Salinas River

The work of this contract includes preparation and maintenance of the work area for emergency repair work at the Salinas River Diversion Facility (SRDF) site. Work will be accomplished under two Phases. This Phase I work addresses temporary cofferdam installation, river bypass pumping, and work area dewatering. A Phase II work will cover the remainder of the repair work. The Salinas River Diversion Facility has sustained some hydraulic damage, especially near the fish-ladder. This was first discovered when a sagging area of the articulated concrete block mat was discovered on the land side of and adjacent to the fish ladder, just downstream from the axis of the diversion dam. When the sagging area of the mat was removed, a significant Erosion Pit was discovered beneath it (approximately 8’ x 14’ x 8’ deep). This prompted sub-aqueous probing and a bathymetric survey of the river bottom from the Diversion Dam to about 100 ft downstream of it. This showed that an approximately 12 foot deep Scour Hole exists next to the fish ladder, presumably caused by overflow from the low flow gate at the left end of the diversion dam. This scour hole approximately extends to the discharge of the fish ladder. A second scour hole was discovered near the downstream right abutment. Damage is known to have occurred, but its exact extent won’t be known until the site is dewatered and open up for inspection. Due to time constraints imposed by the Agency’s obligations for operating Nacimiento and San Antonio Dams and in effect managing the Salinas River, it was decided to combine the dewatering operation and the reparation work into a single construction contract, with the Owner conducting the final forensic engineering during the construction.