Estudillo Canal (Line A) Channel Wall Reconstruction, between Crosby St. and Manor Blvd. in San Leandro, Alameda County, Zone No. 2 Project (F02C91).
The Alameda County Flood Control and Water Conservation District (District) owns and maintains Estudillo Canal (also known as Zone 2, Line A). The Estudillo Canal was constructed in the early 1960s. Much of the existing channel is concrete lined with either inclined or vertical concrete channel walls and bottom. During heavy rains on December 31, 2022, an approximately 200 foot section of vertical concrete channel wall, along the west side of the channel, collapsed just downstream behind the backyards of 15008, 15016, 15024, and 15032 Crosby Street. Heavy rains continued on January 1, 2023, in which an approximately another 100 foot section of vertical concrete channel wall, along the west side of the channel, collapsed behind the backyards of 15072, 15080 and 15092 Crosby Street. Between rain storm events, the District’s maintenance and operations staff removed fallen loose debris in the channel to minimize channel blockage and installed visqueen plastic sheets weighted down by sandbags to temporarily minimize further erosion of exposed banks in the backyards of several homes. Additional emergency measures to wall stabilization included fabrication of steel support brackets to be fastened to the vertical channel walls and connected to the temporary steel struts to be installed above the top of channel wall, along the portions of existing vertical concrete channel walls experiencing leaning condition on February 16, 2023. Proposed permanent repairs include removal of approximately 300 linear feet of existing wall (collapsed portions currently resting on the channel bottom and remaining failed vertical concrete wall to the nearest joint), removal of the temporary stabilization measures, removal of soils deposited as a result of the collapsed wall, and reconstruction of approximately 300 linear feet of new reinforced concrete wall including footing. This would include installation of four (4) temporary cofferdams: upstream of 15008 Crosby St., below 15032 Crosby St., above 15072 Crosby St., and below 15092 Crosby St. The cofferdams would divert summer nuisance channel flows downstream via a temporary bypass pipe. This will prevent construction debris from leaving the work zone. The new concrete channel wall will be reconstructed along the same alignment and height. Structure backfill will be placed behind the reconstructed wall and the eroded backyards will be restored to their original finished ground elevations. The District will obtain a temporary construction easement from the property owner to allow staging and equipment access.