Arroyo de la Laguna Streambank Stabilization and Restoration Project

Pleasanton, CA

NRCS Alameda County
Spring –Fall 2006

Hanford ARC worked with the Alameda County NRCS, San Francisco PUC, Alameda County RCD, Zone 7 Water District, Alameda County Public Works Agency, and Dublin/San Ramon Services District to stabilize an 800-foot long by 30-foot vertical section of the Arroyo de la Laguna on San Francisco PUC property to implement specialized streambank stabilization structures.

This was identified and designed by the Alameda County NRCS as a pilot project, intended to demonstrate the effectiveness of various rock, log and soil bioengineering structures. The Arroyo’s banks had become unstable and rapidly degraded in recent years, in part due to increased urbanization in the watershed area which includes the cities of Livermore, Pleasanton, San Ramon and Dublin.

The low-base flow in the channel averages 25 CFS during the summer, and can vary based on releases from an upstream dam. Hanford ARC installed a lined temporary gravity by-pass channel through the adjacent gravel bar with a 75 CFS capacity, to accommodate the fluctuations, and bridged the channel for access to the work area.

The primary components of the project were 6 rock barbs and one rock J-hook consisting of 1,650 tons of rock, fifty vertically-installed 15-foot eucalyptus ‘pin’ logs, a four-foot diameter willow barb, two anchored Christmas tree revetments, and floodplain grading. Following installation of the project structures, Hanford ARC restored the bypass channel to a gravel bar and planted willow cuttings throughout the project.