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Asc-2 <br />• SEDIMENTATION RESERVOIR <br />NAME: REFUSE DISPOSAL AREA - STOCKPILE - PHASE IV <br />I. RUNOFF AND VOLUMES <br />Determine: <br />Maximum runoff area and peak discharge <br />Reservoir liquid volume <br />Reservoir sediment volume <br />Total reservoir volume <br />Area: 29.84 Ac of disturbed area for the stockpile - use 30.0 Ac <br />Precipitation: <br />P10 1.7 inch(es) (10-year, 24-hour precipitation event <br />from the Precipitation-Frequency Atlas of the West- <br />ern United States, Volume III, Colorado) <br />Curve Number: <br />The refuse material will have a high infiltration rate be- <br />cause 97% of the material will be larger than ~" in size. <br />Therefore, Soil Group B is used. From Figure S-4 in Peak <br />• Flows in Colorado for a dirt road CN = 82. Use CN = 85. <br />Runoff: <br />From Table S-3 (Page 65} <br />For P10 = 1.7 Q10 = 0.58 <br />P25 = 2.1 Q25 = 0.87 <br />Average Slope; <br />2:1 side slopes = 50% x 15.94 Ac = 7.97 <br />Level Areas = 0% x 12.75 Ac = 0 <br />Access Ramp = 6% x 1.31 Ac = 0.08 <br />30.00 Ac = 8.05 <br />8.05 = 0,268 or Average Slope = 26.8% <br />30 Ac <br />Slope Adjustment Factor from TR55 = 1.10 <br />Equivalent Area: 1 = 209a0.6 <br />Where 1 = 2,200 ft a = 50.96 Ac <br />From Figure S-lA with CN = 85 Area = 50.96 CFS = 62 <br />Equivalent Discharge10 = 62 x 1.10 x 0.58 = 39.56 CFS <br />Equivalent Discharge25 = 62 x 1.10 x 0.87 = 59.33 CFS <br />• Actual Discharge10 = 39.56 x 5096 - 23'29 <br />Actual Discharge25 = 59.33 x 30 = 34.9 <br />50.96 <br />These flows will be split with 1/3 to the north of the <br />