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Determinina Pond Surface Area: <br /> Pond Surface Area (ft2)A�, = 2083 x Q�nflow <br /> Where: Qinflow (cfs) = CiA <br /> Where: C = Composite Runof f Coef fecient <br /> i =Average rainfall intensity `n "n <br /> hr Tn <br /> m,n = dimensionless coef fecients given <br /> by COESMM table 5.2 in appendix H <br /> m = 6.31,n = 0.575 for 10 year event,at this location <br /> T = Time of Concentration(minutes) = 6ov <br /> Where:L = longest flow length for basin(ft) <br /> V = average velocity �S`) = k so <br /> W here: k = time o f concentration f actor (St) <br /> so = slope of flow path (ft) <br /> ft <br /> Ap = 2,083 x 13.45 cf s = 27,449 f t2 <br /> Determininp Riser Dimensions: <br /> • Dewatering Orifice <br /> Area =Ao (inz) = 1.44�per cfs of inflow <br /> Where h = head of water above orifice in feet <br /> Diameter=D (in) = 1.13 Ao <br /> D = 1.13( 1.44 3.5)=6.8" <br /> Use 7"� Dewatering Orifice for pond. <br /> • Polyethylene Drainage Tubing Diameter= 2" larger than Dewatering Orifice <br /> Use 10"� Polyethylene Drainage Tubing or nearest size larger than 9" <br /> � OverFlow Riser Diameter <br /> Determiined using Figure 3.5 in Appendix H <br /> Use 18"� corrugated metal riser for both sediment ponds. <br /> Page � 10 <br />