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Redwood City Stormwater Roadmap Appendix B: Data Gaps September 2025 A-13 Schaaf & Wheeler Appendix B: Data Gaps While the City maintains a relatively well documented record of its stormwater system infrastructure, this section reviews gaps for further data collection. Table B-1 provides an overview of data quality, priority, and a rough order of magnitude for cost to complete data gaps. Table B-1: Data Recommendations B.1.1 Topography – Low Priority LiDAR has a comprehensive coverage of the City. While LiDAR may be appropriate for large scale analysis, its accuracy is limited in areas with thick brush or underwater. For capacity analysis involving creeks and coastal reaches, using traditional survey methods or drone/ground-based LiDAR should be considered to provide accurate bathymetry data for the comprehensive Stormwater Master Plan. B.1.2 Pipe Network - Moderate Priority The storm drain network is generally well documented, but segments near City boundaries appear disjointed from the core system. Field investigation is recommended to confirm connectivity and jurisdiction, and to identify any missing pipe segments prior to the Stormwater Master Plan. Additionally, rim and invert elevation data are limited to about 50% of structures. In order to create a comprehensive hydraulic model for the City’s system in the Stormwater Master Plan, using traditional survey methods or drone/ground-based LiDAR should be considered to fill in the gaps when engineering judgment or estimate is not appropriate. The hydraulic ICM model on record is limited to the downtown area. The Stormwater Master Plan may leverage this existing data source in the comprehensive hydraulic model. B.1.3 Condition Assessment – High Priority The City maintains limited condition assessment data, particularly for concrete lined channels and pipe networks. The majority of the City’s storm drain pipes are RCP. However, much of the system is CMP. Since CMP degrades over time, we recommend CCTV and condition assessment of the CMP pipes along with RCP pipes in known problem areas to inform the Stormwater Master Plan. Current Data Quality Data Priority Cost Topography Moderate Low $$$ Pipe Network High Moderate $$$$ Condition Assessment Low High $$$ Pump Stations Moderate High $ Channels Low Moderate $$$ Levees and Floodwalls Moderate High $$$ Structures Low Moderate $$$ Green Infrastructure Moderate Low $ Sea-Level Rise Moderate Moderate $ 11.A. - Page 52 of 53 483