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reach 6 existing channel 0.9 0.011- <br />0.060 trap, 1x1 7-60 cfs <br />reach 7 existing pipe < 6 cfs 0.002 36" 35 cfs <br />reach 8 existing channel < 6 cfs 0.058 trap, 5x5 400 cfs <br />reacfi 9 existing pipe 0.9 0.044 24" 21 cfs <br />reach 10 channel 4-5.1 cfs 0.010 trap, 2x1 6.4 cfs <br />reach 11 existing pipe < 6 cfs 0.030 30" 30.9 cfs <br />reach 12 existing Swale 0.5 cfs 0.040 tri,0.5x10 7.0 cfs <br />reach 13 channel 0.5 cfs 0.041 tri, 1x1 4.9 cfs <br />5.4 Riprap Design for the Fastside Drainage Channel <br />The sizing of riprap for the Eastside drainage channel was completed using two methods. <br />The first is a stability analysis technique proposed by Simons and Sunturk (see attached <br />worksheet), the second is a procedure used by the Colorado Department of Highways and <br />outlined in "Roadway Design Manual" 1990. The results are as follows. <br />~ Simons and Sunturk: bed dso = 12 inches <br />bank dso = 18 inches <br />Colo. Dept of Highways: bed dsu = 10 inches <br />bank dso = 14 inches <br />As you can see the CDH technique results in a slightly lower dso that the Simons and <br />Sunturk method. Based on these results I recommend a bed dso = 12 inches and a bank dso <br />= 14-18 inches. These sizes are based on a side slope of 2:1 which is a recommended <br />minimum for scouring channels. The gradation for the riprap mixture should be as indicated <br />below. <br />size (in) dso dzo dso dao dso dao dso dea dvo d~ao <br />dsa=12, 14' S 7 9 11 14 16 19 21 25 26 <br />dso=18" 7 9 12 14 18 21 24 27 32 36 <br />The thickness of the riprap layer should be at least I.5 times the dso dimension. Standard <br />construction practices, including base preparation and well graded base material should be <br />followed. <br />U <br />8 <br />June 1995 <br />