Reso PC16-23 PC 0116 Reso CEQA - Sandpiper

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Section A.0—Environmental Setting and Discussion oflmpacts in Egret Lane eventually discharges to the Redwood Shores Lagoon. The Redwood Shores Lagoon is a manmade system connected to the San Francisco Bay that controls the elevation of the water and is lowered during the rainy season to provide additional capacity for stormwater runoff. Similar to most urban uses, the runoff from the project site contains varying amounts of non -point source pollutants (e.g., roadway/street contaminants, litter, maintenance/landscaping chemicals, etc.). 49.1.3 Groundwater According to the Geotechnical Study that was prepared for the project, groundwater below the site was encountered at depths of 4.5 to seven feet bgs. This places the groundwater level at sea level, which is expected for areas located near the Bay. Groundwater in the project area is tidally influenced, increasing and decreasing with high and low tides, respectively. Approximately two- thirds of the project site is covered with impervious surfaces; the site is not a designated groundwater recharge area. 49.1.4 Flooding As shown on the FIRM prepared by FEMA for the project area, the project site is located in Zone X. Zone X is defined as areas of 0.2 percent annual chance flood, areas of one percent annual chance flood with average depths of less than one foot or with drainage areas less than one square mile, and areas protected by levees from one percent annual chance flood. The project site is located in Zone X because it is protected by levees from the one percent annual chance flood.24 The San Francisco Bay Conservation and Development Commission (BCDC) has developed findings and policies on climate change and a background report that reflects the current state of knowledge regarding the potential impacts of climate change on the region. The background report, Living with a Rising Bay, Vulnerability and Adaption in San Francisco Bay and on the Shoreline (BCDC 2011 a), identifies potential impacts of climate change on public health and safety. According to this report, global warming is expected to result in a 16 -inch (1.3 feet) sea level rise in San Francisco Bay by mid-century (2050) and in a 55 -inch (4.6 feet) sea level rise by the end of the century (2100). This would result in approximately 180,000 acres of Bay shoreline vulnerable to flooding by mid-century, and 213,000 acres vulnerable to flooding by the end of the century. The project site is in an area which could be exposed to flooding from sea -level rise due to global climate change. 25 Additionally, it is predicted that global climate change would also result in extreme storm events, which in combination with higher sea level, would cause greater flooding within the project area. Flooding from sea level rise is a known hazard for the City's coastal communities. The General Plan EIR states that because of the uncertainty regarding the timing and severity of sea level rise, programmatic mitigation for the vulnerable areas of the City would not be possible at this time. 24 FEMA. Flood Insurance Rate Map: Map Number 06081 C0186E. October 2012. 25 San Francisco Bay Area Conservation and Development Commission. ShorelineAreas Potentially Exposed To Sea Level Rise: Central Bay South. 2005. Accessed September 3, 2014. Available at: httn://www.bcdc.ca.Qov/planning/climate chance/mans/16 55/cbav south.od£ City of Redwood City 57 Initial Study/Mitigated Negative Declaration Sandpiper Elementary School Facilities Expansion November 2016