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City of Pleasanton | Stormwater System Management Plan | PWD 25.601 | PAGE 16 Task 3.6 – Design Storms and Boundary Conditions Wood Rodgers has worked with several municipalities in Alameda County to develop appropriate design storms for minor as well as the sizing for major drainage facilities. The available Zone 7 HEC‐HMS and HEC‐RAS models, along with the Alameda County Hydrology & Hydraulics Manual, will be referenced to develop design storms and boundary conditions appropriate for use with the pipe and open channel networks in Pleasanton. Wood Rodgers will simulate the 2‐, 10‐, 50‐, and 100‐year design storms in the hydraulic model developed under Task 3.2 to assess the drainage system capacity and deficiencies. The 2‐year storm will be used to identify and assess maintenance hot spots; the 10‐ year storm will be used to identify storm drain capacity deficiencies; the 50‐year storm will be used to identify pump station and open channel capacity deficiencies; and the 100‐year storm will be used to identify combined street network, storm drain capacity, and open channel capacity deficiencies. Deliverable(s): 2, 10, 50, and 100‐year Design Storms and Boundary Conditions Task 3.7 – Capacity Deficiencies In order to identify the drainage facilities that require maintenance activities and capacity improvements, and to determine the capacity of the existing facility for infill developments, Wood Rodgers will develop deficiency maps and update the GIS geodatabase to display and categorize drainage facility deficiencies by storm frequency. See Exhibit 14. Wood Rodgers will use the model results to identify maintenance and capacity deficiencies using City and County design standards. The deficiency criteria will address the following: 1.Capacity or Level of Service: This level of service will be defined by the maximum hydraulic grade line (HGL) and floodplain depth and extent allowed for specific storm frequencies. 2.Maintenance hotspots: Using simulated low‐velocity values to identify facilities susceptible to recurring sedimentation. Wood Rodgers will identify, categorize and map storm drains in different levels‐of‐service (e.g. 2, 10, 50, and 100‐year) based on the simulation results. Wood Rodgers will then identify, categorize and map outfall structures along channels that are deficient and require flap gates. The categorized deficiencies will be stored in the City’s geodatabase. Deliverable(s): Deficiency map | Geodatabase updated with capacity deficiencies Exhibit 14 EXHIBIT A Docusign Envelope ID: DF86282A-2A84-404C-9F8A-A035AEFBCFF8