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Willits Pond #5 handles the runoff from the mining azea immediately north of the plant facilities. <br />This area is 3.6 acres. The calculations to demonstrate that this pond is adequate to contain the 100 <br />year 24 hour event aze shown below: <br />Design Volume Calculations <br />Willits Pond #5 <br />Area (acres) 3.6 <br />Design Event 100 yr. storm <br />Design Precipitation 2.8 Calculated S <br />Average CN 67 4.92537313433 <br />Description Porous Gravel Topsoil <br />Piles <br />Calculated Runoff Volume (Q) 0.4886955832 <br />Calculated Runoff Volume (acre-ft.) 0.14660867496 <br />Ponding Percentage 5 <br />Actual Runoff Volume (acre/ft.) 0.13927824121 <br />A CN of 67 is assigned to the gravel since it is neazly void of fines and almost all runoff penetrates <br />into the ground. This pond has a surface azea of 0.14 acres therefore, its required depth is 1.0 feet. It <br />will be dug 2.0 feet deep with 2H:1 V sideslopes. <br />Willits Pond #6 handles the runoff from the northern part of the mining azea. This azea is6.2 acres. <br />The calculations to demonstrate that this pond is adequate to contain the 100 yeaz 24 hour event aze <br />shown below: <br />Design Volume Calculations <br />Willits Pond #5 <br />Area (acres) 6.2 <br />Design Event 100 yr. storm <br />Alma Placer 7/03 28 <br />