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. � <br /> The stortnwata enalyais was done using the WaterWorka Hms Program by Engenious <br /> Systems,Inc. of Seattle,WA. The base calculetion ueed was the SC5 method. The reinfall <br /> amounts end curve numbera uaed were taken from the City of Everett Stmmweter Manual. <br /> 7'he site was broken into two basins(see basin mep ne�page). Beain B-1 includes the <br /> flow from the existing duplex at 5719 Cady Rd. which flowa northwerd,the exist�eB Pe�1°B <br /> accesa end parking erea,aod e portion of the flow from thc adjnccM lot at 5717 Cady Rd. Besin <br /> B-2 is the area of the proposed new duplex. In the calculationa,no flow was introducal es Basm <br /> B-2-dev in the developed model, inatead the increased impervious aree was added to basin B-1- <br /> dev. <br /> The prop�ed detention system ie a bu-ied 30"pipe. The roleaee from the detention <br /> syetem will be�;ontrulled via a control atructure with a circular orifice. The necessary orifice <br /> sius can be calculated eutomatically uaing the softwere for desired releaee rates. Uaing the <br /> software it wea ddermine�that uaing 2 orifices would be most adventaBous. The firet oritice(e <br /> 1"orifice) providea the rolease rate required for the 2 year eveM, while tMe 2ed orifice(a I.5" <br /> orifice located 1.25' higher in the atr�cture) helps provide a higher flow rate for ltvger storm � <br /> events. <br /> No water qudity bmp's have been proposed as the developed poliution co��buting <br /> �rt'aces(propoxd eaphalt acceas end parking)total ia only 4600 s.f. <br /> The correlation wrtection fector was aeen to be about 32%from the table in the Everett <br /> Stmmweter Manuel. The modeled length of detention pipe was 100' while the ectual length to <br /> be installed will be 134'or a 34%corredion factor. <br /> A summary of the rowlta from the calculations eection can be eeen in the following table: <br /> 0.06 N/A N/A <br /> Ex. 2 Year 80.01 181.55 <br /> Dev. 2 Year 0.03 <br /> 0.11 N/A N/A <br /> Ex. 10 Year �50 �g1,86 <br /> Dev. 10 Year 0.06 <br /> 0.20 N/A N/A <br /> Ex. 100 Year 294 182.43 <br /> Dev. 100 Year 0.09 <br /> The existing flow amounts were taken from pages 15-17, end the developed numbers <br /> were taken from pages 22-24. <br /> f <br />