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2175 N California Blvd <br />Suite 315 <br />Walnut Creek, CA 94596 <br />www.woodardcurran.com <br /> T 800.426.4262 <br />T 925.627.4100 <br /> <br /> <br />Via Electronic Mail <br /> <br />October 31, 2024 <br /> <br />Michael Stella <br />City of Pleasanton <br />200 Old Bernal Avenue <br />Pleasanton, CA 94566 <br /> Re: Arroyo Lago Letter Proposal Sewer Impact Study <br />Dear Michael, <br />At the request of the City of Pleasanton, Woodard & Curran has prepared the following scope <br />of services for a task order to provide hydraulic modeling support related to evaluating the impact of the proposed Arroyo Lago development on the City’s wastewater collection system. The work will be based on the hydraulic model developed and used for the Sanitary Sewer <br />Master Plan (Master Plan), which is currently under development although the model has been accepted by the City as appropriate for this purpose. <br />The work items included in this task order are described below. <br />Task 1 – Create Model Loading Scenarios <br />Woodard & Curran will create new model scenarios incorporating the proposed development. <br />Proposed loads for the development will be based on information provided by the City and unit loads consistent with what was used in the Master Plan (160 gpd/unit for single family <br />residential, 130 gpd/unit for multi-family residential). <br />Land Use Scenarios will include: <br />A. Future land use (inside City Boundary only, including proposed Kiewitt development) <br />B. Future land use plus Site H industrial project <br />C. Future land use plus Arroyo Lago <br />D. Future land use plus Senior Housing Project E. Future land use plus Site H, Arroyo Lago, and Senior Housing Project <br />F. Buildout Scenario Alt 1, including Site H, Arroyo Lago, Senior Housing Project, plus <br />Amazon Residential <br />G. Buildout Scenario Alt 1, including Site H, Arroyo Lago, Senior Housing Project, plus <br />Amazon Industrial <br />Task 2 – Evaluate Adequacy of Sewer System <br />Woodard & Curran will run the model for dry weather and design storm wet weather scenarios <br />and assess the capacity impact of the flows from the development included in the analysis on <br />the existing downstream sewers. Base wastewater flow unit flow factors, diurnal wastewater <br />flow profiles, infiltration/inflow parameters, design storm rainfall, and hydraulic criteria will be <br />based on those used for the Master Plan. Woodard & Curran will summarize the model results <br />in a brief Technical Memorandum (TM) for review by the City. The TM will document the model updates and assumptions made for the evaluation and include model hydraulic profile plots of <br />the flow in the relevant downstream sewers. <br />Docusign Envelope ID: 831CC3A6-6687-4445-B7A1-8A9E35D8680DDocusign Envelope ID: 6D78E70B-0517-4742-BD0D-7BE055976862