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The pond volume below the emergency spillway will be comprised of two design needs: <br />1) 10 year storm inflow of 4.8 acre -ft, as described above <br />2) 3 year sediment delivery of 0.1 acre -ft, as based on the calculations shown below. <br />Therefore, the total design volume below the emergency spillway is 4.8 + 0.1 ac -ft which is 4.9 <br />acre -ft. As is shown on the stage storage relationship, the bottom of the emergency spillway is <br />5559', which has a volume of 9.9 acre -ft at this elevation. <br />Pond Volume Calculation based on Universal Soil Loss Equation (SuivCAD) <br />Input Data <br />Landuse Area Rainfall Erod- Length Slope Ls Cf Pf <br />(ft " 2) Factor ability (ft) (%) <br />Reclamat 4491645.8 50.0 0.37 4840.0 3.7 1.73 0.04 1.00 <br />Runoff = 0.563 inch. <br />Sediment Density = 175.000 <br />Time = 3.0 years <br />Drainage Ratio = 0.84 <br />Total Area = 103.114 acres <br />Gross Erosion = 131.772 tons /yr. <br />Total Yield = 110.688 tons /yr. <br />Runoff Volume = 4.838 acre -ft <br />Sediment Volume = 0.087 acre -ft (3 -year total) <br />Total Volume = 4.925 acre -ft <br />* The Cf factor is determined from the chart on page 5, shown in Design Hydrology and <br />Sedimentology for Small Catchments by Haan, Barfield and Hayes. Based on an approximate <br />ground cover of 70% for permanent pasture, a Cf factor of 0.04 was used, which is <br />conservative. <br />REVISED AUGUST 2009 Attachment 2.05.3(3) -6 -8 <br />