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I <br /> C4'.'t-NTECH® <br /> Ili ENGINEERED SOLUTIONS Size and Cost Estimate <br /> IPrepared by John Megrditchian on August 14,2014 <br /> IMcClean Ironworks — Smith Island Facility — Stormwater Treatment System <br /> Everett, WA <br /> I Information provided: <br /> • Total contributing area, ac= 0.62 <br /> • Impervious area, ac =0.55 <br /> Is Water quality flow, Qwq = 0.088 cfs <br /> • Peak hydraulic flow rate, Qpeak= 0.39 cfs <br /> Assumptions: <br /> I • Media = Metal Rx cartridges <br /> • Cartridge flow rate = 11.25 gpm <br /> • Drop required from inlet to outlet = 3.05' minimum <br /> ISize and cost estimates: <br /> The StormFilter is a flow-based system, and is therefore sized by calculating the peak water quality flow rate <br /> Iassociated 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 0.088 cfs. To accommodate this flow <br /> I rate, Contech Engineered Solutions recommends using a 60" StormFilter manhole with 4 cartridges (see attached <br /> detail). The estimated cost of this system is$20,900, complete and delivered to the job site. This estimate assumes <br /> that the vault is 6 feet deep. The final system cost will depend on the actual depth of the units and whether extras <br /> I like doors rather than castings are specified. The contractor is responsible for setting the 60" StormFilter manhole <br /> and all external plumbing. <br /> I Typically the precast StormFilters have internal bypass capacities of 1.0 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 /> Ifinal cost would depend on the actual depth and size of the unit. <br /> I <br /> I <br /> I <br /> I <br /> I ©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 /> I <br />