Cowlitz Falls Dam

Condon-Johnson is performing as a subcontractor on a new fish collector structure at the Cowlitz Falls Dam in Randle, WA for the City of Tacoma. The structure will improve upon the existing system to better capture downstream migrating steelhead and salmon. After collection, the fish are transported by truck around impassable dams and lakes to rivers eventually flowing to the Pacific Ocean. Project scope includes 30” and 48” diameter drilled shafts socketed into bedrock. 48” shafts were drilled adjacent to the existing dam forebay with a Bauer BG-40 just feet above the reservoir. Approximately half of the 30” shafts will be drilled under the existing dam structure with restricted headroom. A permanent shoring wall is being built with 37 soldier piles and 103 tiebacks to allow for the new fish collector structure to be built. The structure will be anchored by 73 tiebacks drilled into the rock hillside.