Geotechnical Drilling & Instrumentation
Puget Sound Energy commissioned three projects at Lower Baker Dam intended to upgrade and improve operations at the hydroelectric facility. The initial phase focused on drilling test holes in the dam’s rock abutments to investigate occurring leakages and perform specialty grouting. Final phases of the program include construction of a floodwall designed to protect the abutment and modernizing the areas above the water line, such as the dam crest, piers, and spillway gates.
Team Members
Puget Sound Energy
Tetra-Tech
Crux Subsurface
Crux’s Role
Crux’s scope of work included drilling and sampling 12 HQ-size oriented core borings, ranging in depth from 12 to 600 feet for a total drilled footage of 4,248 feet. Borings were drilled at multiple angles, and between one and five vibrating wire piezometers were installed in all but one boring. Additionally, Crux performed extensive packer testing, supported dye tracing and downhole imaging.
Access to boring locations varied, requiring a combination of track-mounted equipment, and skid-mounted equipment transported by crane or helicopter. In addition to varying equipment, the project involved a number of different contractors working simultaneously and required constant communication to ensure a safe work environment. Additional challenges included a shifting scope of work, which required all parties to remain flexible in order to meet the changing needs of the project and owner.
Crux successfully completed all 12 borings ahead of schedule and under budget with no lost time incidents.
Challenges included variable access methods and a highly congested work environment
