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Oesian Calculations <br />Hvdroloav <br />Hydrology Inputs <br />Pond 1 Drainage area is shown on the Drainage and Sediment Control <br />Map (Map 20). The drainage area is divided into the following <br />subwatersheds: <br />• JBS 111/SWS 1 The coal stockpile area which drains to <br />drop structure and 12-inch culvert <br />• JBS 111/SWS 2 The coal stockpile area which drains to yard <br />catch basin <br />• JBS 111/SWS 3 The east part of the facilities area <br />All hydrology inputs for subwatersheds are shown on Table 2. SEDCAD+ <br />Version 3.0. Pond 1 and Associated Structure. <br />• The CN numbers used for Pond 1 watershed were obtained from Procedures <br />~ ' for Determining Peak Flows in Colorado and technical Release No. 55 <br />(USDA-SCS, 1980). Based on soil type and vegetation cover, curve number <br />were determined using Table 2.2a and 2.2d. USOA-SCS TR55. for the <br />following conditions: <br />Undisturbed <br />Soil Type: B <br />Ground Cover: ~Ox, Poor <br />Cover Type: Pinyon, Juniper <br />CN: 75 <br />Disturbed <br />Soil Type: B <br />Ground Cover: Dirt Road <br />CN: 82 <br /> <br />14 Revised 4/70/96 <br />Minor Revision No. 30 <br />