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<br />tion. A proposed alignment for the levee extension is shown on <br />Plate 3. The levee alignment could be adjusted according to local <br />conditions and requirements. <br /> <br />This extension, designated th,,, "\,est levee extension," would <br />begin cn the existing levee near where 'the White River and the <br />existing levee take a sharp bend to the north. The we,st levee <br />extension would then continue until it reached ground above the <br />lOO-year flood plain northwest of tehe intersection of CE~dar Avenue <br />and Denver Avenue. The levee would turn teo the south in this area <br />to tie off the downstream end of the levee. The west. levee <br />extension would end just north of East Raven Avenue. ~'he total <br />length of the new levee extension 'would be about 2, 700 fE~et. <br /> <br />To evaluate the effect of the! we,st levee extension on flood <br />water Hurface elevations, a hydraulic model was developed that <br />simulated the effects of an extend,,,d levee. Encroachments were <br />added to cross sections along the levee alignmem1:. These <br />encroachments blocked any flow ar,,,a in t.he, cross sect.ion to the <br />landward side of the levee. The exis.ting levee was assumed to be <br />removed beyond the start of the ~Iest levee. The flood water <br />surface profiles were then computed for this condition. Table 4 <br />lists the lOO-year flood water surface eleva.tions with the i.mproved <br />levee and west levee extension in place compared to those for the <br />current FIS. <br /> <br />Tc determine the required top'-of-'levee elevations, 3 feet was <br />added 1:0 the loa-year water surf,ace elevation computed at each <br />cross f~ection. This provided the freeboard for the levee to be <br />assumec, effective. Between cross sections, the levee profile is <br />sloped directly between the elevat:ions determined at 1:he cross <br />sectior,s. At the inside of river bends, some of the cross sections <br />conver~e and are to be located qUitl~ close together. A,t these <br />locatie'ns, the top-of-levee elevation computed for the upstream <br />sectior, of the bend was carried t,o the downstream sec.tion of the <br />bend. Profiles of the existing leve,,,, the improved existing levee, <br />and the new west levee extension are shown on Plates 4-1, 4"'2, and <br />4-3. <br /> <br />10 <br />