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COME RAIN, WE SHINE:• <br />5��� nRy��i� Ky�t,�I��S Q��r� <br />�I ��ud a F lyG�5 I-}wroU-x�- 4?� <br />sroaMwa�" <br />M.INAOEMENT INC. <br />Mountatn Vlew Plaza - Stormwater Treatment Svstem <br />Size and Cost Estlmate <br />Everett, WA <br />Information orovided: <br />• Total contributing area = 2.5 acres <br />• Impervious area = 1.8 acres <br />• Peak Flow Rate = 0.42 cfs <br />Assum cin ons: <br />• Presiding agency = City of Everett, WA <br />• Media = Perlite/Zeolite/GAC cartridges <br />• Drop required from inlet to outle; = 2.3' minimum <br />b�t10 5aQ -c� <br />� �(,��5 <br />L� <br />� <br />�� <br />� �%) <br />Size and cost estimates: <br />The StormFilter is a flow-based system, a�id therefore, is sized by calculati�g the peak water <br />qualiq� flow rate associated witli the design stonn. However, when the StormFilter is placed <br />downstream of detention the (low rate genereted at L'ie water quality storm is not always <br />representative of the total volume of water that will go through the sys[em or type of <br />pollutant-loading the system may experience in one ��ear. <br />The StormFilter for this site was sized based on a treatment flow rate of 0.03 cfs. To <br />accommodate this flow rate, Stomiwater Management recommends using a 6'x12' precast <br />StormFilter with 11 cartridges (see attached detaiq. The estimated cost of this system is <br />38 200, complete and delivered to the job site. This estimate assumes that the vault is <br />less than 9 feet deep. The final system cost will depend on the actual depth of the units and <br />whetlier extras like doors ratlier tlian castings are specified. The contractor is responsible <br />(or setting the StormFilter vault and all extemal plumbing. <br />The precast StormFilter has an internai bypass capacity of 1.8 cfs. If Ihe peak discharge off <br />the sile is expecled to exceed that rate, we recommend placing a high-flow bypass upstream <br />o( the StormFilter system. Stormwater �9anagement could provide our high-flow bypass, the <br />StormGate, which provides a combination weir-orifice control structure to limit the ilow to ihe <br />StormFiller, for approximately $3,900. The final cost would depend on the actual depth and <br />size of the unil. <br />SMIENGR:LCL 6/27/05 <br />/� <br />