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TABLE 4.2-12 <br />RUNOFF VOLUMES <br />The quantity of runoff from the areas D-1, D-2, D-3 and D-5 <br />are computed from the equation Volume of event = Pe x Area <br />The Pe is based upon the CN Values from Table 4.2-10 <br />and the amount of precipitation from the NOAA Atlas. <br />Basin Area Pe 10 Q10 Pe 25 Q25 Pe 50 Q50 Pe 100 Q100 <br />SQ FT Ac-ft Ac-ft Ac-ft Ac-ft <br />D-1 366,300 0.33 0.23 0.4$ 0.34 0.66 0.46 0.85 0.60 <br />D-2 93,900 0.20 0.04 0.32 0.06 0.46 0.08 0.62 0.11 <br />D-3 184,500 0.20 0.07 0.32 0.11 0.46 0.16 0.62 0.22 <br />D-5 121,968 0.09 0.02 0.17 0.04 0.28 0.07 0.36 0.08 <br />Runoff Area 766,668.0 <br />Required Runoff Volume 0.36 <br />SEDIMENT VOLUME -SEDIMENT POND <br />The run-off calculations presented are calculated based on <br />the maual -Procedures for Determining Peak Flows in Colorado - <br />published by the Soil Conservation Service dated <br />March 1984. <br />The topographic factor LS is difficult to evaluate for mountaious <br />drainage areas. According to the LS Factor table when the length <br />or slope exceeds 400 feet and or percent slope exceeds Z4 percent, soil <br />loss estimates are speculative as these values are beyond the range or <br />research data. Therefore an LS factor using 400 feet and 24 percent <br />slope will be used for this calculation. <br />A=RKLSCP <br />R =rainfall factor 30.00 <br />K =soil erodibility factor 0.37 <br />LS =combined length slope factor 400' - 24°/G 2.40 <br />C =cropping management factor 1.00 <br />P =erosion control practice factor 1.00 <br />A =sediment, tons/acre/year 26.64 <br />ONE YEAR SEDIMENT VOLUME - 0.19 <br />ACRE FEET <br />MC Vol I PAGE 1 Tft-00 10/05 <br />