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■ Willows Apartmrnts <br /> Drainage Study <br /> � 09/16/2009 <br /> SITE HYDRAULIC ANALYSIS <br /> CDetention Device Design: <br /> r P(6-month)= 0.99 <br /> I P2 1.5 <br /> P10 = 2.2 <br /> r P100 = 3.2 <br /> I LEVEL POOL TABLE SUMMARY <br /> MATCH INFLOW-STO--DIS-<-PEAK-> OUTFLOW STORAGE <br /> I <---_-DESCRIPTION--------> (CFS) (CFS)--ID---ID-<-STAGE>ID (CFS)VOL(CF) <br /> 6-MON'f1t...................... 0.00 0.05 POl COMB 323.0613 0.01 I51.28 CF <br /> � 2-YtiAR....................... 0.02 0.07 P01 COMB 323.60 7 0.01 290.96CF <br /> IO-YEAR...................... 0.07 0.12 P01 COMB 323.98 8 0.06 397.15CF <br /> I00-YEAR..................... 0.12 0.18 POI COMH 324.52 9 0.12 534.38CF <br /> � SBUH Correction factor: <br /> %Impervious=0.1904/0.2732=69.7°o Correction Factor= 37.8 %(Fig III-I.l) <br /> t Max Volume Req'd= 534.4 " I 37=732.1 CF 36" Pipe E.�uivalent= 104 LF <br /> 1_ <br /> Detention Layout: <br /> 2 x 3' of 54" SDMH @ 15.9 CF/FT= 95.4 CF <br /> l 91 LF of 36" CMP @ 7.07 CF/FT = 643.4 CF <br /> Detention Provided = 738.8 CF Available <br /> '_ Restriction Device Design <br /> MIJLTIPLE ORIFICE ID No.R01 <br /> OutIM.cie.' 322.00 <br /> I Elev: 320.110 ft Orifice Diameter. 0.6519 in. <br /> Elev: 323.60 ft Orifice 2 DiamMer: 2.0303 in. <br /> Elev: 324.10 ft Orifice 3 Diemeter: 0,8086 in. <br /> ' Emergency Overflow <br /> RISER DISCHARGE ID No.R02 <br /> Riser Diameter(in): 12.00 elev: 325.50 ft <br /> I Weir Coefficient...: 9.739 height: 327.00 ft <br /> OrifCoefticient...: 3.782 increm: O.IOft <br /> ' The standaid 12"-RisedStandpipe wiU be pmvided in the new restrictor as an <br /> emergency release point. According to Waterworks printout for a 12" standpipe <br /> in the printout pages (at EI = 525.5), a Q100 (dev) = 0.18 CFS flow will overflow <br /> � the riser at less than elevation El=525.58 at a spillway depth of less than 0.08 feet <br /> or 1.0-inch and will flow safely to the downstream channel, if the orifices aze <br /> plugged. <br /> � f <br /> � <br /> 6 PfiOIECI':05612 <br /> � <br />