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� ; �'� <br /> � i <br /> � <br /> ��Facility Area at 84.5 ft = 3,909 sf <br /> � Facility Area at 90.5 ft = 12,082 sf <br /> �Facility Volume between EI. 84.5 and 90.5 = <br /> � (3,909 sf + 12,082 sf) x (90.5 —84.5 ft) = 47,973 cf <br /> 2 <br /> The mounding analysis (see Appendix A) shows that the entire volume will be recovered. <br /> in less�than 30 days through percolation. For example, the mounding analysis shows that <br /> , after 2�06 hours (8.6 days) 47,957 cubic feet of runoff have been recovered by percolation, <br /> which 'is greater than required 47,916 cubic feet. <br /> , � <br /> "EMERGENCY" OUTFALL STRUCTURE <br /> tThe weir invert for the "emergency" outfall will be set at elevation 90.5 feet (above the <br /> required volume for storage of the 100 year critical event pre/post volume difference). <br /> � The pre-development discharge rate for the 100 storm event is calculated below using the <br /> rational method: <br /> � �Q = CIA I�' <br /> C pre = 0.52 (see previous section) � <br /> � I (for the 100 year storm event, w/Tc = 10 min.) = 9.5 inches per hour <br /> 'A = 140,992 sf= 3.24 Acres <br /> � � <br /> Q = 0.52x9.5x3.24 = 16.Ocfs <br /> ' � <br /> The routing for the critical storm event, which is the 100 year, 8 hour storm event (see <br /> Appe Idix C for routing analysis and additional routings for all events below and one event <br /> � above'the critical event , shows that the eak rate dischar ed from the ro osed <br /> ) p 9 P P <br /> � stormwater facility is 7.3 cfs with a maximum stage elevation of 90.8 feet (top of bank is <br /> 91.5 feet). This discharge rate is less than the maximum allowable 16.0 cfs. The outfall <br /> structure with the weir is shown in the site construction plans (Appendix E). <br /> , <br /> � <br /> , <br /> ' <br /> � CadM/tlata/99/6001-99/6001-99drainage <br />