Agmt17 Wood Rdogers, Inc. Broadway / Douglas

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Task 2.2 — Site Visits Wood Rodgers will conduct a site visit as necessary for the modeling portion of the scope. During the site visit the Wood Rodgers Team will photograph and document notable components. Photographs will be geo-referenced using handheld GPS and integrated into the project geodatabase. This site visit is separate from the pump station visits. Task 3 Hydrologic & Hydraulic Model Task 3.1 — Convert Existino Models to ICM The Wood Rodgers Team will convert available models collected in Task 2 to ICM, as appropriate. This task will be conducted only if the available models will provide a benefit to efficiency. Task 3.2 —Watershed Parameters in Database Watersheds will be delineated on a base map using the LIDAR, the City pipe system, the street networks, and property development extents. Watershed parameters will be defined using existing land use, soil group, percent impervious (from the land use), and flow paths and will be clearly defined in the project database. A QA/QC task will be conducted and documented in the database. It is assumed that the Broadway Plaza development will not impact the hydrology of the watersheds, and therefore will not be specifically included in the assess. Task 3.3 — Develoo Conduit Parameters in Database The City's GIS database, the 2006 Storm Drain System Map, the 2017 Eastern Low -Lying Area Drainage Master Plan, supplemented with the available as -built information, available survey data will be used to develop the existing pipe and pump system database. The database will include all the pipe trunks shown in the 2006 Storm Drain System Map. Task 3.4 — Develop 2D Mesh The 2010 USGS LIDAR will be used to develop the mesh required for 2D modeling. The Extent of the 2D modeling will be based on existing flooding information (ie FEMA FIRMs) and will be tailored to the deficiencies determined below. Task 3.5 — Boundary Conditions Dynamic boundary conditions reflecting the systems immediately downstream of the pump stations, and the San Francisco Bay, will be developed. The boundary conditions will be used for the ICM model. Task 3.6 —Construct and Stabilize Model Once QA/QC on the pipe data for the major trunks within each of the five watersheds has been completed, the data will be imported from the GIS Database to the model. Conduit and manhole connectivity within the hydrologic portion of the model will be verified and parameterized to create runoff output for the full range of design storms. The detailed sub -watershed runoff developed in the hydrologic component will be directly linked to conduits and open channels in the model hydraulics component. The full hydrologic/hydraulic model will be run initially for the 100 -year design storm to identify instabilities. Model stability will be verified using output of pipe profiles, volume continuity errors, and review of resulting stage and flow hydrographs. Once model stability for extreme events is assured, the model will be run for the full suite of design storms with detailed representation of system tail water conditions. REV: 11-01-17 PR Page 10 of 11 ATTY/AGR.2017.244/Wood Rogers - Broadway/Douglas Storm Study