South Fork of the Santa Clara River, Santa Clarita Valley, California. Supplement

摘要

This report is a supplement to the Final Detailed Project Report (DPR) dated January 1983. The DPR recommended a plan that included a deposition area and 0.8 miles of concrete channel. The land selected for the deposition area is located just downstream of I-5, where an existing mule farm now exists. Subsequent to the Final DPR, the local sponsor, the Los Angeles County Flood Control District, requested a design change. Acquisition of rights-of-way for the deposition area had become too cost prohibitive. The County therefore suggested going back to a plan similar to Plan A that was recommended in the 1976 Feasibility Study. The plan consists of a debris basin upstream of I-5 at the junction of Towsley and Wiley Canyons rather than a deposition area downstream of I-5. The plan recommended herein (plan A) is economically justified, provides Standard Project Flood Protection, and is strongly supported by the local sponsor. The selected plan consists of a debris basin upstream of I-5 that outlets via a spillway into 1.2 miles of rectangular concrete channel. Also included is the construction of seven bridges and the raising of the existing channel walls downstream of Lyons Avenue to SPF levels.