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III. Environmental Setting, Impacts, and Mitigations <br /> K. Hydrology, Geohydrology, and Water Quality <br /> Mitigation Measure K.1. <br /> None warranted. <br /> Impact K.2. The project would relocate the existing 100-year floodplain,and if inadequate <br /> replacement storage volume or routing of ftoodflows occurred,the project could contribute <br /> to downstream flooding or expose the landfill to the effects of the 100-year flood. <br /> (SIGNIFICANT) <br /> Realigning Little Johns Creek would relocate the existing 100-year floodplain. Surface water <br /> controls for the project include provision of protection from flood waters of Little Johns Creek <br /> and the creation of compensatory floodplain storage area to replace the existing 100-year <br /> floodplain on the project site. Existing areas of the 100-year floodplain are shown in <br /> Figure III.K.2. <br /> State regulations (CCR Title 23)require that new Class III landfills be designed,constructed, <br /> g q g <br /> operated,and maintained to prevent inundation or washout due to floods with a 100-year return <br /> period. <br /> Mitigation Measure K.2. <br /> Proposed as Part of the Project <br /> (a) The project includes channel reconfiguration and localized flood protection berms to isolate <br /> the landfill surfaces from floodwaters. <br /> (b) The project design also includes provision of replacement floodplain area and storage <br /> volume in an easement along the relocated Little Johns Creek. <br /> (c) The channel and floodplain storage easement are designed to accommodate the 100-year, <br /> 24-hour storm with a three foot freeboard. <br /> The design must also meet the requirements of the San Joaquin County Flood Control District. <br /> These measures would reduce this impact to a less-than-significant level. <br /> III.K.12 <br />