Arc Flash at a Washington Dam Sends 5 to Hospital

Mattawa, WA – Five electricians and dam operators were hospitalized last week in an arc flash accident at the Priest Rapids Dam located on the Columbia River in central Washington state, bordering Yakima and Grant counties. Six workers total were injured as a result of an electrical equipment malfunction which caused an explosion at the hydroelectric dam.

The Grant County Public Utility District said that the explosarc flash hydroelectricion happened in the dam’s powerhouse. Two dam workers were treated in intensive care with “large burns,” the other three suffered slightly less severe burns. The five men were airlifted to Seattle following the explosion at the hydropower dam.

Pacific Northwest National Lab’s chief electrical engineer Jeff Dagle explained an arc flash results from a short circuit involving high-voltage electricity. Circuit breakers are designed to minimize arc flash and a failure with those may now be a focus of the accident investigation.

The PUD said damage from the explosion was limited to one generating unit. The rest of Priest Rapids Dam continues to operate and no threat is anticipated to downstream communities.

The Priest Rapids Dam was built in the 1950s and is one of two operated by the Grant PUD along the Columbia River. The publicly-owned utility serves about 46,000 customers in Grant County, which is about 150 miles east of Seattle. The concrete dam is 178 feet high and more than 10,000 feet long

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