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2.3/A, <br /> CNTECH <br /> ENGINEERED SOLUTIONS Size and Cost Estimate <br /> Prepared by Mark Zeman on June 1,2012 <br /> Everett Storage Facility — Stormwater Treatment System <br /> Everett, WA <br /> Information provided: <br /> • Total contributing area = 1.35 acre <br /> • Impervious area = 1.215 acre <br /> • Detention release rate, Qtreat= 0.014 cfs <br /> • Presiding agency = City of Everett, WA <br /> Assumptions: <br /> • Media =ZPG cartridges <br /> • Per cartridge flow rate= 5 gpm <br /> • Drop required from inlet to outlet= 1.8' minimum <br /> Size and cost estimates: <br /> The StormFilter is a flow-based system, and therefore, is sized by calculating the peak water quality flow rate <br /> associated with the design storm. However, when the StormFilter is placed downstream of detention the flow rate <br /> generated at the water quality storm is not always representative of the total volume of water that will go through the <br /> system or type of pollutant-loading the system may experience in one year. <br /> For this site, Contech Engineered Solutions LLC recommends using a 72" Manhole StormFilter with (5) Low Drop <br /> rtridges(see attached detail). The estimated cost of this system is$16.300, complete and delivered to the job site. <br /> —this estimate assumes that the vault is 6 feet deep. The final system cost will depend on the actual depth of the unit <br /> and whether extras like doors rather than castings are specified. The contractor is responsible for setting the <br /> StormFilter and all external plumbing. <br /> Typically, precast StormFilters have internal bypass capacities of 1.5 cfs. If the peak discharge off the site is <br /> expected to exceed this rate, we recommend placing a high flow bypass upstream of the StormFilter system. <br /> Contech Engineered Solutions could provide our high flow bypass, the StormGate, which provides a combination <br /> weir-orifice control structure to limit the flow to the StormEilter. The estimated cost of this structure is$4,000. The <br /> final cost would depend on the actual depth and size of the unit. <br /> ©2012 Contech Engineered Solutions LLC 11835 NE Glenn Widing Dr.,Portland OR 97220 Page 1 of 1 <br /> www.ContechES.com Toll-free:800.548.4667 Fax:800.561.1271 TS-P022 <br />