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The dikes are 18 to 50 feet high and are at three large coal-fired power plants near Becker, Cohasset and Hoyt Lakes. They enclose ponds filled with wet ash, and contain lead, mercury and other compounds.
State regulators and the dams’ owners, Xcel Energy and Minnesota Power, said the dikes and ponds have not caused environmental problems. In addition, the Minnesota dikes are made of strong earth fill, not ash.
State Dam Engineer Jason Boyle said the inspections will occur later this year.
The inspections come after a dike failed last month in Tennessee. That dike at a Tennessee Valley Authority power plant was built of dredged ash and failed Dec. 22 after it had been soaked by rain. The failure sent sludge into a river, damaged riverfront homes and left traces of heavy metals in the water.
The disaster highlighted concerns over coal ash disposal and the risk of groundwater contamination.
“Any time we get hear of a dam failure, it gets our attention,” Boyle said.
Xcel Energy is the owner Minnesota’s highest ash dike, at its Sherco plant near Becker. The plant has a 40-acre ash pond surrounded by a 50-foot-high dike off the Mississippi River. Boyle said it was inspected by the state in the past year.
Terry Coss, Xcel’s environmental director, said he doesn’t believe a catastrophic accident could occur at the Sherco dike.
Boyle said he could find no record of inspections by state engineers at the two other ash dikes. He didn’t know why they hadn’t been checked.
Those dikes are at two Minnesota Power stations: Laskin Energy Center in Hoyt Lakes and Boswell Energy Center in Cohasset. The company said it had no concerns about its dikes.
“We have been handling coal ash for 30-plus years ... and we are proud of our track record,” said Amy Rutledge, a company spokesman.
