Reso 2020-149 Bay Fair TOD - Laserfiche WebLink

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CHAPTER 6 INFRASTRUCTURE + SERVICES Storm Drainage and Flood Control All of the drainage within and surrounding the Plan Area flows to the Estudillo Canal Flood Control Channel (Canal) which bisects the project area, as shown in Figure 7.2. Within this Plan Area, stormwater will be collected with drainage inlets and conduits that discharge into the Canal. The Canal is owned and operated by the Alameda County Flood Control & Water Conservation District while the area drain system will be owned and maintained by the City. Portions of the Plan Area are presented as being within a Special Flood Hazard Area (SFHA) "AH (El. 33)" by the effective Flood Insurance Rate Map. Zone AH is designated as "areas with a 1 % annual chance of shallow flooding, with an average depth ranging from 1 to 3 feet. The "base flood elevation" is determined as elevation 33 feet (NAVD 88). The Alameda County Flood Control and Water Conservation District is developing alternatives for improvements to the canal in ordertogain capacityforthe I %annual chance flood, thus eventually removing the Plan Area from the SFHA. Significant improvements to the Canal and channel crossings, through the Bay Fair TOD, may include the following, but not limited to: channel improvements, floodwalls, culverts, and elevating road crossings. The channel crossings that may or may not require improvements include: Union Pacific Railroad, existing maintenance bridge, Hesperian Blvd, BART, pedestrian walkway bridge, Bayfair Dr, Coelho Dr, and E. 14th St. Further analysis is required to determine the level of improvements. Although work will begin on the canal, downstream near the San Francisco Bay, funding and schedule for the reach through the Plan Area is currently under development. The City is party to the San Francisco Bay Region Municipal Regional Stormwater NPDES Permit, Order R2-2015-0049 (MS4). This permit requires the incorporation of Low Impact Development (LID) and Stormwater Treatment technologies in new development and redevelopment projects, in order to mimic the natural hydrology of the lands prior to disturbance. The objective of LID and post - construction BMPs for stormwater is to reduce runoff and mimic a site's predevelopment hydrology by minimizing disturbed areas and impervious cover and then infiltrating, storing, detaining, evapotranspiring, and/ or biotreating stormwater runoff close to its source. LID employs principles such as preserving and recreating natural landscape features and minimizing imperviousness to create functional and appealing site drainage that treats stormwater as a resource, rather than a waste product. Practices used to adhere to these LID principles include measures such as rain barrels and cisterns, green roofs, permeable pavement, preserving undeveloped open space, and biotreatment through rain gardens, bioretention units, bioswales, and planter/tree boxes. The Plan must incorporate these permit requirements during construction and maintain BMP facilities in perpetuity. MO