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Redwood City Stormwater Roadmap <br />Appendix A: Data Review <br />September 2025 A-6 Schaaf & Wheeler <br /> Wet Weather Wastewater Flow Management Program (Kennedy/Jenks, 1992) – <br />Assessment of inflow and infiltration into the sanitary sewer system, finding limited <br />stormwater intrusion except in isolated low-lying areas north of Highway 101. <br />A.3 Flood Control <br />A.3.1 Open Channels and Creeks <br />A.3.1.1 Structural Deficiency Reviews <br />The City has conducted multiple structural assessments of Redwood Creek to evaluate the <br />condition of its concrete-lined and natural channel segments. These assessments identified <br />significant deficiencies that could compromise long-term channel stability and stormwater <br />conveyance if left unaddressed. <br /> Redwood Creek Deficiency Review (BKF Engineers, 2012) <br />This assessment identified widespread structural concerns in the concrete-lined channel <br />and culverts of including longitudinal and transverse cracking, panel joint separation, <br />concrete spalling, and undermining. It recommended repairs be prioritized based on <br />severity, with particular focus on areas at risk of structural failure during major storm <br />events. <br /> Redwood Creek Channel Structural Assessment Memorandum (Wood Rodgers, 2023) <br />Conducted following recent severe storms, this memorandum documented storm-related <br />damage along Redwood Creek, including erosion at unlined segments, sediment <br />buildup, cracking in lined sections, and loss of energy dissipation at culverts. The report <br />recommended targeted structural repairs, joint sealing, slope stabilization, and improved <br />energy dissipation measures at key outfalls. It emphasized the importance of proactive <br />maintenance and routine inspections to prevent escalation of damage and reduce long- <br />term repair costs. <br />These studies collectively support the need for capital improvement investment in Redwood <br />Creek, particularly in high-flow sections adjacent to developed areas. <br />A.3.1.2 Photos and Videos <br />The City currently maintains open channels through visual inspection at locations covered by <br />maintenance permits from the regulatory bodies along Redwood Creek and during the annual <br />cleanup of Cordilleras Creek culverts and the Bayfront Canal. The City has provided photos of <br />channel failures and maintenance videos along lengths of Redwood Creek. <br />Visual inspection data is not available for other open channels and creeks. <br />A.3.1.3 Existing Studies and Reports <br />The City maintains extensive documentation of flooding sources, channel conditions, and <br />hydrologic analyses related to its open channels and creeks. These studies have helped identify <br />capacity limitations, structural vulnerabilities, and potential mitigation strategies for reducing <br />flood risk in key drainage corridors. Most recent include: <br />11.A. - Page 45 of 53 <br />476