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• <br />Q10 425 Q100 <br />Drainage Q10 Q25 Q100 Total Total Total <br />Area cfs cfs cfs ac/ft ac/ft ac/ft <br />Explosive Storage Area 15.9 3.5 6.7 12.7 .27 .50 .94 <br />The explosive storage area impoundment is designed to contain the 10-year, <br />24-hour storm (65' x 65' x 3' deep) and capable of conveying, through an <br />emergency 24" CMP spillway, the peak flow (12.7 cfs) from the 100-year, 24-hour <br />storm event. <br />Two sediment traps on the reclaimed backfilled area (Map 11) were designed <br />• <br />and constructed to control erosion and sedimentation impacts from the 10-year, <br />24-hour storm event. Traps were designed with the intent to control erosive <br />flow velocities and located to minimize erosion and sedimentation impacts from <br />small areas within the disturbed area. Appendix 2.05.3-10 presents the flow <br />calculations and analysis. Traps are located on Map 9 and with flow calcula- <br />tions presented in Appendix 2.05.3-10A (Northwest Reclaimed Area) and Appendix <br />2.05.3-1OB (Southeast Sediment Trap). <br />Sediment collected in traps will be maintained using the procedures <br />outlined in the previous sedimentation pond section. <br />Sun Coal Company designed and constructed sediment structure outlet ditches <br /> <br />(Appendix 2.05.3-11) to control offsite erosion and sedimentation impacts pur- <br />suant to CMLRD 4.05.3. The outlet ditches are designed, with adequate free- <br />board, to convey the peak flow runoff from a 10-year, 24-hour storm and <br />riprapped, where necessary, to protect the channel from excessive flow veloci- <br />ties. Diversion ditches are located in the following areas: <br />- 192 - <br />(Rev. 5/86) <br />