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1 <br />:`" • Collection Ditch for South East Side of Pile <br />Area: 19.0 Acres = Aa <br />CN = 88; Appendix X, Permit Application, Pond 6 <br />Precipitation Event: 100 year 24 hour <br />Precipitation: 2.2 inches; figure S-7, Peak Flows. <br />Direct runoff: 1.13 inches; Page 68, Peak Flows <br />Average Slope: S = 0.25z (Lc25 + Lc 50 + Lc 75)/DA <br />z = Elevation Difference, ft <br />Lc~9 = Contour Length, ft. <br />Da = Drainage Area, ft2 <br />S = 0.25 (310)(1710 + 1230 + 360)/19.0 (43560) <br />S = 0.31 <br />Peak Flow Caicuiations <br />`.;• ] = Slope Length ='1800', Exhibit 9C <br />Ae = Equivalent Area = (1/209) 1.667 <br />_ (1800/209) 1.667 = 36,2 acres <br />qe = Unadjusted Peak Discharge = 50.0 cfs/in runoff <br />(36.2 acres, 16% slope, Type II storm, CN 88 <br />Figure S-lA Page 18, Pf~ak Flows <br />Slope Adjustment = 1.15 Table E-1, Peak Flows <br />Qe = (50.0 cfs/in. runoff)(1.13 in runoff) 1.15 = 65.0 <br />Qa = Actual Peak Flow = qe (Aa/Ae) <br />= 65.0 (19.0/36.2) = 34.1 CFS <br />3/4 LMR NEW 10-23-87 <br />~- ~. <br />~. <br />CRDA1 - 12 <br />