City of West Linn, Bolton Reservoir

The original City of West Linn Bolton Reservoir was a 2.5-MG, concrete structure built in 1915. The city determined the reservoir was seismically deficient and undersized. The City determined repurposing the same site as the best option for the new reservoir. The new reservoir was planned to be a partially embedded 4-MG, concrete reservoir established in a cut up to 25 feet deep. GRI completed a preliminary geotechnical evaluation to support the conceptual siting analysis for the reservoir. The evaluation consisted of review of existing geotechnical information for the site, a geologic reconnaissance, review of LiDAR landslide imagery, monitoring of existing slope instrumentation, subsurface explorations, and limited laboratory testing. contracted GRI to provide engineering geology, geotechnical engineering, and construction observation services for the new reservoir.  GRI provided foundation and landslide mitigation construction services through completion in 2017 and the reservoir is operational and performing as designed.

Location: West Linn, Oregon

Owner: City of West Linn

Market Sector: Water & Environment