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5.ENVIRONMENTAL CHECKLIST MOUNTAIN HOUSE NEIGHBORHOODS KAND L INITIAL STUDY <br /> S.HYDROLOGY AND WATER QUALITY <br /> Revision (CLOMR) issued by FEMA on November 29, 2005. The property would <br /> be formally removed from the 100-year floodplain upon a civil engineer certifying <br /> the final pad elevations after grading. In addition, as discussed above, portions <br /> of the project site that are located within the 200-year flood hazard zone for Old l <br /> River would be elevated above the 200-year floodplain by elevating building pads <br /> above the 200-year base flood elevation. Therefore, the proposed project would <br /> not result in negative impacts associated with 100-year or 200-year flood hazard <br /> areas and no additional mitigation measures are required. <br /> h) Would the project place within a 900 year food hazard area structures <br /> which would impede or redirect flood flows? <br /> See the discussion under Items(d)and (g)above. <br /> i) Would the project expose people or structures to a significant risk of loss, <br /> injury or death involving flooding, including flooding of as a result of the <br /> failure of a levee or dam? <br /> The proposed project would not rely on levees for flood protection. Flood <br /> protection would be provided by elevating building pads above the 100-year flood <br /> hazard, Additionally, improvements to Mountain House Creek constructed as <br /> part of prior developments were designed to convey the 100-year storm event <br /> and to accommodate runoff resulting from a sudden and complete failure of both <br /> earthen dams located upstream of the project site, in Alameda County. Thus,the <br /> proposed project would not expose people or structures to flood hazards as a <br /> result of the failure of a levee or dam. No additional mitigation measures are <br /> required to reduce project impacts related to levee or dam failure. <br /> j) Would the project be subject to inundation by seiche, tsunami, or <br /> mudflow? <br /> A seiche is a rhythmic motion of water in a partially or completely landlocked <br /> water body caused by landslides, earthquake-induced ground accelerations, or <br /> ground offset. The proposed lake features in Neighborhoods K and L would be <br /> landlocked and surrounded by new development. However, the lake features <br /> would wind through the neighborhoods and would not be large enough to pose a <br /> threat of inundation by seiches. Neighborhoods K and L are not situated in an <br /> area that is vulnerable to tsunamis or mudflows. Therefore, project impacts <br /> related to inundation by seiche, tsunami, or mudflow are considered less than <br /> significant. No mitigation measures are necessary. <br /> Sources of Information <br /> Carlson, Barbee, &Gibson, Inc.,2010. Neighborhood `K'Lake Outfall, Mountain <br /> House, California. May 19. <br /> Condor Earth Technologies, 2010, Farm Irrigation Report, Neighborhoods K and <br /> L, Mountain Nouse, California. October. <br /> (sMi1) 5-118 <br />