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lideli01111TECH®ENGINEERED SOLUTIONS Size and Cost Estimate <br /> Prepared by Chris Hass on August 15,2014 <br /> Silver Lake Center— Stormwater Treatment System <br /> Everett, WA <br /> Information provided: <br /> • Total contributing area = 1.34 <br /> • Impervious area = 0.91 <br /> • Water quality flow, Qwq = 0.14 cfs <br /> • Peak hydraulic flow rate, Qpeak= 0.89 cfs <br /> • Presiding agency = City of Everett <br /> Assumptions: <br /> • Media = ZPG cartridges <br /> • 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 is therefore sized by calculating the peak water quality flow rate <br /> associated with the design storm. The water quality flow rate was calculated by the consulting engineer using <br /> WWHM and was provided to Contech Engineered Solutions LLC for the purposes of developing this estimate. <br /> The StormFilter for this site was sized based on a water quality flow rate of 0.14 cfs. To accommodate this flow rate, <br /> Contech Engineered Solutions recommends using an 96 StormFilter with 13 cartridges (see attached detail). The <br /> estimated cost of this system is $32,715, complete and delivered to the job site. This estimate assumes that the <br /> manhole is 8 feet deep. The final system cost will depend on the actual depth of the units and whether extras like <br /> doors rather than castings are specified. The contractor is responsible for setting the StormFilter and all external <br /> plumbing. <br /> Typically the precast StormFilters have internal bypass capacities of 1.8 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 StormFilter. 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-P027 <br />