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Consulting Services Agreement between City of San Leandro and Last revised 04/17/2023 Terraphase Engineering for Sea Level Rise Master Plan Exhibit A – Page 2 of 13 order to identify existing conditions and will prepare a set of base maps of the vulnerable assets identified in the 2021 San Leandro Climate Action Plan, including vulnerable and disadvantaged communities, critical infrastructure, critical community and emergency facilities, natural and cultural resources, planned levee adaptation projects, and industrial facilities that could potentially release chemicals if flooded. The Terraphase Team will perform an exposure analysis for these vulnerable assets by mapping and quantifying flooding due to the combined effects of surface water inundation and groundwater rise for multiple SLR projections. SLR projections under the high risk-aversion scenario as presented in the 2018 Ocean Protection Council (OPC) guidance (OPC 2018) are approximately 24 inches (2 feet) by year 2050, and up to approximately 84 inches (7 feet) by year 2100 in the Bay Area. These projections provide the lower and upper bounds for evaluation of flooding impacts. Several online tools and downloadable georeferenced databases that evaluate surface water inundation and/or groundwater rise in the Bay Area are available for use in this evaluation. Terraphase has conducted thorough reviews of the published reports and databases associated with each of these tools and has used them at multiple sites along the California coast, including at the Tony Lema Landfill in support of the long-term flood protection plan. Terraphase will evaluate the combined effects of surface water inundation and groundwater rise using the following datasets: • Pathways Climate Institute LLC (Pathways) and the San Francisco Estuary Institute (SFEI) Shallow Groundwater Response to Sea-Level Rise study: Pathways and SFEI gathered and analyzed multiple data sets and collaborated with city and county partners to analyze and map the existing “highest annual” shallow groundwater table and its likely response to future SLR. Available data from this study include modeled depth to groundwater relative to a digital elevation model (DEM) of Bay Area topography under current conditions and future SLR scenarios from 12 to 108 inches. Terraphase is currently using these data to evaluate SLR vulnerabilities at the Tony Lema Landfill. Terraphase has also obtained the modified DEM used in this study to ensure that the current and future mapped scenarios of SLR are correctly superimposed onto key topographic features such as levees and other shoreline flood protection features. • Bay Conservation and Development Commission (BCDC) Adapting to Rising Tides (ART) study: Available data from this study include raster data of the depth of land flooding due to SLR scenarios of 12 to 108 inches superimposed on current mean higher-high water (MHHW), shoreline overtopping depth, and identification of disconnected low-lying areas. Terraphase will overlay these datasets with the Pathways/SFEI datasets. • United States Geologic Survey Coastal Storm Modeling System (USGS CoSMoS): This modeling system includes results of surface water inundation and groundwater rise for multiple SLR scenarios, and accounts for the influence on rising groundwater levels due to topography. This model system is important to use in the assessment because these raster datasets include not only surface water flooding for various SLR scenarios and storm frequencies (annual, 20-year and 100-year), but also include results of flood duration and wave height, both of which impact vulnerability and adaptive capacity. These datasets will be compiled and evaluated to develop flood maps for each SLR scenario (from 24 to 84 inches [2 to 7 feet]). The maps will quantify the magnitude of flooding due to the combined impact of surface water inundation and groundwater rise and will be overlaid with the existing asset