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I ~ The trap will be designed to contain the 100 yeaz runoff of 0.30 acre-feet and O.OS ac-ft for sediment <br />buildup using a sand and gravel dam that will detain the water for 24 hours but will allow it to seep <br />through so that the water is returned to the natural drainage. The dam will be less than 6 feet high <br />and will have 2.SH:1 V sideslopes. The trap azea as shown on Map C-2 is 0.095 acres, therefore the <br />average depth is 3.7 feet. Much of the volume will be attained by excavation within the pond area. <br />Collection Ditch #1 will be v-ditch of 1.5 feet depth and 2:1 sideslopes cut out of the natural gravel <br />and shale below the gravel deposit. No lining is needed. After reclamation, these two detention <br />basins and their associated collection ditches will be regraded and reclaimed. <br />C) Sediment Pond #2 and Collection Ditch 4 that handle runoff from the majority of the eastern <br />disturbed azea. As is seen on Map C-2, the sediment pond will drain an area of 8.07 acres. The <br />calculations for runoff volume aze shown below: <br />Design Volume Calculations Sediment <br />Pond #2 <br />Area (acres) 9.38 <br />Design Event 100 yr. storm <br />Design Precipitation 2.2 Calculated S <br />Average CN 83 2.04819277108 <br />Description Undisturbed South facing Slope <br />and Part Undisturbed Pinon <br />Juniper <br />Calculated Runoff Volume (Q) 0.83505245086 <br />Calculated Runoff Volume (acre-ft.) 0.65273266575 <br />Ponding Percentage 4 <br />Actual Runoff Volume (acre/ft.) 0.62662335912 <br />Bellgardt Pit 1/06 13 <br />