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COMMENTARY SHEET 16 or: 45 STATIONS 1456+00 TO STATION 1512+00 REACH 4 CCtlMENTARY SHEET 16 OF 45 STATIONS 1456+00 TO STATION 1512+00 REACH 4 (Continued) land use on both banks is primarily industrial. A floodplain area on the left bank between Stations 1470 to 1477 is cause-d by the low banks. The flooding in this area is approdmately 2 feet deep. In many locations the overbank areas are lower than the existing 100.year flood elevation, but are not flooded because of the levees along the river. All the improvements in this reach have approximately equal priority. Thereconrnended plan is limited structural improvements l>t1ichwill elimi. nate the 100-year floodplain on the left bank and reduce the probability of the 100.yearflood affecting the Mississippi Avenue bridge. from Station 1456 to 1464 the right bank should be cut back 20 feet. The Channel bottom should be lowered approximately 2 feet from Sat ion 1456 to 1480 and the banks protected with riprap as shown on Detail B, Sheet 44. At Station 1480 a Highway Department dam has been replaced at an elevation 5 feet lower than the d~~ which existed at the time of the mapping for this study. It is expected that this lower dam will cause a lowering of the channel bottom from Station 1480 to Station 1493. At Station 1493 the weir pro- tecting a pipe crossing for the Gates Rubber Company has been reconstructed by the Urban Drainage & flood Control District. If it were lowered another 2 feet it would allow the water to flow under the Mississippi Avenue bridge dl.ll'ing the 100-year flood, however, this is not areCOl1l11endation of the Phase B report because the Mississippi Avenue bridge is schedulP<1 to be ~epl aced. In order to provide additional capacity, the debri s and rock which have accumulated at the base of the walls on both banks between Stations 1474 and the Missi%ippi Avenue bridge should be removed and the walls on the 1 eft and right ban~s deepened to provide adequate protect ion iigainst erosion damage. The floodplainrnanagement strategy in this reach is to encourage purchase of flood insurance for those structures in the identified flood hazard area and enfo~ce flOOdplain rnana~ement regulations. COST ESTlM,Uf SHEET 16 OF 45 SOUTH PLATTE RIVER STATIOM 14,6+00 TO STATIOM 1517+00 CONSTRUCTION O~ainage improvement costs S817, 379 Street c~ossing costs 3,000 Utility relocation costs Total construction costs R20,379 Eng;neer;nq and contingencies 246,114 (30% nf total construct ion co~t.s) Propertyacguisition 135,000 TOTAL IMPROVEMENT COSTS n,19R,493 Ooe~ation and Maintenance $8,280