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<br /> <br />Mr. Luke Russell -2- September 21 1993 <br />of the subbasin runoff computations and the estimated runoff amounts are shown in <br />Table 1. <br />TABLE 1 <br />BULLDOG MINE <br />24•HOUR RUNOFF COMPUTATION SUMMARY <br />24-hour <br />SCS Rainfall Runoff Peak Flow <br />Area Curve PMP/100 yr PMP/100 yr .PMP/100 yr <br />subbasin (ac) Number (in) (in) (cfs) <br />Upper Tailing Pond 85 55 16.0/2.8 9.15/0.13 513/3 <br />Lower Tailing Pond 177 55 16.02.8 9.15/0.13 1,296/8 <br />Windy Gulch Above 982 55 16.0/2.8 9.15/0.13 3,549/24 <br />Waste Dump <br />Channel Capacity <br />Parameters used in evaluating existing channel capacities are based on Manning's Equation <br />for open channel flow. They include the existing channel bottom width, side slope, channel <br />slope, channel roughness, and flows developed in the hydrologic evaluation discussed <br />above. The Windy Gulch channel evaluation includes parameters based on two different <br />channel slopes and two different side slopes. The evaluation of the Lower Tailing Pond <br />diversion channels utilizes a flow of one half the PMP and 100-year events, as the two <br />channels each route one half of the runoff. A summary of the channel evaluation <br />parameters for the PMP and 100-yeaz flows is listed in Table 2. <br />