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<br />COMMENTARY <br />SHEET 18 OF 4S <br />STATIONS 1347+00 TO STATION 1402+00 <br />REACK 4 <br /> <br />C()IMENTARY <br />SHEET 18 OF 45 <br />STATIONS 1347+00 TO STATION 1402+00 <br />REACH 4 <br />(Continued) <br /> <br />The river flows parallel to Interstate 25. The de~elopment on both banks <br />of the river is primari1yindustrial. The l00.year floodplain in,ludes90 <br />acres on the left bank between 6th A~enue and 3rd Avenue, 33 acres between <br />6th Avenue and theronfluence of Weir Gul'hontheleftbank,andlla, re, <br />on the right bank at 8th Avenue. In many locations the overbank areas are <br />lower than the existing IDO-year flood elevation, but are not flooded <br />be,ause of levees along the river. <br /> <br />right banks through this reach is below the river banks. lnaddition,the <br />abandoned3rd Avenue bridge should be removed slnce 1t Is impacted by the <br />100-year floOd and could serve as a debris ,at,her. <br /> <br />In this reach the channel lowering and deepen t n':l should receive fir,t pri_ <br />or1tyfor implementation. All improvements in this rea,h should be tied <br />clo,ely to improvements carried out on Sheet 19 downstream. <br /> <br />ThereCOlllllended plan for this reach is limitedstru,tural improvements in_ <br />cludin9 lowering the,hannel bottom by excavation from Station 1347 to the <br />base of the 3rd A~enue d <n at Stat ion 1390. Loweri ng the ,hanne 1 bottom in <br />this reach will require modifications to bridges at 3th Avenue, 6th Avenue, <br />and the railroad at 3rd Avenue to a,commodate the deeper channel. The <br />channel should be widene<1 to provide amini'11umwidthaf 120 feet throuqh <br />this reach. In order to maintain a stable slope, it will probJbly be <br />necessary to provide rock drop structures which would be desiqned to <br />provide riffles for fish and wildlife. To provide a wider ChJnnel, the <br />ex i st ipg pedes tri an trai 1 underneath 8th A~enue on the 1 eft bank shaul d be <br />moved next to the left Jbutment an~ set on a ~erticill r€tilining w~ll, and <br />the pedestrian brldqe upstream of 3th Avenue should be modified with J left <br />span 20 feet wi der. At the 6th A~enue bridge, the tr ai 1 shoul d ill so be <br />moved i1djacent to the right i1butment and placed on top of aretainin gwall. <br />Two areas on the right bank should be benched to provide additional flow <br />capacity and to pravide a pocket pdrk settingbetwnenStation 1347 and 1355 <br />and upstream of 6th Avenue between Stations 1371 and 1316. Ihetoesofthe <br />ex;sting slopes should be protected u~ing ~pck riprap. These improv~..nts <br />will permit the lOO_year flood to be lo....ered suffi,iently to allow some <br />freeboard bplow the nJtural Ddnk<; ,incemllch nf the area on thel"ft and <br /> <br />The floodplain management strategy in th1sreach is to encourage purchasl' <br />of flood insurance for those <;tructlJres in the idl'ntified floodplain, and <br />enforce floodplain manaqement regulat;ons. <br /> <br />COST ESTlfolATE <br />SHEET III OF 45 <br />SOUTH PLATTE RIVER <br />STATIO~ 1347+00 TO STATION 1402+00 <br /> <br />CONSTRUCTION <br /> <br />Orainageimprovementcosts <br />Street crossinq costs <br />Utility relocatIon costs <br /> <br />$1.392,778 <br />289,556 <br /> <br />Total construction casts <br /> <br />1,682,334 <br />504,700 <br /> <br />Engineering and contingencies <br />(30% of total construction ,ost,) <br />Property acquisition <br /> <br />TOTAL IMPROVEMENT COSTS <br /> <br />270,000 <br />$?457,m4 <br /> <br />()pef'ation and Maintenance <br /> <br />$21,9/0 <br />