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2 <br /> 9610 19th Avenue SE •G <br /> July 27, 2012 <br /> Revised September 18, 2012 <br /> Page 9 <br /> E. Stormwater Treatment Plan <br /> After determining "pollutants of concern" it is determined that a "basic" water <br /> quality treatment facility is required (see attached Treatment Facility Selection <br /> Chart.) Also, the treatment facility will be privately owned (not City owned.) An <br /> oil/control facility is not required since the site does not have an ADT of 100 vehicles <br /> per 1,000 SF, storage of petroleum, storage or maintenance of trucks exceeding 10 <br /> tons, and it is not a road intersection. <br /> For water quality treatment sizing calculations, we have used the total drainage basin <br /> area contributing to the facility - 1.3 acres. A standard "Contech Stormfilter" using <br /> five (5) "ZPG" cartridges is proposed just downstream of the detention vault. The <br /> stormfilter was sized by Contech using the release rate from the detention vault as <br /> well as the "mass loading" calculations. The per cartridge flow rate is 5 gpm. <br /> In addition to the Contech Stormfilter, the stormwater plan includes a "floatable <br /> materials separator" on the catch basin immediately upstream of the detention vault. <br /> The following pages contain the City of Everett Volume 1, Table 3.1 "Treatment <br /> Facility Placement in Relation to Detention", Figure 4.1 "Treatment Facility Selection <br /> Flow Chart", and the Contech Stormfilter Calculations prepared by Contech. <br /> Ph: (206)403-0933, email:jayd@deckerce.com <br />