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bean <br />• NORP,IS SEDIPIENTATION POND <br />Flow Desion Calculations <br />1. Determine drainage area (Exhibit _). <br />Area 1 = 4.73 acres = 86.29'0 <br />Area 1A = 0.76 acres = 13.8% <br />Total area = 5.49 acres = 100.0% <br />2. Determine weighted curve number. (Pp 2-5,23,SCS)(Ah1C II) <br />Area 1 = 86.2% * 89CN = 7671.8 <br />Area lA = 13.8"0 * 79CN = 1090.2 <br />8762.0 <br />_> 87 .62 <br />• _> 88 CN <br />3. Determine precipitation <br />l0yr -- 24hr = 1.6 inches <br />25yr -- 24hr = 1.8 inches <br />4. Determine volume of runoff for CN88 (Pp 68, SCS) <br />l0yr -- 24hr = 0.66 inches <br />F 5.49 acres <br />= 3.62 acre inches <br />= 0.30 acre feet <br />25yr -- 24hr = 0.81 inches <br />5. Determine peak discharge of runoff CN88 (Pp 18 - FIG. S-lA, SCS) <br />25yr -- 24hr = 11.0 cfs/inch of runoff <br />< 0.81 inches <br />• = 8.9 cfs <br />