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2 Environments 7.B. - Page 87 <br /> of 42-inch storm drain that would convey the existing stormwater runoff from the Bair Island Road <br /> area to the new pump station and approximately 100 feet of 24-inch pipe to tie into the existing 24- <br /> inch discharge line to Redwood Creek. (Less than Significant Impact) <br /> f) Otherwise substantially degrade water quality? <br /> With the proposed mitigation measures, the project would not substantially degrade water quality. <br /> See the response to a) above. (Less than Significant Impact with Mitigation Incorporation) <br /> g)Place housing within a 100 year flood hazard area as mapped on a federal Flood Hazard <br /> Boundary or Flood Insurance Rate Map or other flood hazard delineation map? <br /> The proposed project would not place housing within a 100-year flood hazard area. (No Impact) <br /> h)Place within a 100-year flood hazard area structures which would impede or redirect flood <br /> flows? <br /> The proposed facilities would be within a 100-year floodplain, but would not impede or redirect <br /> flood flows. (Less than Significant Impact)) <br /> i)Expose people or structures to a significant risk of loss,injury or death involving flooding, <br /> including flooding as a result of the failure of a levee or dam? <br /> The project area is tidally influenced and would be subject to increased water levels during peak <br /> storm events. The present flood level and tidal data for Redwood Creek are as follows: <br /> Datum Elevation (ft,NAVD 88) <br /> 100-Year (stillwater) 9.7 <br /> 50-Year (stillwater) 9.6 <br /> 10-Year (stillwater) 9.3 <br /> MHHW(tidal) 7.4 <br /> MLLW(tidal) -0.8 <br /> NAVD 88=North American Vertical Datum 1988 <br /> The floodplain data is "stillwater data,"which includes storm surge and astronomical tides, but not <br /> the effects of waves or tsunamis. The tidal data is from the period October 1997 to October 2011. <br /> The City would construct the creek-side retaining wall to a height of 10.0 feet,which would be higher <br /> than the current 100-year stillwater elevation. <br /> The proposed facilities would not have a significant effect on flood levels in the creek, but would be <br /> subject to increased flooding. Future sea level increases would modify the floodplain elevations in <br /> the project area. Assuming a sea level rise of 1.3 ft (16 inches) by the year 2050,the MHHW <br /> elevation would be 8.7 feet,and the 10-year stillwater elevation would be 10.6 feet. If the sea levels <br /> 2-47 US 101 Pedestrian Undercrossing and Bair <br /> Island Road Storm Drain Pump Station Project <br />