Z--Lower Granite RSW Repair Work

Repair Work on the Removable Spillway Weir (RSW) at Lower Granite Lock and Dam. The major focus is to repair the position-sensing system. Components of the existing system will be replaced with new assemblies similar to the ones on the Lower Monumental RSW. Associated work will include improvements to air supply lines and valves as well as installing debris shields over some parts that are currently exposed during a stow operation. General Scope: Diving with underwater installation of mechanical parts; fabrication of some assemblies for mechanical systems; surface installation of mechanical components such as valves, piping, shield covers, etc. Summary Scope of Work: 1. Repair RSW Position-Sensing System. Diving depths of 80-90 feet to install mechanical components of the RSW position-sensing system will be required. Components would be cables, conduit or pipe, pulleys, etc. Some fabrication (surface) of components will be required prior to installation. 2. Modify air delivery lines. Add check valves to air delivery lines in front of existing emergency valves. This activity should be entirely surface work. 3. Debris Protection. Rerouting of some air drain lines on the RSW to more convenient locations will be required. Fabricating and installing steel cages around valves mounted on the RSW. This activity would also require fabricating and installing a plate shield to cover the air lines and position-sensing system cable mounted on the face of the dam. Installation of the plate shield would be below the water surface requiring diving. Other debris protection work should be above water. 4. Inspect and Repair RSW mounted valves. Inspect RSW mounted valves and report condition. Repair or replace any valves determined to be in poor condition. This activity would be surface work. 5. Reroute plumbing in the RSW valve cabinet. Extend any air lines that currently vent into the RSW valve cabinet so they vent to the outside of the cabinet in the back where a sudden venting would not be a safety hazard. This activity would be entirely surface work.