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- V 1 - <br /> <br />' For comparison purposes, estimation of peak flow at the gaging station location <br />1 near the mine will also be done using S(:S. The procedure is slightly different <br />- since the larger area involves rating flow from several subareas, with different <br />' curve numbers. The procedure used is outlined in SCS Technical Release No.55. <br />The calculations are summarized on the work sheet that follows. <br />The basic procedure is: <br />r <br />' 1. Summarize data for each subarea (Figure H.7) <br />Drainage Area <br />' P24 for 10-year frequency <br />Curve Number (from Table H.9) <br />Runoff, Q (in., from Table H.8) <br />' (Subarea 2 is the Sunlite Ski Area, a much higher CN value was assumed) <br />' 2. Determine Tc and Tt for each subarea <br />Tc is from Figure H.8 <br />' Tt is calculated as Tt L/(V x 3600 sec/hr) <br />where L is channel length <br />V is channel velocity (3fps was assumed) <br />3. Determine hydrograph coordinates for each subarea. Using Figure H.9 <br />' according to Tc and Tt, hydrograph coordinates (qp, cfs per sq.mi. per inch) for <br />' each hydrograph time can be obtained. The runoff values (q,cfs) are then computed <br />by <br />1 q=gpAQ <br />1 <br />~1 <br />41 <br />