O'Shaughnessy Dam was completed in 1923 and raised in 1938. A Condition assessment of the dam outlet works revealed deficiencies. This rehabilitation project addresses deficiencies of the existing outlet works system at O'Shaughnessy Dam.
Seven projects were identified and have been prioritized. Phase I will include four projects. (A) supply and installation of nine new bulkheads; (B1) refurbishment of twelve existing slide gates; (B2) rehabilitation of existing drum gates to replace the seals, replace the hinges and rivets, recoating the gates, and repair the spillway concrete; and (C) installation of new diversion pipe and isolation butterfly valve.
The existing control gates and valves are essential features for dam safety and reservoir operation. The Project is needed to maintain safe and reliable operation of these aging assets.
The project is part of a larger Hetchy Capital Improvement Program (HCIP), a multi-year capital program to upgrade or improve water conveyance, water storage, and power generation facilities in the Sierra Nevada portion of the Hetch Hetchy Regional Water System.