Corps earthquake response exercise assesses dam safety in NW

Damage assessment, triage & communications get strong marks

In mid-June the Northwestern Division of the U.S. Army Corps of Engineers conducted an earthquake response exercise to prepare emergency planners, operators and engineers for the possibility of a severe earthquake.

Ross Hiner, Dam Safety Program Manager reported, “the Pacific Northwest has a 40% chance of experiencing a very large earthquake — possibly as large as magnitude 9.2 during the next 50 years.

The Cascadia Subduction Zone, a 700-mile “megathrust” fault line, stretches from British Columbia into northern California.

BC Hydro already announced plans for seismic upgrades for the John Hart Dam on the Campbell River. The organization has also proposed seismic safety upgrade projects at the Ladore and Strathcona facilities within the same river system.

Local damage assessment

The Corps exercise includes dispatch of local damage assessment teams to check on the nearly 30 dams it operates and maintains in the Pacific Northwest. Small groups of engineers who live near the assets perform the dam safety inspections.

Timely collaboration

The exercise also confirmed the ability and timeliness of partnering districts to fly in engineers to inspect remotely operated, isolated dams that would take primary operations teams longer to reach. Immediate assessments would triage emergency management of dams and reservoirs for the best outcome for communities living downstream.

Communications infrastructure

Under a most dire scenario, small battery-powered satellite units were put into operation throughout the 13-dam Willamette Valley System, the Corps location with potentially the hardest impact. The infrastructure will allow teams to relay data and information to an emergency operations center at Walla Walla District.

According to Hiner, even for earthen embankment dams which could be more vulnerable to an earthquake, dam failure is rare and remains unlikely.

Nevertheless, the Portland District has launched seismic studies and risk assessments at each of its dams in recent years to better anticipate the structures’ performance in the event of a major earthquake. Findings from those studies will determine long-term measures to improve dam safety.

The Northwestern Division of the U.S. Army Corps of Engineers encompasses the Portland, Seattle, Walla Walla, Omaha and Kansas City districts.

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