Reso13 PC 13-24 2920 PC Reso-Adopt the Intitial Study MND - Undercrossing

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Z E�vironmentcal Analysi.r h)Expose people or suuctrsres to a srgrzrftca�t tisk oflass,injury ar death involvtr�g wildland fires, rncludtng where wildlartds are adjacerlt to ur8anized a.reas or ichere resJdetices are tntermixed with wildlands? " According to Figure PS-6 in the City General Plan, the project area is nat«nthin a Fire Hazard Severity Zone (City of Redwood City,2011). Therefore, the proposed project would not have any impacts from wildland fires. (No Impact) 2.9 HYDROLOGY AND WATER QUALITY The Location Hydtaulic Study Report in Appendix H sutrunarizes the floodplain management regularions,describes the exisung floodplain conditians in the praject area,evaluates potential flooding hazards from the pxoposed ptoject,and details canformance with the applicabie requixements. The Water Quality Report in Appendix I suininarizes the water quality regulations and guidelines, describes the quality of surface waters in the area, evaluates potential project impacts of�he project to water quality,and includes measures that will be implemented to maintain water quality objecrives. Average annual rainfall in the City is appro��ately 19.16 in. (Western Regional Climate Center, 2012).The project is adjacent to Redwood Creek,a 9.5-mile long�erennial srream that drains a watershed in the Emerald Lake Hiil area and dischaxges into San Francisco Bay at the Port of Redwoad City. The porrion of the creek at US 101 within the project area is tidally influenced. Based an the nearest gauge,the MHHW elevation is 7.4 feet abo�re sea level,and the Mean Lower Low Water (MLL� elevation is -0.$ feet (WRECO,2013). Higher and lower water levels occur in Redwood Creek,depending on ridal cycles and stormwatet events. According to the Flood Insurance Rate Map {FIRI1� 0301E,the project area would be located within a 100-year flood zone,Zone AE, with a base flood elevatian of 10 feet (FEMA,2012}. T'he San Francisco Bap Conse�vat�on and Development Coi�ni�nission (BCDC) and Cali£ornia Department of Water Resources (DWR),estima�e that continued sea level rise will increase the water level in the San Francisco Bap by 16 inches (1.3 feet) by 2050 and 55 inches (4.6 feet} by 2100 (DWR, 2011). The existing Bair Island Road ptzmp station at end of East Bayshore Road receives stormwater from a 22.25-acre atea on both sides of Bair Island Road and discharges to Redw�ood Creek through an e�sting 24-inch storrri drain pipe approxirnately 25 feet northeast of US 101 (KI'FF 2008). The e�sting pump station has a dischatge rate of 13.37 cfs,which is inadequate £ox the 32.40 cfs �eak flow from the 100-year storm. Redwood Creek is within the Santa Clara Valley Groundwater Basin and in tt�e San Mateo Plain Groundwater Basin (Basin Number 2-9.03). The National Resource Conservation Service Web Sail Survey for the project area indicates that that the depth of the groundwater table is more than 65 feet deep (`�RECO,2013}. CE&G detected groundwater at 2 to 4 feet during its baring. WREC� '-�r US 101 Pedestnan Undercro.r.ring and Bair I.rland Aaad Starrl?Draira Pump Stat�ara Project