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I <br /> WASHINGFOA STATE <br /> OEPAA' MA NI OF <br /> ECOLOGY <br /> January 2013 <br /> GENERAL USE LEVEL DESIGNATION FOR BASIC (TSS) TREATMENT <br /> For <br /> CONTECH Engineered Solutions <br /> Stormwater Management StormFilter® <br /> With ZPG Media at 1 gpm/sq ft media surface area <br /> Ecology's Decision: <br /> Based on the CONTECH Engineered Solutions' (CONTECH) application <br /> submissions, Ecology hereby issues a General Use Level Designation (GULD) for the <br /> Stormwater Management StormFilter®(StormFilter): <br /> 1. As a basic stormwater treatment practice for total suspended solids (TSS) <br /> removal, <br /> • Using ZPGTM media (zeolite/perlite/granular activated carbon),with the size <br /> distribution described below, <br /> • Sized at a hydraulic loading rate of 1 gpm/ft2 of media surface area, per <br /> Table 1, and <br /> • Internal bypassing needs to be consistent with the design guidelines in <br /> CONTECH's current product design manual. <br /> fTable 1. StormFilter Design Flow Rates per Cartridge <br /> Effective Cartridge Height (inches) 12 18 _ 27 <br /> Cartridge Flow Rate (gpm/cartridge) 5 7.5 11.3 <br /> 2. Ecology approves StormFilter systems containing ZPGTM media for treatment at <br /> the hydraulic loading rates shown in Table 1, to achieve the maximum water <br /> quality design flow rate. The water quality design flow rates are calculated using <br /> the following procedures: <br /> ' • Western Washington: For treatment installed upstream of detention or <br /> retention, the water quality design flow rate is the peak 15-minute flow rate <br /> ' as calculated using the latest version of the Western Washington Hydrology <br /> Model or other Ecology-approved continuous runoff model. <br /> I <br /> I <br /> CONTECH-StormFilter®GULD Maintenance Update(November 2012) 1 <br /> I <br />