For San Luis Obispo County
Cambria, California

Questa designed a comprehensive flood management project to protect the coastal town of Cambria, which had experienced frequent flooding from Santa Rosa Creek, in part due to development on the floodplain and the influence of the Coast Highway 1 Bridge. The project included detailed biologic, geomorphic, and geotechnical studies, development and calibration of a HEC-HMS watershed runoff model using stream gauge data, and detailed channel hydraulic analysis using HEC-RAS. A flood bypass system, levee modifications, new pump station, and new Highway 1 bridge, including roadway elevation, were designed. Initial conceptual design alternatives examined included upstream detention, channel modification, use of floodwalls, channel diversions, and pump systems, as well as bridge modifications. These design concepts were turned into construction plans for review and approval by the County and Caltrans. Since the creek supports sensitive species, it was important to develop a plan that minimized aquatic habitat impacts and provided aquatic habitat enhancement. Questa obtained permits, prepared the CEQA documentation, and completed final specifications, plans, and cost estimate for the project, which was constructed in 2008.