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Hydraulic Model Development and Calibration City of Redwood City (0011239.02)2-17 Woodard & Curran, Inc. Sanitary Sewer Capacity Master Plan November 2023 2.4.2 Wet Weather Calibration During wet weather calibration, the percentage volume of each of three RDI/I component parameters, illustrated in Figure 2-11, are adjusted by the model user to simulate the volume and timing of RDI/I for monitored storm events to best match the overall wet weather hydrograph shape and magnitude of peak flows. Through the wet weather calibration process, RDI/I hydrograph parameters were developed for each metered area. Figure 2-13 presents a plot of model versus metered wet weather flow for one meter for the 2018/19 wet weather calibration period. This graph shows an example of a good wet weather calibration, as indicated by a close match of modeled and metered peak flows for all of the storms, and good match to the hydrograph recession following the later February storms. It is usually not possible to match the hydrograph shape of all storms with a single set of RTK parameters, as the response to rainfall may vary based on antecedent conditions. Figure 2-14 shows the resulting graph for the Maple Street Pump Station. In these graphs, the black line depicts the monitored data and the green line shows the model-simulated flow, with the rainfall shown on the top graph. During the 2019 wet weather period, peak flows to the Maple Street Pump Station reached about 26 MGD. Attachment B of the Model Development TM in Appendix A contains copies of calibration graphs for the meters in the Main City Area. The graphs include the dry weather calibration periods in late December/early January and late January, as well as the wet weather periods in January and February. The calibration graphs for the Redwood Shores and Seaport/Pacific Shores networks are included in Attachment C of that TM, which includes the same 2018/19 dry and wet weather periods for the meters installed this past season in those areas, as well as graphs for the pump stations (and open-channel sites) from the 2016 pump station monitoring period. Figure 2-13:Wet Weather Calibration Graph (Meter FM17) __________ Metered flow __________ Modeled flow ATTY/RESO.0077/CC RESO SEWER SYSTEM MANAGEMENT PLAN - EXHIBIT A REV: 07-14-25 LF Page 133 of 317