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Redwood City Stormwater Roadmap
<br />Recommended Assessments
<br />September 2025 6-2 Schaaf & Wheeler
<br />6.1.3 Infrastructure Data Collection and Condition Assessment
<br />A field data collection system should be developed and may utilize tools such as ArcGIS. The
<br />condition of infrastructure should be ranked to inform the prioritization process. In general, cost
<br />of data collection and condition assessment is related to level of detail and effort. Infrastructure
<br />that should be included in the field data collection and condition assessment are as follows:
<br /> Pipes
<br />The condition of the pipe should utilize an industry standard rating system, like NASSCO.
<br />Conditions assessed may include, but are not limited to, signs of high water, infrastructure
<br />damage, and debris or sediment buildup. Data collection may include documenting
<br />inverts, pipe sizes, and pipe material. For most pipe sections, field inspection using open
<br />manholes and catch basins may be sufficient. Any pipes that are hard to access or appear
<br />to require more detailed inspection may be flagged for CCTV inspection.
<br />Estimated Cost: $200,000 to $400,000
<br /> Concrete and Natural Channels
<br />Two ranking systems are recommended for the open conveyance system condition:
<br />environmental (scour, erosion, illegal dumping, etc.) and hydraulic capacity (obstructions,
<br />sedimentation, and debris). Walking the open channels and taking geocoded photos to
<br />compare with previous studies is recommended. Conditions assessed may include, but
<br />are not limited to, channel erosion, debris or sediment deposition, channel shape (bottom
<br />width, height, and top width), signs of damage or high water, and hydraulic obstructions
<br />(dams, weirs, structures in channel).
<br />Estimated Cost: $150,000 to $300,000
<br /> Culverts and Bridges
<br />Culvert inspection may include field measurements in conjunction with topographic data
<br />to inform the hydraulic modeling analysis. The information documented may include: type
<br />of culvert, diameter, width, height, length, material, etc.
<br />Within the context of a Stormwater Master Plan, the condition of the bridges along open
<br />channels is not the focus. However, it is recommended that measurements of the bridge
<br />be taken to inform the hydraulic modeling analysis. This may include, but is not limited to,
<br />low chord elevations, bridge span length, bridge width, pier measurements, etc.
<br />Estimated Cost: $40,000 to $60,000
<br /> Basins and Lagoons
<br />Basins and lagoons are recommended to be inspected for the following conditions: debris
<br />and sediment build up, stagnation, signs of high-water level, etc.
<br />Estimated Cost: $60,000 to $90,000
<br /> Pump Stations
<br />Each of the City-owned stormwater pump stations is recommended to be visited with the
<br />City operations staff to evaluate the effectiveness of the current stormwater pump stations.
<br />Conditions assessed may include, but are not limited to, electrical condition, structural
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