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Redwood City Stormwater Roadmap <br />Appendix A: Data Review <br />September 2025 A-7 Schaaf & Wheeler <br /> Bayfront Canal and Atherton Channel Flood Protection (NHC, 2018) <br />The most recent study, prepared by Northwest Hydraulic Consultants Inc. for San Mateo <br />County, updated the hydraulic model of the Bayfront Canal and Atherton Channel to <br />evaluate flood conditions and assess proposed mitigation alternatives. The study <br />identified persistent flooding issues caused by limited channel capacity, undersized tide <br />gates, and downstream restrictions. It recommended construction of a siphon structure <br />to divert high flows into adjacent managed ponds, estimating substantial flood volume <br />and peak reduction benefits for up to the 25-year storm event. The City has noted that <br />some of these recommendations have already been implemented. <br /> Flood Insurance Study (FEMA, 2017) <br />This evaluation identified hydraulic restrictions along Cordilleras Creek, particularly at <br />culverts and undercrossings, that contribute to flooding during large storm events. <br />Channel improvements and culvert replacements were recommended to reduce risks to <br />adjacent residential and commercial development. <br /> MidPen Housing Hydrologic Assessment (BKF Engineers, 2017) <br />Conducted in support of a redevelopment project near Bradford Street, this assessment <br />evaluated the hydrologic function and geomorphic condition of the adjacent segment of <br />Redwood Creek. The study identified erosion concerns and recommended creek <br />setbacks, vegetation buffers, and bank stabilization measures to reduce long-term <br />erosion and protect nearby infrastructure. The City has noted that some of these <br />recommendations have been implemented. <br />A.3.1.4 As-Builts and Record Drawings <br />Redwood City maintains the following scanned record drawings and improvement plans for its <br />creek infrastructure. A few include: <br /> Redwood Creek (Alameda de las Pulgas to Massachusetts Avenue) <br />Scanned record drawings of the concrete-lined channel dated 1970, covering the reach <br />from Alameda de las Pulgas to Massachusetts Avenue. <br /> Redwood Creek (Virginia Avenue to El Camino Real) <br />Scanned as-built drawings dated 1967 for the concrete-lined channel between Virginia <br />Avenue and El Camino Real. <br /> Redwood Creek (Near 1891 Palm Avenue) <br />Improvement plans dated 2024 documenting recent reconstruction of the concrete-lined <br />channel near 1891 Palm Avenue. <br /> Redwood Creek (Near 1525 Connecticut Drive) <br />Channel repair as-built plans of Redwood Creek dated 2024. <br />Further as-builts and improvements plans may be requested from the City. <br />A.3.1.5 Geotechnical Reports <br />The Geotechnical Investigation Proposed Residential Building Bradford Apartments (Rockridge <br />Geotechnical, 2016) is one of many geotechnical reports the City has on file for Redwood <br />Creek. It evaluated subsurface and groundwater conditions at 707 Bradford Street, adjacent to <br />Redwood Creek. The study identified key geotechnical challenges, including shallow <br />groundwater, liquefiable soils, and compressible deposits. It recommended ground improvement <br />11.A. - Page 46 of 53 <br />477