As a subconsultant and for the Portland Water Bureau, GRI completed a preliminary geotechnical investigation for the planned 20- to 25-MG Kelly Butte reservoir. GRI investigated the reservoir site with 14 borings and seven test pits. A 100-foot downhole seismic array was installed in one of the borings to evaluate shear wave velocities. The site was underlain with dense materials of the Troutdale Formation; however, portions of the site were mantled with significant thickness of uncontrolled fill and intrusive volcanics. GRI provided recommendations to address potential differential settlement associated with extensive uncontrolled fill present beneath a portion of the reservoir if the north-south configuration is selected.

Location: Portland, Oregon

Owner: City of Portland Water Bureau

Market Sector: Water & Environment

Services: Geotechnical Engineering, Seismic Engineering