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COMMENTARY SHEET 15 Of 45 STATIONS 1512+00 TO STATION 1572+00 REACH 4 cutback to within 10 feet of the road and replace<l by a vertical wall and bench. The bench should be at approximately the 24year flood elevation. This bench and wall tie into the bench and wall which are downstream of the Evans Avenue bridge on Sheet 14. This reach includes the Overland Park Golf Course on the right bank. There are no identified flood problems in this reach and other than a small area on the left bank whiCh rece1ves water from the overflow upstream of Evans Avenue. The removal of the Florida Avenue dam will result in a lowering of the channel bottom in this reach. The occasional QutcropsQfbedrockmayhave to be loosened by heavy equi pment and remo~ed to all ow tn i s deepeni ng pro- cess to occur. H<Jwever, it is anticipated that the majority of the channel lowering could be accomplished through natural processes rather than through actual excavation and removal. As the channel lowers it 1'1111 be necessarytoprovidebankprotectionasshowninOetail B,Sheet44. The recOfm1ended plan in this reach is limited structural improvements which will provide a lower 100-year water surface elevation downstream of the Evans Avenue bridge. These 1imited structural improvements in conjunction with the Evans Avenue bridge improvements on Sheet 14will eliminate the flooding on the left bank upstream of Evans A~enue. The 1 eft bank between Sanderson Gulch and Florida Avenue Should be cut back to within 10 feet of the road. At the Florida Avenue bridge the existing trail should be moved closer to the right abutment and the material between the existing trail ~nd the ri ver repl aced by a vert i Cd 1 retainl ng wa 11 . The Florida Avenue d.vn, 300 feet upstream of t!le Florida Avenue bridge, should bere<noved and the channel widened on the riqht bank 100 feet upstream and downstream of the da11. The Florida Avenue dam is used by the Denver P~rks Department to provide water for the Overland Par~ Golf Course and could be repl aced by a wellfield in the general vicinity, or by pumping from the two lakes w!lich are on the right bank of the $outh Platte River itll1lediately downstream of Florida Avenue. 1norder to P\lllP from these lakes, a diversIon structure would be constructed upstream of the existing Florida Avenue dam. The right h~nk between Stat inn~ 1556 and 156~ should be ",ove~ back toward the golf course 50 feet. An abandoned sewer line crossing at Station 1563 should be removed. The left bank b"'tweenStation 1567 and 1572 Should be The first priority for structural irnprovements in this reach is the rEl1loval oftheFloridaAvenuedamlnordertoachievethechannelloweringupstream necessary to provide capacity under the Evans Avenuebridqe. Cuttingback therlght bank next to the Overland Park G:llf Course and the construction of the wall and bench area on the left bank will tie into improvements made on Sheet 14. Th'" ~li)odplain "'~Mg~n"llt Strat"'9Y in this reaCh i<; to ",nC01J>'ag", n'lrcha,.. of floi)d Insurance and enforce floodplain manaqPment regulations. COST ESTIMATE SHEET 16 OF 45 SOUTH PLATTE RIVER STATION 1512+00 TO STATION 1572+00 CONSTRUCTION Drainage improvement costs Street crossill9 costs Utility relocation costs Total construction costs $849,633 15,/73 Engineering and contingencies (30% of total construction costs) Propert.yacqulsition R65,406 259,622 TOTAL 1MPROVEMENT COSTS 7,200 Sl,13l,228 OperaUon and Maintenance $16,863 l !