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A. Using the method described in the Engineerino Field <br /> <br />Manual for Conservation Practices, USDA, Soil Conservation <br />Service: <br />1) Estimated maximum watershed = 40 acres <br />2) Soil Hydrologic Group = B <br />3) Estimated depth of runoff, assuming type II, 10 year - <br />24 Hour storm intensity, plus 10% safety facl;or = 3.7 <br />inches. <br />4) 4atershed slope = steep, 8% or greater. <br />5) Runoff curve number, assuming average antecedent moisture <br />condition = 60. <br />The peak discharge or runoff was found to be 15 cubic <br />feet per second (cfs). <br />6. Based upon the Field Engineering Manual for Con~;ervation <br />• <br />Purposes and the Handbook of Channel Design for Soil and <br />Water Conservation SCS-TP-61, the diversion structure <br />will be constructed according to the following criteria. <br />1) Tire diversion discharge will empty at a natural outlet <br />located approximately 150 feet from the fina'I toe of <br />the waste dump. (See Exhibit F). <br />2) A stand of vegetation with an average height of from <br />2 to 6 inches will be established in the bot~:om of the <br />parabolic diversion structure. This will yield a per- <br />missible velocity through the diversion channel of from <br />2.0 to 3.0 feet per second. <br />Therefore, a diversion channel 2.3 feet deep, with an 11 foot <br />r <br />top width, and 1050 feet lono at a 1.0% grade will be constructed. <br />E-4 <br />