3003 W CASINO RD BLDG 40-58 Geotech Report 2022-10-25

• consisting of either Gravel Borrow, Select Borrow, or native glacial till. See Section 3.2 for additional requirements of fill material types beneath slabs-on-grade. We recommend that a capillary break layer be included in design of the interior floor slab. A minimum of 6 inches of clean, free-draining material(less than 3 percent fines), such as nominal 5/8-inch washed gravel should be used as a capillary break material. For portions of interior floor slabs where current or future occupancy could require the use of flooring materials that are moisture-sensitive, we recommend the use of a condensation barrier as described below. This would reduce the potential for a situation where condensation could develop on the bottom of the slab and wick upwards through the concrete slab. The condensation barrier should consist of a minimum 10-mil membrane with tape-sealed joints placed atop the capillary break layer. The American Concrete Institute (ACI) guidelines recommend that 4 inches of compacted granular fill, such as%-inch minus crushed rock be placed over the barrier to facilitate curing of the concrete floor slab and to protect the vapor barrier. The ACI no longer recommends sand for the protection layer. Lightly-loaded exterior concrete slabs-on-grade, such as sidewalks, may be supported directly on the existing subgrade soils or rubblized asphalt; however, long-term performance will be enhanced if these exterior slabs are placed on a layer of clean,durable,free-draining granular material. 3.10 FLEXIBLE PAVEMENT New asphalt pavement will be constructed along the reconfigured Perimeter Road alignment. Asphalt pavement will also be placed along the building access roads along the south and west sides of the proposed building, in parking areas, and other locations within the Boeing — Everett factory road network. The traffic data necessary for a conventional asphalt pavement design under post-construction traffic characteristics is not available at the time this interim draft report was prepared. However, assuming that post-construction traffic characteristics will be similar to the current traffic characteristics, the asphalt pavement thicknesses encountered during recent drilling could serve as an initial basis of pavement thickness for cost estimation purposes. An asphalt pavement section in parking areas could consist of 2 inches of asphalt over 4 inches compacted CSBC meeting the criteria established in Section 9-03.9(3) of the 2014 WSDOT Standard Specifications. Final pavement design for Perimeter Road and for factory roads should be based upon an accepted design methodology such as that presented in the 1993 AASHTO design manual (AASHTO 1993). However, based upon an initial estimate of traffic characteristics, the thickness and performance of existing pavement at these locations, and AASHTO's guidance for low-volume road design (that is, low truck volume),the Perimeter Road pavement section should consist of a 4-inch layer of asphalt over 6 5/16/14 P:\1423\002\010\PileRm\R\Draft Bldg 40-58 Report\Bldg 40-58_draft rpt.docx INTERIM DRAFT 3-9