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Consulting Services Agreement between City of San Leandro and August 3, 2023 Schaaf and Wheeler for Storm Drain Master Plan Exhibit A – Page 2 of 3 We will review drainage boundaries presented in previous studies, digitizing them in ArcGIS if necessary, to verify them. Using topography data, we will refine the boundary of the area draining to the City’s storm drain system, then divide the watershed into sub-catchments draining to various points in the “backbone” pipe system (18-inch diameter or larger, and not including small laterals or private/local systems). Hydrology will be developed using verified land use data and the Alameda County Hydrology Manual. Task 2: Hydrologyic and Hydraulic Modeling Relationship to ACFCD Facilities All of the City’s storm water runoff is eventually routed and discharged to a facility under Alameda County Flood Control District jurisdiction. Traditionally, SDMP processes assume that the peak of runoff from a watershed tributary to a creek at any point is coincident with the maximum stage (for any particular storm frequency) of the creek at that same location. This is a conservative assumption and is generally appropriate for SDMP and capital improvement development. However, the City should understand the implications of this potential source of conservatism. Portions of the ACFCD system may be added to the models to create continuity. This study is not intended to analyze the County infrastructure. Storm Drain System and Surface Capacity Analysis This study is primarily focused on evaluating “backbone” system capacity against an established performance standard and developing a capital improvement strategy that will correct deficiencies in a cost-effective manner. Initial development of the hydraulic model will include the City pipes that are 18 inches in diameter or larger in order to first identify capacity limitations of the pipe system itself. Schaaf & Wheeler will use the DHI MIKE+ modeling software to analyze the County’s 10-year design storm under existing condition. Additional analysis that may be desirable, but not covered under this scope, includes evaluation of “future” land use. Task 3: Capital Improvement Program The most important aspect of an SDMP is interpreting the results of the model to formulate an efficient improvement strategy. After documenting the system’s ability to meet level of service criteria under duress, those locations where the system falls short through deficient capacity and the resulting residual flood plains will be mapped. Solutions to remedy the deficiencies will be formulated and presented to the City along with their capital costs and other project implementation criteria to develop a prioritized Capital Improvement Program (CIP) likely to be accepted by San Leandro citizens and their City Council. Schaaf & Wheeler will provide support in developing presentations to ensure the community understands the results of the storm drain system capacity analysis and improvement recommendations. The highest priority projects will be scheduled for a construction window that the City prefers after consultation. Cost often strongly influences project priority rankings. Projects will generally be prioritized such that a single project, completed on its own, does not worsen residual flooding at other locations. All capital improvement, long-term replacement, and maintenance costs will be clearly summarized and adjusted to current ENR indices. This documentation will be useful for future use in financial analyses or fee studies. One climate change scenario will be analyzed under this scope of services. Rainfall and/or sea-level rise predictions will be modeled against the proposed CIPs to determine direct impacts from climate change. Additional CIPs will be developed and costed. DocuSign Envelope ID: 8107D769-50CA-440D-916A-9BD656730E41