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APPENDIX M (cunt) <br />SMALL AREA EXEMPTION # 2 - SAE-2 <br />TOPSOIL STOCKPILE :SURFACE WATER CONTROLS <br />To control the runoff of sediment from the Topsoil stockpile, a perimeter ditch <br />and sediment trap will be constructed. In accordance with applicable regulations, <br />these calculations will show that the sediment containment structures are <br />capable of containing the design event. <br />SPECIFICATIONS <br />Area of pile 17,000 sgft 0.39 acres Ave. Slope = 16 °~ <br />Veg. cover = 70 °k <br />Length = 200 ft Soil Group = B <br />PEAK FLOW CALCULATIONS <br />1. From "Peak Flows In Colorado" P10 = 1.7" P25 = 2.1" <br />2. Runoff: CN disturbed and revegetated Use CN = 68 <br />RUNOFF Pe 10 = 0.11 inches Pe 25 = 0.23 inches <br />• 3. For Area = 1 acre & Slope = 16 °~ Slope Adj. Factor = 1.0 <br />4. For Hydraulic Length = 200 ft Equivalent Area = 0.93 <br />5. For CN = 68 and Area = 1 ac ; Peak Discharge = 2.7 cfslnch <br />6. Equivalent discharge q10 = 0.30 cfs <br />q25 = 0.62 cfs <br />7. The ACTUAL DISCHARGE is '010 = q10 " A / Ae = 0.12 ds <br />025 = 1.00 ' 0.77 / 0.93 0.26 cfs <br />8. VOLUME DISCHARGED is: X yr runoff' A/12 = 0.3"' 33,600/12 <br />V10 = 155.8 cult <br />V25 = 325.8 tuft <br />SIZE OF THE SEDIMENT TRAP <br />Length = 15 Depth below Grade = 2.5 <br />Width = 10 <br />The VOLUME of the trap will be 375 CUBIC FEET. <br /> <br />Mc Vol lil PAGE M - 3 10-1397 <br />