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.”
Engineer:
Raytheon Infrastructure, Inc.
Bellevue, WA
