Lower Granite Dam RSW Removable Spillway Weir

Lower Granite Dam RSW Removable Spillway Weir | 2000-2002

The RSW is a 1100 ton prototype fish bypass structure installed in spillbay 1 on the upstream side of the Dam. The RSW is hinged on the dam face and rotates to an up or down position using ballast tanks. The buoyancy tanks are operated by a computerized system that controls ascent and descent. Underwater installation tasks included drilling 11’x3.5″ holes for grout injected anchor bolts, side seal hinges, and bearing pads. Remote drills, sonar, sub-sea cameras and divers were incorporated to install the various components required to connect the Weir. Hundreds of dives to -135′ FSW were conducted for the construction of the upstream landing pad.

The project required as many as twenty divers working multiple daily shifts throughout winter and spring to complete. It was completed under severe time constraints, on time, with no lost time accidents.

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