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Runoff from the initial gold mining area and the prep plant azea will be directed to Pond A. Although <br />Pond A generally contains water, it is never allowed to be within 3 feet of the top of the dam. There- <br />fore, storage volume is available for stone runoff. <br />Design Volume Calculations <br />Sediment Pond #A <br />Area (acres) 31.1 <br />Design Event 100 yr. storm <br />Design Precipitation 2.8 Calculated S <br />Average CN 72 3.88888888889 <br />Description Porous Gravel Topsoil <br />Piles <br />Calculated Runoff Volume (Q) 0.6918128655 <br />Calculated Runoff Volume (acre-ft.) 1.79294834308 <br />Ponding Percentage 35 <br />Actual Runoff Volume (acre/ft.) 1.165416423 <br />Since only 1.0 acre feet of storage is needed and the pond contains 1.65 acres x 3.0' height = 4.95 <br />acre feet available, the pond is more than adequate to contain the runoff from the 100 yeaz storm for <br />the drainage area designated. Pond A will also handle the runoff from the sand and gravel mining <br />operation. The lazge pond azea combined with the porous pond bottom will ensure that the water <br />seeps into the ground to replenish the water from the pit pumping and to ensure that no dischazge <br />occurs from the site. <br />Alma Placer 7/03 16 <br />