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• with the Division in order to determine appropriate curve numbers (Trapper, 1986). The curve <br />number of 47 for AMC II conditions was determined to be applicable to undisturbed drainages. <br />The antecedent moisture condition III was chosen for this analysis to represent a spring season <br />worst case condition. The curve number of 87 corresponds to this moisture condition. <br />Runoff volumes and peak runoff rates were generated for both the 10 -YR, 24 -HR and 100 -YR, <br />24 -HR rainfalls using the SCS curve number method incorporated into the computer package <br />(Sedimot II). A type II storm distribution was used with rainfall depths of 1.7 inches and 2.5 <br />inches for the 10 and 100 year rainfall depths (Trapper, 1980). The time of concentration was <br />calculated using the equation: <br />I. = [(0.0078 L") (UH)°)j/e0 <br />where: I, =time of concentration in hours <br />L = length of longest water course (ft) <br />H = elevation change of longest water course (ft) <br />A total of eight sub -basins were analyzed, namely: West, Middle and East Pyeatt; and West <br />• Flume (Grouse and Sage), Middle West Flume (Oak), Middle Flume (West Flume), Middle East <br />Flume (Middle Flume) and East Flume (East Middle Flume). The input into the calculation is <br />given in Tables 2.7-12a and 2.7-12b. The locations of the drainages are given on Map M51 <br />(names in parentheses are new Map M51 nomenclature). The storm hydrograph volumes and <br />peak runoff rates for the eight basins are given in Table 2.7-12a. <br />Runoff volume for the 10 -YR, 24 -HR storm event with an antecedent moisture condition of III <br />ranged from 1.16 to 10.2 acre -ft. This volume corresponds to a runoff of a .09 inch per unit area. <br />The 100 -YR, 24 -HR storm volumes ranged from 4.57 to 40.0 acre -ft. This corresponds to a <br />runoff of .36 inches per unit area. The <br />• 2414e <br />" X998,..... <br />