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n <br />LJ <br />HYDROLOGIC DOCUMENTATION <br />SMALL AREA EXEMPTION <br />RAILROAD LOOP <br />The following calculations demonstrate that the railroad loop meets the intention of the CDMG Regulations, <br />section 4.0.2(3). The analysis was conductcd on the entire 70.8 acre reclaimed site. <br />Runoft'peak discharge and sediment calculations were performed utilizing the SEDCAD+ computer model. The <br />analysis was conducted using a l0-year, 24-hour storm event. <br />Hvdroloev Inputs <br />The curve numbers (CN) used were obtained Gom Procedures for Determining Peak Flows in Colorado and <br />Technical Release No. 55. Based on soil type and vegetation cover, curve numbers were determined for the <br />following condition. <br />Reclaimed <br />Soil Type: B (Topsoil) <br />Ground Cover: Good <br />Cover Type: Herbaceous <br />CN: 62 <br />• <br />• <br />All other hydrology inputs are shown on the attached SEDCAD+ computer printouts <br />SedimentoloQy In u~ts <br />Reclaimed <br />Soil Tvpe: <br />K factor <br />Average Slope <br />Average Slope Length <br />C: <br />P: <br />CP: <br />Hydrology Results <br />Peak Discharge: <br />Runoff Volume: <br />Sedimentolow Results <br />Sediment: <br />Peak Settleable Conccntra[ion: <br />(Topsoil) <br />32 <br />20 <br />40 Q <br />0.042 (no canopy, 60% ground cover) <br />0.6~ (moderate roughness) <br />0.27 <br />0.027 cfs <br />0?0 ac-ft <br />0.3 tons <br />0.42 mUl <br />i ,2 -o a. <br />S~Bn~iT~/9L Dry7E 9/~~/96 <br />