater from an old coal ash pond into Lake Wylie at Duke Energy’s Allen power plant.
Environmental advocates touring the site last week as part of lawsuits against Duke spotted the 24-inch corrugated metal pipe, which is visible only when the lake level is low.
Duke said boron, a chemical that indicates coal ash contamination, was detected in the leak but that the draining water meets state water standards. Duke said no more than 10 ounces of water a minute is leaking and that it will plug the pipe.
Catawba Riverkeeper Sam Perkins, who spotted the pipe, views it as a potential threat to the lake.
The pipe runs to an old, drained ash pond that now lies under a lined ash landfill. Perkins said much of the ash still in the former pond lies in groundwater. If the pipe breaks, he said, ash could flow to the lake.
Perkins said the pipe “significantly concerns us because it is a situation that is very similar to what happened at Dan River,” referring to Duke’s large ash spill in 2014.
In that case, a corrugated metal stormwater pipe ruptured under a pond filled with ash and water, dumping up to 38,000 tons of ash into the river.
Duke disputed Perkins’ characterization of the risk posed by the Allen pipe, which isn’t exposed to the millions of gallons of water present at the Dan River power plant.
“It’s not a parallel at all to Dan River or a Dan River-like event,” said Duke spokeswoman Erin Culbert.
But there are some similarities. Duke found only after the spill that the broken Dan River pipe was partially made of corrugated metal, not the stronger concrete Duke had assumed.
At Allen, the newly discovered pipe was documented in some files but not in those Duke used to review the safety of all its ash ponds after the Dan River spill.
Since the pipe’s discovery, Duke said it has reviewed files for other hidden pipes at all its power plants but has found none.
The state Department of Environmental Quality, which Duke alerted Tuesday, said it’s investigating the pipe.
“We’re awaiting the analytical data from sampling and will evaluate the results to determine if there are any water quality violations,” said spokesman Mike Rusher. “The utility has notified the department of its plans to repair the pipe and eliminate the discharge.”
Allen is among six North Carolina power plants at which Duke plans to cap coal ash in place, instead of excavating it, to comply with state law. Active and unused ponds at the power plant hold 16.5 million tons of ash.