Progress Energy has made temporary repairs to a breached ash pit that accidentally released waste from coal-burning power plants near Wilmington.
A giant gash in the 38-year-old waste reservoir Monday released an estimated 10 cubic yards of ash down a steep embankment, after heavy rains inundated the area around the company's Sutton Electric Plant.
The Wilmington Star News reported that the breach sent clay and ash cascading down the side of the pit's retaining wall. Raleigh-based Progress installed a temporary patch using rocks and soil to keep the breach from expanding.
The accident does not pose a threat to public safety, the company said. The spill is nowhere near is scale to the 2008 blowout in Tennessee that released 5 million cubic cards of ash and water and flooded more than 300 acres.
The Tennessee accident drew widespread attention to the conditions of the nation's coal ash pits. Environmentalists say the arsenic, lead, mercury and other toxins in toxins is slowly seeping into groundwater and nearby streams.
The U.S. Environmental Protection Agency has since begun reviewing ash pit safety and is considering tougher regulations that would treat coal ash as a hazardous waste.
The state Division of Water Quality this year asked Progress and Duke Energy to install additional wells to improve monitoring of groundwater quality around the ash containment sites in this state.
Progress spokesman Scott Sutton said the breach was discovered by a pair of Progress employees who were inspecting the dam Monday night during a torrential downpour. The two were driving along the wall on top of the dyke in a light duty pickup truck, when the road gave way and swallowed their truck.
The vehicle dropped about 9 feet and came to rest in a bed of clay, dirt and ash. The workers were not injured.
"The truck was driving along the road and fell into it," Sutton said. "They throught along the lines that it was a sinkhole."
The next day the crew returned with a winch to pull out the truck and realized that the retaining wall had caved in.
The hole measures 22 feet across and is 9 feet tall. The 10 cubic yards that spilled out is enough to fill the bed of a dump truck.
The ash pit stores 550,000 cubic yards of dry ash, held back by 34-foot walls.