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Use a 2' orifice in bottom pla[e of CB 1114. <br /> Tc = 300 ft. = 3.57 min. + 10 min. = 13.57 min. <br /> (1.4 ft./sec.) (60 sec.) <br /> Q25 = (0.41) (1.90 in./hr.) (3.79 ac.) = 2.95 ft.3/sec. <br /> Filling Time = 4600 f .3 <br /> 2.95 ft.�/sec. - 1559 sec. or 26 min. <br /> Therefore Tc = 26 min. + 14 min. = 40 Tin. <br /> So Q = (0.41) (1.10 in./hr.) (3 J9 ac.) = 1.71 cfs <br /> Assuming the grate eleva[ion of the restrictor catch basin is 5.68 fee[ <br /> above the top of the riser and an underground detention system, fron <br /> Figure 6, by extrapolation, a 15" riser. will be required. <br /> Use 15" CP outlet pipe at SL = 0.0050; capacity of 15" CP ' 4.95 cfs <br /> 1.71 cfs. <br /> AREA 2 Qallow = O.Oi cfs _ <br /> h = 4.92 <br /> D = 6.12 0.07 cfs <br /> (4.92) : <br /> D = 1.03": Use 2.00" <br /> Use a 2" orifice in bottom plate of CB IiS. <br /> Tc = 280 ft. = 3.33 min. + 10 min. = 13.33 m_n. <br /> (1.4 ft./sec.) (o0 sec.) <br /> Q25 = (0.53) (1.92 in./l�r.) (1.07 acres) = 1.09 ft.3/sec. <br /> Filling Time = 1705.56�it.3 = 1565 sec. or 26 min. <br /> 1.09 ft. /sec. <br /> Thereforn Tc = 26 min. + 13 min. = 39 min. <br /> So Q = (0.53)(1.10 in./hr.) (1.07 acres) = 0.62 cfs <br /> Assuming the grate elevation of the restrictor catch basin is 4.92 feet <br /> above the top of the riser and an underground detention sys[em, from <br /> Figure 6, by extrapolation, a 12" riser will be required. <br /> Use 12" Q' outlet pipe at SL = 0.0050; Capaci.ty ef 12" CP � 2.75 cfs <br /> 0.62 cfs. <br />