Mason County Utilities & Waste Management
This earth-filled dam stands 80 feet tall at its apex and can impound 60 million gallons of treated wastewater. The overall containment area is 20 acres. The dam was constructed with 180,000 cubic yards for on-site materials and is anchored into the existing topography. Additional features include chimney drains, armored slopes and low level and emergency outlet structures. The operation of the storage reservoir is controlled through an integrated cast-in-place concrete inlet/outlet pumping facility.
Cushman Dam No. 2 Right Abutment Concrete Buttress
City of Tacoma Department of Public Works
City of Tacoma Department of Public Works, Tacoma Power
The Cushman Dam project centered on the construction of a 120 foot tall, mass concrete fill of a cleft located on the west abutment of Cushman Dam No. 2. Limited access to the west abutment required all excavation, 2,350 cubic yards, and all concrete fill, 4,882 cubic yards, to be placed with a 125 ton crawler crane which was physically post-tensioned to the 11 foot wide dam deck. All work was performed over the side of the dam originating 180 feet below the dam's deck. Some pours were continuous and lasted up to 20 hours. Received the 2008 Award for Excellence in Concrete Construction in the Technical Merit category.
Cedar Falls Masonry Dam Intake Rehabilitation
City of Seattle Light Department
North Bend, WA
Raytheon Infrastructure, Inc.
The project objective was to install an emergency slide gate that could be dropped into an 11 foot supply tunnel to stop the water from draining the reservoir in the event of a catastrophic failure of the bridge structure that supports the downstream penstock. This 7 ton, 11 foot tall slide gate had to be built and installed to 1/64" tolerences. BOSS had to locate and intersect the 100 foot deep tunnel with a new 11 foot shaft on the side of the mountain through solid basalt rock, place and move drill head through the tunnel, assemble, raise borehead then shuttle drill tailings back into tunnel, remove and treat cuttings, install rock bolts, shotcrete, cast-in-place concrete and gate rails in the gate shaft, provide erosion control and water treatment of jobsite disruptions in this most pristine environment; "Seattle's Drinking Water Reservoirs."
Tolt River Intake Seismic Upgrade
Seattle Public Utilities
Seattle Public Utilities
The intent of this job was to provide a seismic upgrade to the intake structure and emergency overflow structure of the Tolt Dam, "Seattle's Largest Drinking Water Source." This included installation of, at that time, the world's largest and deepest cable tendons, tensioned to over 1.6 million pounds. This had to be accomplished by drilling down through the intake structure which stood at the deepest part of the lake and into the bedrock below. The overflow structure underwater concrete columns were wrapped with steel and grouted. Coffer dams were custom designed and built by BOSS to complete this work. Jobsite containment included installing turbidity curtains, drill cutting collective systems and piping to treatment systems.