Cerrito Creek Restoration

El Cerrito, CA

City of El Cerrito
Summer/Fall 2003

This project spans approximately 680 feet of Cerrito Creek, located immediately south of El Cerrito Plaza between Talbot Avenue and Kains Avenue. The stream had been reduced to an incised ditch over the years by construction on both banks. The north side (right bank) is bordered by the Plaza parking lot for the full length of the project, and the south side (left bank) is bordered by single-family residential, high density residential, and commercial uses. The watershed is highly urbanized, with a very short time of concentration resulting in flash flows through the project. Furthermore, the project is in the lower reaches of the watershed with a number of storm drains discharging into the reach and a significant amount of trash deposited into the channel.

Undaunted by the challenges, Friends of Five Creeks conceived of restoring this section of stream, and Wolfe-Mason Associates was hired by the City of El Cerrito to design the project. As part of a renewal project for El Cerrito Plaza, the shopping center agreed to move the parking lot back from the creek, giving approximately 20 feet of additional space for a new stream channel and flood terrace. In addition, PG&E moved a series of utility poles back from the edge of the channel.

At this point, Hanford ARC contracted with the City of El Cerrito to grade a new, meandering channel, stabilized with rock weirs and rock toe protection, and revegetated with native plants. Hanford ARC installed a 24-hour bypass to handle the low flow, capturing several pipes discharging to the channel along the reach. Once dewatered, we cleared the channel, and removed a large amount of debris, including concrete, asphalt, riprap with shotcrete, base rock, and other trash.

Approximately 3,000 CY of soil was removed in the excavation, and a new low flow channel was constructed with several small terraces. The logistics during excavation were very challenging due to a confined work area with 12-feet of access in the parking area for loading and hauling material off-site. Furthermore, overhead powerlines limited the size excavator allowable. To keep the project schedule and meet permit requirements, Hanford ARC employed two smaller excavators and a large tracked skid-steer loader.

Although the channel was re-constructed with increased capacity and sinuosity, the finished channel gradient was such that rock was required for both grade stabilization and toe protection. A series of eight vortex weirs (see photo left) were constructed and a rock toe was placed to bankfull height at the outside bends and in the upper segment of the channel.

Other site appurtenances included two block retaining walls with segments for seating and a mulched path. Following finish grading, the channel banks were stabilized with a native seed mix and fabric, and the site was planted with approximately 4,000 plants. Also, the rock toe was planted with willow and dogwood cuttings approximately three-feet on center. Hanford ARC maintained the site for three months following construction, at which time the City assumed maintenance.