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a Unless other wise noted Figures or Tables referred to are <br />from P)ROCSDOSISS FOS DER'EF~1I~I19G PEASt FLQ~S II8 COLORADa; by SCS, <br />S.G Wilkes, E.C. Ring. <br />PEAK DISCHARGE FROM WATERSHED IN QUESTION. <br />Type IIA Storm, 100 yr/24 hr event, Elevation <8000 ft., <br />Area A=78.94 acres, Height of Drainage Z=672 ft., <br />Lc25 =3400 ft, Lc50 = 2000 ft, Lc75 = 1350 ft <br />Average cover assumed to be 408, Soil type C <br />CN=77.5 (Juniper-Grass) Fig. S-3 <br />Rainfall P=3.4" Fig. S-7 <br />Runoff in inches (interpolated) = 1.41 Table 2-1 <br />Slope Adjustment Factor (interpolated) = 1.273 Table E-1 <br />Calculations <br />Slope of drainage <br />S = 0.25Z(Lc25+L 50+Lc7~ = 0.25(1032)(3400+2000+1350) = 0.506 (50.68) <br />(Area)(43~60) (237)(43560) <br />Peak Discharge = 85 cfs/inch of rain Fig. S-lA Sheet 3 of 6 <br />q = Pd (runoff factor) (Slope factor) = 85(1.41)(1.273) <br />q = 152 cfs <br />CURRENT DRAINAGE SYSTEM <br />Length 3800 ft., width 1.5 ft, depth 0.5 ft., CN=77.5, P24= 3.4" <br />n = 0.029 from Fluid F7echanics nitb Engineering Applications <br />Table 11.1 pp 327 <br />Q = 1.41 inches <br />Manning formula V= (1.49/n)(Rh0.6667)(50.5) <br /> Calculations <br /> Rh = A/P =(1.5*0,5)/(2*1.5)+0.5 = 0.214 <br /> S = 1/3.68 = 0.272 <br /> V = 1.49/0.029 (0.214)•6667 (0.272)0.5 = 9.59 fps <br /> Tt = 3800/9.59 = 396.25 sec = 0.11 hrs. <br /> qp = 950 csm/inch Fig 5,2 <br /> q = g <br />AQ = 950(0 <br />123)(1 <br />41) = 155 <br />ff <br /> p <br />. <br />. <br />c <br />s <br /> FUTURE <br /> Modification of final 470 feet of channel by placing a 6 inch <br /> corrugated pipe under.the proposed fill. <br />a Length 470 ft, 6 inch pipe, Cn=77.5, P24 = 3. 4", n= 0.21 from <br /> Fluid Mechanics with Engineering Applications Table 11.1 pp 327. <br /> Q = 1.41 inches <br /> Calculations <br />7 <br />a <br />