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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />requested alignment. The levee could easily be shifted during final design according to <br />the City's desires. The proposed alignments were chosen to maximize flood protection <br />benefits and to minimize impacts to roadways and buildings where possible. The ends <br />of the 100-year and SOO-year levees should tie into high ground at an elevation that is at <br />least as high as the respective flood levels. <br /> <br />Water surface elevations from the FIS and FIRM were used to determine the crest <br />elevations of the proposed levees. Due to the elevation discrepancies between the 1971 <br />topographic mapping and the city-surveyed cross-sections, the actual levee heights <br />could not be determined with any Ievel of confidence. The levee elevations shown on <br />plate 2 depict minimum elevations required for 100-year and SOO-year levels of <br />protection. These elevations do not account for any freeboard. The proposed levees <br />should provide adequate flood protection for structures behind the levees, but would <br />not be sufficient to remove the structures from the floodplain from a regulatory <br />standpoint. Certain freeboard and construction requirements would need to be met in <br />order for the Federal Emergency Management Agency (FEMA) to consider removing <br />levee-protected areas from the regulated floodplain. <br /> <br />The constructed levee should adhere to Corps of Engineers criteria which includes, at a <br />minimum, a 10-foot top width and 3H to 1 V side slopes. A compaction of 95 percent for <br />the embankment material should also be achieved. A typical levee cross-section is <br />shown on plate 2, however a more detailed investigation of Corps criteria should be <br />investigated prior to final design of the levee. <br /> <br />For the purpose of developing preliminary quantity and construction cost estimates, the <br />1oo-year levee was assumed to have an average height of 3 feet. The SOO-year levee <br />height was assumed to be 3 feet plus the difference between the 100-year and 500-year <br />water surface elevations which are pIotted in the FIS. Ground elevations along the final <br />levee alignment should be surveyed and tied to MSL datum so that the actual levee <br />height can be appropriately designed. <br /> <br />A cursory analysis was performed to evaluate the necessity for interior drainage <br />features through the proposed levee at site" A". The need for interior drainage facilities <br />arises when a Ievee, constructed along a waterway, prevents local surface runoff from <br /> <br />8 <br />