The Water Temperature Conditioning Phase 2 of the Jackson Hydroelectric Project was intended to provide water temperatures beneficial to aquatic resources within the 6.4-mile reach of the Sultan River, located in Western Washington. The project involved construction of a new water conveyance tunnel, which would intersect with the current power water tunnel that conveys water to the power house.
Snohomish County PUD, J.S. Redpath, DiGioia Gray, Crux Subsurface
Crux drilled and sampled one 40-foot horizontal boring from the power water tunnel to assist in the eventual intersection of the water conveyance tunnel. Access to the boring location was challenging, requiring specialty compact equipment. Equipment was lowered 140 feet down the intake shaft by crane, limited to a 3-foot by 5.5-foot opening at one threshold and requiring strategic angling to transition from the shaft to the power water tunnel. Equipment was then placed on rolling carts and transported 800 feet down the tunnel.
After drilling, crews completed packer testing and installed a graduated marker rod, with the purpose of informing tunnel crews when they are within 40 feet of the intersection point. All work needed to be completed within the facility’s 5-day annual maintenance outage when the power water tunnel was drained, requiring both day and night shifts to ensure the strict schedule was met. Crux provided an onsite mechanic and reserve parts to ensure there were no delays caused by equipment failures.
This was the first phase of the tunnel project, and an on-time completion was vital to a successful project. Crux completed all work ahead of schedule and with no safety incidents.