Utah assessing how much Rocky Mountain Power coal waste washed into Price River

A flash flood Thursday afternoon cut through a massive repository of coal ash outside Helper and pushed unknown quantities of the waste into the Price River.

Over the past six decades, Rocky Mountain Power has filled a side canyon to Price Canyon, just downstream of its Carbon Power Plant, with the plant's ash. The plant was retired in April 2015 and the power company has been in the process of grading and capping the ash pile for permanent closure.

But a cloudburst Thursday sent floodwaters down Panther Canyon, overwhelming storm water systems. Paul Murphy, a spokesman for Rocky Mountain Power (RMP), said the company is in the process of installing safeguards — construction crews were on site when the flood hit — designed to withstand a 100-year storm event in the canyon landfill.

Those controls were able to divert some of the storm water away from the landfill, he said, until "very intense flooding" filled a culvert with debris.

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