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VIII-2 engineering data are for the use of the designers and reviewers in handling the master planning effort. Each reach is described below in narrative form. The narrative was adopted from Stevens 1983 report to the Urban Drainage and Flood Control District and for that reason the river reaches are delineated differently than for the overall master planning and hydraulic analysis. TABLE VIII-l SOUTH PLATTE RIVER CHARACTERISTICS ChatfIeld to ColumbIne HMlpden Sand Cre<>< !04th Geometrlc Parameter Columblne to Hampden to Sand Creek to 104th to Brlghton Ch er acter of Reach Rural Suburban Urban Suburban Rural MllIJor drops, number 2 2 9 2 2 Major drops, feet 14 19 57 10 13 Overall slope 1O.87 ft/ml 13.74 ft/ml H.52 ft/ml 9.51 ft/ml 8.06 ft/ml Slope between drops 7.33 ft/ml 11.96 ft/ml 7.39 ft/ml 6.71 ft/ml 6.83 ft/ml SInuosIty 1.02 1.25 !.09 1.18 1.26 Bankfull wIdth, feet 264 2!2 192 372 347 Botton wIdth J feet 160 160 120 250 250 Depth, feet 6.5 9.3 13.4 7.3 6.8 WIdth to depth ratIo 41 23 14 51 51 Bars per mIle 10 9 4 8 7 StabIlity of banks ErodIng SemI-stab Ie Stab Ie SemI-stable Erodl ng Chatfield Reservoir to Columbine Valley. This reach is characterized by the Littleton Floodplain Park and gravel pits. It is 3.7 miles long with a slope of 10.87 feet/mile for a total drop of 4D feet. The first 4,700 feet of river bed is channel constructed as part of the Chatfield Dam construction. The channel is 100 feet wide, Where the outlet channel empties into the South Platte River, there is a check dam of rocks which drops approximately 6 feet. Thereafter, the river flows in its natural channel for which the bottom is 160 feet wide on the average. The high bank is approximately 7 feet high, There is a sewer line encased in concrete across the riverbed immediately downstream from the State Highway 470 bridge. The sewer line has been exposed due to river bed and bank erosion. Thereafter, the South Platte River is eroding its banks in places. The river has moved itself appreciably, probably aided by the gravel mining operations. Between 1964 and 1978, the maximum lateral movement of the meander loops has been approximately 900 feet. The reach between C-470 and Columbine Valley is planned to remain in a semi- natural condition as a floodplain park, however, bank stabilization is a high priority. The river is termed rural in this reach. Columbine Valley to West Ha~pden Avenue. In this 5.6 mile reach which drops 77 feet, the South Platte is a suburban river. The sinuousity is 1.25. The outside banks on most of the bends have been blanketed with rubble to stop the bank erosion. In places, the low bank has been built up with fill and the river pinched to a narrower width.