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REV: 11-19-25 LR b.Task 5.a.2 Modify Criteria: a.Consultant will review the existing City’s open channel level of service criteria, including the details of determining that level of service. Details include the hypothetical design storms: storm depths, storm durations, storm time increments, storm distribution; the channel freeboard, and other requirements. Consultant to document the existing criteria, review with the City’s Project Manager, and City Staff, modify and set the criteria for determining deficiencies for this project. b. Consultant to use the current Creek Model for basis to develop 30-year and 100-year rainfall data. The current Creek model uses 100- and 500- year spatially varying design storms developed using Valley Meter MetSat PFEs. c. Consultant to set tidal boundary conditions and concurrent fluvial and tidal flooding criteria to identify actual flood risk without under-or over- stating this risk. This will be accomplished by evaluating riverine events coupled with appropriate tidal events (and vice versa) to realistically evaluate the potential flood envelop. At the lower parts of the watershed below El Camino Real, the Consultant’s assessment will include the evaluation of both daily and extreme tide levels to assess impacts from both cases overtime to understand the flooding risks due to tidal flooding and Sea Level Rise (SLR). d. Consultant to evaluate conditions for mid-century (2050) and late- century (2100). For future conditions analysis, the precipitation, tidal levels, and ground water table will be adjusted to reflect the impact of changes in climate patterns and SLR. Consultant will utilize the latest SLR guidance document for California (2024 OPC), extreme precipitation guidance such as Cal-Adapt and the 2023 SF Bay Precipitation guidance developed for the City of San Francisco. The 2023 CCSF guidebook is a more recent extreme precipitation study for the SF Peninsula, so preferable consideration to this study over the 2023 CCSF guidebook will be done by the Consultant. Moreover, the consultant will use the 2022 SFEI Groundwater Report and associated depth to groundwater surfaces to define current groundwater depths and predict future groundwater conditions. The 2024 OPC guidance for Alameda for the Intermediate/High SLR scenario as it is the closest NOAA gage listed in the OPC guidance. A still water tide level approach will be used for modeling as the extent of Project is not currently subject to significant wave hazards. Waves will be considered in the design of improvements in Task 10. c.Task 5.a.3 Modify Criteria: a.The Consultant will use the Creek Model as a base model as it includes the entire project area, and incorporate features from the detailed ELLA Model (such as one-dimensional open channel and bridge modeling in the lower ATTY/AGR.2025.317/Wood Rodgers, Inc. (Page 18 of 77)