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C()1MENTARY SHEET 17 OF 45 STATIONS 1402+00 TO STATION 1455+00 "EACH 4 COST ESTIMATE SHEET 17 OF 45 SOUTH PLATTE RIVF.R STATION 1402+00 TO STATION 1456+00 CONSTRUCTION TheSoutbPlatteRlverlnthlsreacbflowstbrougharesldentlal and indus- trial area with nofloodifl<;l prob1ems. Drainage improvement costs Street crossing costs Utility relocation costs The recomnended plan Is limited structural Improvements lOhich would lower the water surface elevation and prevent overbank flooding on the left bank at Station 1470 on Sheet 15. Therecorm1endedimprovements include lowering the weir located 100 feet downstream of the Alameda Avenue bridge and a dd- Ing dbodtchute. This weir WdS constructed to protect the foundation of the Alameda bridge and now presents an obstruction to flood flows. In order to provide protection to tbe Alameda Avenue bridge foundations, the channel should be excavated approximately 3 feet and grouted riprap pla ced on the lowered bottombetW€en the !<lair structure and the bridge. It is expect!>d that 1,wering the Alameda Avenue !<Ieir and thecbanne1 under the Alameda Avenue bridge will result in a lowering of the channel upstream. 1n addition to lowering the channel bottom, the recoowended plan is to widen the cMnnel to 150 feet and cut back the right bank between the Alameda Avenue bridge and Station 1456. In order to prod de protection against erosion rock riprap should be provided dt the toes of the slopes on both banks as the river degrades, as ,;hownon Oetail 8,Sheet44. Total construction costs Eng1neerlng and cont1ngencies (30% of total construction costs) Property acquisition TOTAL IMPROVEMENT COSTS Operation and Maintenance The first priority for improvements on this sheet is the lowering of the Alalneda Avenue weir dnd installation of the boat chute. In order to pro- tl'ct th.. Al amf'da AVl'nul' bri dgf> it wi 11 bf> Of>CI'~~dr y tn ~ im'lltdnf>OU~ 1 y ex_ cavate the channel and install groutedriprap. \lidening the channel and cutting back the slopes can be implemented at a later date. The floodp1ai n management strategy for thi S re~Ch is to enforcement of floodplain management regulations. ~225.208 3,375 228,583 68,575 210,000 1507,158 $9,760