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Infiltration Chamber Gallery <br /> Infiltration Chambers and End Caps <br /> Infiltration Chambers shall be fabricated according to the dimensions shown on the <br /> Plans. Chambers shall conform to the requirements of ASTM F 2418, "Standard <br /> Specifications for Polypropylene (PP) Corrugated Stormwater Collection Chambers" and <br /> ASTM F 2787, "Standard Practice for Structural Design of Thermoplastic Corrugated <br /> Wall Stormwater Collection Chambers. <br /> The chamber product used for layout in design was Stormtech MC-3500. <br /> Chamber rows shall provide continuous, unobstructed internal space with no internal <br /> support panels that would flow or limit access for inspection and maintenance. The <br /> structural design of the chambers, the structural backfill and the installation requirements <br /> shall ensure that the load factor specified in the AASHTO LRFD Bridge Design <br /> Specifications section 12.12 are met for: <br /> A. long-duration dead loads and <br /> B. short-duration live loads, based on the AASHTO Design Truck with consideration <br /> for impact and multiple vehicle presences. <br /> Only chambers that are approved by the engineer will be allowed. The contractor shall <br /> submit three sets of the following to the engineer for approval before delivering <br /> chambers to the project site: <br /> 1. A structural evaluation by a licensed structural engineer that demonstrates <br /> that the load factor specified in the AASHTO LRFD Bridge Design <br /> Specifications, Section 12.12 are met. <br /> 2. Structural cross section detail on which the structural cross section is based. <br /> Infiltration Gravel <br /> Infiltration gravel shall conform to Gravel Backfill for Drywells as specified in WSDOT <br /> Standard Specification 9-03.1(5). <br /> Geotextiles <br /> Geotextile surrounding the infiltration gravel shall be Non-woven Geotextile for <br /> Underground Drainage, Moderate Survivability with Class A Filtration Properties per <br /> WSDOT Standard Specifications Section 9-33.2(1). <br /> Stormwater Detention Tank System <br /> Steel Rib Reinforced Polyethylene Storm Sewer Pipe 9-05.22 <br /> Gravel Backfill for Pipe Zone Bedding 9-03.12(3) <br /> Detention tank system shall be pre-fabricated tanks constructed in accordance with the details <br /> in the Plans and Snohomish County Design Standard Drawings 5-290 and Snohomish County <br /> EDDS-2016 except tank material per this section of the Special Provisions. <br /> Access panels, grating, frame, and hardware shall be aluminum, or steel which is hot dipped <br /> galvanized in accordance with AASHTO M 111 and AASHT M 234. Minimum loading shall be <br /> H-25. Torsion spring assist shall be provided for grate, along with a recessed padlock hasp so <br /> that the grate shall not exceed 50 pounds. <br /> Swift Green Line—Corridor Stations Special Provisions SP96 <br /> May 2017 <br />