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i <br /> w�������ewu� <br /> � ���.►�•� : ��� �ize and Cost Estimate <br /> STORMWATER <br /> SOLUTIONS u+c. <br /> � <br /> � Prepared by Kathryn Thomason on November 9, 2006 <br /> � Seaway Lot 3B — Stormwater Treatment System <br /> � Everett, WA <br /> � Basin A: <br /> � Information provided: <br /> I • Water quality flow, Qv,q = 0.15 cfs <br /> • Peak hydraulic flow rate, Qpeak= 0.62 cfs <br /> • . Flow rate per cartridge = 15 gpm <br /> ( Basin B: <br /> Information provided: <br /> . Total contributing area = 0.38 acre <br /> I • Impervious area = 0.2� acre <br /> . 2 year release rate from detention, Qwa = 0.002 cfs <br /> • Peak release rate from detention, Qpeae= 0.24 cfs <br /> � • Flow rate per cartridge = 7.5 gpm <br /> Assumptions: <br /> i . Vortechs� unit sized at an operating rate of 35 gpm/ftZswirl chamber per D.O.E. <br /> , • Media = ZPG cartridges <br /> • Drop required from inlet to outlet = 2.3' minimum <br /> I • Presiding agency = City of Everett <br /> Basin A: <br /> � StormFilter0 Sizing: <br /> The StormFilter is a flow-based system, and therefore, is sized by calculating the water quality flow rate associated <br /> I with the design storm. The water quality flow rate was calculated using the SBUH method and provided by the <br /> engineer. <br /> The StonnFilter for this site was sized based on a water quality flow rate of 0.15 cfs. To accommodate this flow rate, <br /> I CONTECH Stormwater Solutions Inc. recommends using a 72" precast Manhole StormFilter with 5 cartridges (see <br /> attached detail). The estimated cost of this system is S21.E00, complete and delivered to the job site. This estimate <br /> assumes that the vault is 6 feet deep. The final system cost will depend on the actual depih of the units and whe!her <br /> � extras are specified. The contractor is responsible for setting the StormFilter vault and all external plumbing. <br /> i <br /> The StormFilter has an internal bypass capacity of 1.8 cfs. If the peak discharge off the sife is =xpected to <br /> � exceed that rate, we recommend placing a high-flow bypass upstream of the StormFilter system. CONTECH <br /> j Stormwater Solutions Inc. could provide our high-flow bypass, the StormGate, which provides a combination <br /> weir-orifce control structure to limit the flow to the StormFilter, for approximately $4,500. The final cost would <br /> depend on the actual depth and size of the unit. <br /> I <br /> , <br /> ` 07006 CONTECH Slormwaler Solutions 12021-8 NE AirpoA Way, Portland OR 9722D Page 1 of 2 <br /> Icon(echstormwateccom Toll-(ree�800.548.4667 Fax:800.561J271 TS-P027 <br />