RECOVERY-C-PROJECT CODE: 4990, Study of existing control tower shaft seepage (which is corroding electrical and mechanical equipment) and repairs. Will prevent continued equipment failure and potential downstream flooding or impact to endangered species.

This scope of services (SOS) defines the work required to complete the Control Structure Seepage Study project. When the outlet works Control Structure was first put into service, the leakage of water into the structure was serious enough to cause corrosion and operating problems with the equipment. Cement grout placed around the outside of the structure to stop the leakage was partially successful. Epoxy grout was tried for the structure interior. This was also only partially successful. At this time, the leakage of water into the control structure has been reduced significantly and the conditions inside the Control Structure are much improved. However, the elevator shaft still has substantial leakage and causes ongoing problems with the elevator. The Control Structure is a below ground concrete shaft approximately 37 feet around at the top elevation of 519 ft msl to elevation 323 ft msl where it widens to approximately 45 feet at elevation 220 feet msl and concrete thickens. The structure is approximately 300 ft deep from surface to base. The goal of this study is to have the control structure inspected and evaluated to be completely sealed and free of leaks. This SOS requires a study that shall recommend a reasonable or practical solution for further improvement and the overall cost for completing the work. If an engineering study determines that further grouting shows little promise for success, or that cost would outweigh the benefits, then the goal would be to at least correct the problem in the elevator shaft. If the elevator shaft leakage cannot be eliminated, then the study shall evaluate options for the shaft to be lined in a way that would protect the elevators operating equipment. Alternatively, the A-E shall evaluate replacement of the elevator with a unit designed for operation in a continuously wet environment. The study shall recommend methods to improve the environment in the outlet works Control Structure for reasons of safety, protection of electrical and mechanical operating equipment, and the long term efficiency of the facility. The study shall ultimately result in the preparation of plans and specifications for a repair contract that shall implement the selected improvements.