WILMINGTON, N.C. (CN) – Floodwaters inundated a coal ash landfill at Duke Energy’s Sutton Steam Plant, causing a breach after Hurricane Florence dumped heavy rain on North Carolina last weekend.
Enough coal ash to fill two-thirds of an Olympic swimming pool was displaced by large quantities of stormwater at the Sutton plant near the Cape Fear River in Wilmington over the weekend, Duke Energy Spokeswoman Sara Collins told Courthouse News.
Duke Energy says erosion took place on an interior slope of a retaining wall lined with cement and packed soil. As a result, about 2,000 cubic yards of coal ash material to came in contact with stormwater.
Hurricane-force winds caused drain pipes to “blow out,” contributing to the side-slope failure, Laura Leonard, the state’s Department of Environmental Quality Wastewater Branch told Courthouse News. But, minimal amounts of coal ash are believed to have escaped the property.
“The landfills are divided into six durable cells that are each lined with soil and cement,” Leonard said. “The cell that eroded was already closed and prepared for the storm.” The division of coal ash material makes it possible to move it from one cell to another.
She said other cells were under construction to comply with aforementioned legislation passed by the General Assembly before the storm hit. Those cells were unharmed.
The two pipes that became damaged were secured in cement. Winds from Florence were so strong they were essentially uprooted, she said. “They were lying down on the side of the landfill.”
“It is important to clarify that it was a landfill and not a pond that breached,” Leonard said.
She said the department plans to begin water sampling in the surrounding area and will have results within seven to 10 days.
Duke Energy is confident that the coal ash breach is a “non-issue,” Collins said on Monday.
In a written statement, Duke Energy says crews are continuing to monitor the situation.
Before Tropical Depression Florence hit the southeastern coast near Wilmington, the company responded to growing concerns about the landfill.
“We have deployed numerous resources to assess the situation and have positioned repair materials so we can rapidly respond once the river conditions are safe to do so,” said George Hamrick, a senior vice president with Duke Energy in a statement.
Though two large valves were opened to drain a portion of the plant’s nearby cooling lake before the storm, the Cape Fear River overtopped it.
The Sutton plant halted the use of its coal-burning units in 2013.
The General Assembly passed a statewide law ordering Duke Energy to close coal ash ponds at 14 of its North Carolina power plants that were deemed problematic after about 39,000 tons of the material spilled into the Dan River in 2014.
In 2015, Duke Energy pled guilty to nine misdemeanor violations of the Clean Water Act related to its management of coal ash in a federal court in the Eastern District of North Carolina.
The state law requires water to be safely removed from all basins to prevent leakage into groundwater and nearby bodies of water.
Duke Energy agreed to eliminate the wet ponds and move coal ash into dry, lined storage by 2029. In compliance with the measure, the company began recycling coal ash for use in construction after excavating some ponds and capping other coal ash landfills in place.
The Sutton landfill is considered to be in compliance with the measure, because it is lined and does not usually contain water.