DWR is proposing to implement the project to seismically retrofit the high intake tower bridge at Castaic Lake, the terminal reservoir of the State Water Project's West Branch, located within the Castaic Lake State Recreation Area. Construction would occur at the tower bridge, tower bridge abutment, Piers 2 through 4, and Abutment 5. The tower bridge retrofit includes upgrading the high tower's electrical system, installing restrainer cables to transfer longitudinal seismic forces to the adjacent spans or frames and carbon fiber reinforcement jacketing of the piers. Carbon fiber reinforcementis an extremely strong and light-weight, carbon fiber-reinforced plastic. Each pier jacket would strengthen the pier structure to meet seismic requirements.
Project implementation would require the lake's surface elevation would be lowered from the normal operation elevation of approximately 1,505 feet above mean sea level (ams!) to 1,380 feet ams! to access project components, such as the piers and abutment structures holding the tower bridge above water level. Construction staging areas would only be located in un-vegetated areas near the dam's right abutment. Existing paved and dirt roads would be used for hauling and transporting materials within the project area. Project construction is anticipated to take 15.5 months with the drawdown ofCastaic Lake taking approximately 10 months. Construction work hours would generally range between 7:00 a.m. to 7:00 p.m. , Monday through Friday.