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6.1.A. - Page 16 <br />a uuun i rol: SAN MATEO <br />0 <br />DEPARTMENT OF PUBLIC WORKS <br />u <br />FLOOD RESILIENCE PROGRAM <br />Exhibit A <br />Bayfront Canal and Atherton Channel Flood Management and Restoration Project <br />Prepared by County of San Mateo <br />September 12, 2017 <br />Purpose: <br />To complete the planning, design, environmental permitting, and secure property access rights for the <br />Bayfront Canal and Atherton Channel Flood Management and Restoration Project (Project) on behalf of <br />the Cities of Redwood City and Menlo Park, the Town of Atherton (Cities), and the County of San Mateo <br />(the County) also referred to as the Bayfront Canal/Atherton Channel Collaborative (Collaborative). This <br />is the first project in a series of anticipated future projects that will provide flooding relief to this cross - <br />jurisdictional region. <br />Project Background: <br />The Bayfront Canal is located just north of Highway 101 in the City of Redwood City. The Bayfront Canal <br />extends from west to east, from Douglas Court to Marsh Road and is bounded to the north by Cargill's <br />salt ponds and to the south by residential and industrial properties. The Atherton Channel has <br />approximately 6.5 square miles of tributary drainage area and discharges into the Bayfront Canal near <br />Marsh Road. The Bayfront Canal has an additional 3 square miles of tributary drainage area, most of <br />which is located on the south side of Highway 101. The combined flow from the Atherton Channel and <br />Bayfront Canal, a total of 9.5 square miles of contributing area, discharges into Flood Slough through a <br />tide gate control structure. The watershed area, Project location, and planned future projects within the <br />watershed are summarized in Figure 1. <br />Hydrology: <br />The peak flow rates from the Bayfront Canal Hydrology and Hydraulic Evaluation, prepared for Stanford <br />Hospital & Clinic in October 2013 by BKF, was used to calculate the proportional jurisdictional flow based <br />on watershed areas. The flow contribution percentages presented in Table 1 will provide a baseline <br />funding strategy. These contributions will be expanded upon based on participation and for funding of the <br />construction and operation and maintenance phases of the Project. A reduction of flow contributions per <br />jurisdiction will be evaluated if upstream detention and storm water capture projects are implemented <br />within the watershed. <br />Table 1. Jurisdictional Flow Contributions <br />Jurisdiction <br />Watershed <br />Flow <br />Financial <br />Financial <br />Area <br />Contribution <br />Contribution <br />Contribution <br />Town of Atherton <br />44 <br />38.0 <br />39.8 <br />398,000 <br />City of Redwood City <br />13 <br />26.0 <br />26.1 <br />261,000 <br />San Mateo County <br />20 <br />22.0 <br />22.6 <br />226,000 <br />City of Menlo Park <br />17 <br />10.5 <br />11.5 <br />115,000 <br />Town of Woodside <br />6 <br />3.5 <br />0.0 <br />0 <br />This Project is the first step towards providing capacity for future projects within the watershed to reduce <br />flooding. The most recent proposed solution recommends the installation of 4 — 63" HDPE siphon pipes <br />is shown in Figure 2. The alignment passes under Marsh Road to the north of Highway 101 and connects <br />F:� Users �FloodResilienceProgram � EF001 BayfrontCanaA02 MOU�2017-09-12 MOU Final Drafti20170912_Bayfront ExibitA_Draft.docx <br />