San Luis Reservoir/
Sisk Dam Improvements

The Sisk Dam (also known as San Luis Dam) is located on the west side of the Central Valley near the community of Santa Nella and is approximately 12 miles west of Los Banos via State Route 152. The project involves the construction of a dam stability project for Sisk Dam. This project includes the construction of haul roads, three borrow sites, stability berms, and the removal of rip-rap upstream of the dam, rock blanket on the downstream side, and on the embankment. Areas immediately downstream of the dam, that have been identified as having soft soils will be excavated down to bedrock and the existing toe drain will be removed. The project will excavate down to approximately 20.0-60.0 feet deep, and excavation will be backfilled with rock fill to provide additional strength. The project will create dam stability berms which range from 20.0-60.0 feet deep and will involve 177.7 acres of undeveloped lands and yard/laydown areas. These berms will be backfilled with rock fill to provide additional strength. A blanket drain will be extended to service the new construction area. Rock slope protection would be installed on the downstream side of the stability berms. Foundation shear keys will be developed by removing the weakened overburden and replacing it with a higher shear strength material. The top 6.0 feet of the dam will be removed in an area that is 30.0-40.0 feet wide. A crack filter will be installed on existing and new crest embankment.
Temporarily impacted construction areas will be restored to pre-project contours and hydro-seed with native grasses. Blasting is proposed at the quarry borrow site to obtain usable fill material. Ripping and excavation are proposed at the other borrow areas to obtain usable fill materials. The project proposes to raise the crest of the dam by 12.0 feet.

Develop Construction SWPPP and QSD/QSP Services

SR 152, 12-miles West of Los Banos, CA

Bureau of Reclamation