With plans already approved for the closure of 12 of its coal ash basins, Duke Energy on June 23 recommended the full excavation of 12 additional basins located in North Carolina.

The company proposed excavating five basins each at its Cape Fear Plant in Moncure and its H.F. Lee Plant in Goldsboro. Additionally, it recommended excavating one basin at the W.H. Weatherspoon Plant in Lumberton and an inactive basin at the Cliffside Steam Station in Mooresboro. Duke said the removed material would be reused in lined structural fills or permanently disposed of in lined landfills. The proposals are subject to public input and approval by the North Carolina Department of Environment and Natural Resources and the North Carolina Coal Ash Management Commission.

The previously approved proposals include coal ash excavation—already in progress—at the company’s Riverbend Steam Station in Mt. Holly, the Asheville Electric Generating Station, and the W.S Lee Steam Station in Belton, S.C. Plans are also in place to excavate coal ash at the Dan River Steam Station in Eden, N.C., L.V. Sutton Steam Electric Plant in Wilmington, N.C., and H.B. Robinson Plant in Hartsville, S.C.

Duke has 12 additional basins for which a broader range of closure options are being considered, including an approach that it says consolidates the ash on site, caps it with a durable and impermeable liner, and protects groundwater.

“A blue ribbon national advisory board and independent engineers, scientists, and dedicated teams at Duke Energy are spending thousands of hours studying data, building enhanced groundwater and surface water protection programs, and identifying closure options that protect people and the environment in a cost-effective manner,” Lynn Good, Duke’s president and CEO, said in a press release.

The blue-ribbon panel of international experts has been reviewing the company’s strategy and technical approach to closing ash basins since last October. The National Ash Management Advisory Board (NAMAB) is led by Dr. John Daniels, PE, a former program director at the U.S. National Science Foundation and current professor and chair of the Department of Civil and Environmental Engineering at the University of North Carolina, Charlotte.

Working with Duke engineers and scientists, NAMAB developed a set of guiding principles for safe basin closure, which include:

  • Ensure continued stability, meeting appropriate safety factors.
  • Ensure effectiveness during storm/flooding.
  • Ensure groundwater impacts are effectively mitigated.
  • When excavation is required, leverage beneficial reuse, on-site landfills, and consolidated storage.
  • Comply with the North Carolina Coal Ash Management Act and federal Coal Combustion Residual regulations.
  • Seek solutions that address environmental impacts and balance stakeholder interests.

“Protecting groundwater is essential for the long-term storage of ash and I want to emphasize that any closure solution that we recommend or implement will protect groundwater. We understand how important it is,” Good said in a video commenting on the safe closure of coal ash basins.

Duke entered into a $102.2 million plea agreement with federal prosecutors in February to settle charges of violating the Clean Water Act and other federal regulations stemming from improper disposal of coal ash at multiple sites in North Carolina. The company is confident that it can comply with state deadlines to have all coal ash basins in North Carolina closed by 2029, depending upon the time it takes for the review and approval process to play out. Individual basin closure timelines will be determined by the state’s classification process and other factors, Duke said.

Aaron Larson, associate editor (@AaronL_Power, @POWERmagazine)