Laserfiche WebLink
City of San Leandro Alvarado Commerce Center Project <br /> 56 <br /> <br />Potentially <br />Significant <br />Impact <br />Less than <br />Significant <br />with <br />Mitigation <br />Incorporated <br />Less than <br />Significant <br />Impact No Impact <br />g. Place housing in a 100-year flood hazard <br />area as mapped on a federal Flood <br />Hazard Boundary, Flood Insurance Rate <br />Map, or other flood hazard delineation <br />map? □ □ □ ■ <br />h. Place structures in a 100-year flood <br />hazard area that would impede or <br />redirect flood flows? □ □ □ ■ <br />i. Expose people or structures to a <br />significant risk of loss, injury, or death <br />involving flooding, including that <br />occurring as a result of the failure of a <br />levee or dam? □ □ ■ □ <br />j. Result in inundation by seiche, tsunami, <br />or mudflow? □ □ □ ■ <br />Existing Setting <br />The project site is located in the San Francisco Bay Hydrologic Region, which covers approximately <br />4,500 square miles and encompasses 10 counties, including Alameda County. It corresponds with <br />the boundaries of the San Francisco Regional Water Quality Control Board Region 2 and the San <br />Francisco Bay Area Integrated Regional Water Management Plan. The San Francisco Bay Hydrologic <br />Region is a complex network of watersheds, marshes, rivers, creeks, reservoirs, and bays mostly <br />draining into the San Francisco Bay and the Pacific Ocean (San Leandro 2016f). <br />The project site is located in the Estudillo Canal Watershed. Stormwater runoff is collected through <br />a system of underground culverts, storm drains, and engineered channels that drain into the <br />Estudillo Canal, which ultimately discharges into San Francisco Bay (San Leandro 2016f). The storm <br />drains in Aladdin Avenue connect to this system. <br />The City of San Leandro Department of Public Works owns and maintains 175 miles of storm drain <br />conduits throughout the city. The City’s storm drain system feeds into a larger system owned and <br />operated by the Alameda County Flood Control and Water Conservation District. This system <br />includes the lower reaches of San Leandro and San Lorenzo Creeks, as well as a number of channels <br />extending into San Leandro neighborhoods west of I-880. The District’s drainage facilities include <br />levees, pump stations, erosion control devices, and culverts (San Leandro 2016f). <br />Stormwater runoff pollutants vary with land use, topography, and the amount of impervious <br />surface, as well as the amount and frequency of rainfall and irrigation practices. Runoff in developed <br />areas typically contain oil, grease, litter, and metals accumulated in streets, driveways, parking lots, <br />and rooftops, as well as pesticides, herbicides, particulate matter, nutrients, animal waste, and <br />other oxygen-demanding substances from landscaped areas. The highest pollutant concentrations <br />usually occur at the beginning of the wet season during the “first flush” (San Leandro 2016f). <br />353