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Element 8 – System Evaluation, Capacity Assurance, and Capital Improvements <br />City of Pleasanton Sewer System Management Plan, July 2025 33 <br />required capacity improvements will be funded and constructed by future developers and/or <br />incorporated into the long-term CIP once identified. <br />8.3.4: Infiltration and Inflow <br />The hydraulic model was used to evaluate the magnitude of infiltration and inflow (I/I) into <br />the City’s sewer system. Peak I/I flow (for the 25-year design storm) was expressed as a wet <br />weather peaking factor (ratio of peak I/I flow to average dry weather flow) for each flow <br />meter tributary area. The wet weather peaking factors ranged from about 1.5 to 5, with most <br />areas having peaking factors less than 4. While these values certainly indicate that the system <br />is subject to I/I, the values are lower than many other San Francisco Bay Area systems. Based <br />on the results of the capacity assessment, the City does not consider I/I to be excessive and <br />warranting a targeted I/I investigation program, but it will continue to monitor flows (at its <br />key pump stations and influent to the DSRSD treatment plant, and through future flow <br />monitoring programs) and re-visit the need for a focused I/I program in the future. <br />8.4: Impacts of Climate Change <br />It is generally accepted that storm frequency and intensity will increase in the future as a <br />result of climate change. Already, published rainfall statistics (e.g., NOAA Atlas 14) are likely <br />out-of-date and are currently being updated. NOAA Atlas 15 is anticipated to be released in <br />2026. At that time, the City will re-evaluate its design storm and make adjustments if <br />warranted in the capacity assessment. The City will continue to monitor conditions in the <br />system during large wet weather events and take future action if observations indicate <br />increased flows or risk of spills due to insufficient capacity during such events. <br />8.5: Project Funding <br />The City conducts sewer rate and connection fee studies on a periodic basis to assess the <br />funding needs to support CIP, as well as O&M programs. The next sewer rate and connection <br />fee study is scheduled to be complete as shown in Section 1.2. <br />8.6: References <br />• WDR Attachment – Section 8 <br />• Sewer Capacity Evaluation Report, November 2024 <br />• NOAA Atlas 14