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CITY OF EVERETT SPECIAL PROVISIONS <br /> <br />Beverly Lake Water Quality Retrofit Division 7 – STORM, SEWER, WATER August 2023 <br />WO No. - UPUP3745 SP – 190 <br />Provide a manufacturer’s certificate of compliance in accordance with Section 1- <br />06.3 demonstrating that the proposed product complies with the following <br />requirements: <br /> <br />Washington State Department of Ecology approval requirements: general use <br />level designation for pretreatment. <br /> <br />Treatment: <br /> <br />The pretreatment unit shall be sized to treat the design flow rate designated in <br />the Drawings. The pretreatment unit shall be capable of capturing and retaining <br />100 percent of pollutants greater than or equal to 2.4 millimeters (mm) regardless <br />of the pollutant’s specific gravity for flows up to the design flow rate. The <br />pretreatment unit shall be designed to retain all previously captured pollutants <br />addressed by this subsection under all flow conditions. The pretreatment unit <br />shall be capable of capturing and retaining total petroleum hydrocarbons and <br />shall be capable of achieving a removal efficiency of 92 and 78 percent when the <br />device is operating at 25 and 50 percent of its rated-treatment capacity. These <br />removal efficiencies shall be based on independent third-party research for <br />influent oil concentrations representative of storm water runoff (20 ± 5 mg/L). The <br />pretreatment unit shall be greater than 99 percent effective in controlling dry- <br />weather accidental oil spills. <br /> <br />The treatment unit shall be capable of treating the design flow specified without <br />prematurely bypassing flows via an internal bypass or external flow splitter. <br /> <br />The treatment unit shall be designed with a sump chamber for storage of <br />captured sediments and other captured pollutants. <br /> <br />Hydraulics: <br /> <br />The pretreatment unit shall convey the flow from the peak storm event of the <br />drainage network, in accordance with required hydraulic upstream conditions as <br />defined by the Engineer. If a substitute treatment unit is proposed, supporting <br />documentation shall be submitted that demonstrates equal or better upstream <br />hydraulic conditions compared to the device specified. This documentation shall <br />include a hydraulic gradeline for the upstream and downstream system and <br />headloss though the treatment unit during the 100-year storm. This <br />documentation shall be signed and sealed by a Professional Engineer registered <br />in the State of Washington. All costs associated with preparing and certifying this <br />documentation shall be born solely by the Contractor. <br /> <br />Water Quality Treatment Structures <br /> <br />Provide a manufacturer’s certificate of compliance in accordance with Section 1- <br />06.3 demonstrating that the proposed product for Water Quality Treatment <br />Structure 3 complies with the following requirements: <br /> <br />Water quality treatment structures shall meet the Ecology General Use Level <br />Designation (GULD) certification for the treatment level indicated in the following: <br /> <br />Water Quality <br />Treatment <br />Structure <br />Required Treatment <br />Level