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COMMENTARY Sf-IEET70f45 STATION 1916+00 TO 1972+00 REACH 1 CiJ'1MENTARY SHEET7OF45 STAT10N 1916+00 TO 1972+OO REACH 1 (Continued) The southern portion of the floodpla1n on this sheet consists oft he South Platte Park (Littleton Floodplain Park). Further north the floodplain begins to encroach on the City of Col<Kllbine Valley. The river itself meanders considerably with several sharp bends. Lateral migration is evident in distances up to 800 feet. Bank erosion exists and in some places is severe. will be reduced significantly, most specifically downstream of Station 1940+00, floodplain re9ulations should be superimposed on therecOIllTlended improvements. Prior to theconstruct1on of the recorrmended improvements, floodplain management practices should be in accord with the flOOd hazard identified fOr ti1e existing channel conditions. The improvements proposed to the southern portion of this reach are limiteo to protection of bank frem erosion. At Station 1940+00 the delineation between Reaci1 I and Reach 2 exists. Reach I will be protected using prima- rily vegetation or riprap with vegetation in order to stabilize the channel banks. The northern portion of ti1is sheet is located within Reach 2 and is the area of th<> Corps of Engineers proposed chan~el improvements. These improvement> are being designed and constructed by the U.S. Army Corps of Engineers. COST ESTlMATE SHEET 7 OF 45 SOUTH PLATTE RIVER STATION 1916+00 TO STATION 1972+00 Bank protection prodded in this study inCludes riprap with vegetation as ,hown on ~tail II on Sheet 44 between Stations 1956+50 and 1972+00. Thi, protection is located along the west channel bank as intended to protect the overhank gravel pit lake embankment from erosion. Between Stations 1940+00 and 1956+50 v~etation is proposed along portions Of both banks in order to prevent erosion andmeanderlng of ti1eriver. Only the portion of the banks exposed to less frequent floods will be protected solely by vege- tation. Thelowflowchannelwi11 be protected with riprap. CONSTRUCTION Orainage improvement costs Street crossing costs Utility relocation costs Total construction costs $713,100 Engineering and contingencies (3~ of total construction costs) 213,100 63,900 In areaswl1ere there is no reolJCtion in the flOOdplain limits, floodplain regulations shnulrJ ho> pnfnrcP<i. This will inswe that no il11prudent devel_ oP'llent OCCtJl', in the 100-year floodolain. In areas wI1ere the floodplain Property acquisition TOTAL :MPROVE~ENT COSTS Operation and Maintenance 277,000 ~13,320