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CITY OF EVERETT SPECIAL PROVISIONS <br /> <br />3rd Ave Water Quality Facility Division 7 – STORM, SEWER, WATER September 12, 2024 <br />WO No. – UP 3775 SP – 182 <br />All system components including engineered proprietary treatment soil mix media, <br />underdrain stone, and mulch must be included as part of the water quality treatment <br />facility system and shall be provided by the manufacturer, except as noted herein. <br /> <br />Engineered treatment soil mix media shall consist of both organic and inorganic <br />components. Stormwater shall be directed to flow vertically through the media profile, <br />saturating the full media profile without downstream flow control. The media shall meet <br />the following parameters: <br /> <br />1. Engineered biofiltration media minimum treatment flow rate shall be 175 inches/hr. <br />2. The system shall be designed to ensure that high flow events shall bypass the <br />engineered biofiltration media preventing erosion and resuspension of pollutants. <br />3. The system shall remove a minimum of 85% Total Suspended Solids (TSS). <br />4. The system shall remove a minimum of 62% Total Phosphorus (TP). <br />5. The system shall remove a minimum of 34% Total Nitrogen (TN). <br /> <br /> <br />Water Quality Treatment Facility Installation <br />The Water Quality Treatment Facility shall be installed in accordance with the <br />manufacturer’s recommendations and related sections of the contract documents with <br />approval by the Engineer. The manufacturer shall provide the Contractor installation <br />instructions and offer be on- site guidance during the installation and activation as <br />defined in the installation procedure submittal. <br /> <br />The subgrade of the facility shall be protected from equipment access for the final 12- <br />inches of depth to preserve existing infiltration. The subsurface shall be sacrificed to a <br />depth of 4-inch with hand leveling, as needed prior, to installing the geotextile liner. <br /> <br />Activation of the system must be provided by the Contractor under the supervision by <br />the manufacturer and City. A minimum of three (3) business days’ notice shall be <br />provided to the manufacturer prior to their performance of the services included under <br />this subsection. <br /> <br />Plantings which are part of a water quality treatment structure, where indicated in the <br />Plans, shall be installed in accordance with the manufacturer’s recommended <br />procedures and Section 8-02.3(8). Where conflicts exist the manufacturer’s procedures <br />shall take precedence. <br /> <br />7-06.3(5) Roof Drain Connection <br />The contractor shall replace the existing roof drains with new PVC drain pipes <br />connection to the roof downpipe and discharging at locations as shown in the Plans. <br /> <br />The Roof Drain Connection piping and required fittings shall convey runoff from private <br />roof drains to locations shown on the Plans without restriction.