San Antonio Backup Pipeline

The San Francisco Public Utilities Commission (SFPUC) wanted to implement the San Antonio Backup Pipeline (SABPL) project to provide reliable conveyance capacity for planned and emergency discharges of Hetch Hetchy water out of the SFPUC regional water system under future flow conditions.  The improvements included a 7,000-foot-long backup pipeline, discharge facility, cutoff wall, dewatering facilities, pump station and wet well, and new conveyance pipelines.  These improvements allow the SFPUC to discharge the full maximum future flow to a quarry pit, and subsequently conserve the discharged water by pumping the water to either San Antonio Reservoir for storage or to the Sunol Valley Water Treatment Plant for treatment and subsequent delivery to customers.  The project also increases operational flexibility and delivery reliability during emergencies and planned maintenance activities, thereby minimizing the risk of water supply service interruption.

The work included the installation of approximately 6,600 feet of 66-inch diameter of welded steel pipe located along the west side of Calaveras Road from the Alameda Siphons on the south to the edge of the SMP-24 quarry pit on the north. Prime features included installation of 4 EA 66” Butterfly Valves, 4 EA 60” Butterfly Valves, 1 EA 54” Ball Valve, 2 EA 20” Wafer Check Valves, 66” Multipath Flowmeter, an 8,000 Gallon Calcium Thiosulfate Tank plus 2 waste tanks, a chemical building complete with all associated piping, 2 Chlorine Analyzer stations, a Quarry Pit Dewatering Pump System and Erosion Protection. The project also included an open cut crossing of the San Antonio Creek channel, discharge structure, cutoff wall, pipe and appurtenances.