Coal Ash Continues to Challenge Duke Energy

On Sept. 23, Duke Energy told the Public Service Commission of South Carolina that it intends to excavate a portion of coal ash at the W.S. Lee Steam Station located in Anderson County.

The company has been dealing with a coal ash release from its Dan River Steam Station that occurred on Feb. 2, and it also received a citation for a crack in an earthen dam at its Cape Fear Plant ash impoundment on March 28. While Duke reached an agreement with the U.S. Environmental Protection Agency in May regarding cleanup of the Dan River release and performed emergency repairs on the crack at Cape Fear, the long-term effects of these incidents will be felt well into the future.

In March, Duke suggested that fallout from the Dan River incident could result in the retirement of 932 MW of coal-fired generation in North Carolina. The following month the company said that coal ash storage problems in the state could cost up to $10 billion to resolve.

At the 1950s-vintage W.S. Lee plant, Duke is evaluating a variety of ash disposal options. The plant has two active ash basins, an inactive ash basin, a structural fill, and an ash fill. The company has already determined that a capping solution is not suitable for the inactive basin because the dike walls are steep and require extensive tree removal, as well as additional work.

“Based on the engineering work we’ve conducted at the site, we are opting to pursue a fully lined solution for the ash located in the inactive basin and the ash fill, while we continue evaluating the best closure method for the remaining ash,” said John Elnitsky, senior vice president for Duke Energy ash basin strategy.

Duke said it is considering permitting a landfill on plant property or relocating ash to an off-site landfill or structural fill. In any of these cases, the solution will include a double bottom liner, leachate collection, synthetic capping system, and groundwater monitoring. The company plans to submit a strategy for its two active ash basins and the structural fill to the South Carolina Department of Health and Environmental Control by year-end.

W.S. Lee Unit 3 will be converted to fire on natural gas next year, so the station intends to cease using coal by April 2015. In addition, a new 750-MW natural gas combined cycle plant is planned for construction on the site.

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

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