Duke says ash ponds safe, but reports cite problems

An East Tennessee spill that covered 300 acres in toxic sludge has renewed scrutiny of coal ash, which accumulates by millions of tons at Charlotte-area power plants.

The ash -- coal-burning residue stored in open basins -- is laden with metals that in high concentrations can cause cancer and other health problems.

Duke Energy's eight Carolinas coal-fired plants produce 2.2 million tons of ash a year, two-thirds of it dumped into landfills and ponds. Groundwater contamination forced Duke to close one ash landfill this year, the Observer reported in February. The company is installing wells to detect tainted groundwater at its plants.

But the Tennessee spill raised a different question about ash basins: the stability of earthen dams that contain them.

Duke, which operates 10 ash basins, and the N.C. Utilities Commission reviewed recent dike inspection reports following the TVA spill. The most recent inspections at Duke's plants found no imminent instability.

“We reviewed all inspections to date, and we're confident in those inspections,” said Duke spokesman Tim Pettit.

But the reports, reviewed by the Observer, describe potential problems at dikes that are as much as 90 feet high and 3,000 feet long.

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