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Storm Drainage Calcs. - Evergreen Business Park - 2- Sept. 27, 1979 <br />Additional Storage due to Lag Time (cont�d.) <br />Additional Storage Required = 0.28(5.0)(60) - 83 <br />Total Storage Required = 1973 cf. <br />Storage Provided <br />Parking Lot - 13C00 sf. 6" deep = 2167 cf. <br />Sizing Orifice @ CBMH 2 <br />A= �/ C d�= 0.55/0.63 64.4(3.12 = 0.06 sf, <br />Dia. - 4A = 0.28 ft. = 3.33 in. <br />'TI' <br />Use 3-3/8" dia. orifice. <br />Check o for 3-3/8" orifice with 3.12 ft, head. <br />A=�RDZ = 8.95 in.2 = 0.06 ft,z <br />T <br />�- Cda 2gh = 0.55 cfs. OK. <br />Check capacity of 12" CMP. <br />Flow Full 0.55 cfs. - Slope 0.5% min. <br />(Chart 2) <br />For West Portion <br />Pre-development <br />VE = 0.2(2.091(0.43 x 43,560) = U.?(2.09)(1561) = 657 cf. <br />12 <br />Post-development <br />VD = 0.77(2.09)�1561) _ <br />Run-off Differential = <br />z512 <br />1861 cf. <br />