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HYDROLOGIC DOCUMENTATION <br />SMALL AREA EXEMPTION <br />EXPLOSIVES BUNKER AREA <br />The following calculations' demonstrate the amount of sediment fence surface area required to <br />adequately handle the runoff from the explosives bunker area and the parameters of a clean water <br />diversion berm and collection berm that will adequately control run-on and run-off from the <br />Explosives Bunker Area. <br />Runoff volume and peak discharge calculations were performed utilizing the SEDCAD+ <br />Computer Model consistent with the methodology previously discussed in this exhibit. The <br />sediment fence, diversion berm, and collection berm were designed to handle the peak discharge <br />from a 10-year, 24-hour storm event. <br />1.0 South Diversion Berm <br />1.1 Hydroloeic Inauts <br />All hydrologic inputs are shown on the SEDCAD+ computer printouts. <br />The CN numbers used For the berm watershed were obtained from Procedures for <br />Determining Peak Flow in Colorado and Technical Released No. 55 (USDA-SCS. 1980). <br />Based on soil type and vegetation cover, curve numbers were determining using Table 2- <br />2a and 2-2d, USDA-SCS TR-55, for the following conditions: <br />Disturbed: <br />Soil Type: B <br />Ground Cover: <30%, Poor <br />Cover Type: Pinyon -Juniper <br />CN: 75 <br />1.2 Hydrolog~Results <br />Peak Discharge <br />10-year, 24-hour event 0.48 cfs <br />1.3 Berm Desien <br />The berm was- designed using Manning's Equation Far open channel Flow assuming a V- <br />shaped channel. The results are summarized as follows: <br />Channel slope: I.0 % <br />Side slopes: 2H:1 V <br />Manning's n: 0.035 <br />Depth of Flow: 0.4 ft <br />Velocity: 1.4 fps <br />Berm height: 0.7 ft <br />Freeboard: 0.3 <br />1 <br />~ J <br />