Grant PUD in Washington, US, has lowered its Emergency Action Plan classification for the Wanapum Dam spillway after surveys confirmed the stabilization of a crack found at the end of February.
The PUD lowered the classification to a 'non-failure emergency' after operating under the condition of a 'developing failure' since February 28.
Its Emergency Action Plan (EAP) includes the notification procedures in the event of a "non-failure emergency" at Wanapum Dam, including situations that would necessitate the utility maintaining low water levels behind the dam to prevent a more serious emergency. The EAP describes the initial roles and responsibilities of Grant PUD personnel and other agencies based on the capabilities of each agency to respond in the event of an emergency situation at Wanapum Dam.
The news of a downgrade comes as a result of engineering surveys conducted March 3 and 4 that show continued stabilization of the fractured area found on one of the dam's spillways. The impacted area is stable, the fracture has closed and the damaged section of the spillway monolith has moved back upstream by nearly 1.75-inches as a result of the utility's actions to lower water above Wanapum Dam and reduce pressure on the damaged spillway, the PUD said in a statement yesterday.
The dam is continuing to generate electricity, but at a reduced rate.