Chabot Dam Upgrade

completed

habot Dam Chabot Reservoir is a 10,350 acre-foot raw water storage facility operated by the East Bay Municipal Utility District (EBMUD) in the cities of San Leandro, Oakland, and Castro Valley in Alameda County, California. The 135-foot high earthen Chabot Dam was initially constructed in 1875 and subsequently upgraded and re-graded in 1892, 1967, and 1980. The reservoir collects water via perennial creeks and local stormwater runoff draining from the surrounding San Leandro Creek watershed. EBMUD releases water from the reservoir into San Leandro Creek below the dam via an outlet works structure adjacent to the right abutment. There are two emergency spillways that drain into San Leandro Creek in the event of high lake levels after heavy rainfall. The earth dam is located within one quarter mile of the active Hayward Fault. Based on seismic hazard studies, EBMUD worked with the State Department of Water Resources (DWR), Division of Safety of Dams (DSOD) to implement a seismic upgrade to the dam and outlet works structure to improve the performance of the facility during a large earthquake. The project included the construction of a cement deep soil mixing (CDSM) toe buttress and seepage collection trench across the downstream face of the dam in order to stabilize the earthen structure against the large seismic forces expected during the design earthquake. In addition, EBMUD successfully improved the operational reliability of the outlet works by demolishing the seismically vulnerable tower and pavilion, retrofitting the existing access shaft, and replacing the knife gate valves and intake piping needed to manage the water levels within the reservoir. EBMUD also installed new instrumentation to augment the un-going dam monitoring program at the facility. Construction was completed in October 2017. Contact : For after-hours, call EBMUD at 866-403-2683.

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