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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 – 180 <br />The riser bubble shall be bolted in to the rise pipe with stainless steel hardware. <br /> <br />The underdrain cleanout shall be installed per City of Everett Standard Plan 604, Type <br />3. A stub marker shall not be installed. The connection to the underdrain pipe shall be <br />with a 45-degree bend without horizontal stub. The elevation of the bottom of gasket <br />cap shall be 2-inches above the maximum ponding depth, as shown on the Plans. <br />Gasket cap shall be attached to the pipe with a minimum of three stainless steel screws. <br /> <br />7-06.3(2) Pretreatment Unit <br />Each stormwater treatment system shall include a circular aluminum “swirl chamber” (or <br />“grit chamber”) with a tangential inlet to induce a swirling flow pattern that will accumulate <br />and store settleable solids in a manner and a location that will prevent re-suspension of <br />previously captured particulates. <br /> <br />Housing unit of stormwater treatment device shall be constructed of pre-cast or cast-in- <br />place concrete, no exceptions. Concrete for precast stormwater treatment systems shall <br />conform to ASTM C 857 and C 858 and meet the following additional requirements: <br />1. The wall thickness shall not be less than 6 inches (152 mm) or as shown on the <br />dimensional drawings. In all cases the wall thickness shall be no less than the <br />minimum thickness necessary to sustain HS20-44 (MS18) loading requirements as <br />determined by a Licensed Professional Engineer. <br />2. Sections shall have tongue and groove or ship-lap joints with a butyl mastic sealant <br />conforming to ASTM C 990. <br />3. Cement shall be Type II Portland cement conforming to ASTM C 150. <br />4. All sections shall be cured by an approved method. Sections shall not be shipped <br />until the concrete has attained a compressive strength of 4,000 psi (28 MPa) or until <br />5 days after fabrication and/or repair, whichever is the longer. <br />5. Pipe openings shall be sized to accept pipes of the specified size(s) and material(s), <br />and shall be sealed by the Contractor with a hydraulic cement conforming to ASTM <br />C 595M. <br />6. Brick or masonry used to build the manhole frame to grade shall conform to ASTM <br />C 32 or ASTM C 139 and shall be installed in conformance with all local <br />requirements. <br />7. Casting for manhole frames and covers shall be in accordance with ASTM A48, <br />CL.35B and AASHTO M105. <br /> <br />Internal Components and appurtenances shall conform to the following: <br />1. Internal aluminum plate components shall be aluminum alloy 5052-H32 in <br />accordance with ASTM B 209. <br />2. Sealant to be utilized at the base of the swirl chamber shall be 60 durometer extruded <br />nitrile butadiene rubber (Buna N) and shall be provided to the concrete precaster for <br />installation. <br /> <br />Access covers shall be designed in accordance with Section 4-4.2 (3) of the Design and <br />Construction Standards and Specifications and the following: <br />1. All lids, grates, and hatches larger than 24 inches in a dimension shall be constructed <br />in a manner which allows a single individual to open them without special equipment. <br />2. All lids, grates, and hatches shall be equipped with a pick-hole or handles.