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Posted on Nov 7, 2018

Non-failure emergency status removed at Priest Rapids Dam

Grant PUD officials, working with the Federal Emergency Regulatory Commission, removed the non-failure emergency condition at Priest Rapids Dam on Oct. 15, Grant PUD stated in a press release.
The dam had been operating under the non-failure emergency condition since March 28, when leaking water was discovered in the dam’s spillway monoliths during an investigational drilling program. Out of an abundance of caution, the reservoir behind the dam was lowered and held in what is considered the normal minimum operating range of 484.5 to 481.5 feet above sea level. The maximum reservoir elevation is 488 feet. The emergency never presented a safety risk for the public or Grant PUD workers, Grant PUD said.
During the past six months, crews conducted more drilling to determine the source of the leaking and also relieve pressure in the leaking area. Workers have also been installing more monitoring equipment in the spillway. Through analysis of the spillway in the full operating range of the reservoir, officials have determined the emergency designation is no longer required.
Early in the response, investigators discovered the leaking water was the result of a disbonded lift joint, or seam in the mass concrete making up the spillway’s support structures, called monoliths.
Officials are conducting a root-cause analysis to discover why the lift joint became disbonded and are determining if and what future remedies are needed, Grant PUD said.

By Post-Register Staff