A culverted section of San Pablo Creek, underneath Via Verdi (Street) collapsed without warning in Spring of 2010. The resulting sinkhole was estimated to be about 120 feet long, 40 feet wide, and 30 feet deep. Via Verdi Street serves as the only ingress and egress for a neighborhood of about 85 single family homes and 100 apartments.
Scope of work included: removing the temporary channel, constructing a new permanent headwall, constructing a permanent culvert, tying the headwall to the permanent culvert and the permanent culvert to the transition headwall, installing Engineered Fill; constructing Via Verdi and restoring the private parcel to its original condition. All work took place on an accelerated schedule between April 15 and October 15 because of restrictions of the Regional Water Quality Control Board and other resource agencies. Additionally the water from San Pablo Creek was diverted through a temporary pumping station and temporary piping for the duration of the work in the creek area. The stream banks were restored using willow stakes, brush mattresses and erosion control blankets. The construction project necessitated additional coordination with, and cooperation from numerous outside entities, including; utility companies, CalTrans, AC Transit, Corps of Engineers, RWQCB, California Dept. of Fish and Game, and Contra Costa County Flood Control District. The project also required construction of numerous temporary retaining structures to facilitate the construction of the permanent channel structure.