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<br />Section 4 <br /> <br />Mitil!ation Criteria and Standards <br /> <br />Section 5 of this report includes Site Reports for each of the pond sites. The first three subsection <br />of each of those Site Reports describe historic flooding, the field surveys conducted by the CWCB <br />and the flood risk at each site. The final subsection of each Site Report provides preliminary <br />recommendations for mitigation at each site. <br /> <br />. <br /> <br />Section 4 explains the criteria and standards used by CWCB staff in recommending particular <br />mitigation strategies. These criteria and standards, which are presented in Table 3 below, are in <br />compliance with those commonly used by state and federal agencies with responsibilities in <br />floodplain management, river mechanics and stream morphology. Because the 8 ponds are existing <br />facilities, any mitigation will involve retrofitting. Retrofitting inherently limits flexibility when <br />compared to new construction, The strategies recommended for the 8 ponds are limited in their <br />scope and design as a result of their having to be retrofit strategies. <br /> <br />TABLE 3 <br /> <br />RECOMMENDED MITIGATION DESIGN CRITERIA AND STANDARDS <br /> <br />I - <br /> <br />IMlTIGA.TION MEASURES I RECOMMENDED STANDARDS I <br />LEVEE SYSTEMS <br />Design Flood Side Slope Top Width Freeboard <br />- 10 YEAR not recommended <br />- 50 YEAR 3H:IV 10 FT 2 FT <br />- 100 YEAR 3H:IV 10 FT 3 FT <br />- 500 YEAR 3H:IV 10 FT 3 FT <br />STREAMBANK PROTECTION <br />- Velocity less than 7 fps Soft Treatment: <br /> Flatter side slope (4H:IV) <br /> Need vegetative cover; can also include organic matter <br />- Velocity greater than 7 fps Hard Treatment: <br /> Rock lining, rock jetty, concrete, etc. <br />OTHER MEASURES <br />Flood warning system Warns of flood event greater than the to-year event <br />Relocation activities not applicable <br />Siting of recreational facilities Locate at or above the lO-year flood <br />Lowest floor of residential structures Build at or above the 100-year flood <br /> <br />11 <br />