11831 AIRPORT RD WHOLE SITE FILE 2020-01-21

Tank Design Loads: AASHTO HS-25 and fire truck outrigger load per Snohomish County EDDS-2016 Edition. Tanks shall be designed for saturated soil loading with a minimum cover of 2 feet. The groundwater table shall be assumed to be at the top elevation of the tank. The Contractor shall provide the tank design and method of shoring the tanks for the Engineer's approval at the time of the pre-construction meeting. The tank design shall satisfy the design criteria and professional engineer's certification, as specified herein. Ladders, Covers and Risers Access covers, and risers shall be installed per Snohomish County EDDS 5-170, Tank access ladders shall be made of polypropylene coated steel materials and meets requirements of AASHTO M199. 7-05.3 Construction Requirements Section 7-05.3 is supplemented with the following: All manholes and catch basins within paving areas shall be adjusted to grade after paving operations are complete. The Contractor shall adjust the manholes with concrete adjusting rings, brick and mortar. All catch basins and manholes for storm sewers shall be grouted water tight, including under frames, rims, manhole barrel, riser sections, and pipe collars. All catch basins shall have locking vaned grates per WSDOT Standard Plan B-30.30-00, unless otherwise noted on the Plans.Anti-seize compound shall be placed on locking bolts prior to installation. All solid covers for drainage structures shall include the lettering "DRAIN" per WSDOT Standard Plan B-30.70-03. Where utility covers fall within the sidewalk or curb ramps, the cover shall be coated with a slip- resistant coating meeting ADA standards. Wetland Treatment Catch Basin The wetland treatment catch basin shall be constructed to the size, type, elevations and grades as indicated in the plans and details. The structure(s) shall be installed to include all required or necessary appurtenances, treatment elements, and connection to properly treat the surface drainage as recommended by the manufacturer. The Contractor shall submit product information, specifications, and configuration related to other proposed aspects of construction to the Engineer for approval prior to ordering and installing the system. TREATMENT MEDIA An initial installation of the treatment media shall fill the treatment chambers to 9 inches below the top of the vault, and spread level within each treatment cell. The 3 inch thick plant support Swift Green Line—Corridor Stations Special Provisions SP97 May 2017