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• Eastern 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 one of the three methods described in Chapter 2.2.5 of the <br /> Stormwater Management Manual for Eastern Washington (SWMMEW) or <br /> local manual. <br /> • Entire State: For treatment installed downstream of detention, the water <br /> quality design flow rate is the full 2-year release rate of the detention facility. <br /> 3. This designation has no expiration date, but Ecology may amend or revoke it. <br /> Ecology's Conditions of Use: <br /> The StormFilter with ZPG media shall comply with the following conditions: <br /> 1. Design, install, operate, and maintain the StormFilter with ZPG media in <br /> accordance with applicable Contech Engineered Solutions manuals, <br /> documents, and the Ecology Decision. <br /> 2. Install StormFilter systems to bypass flows exceeding the water quality <br /> treatment rate. Additionally, high flows will not re-suspend captured <br /> sediments. Design StormFilter systems in accordance with the performance <br /> goals in Ecology's most recent Stormwater Manual and CONTECH's <br /> Product Design Manual Version 4.1 (April 2006), or most current version, <br /> unless otherwise specified. <br /> 3. Owners must follow the design,pretreatment, land use application, and <br /> maintenance criteria in CONTECH's Design Manual. <br /> 4. Pretreatment of TSS and oil and grease may be necessary, and designers <br /> shall provide pre-treatment in accordance with the most current versions of <br /> the CONTECH's Product Design Manual(April 2006) or the applicable <br /> Ecology Stormwater Manual. Design pre-treatment using the performance <br /> criteria and pretreatment practices provided on Ecology's "Evaluation of <br /> Emerging Stormwater Treatment Technologies"website. <br /> 5. Maintenance: The required maintenance interval for stormwater treatment <br /> devices is often dependent upon the degree of pollutant loading from a <br /> particular drainage basin. Therefore, Ecology does not endorse or <br /> recommend a "one size fits all" maintenance cycle for a particular model/size <br /> of manufactured filter treatment device. <br /> • Typically, CONTECH designs StormFilter systems for a target filter <br /> media replacement interval of 12 months. Maintenance includes <br /> removing accumulated sediment from the vault, and replacing spent <br /> cartridges with recharged cartridges. <br /> CONTECH-StormFilter®GULD Maintenance Update(November 2012) Page 12 <br />