3003 W CASINO RD BLDG 45-06 Geotech Report 2025-03-03

Geotechnical Engineering Report lrerracon Proposed Flight Line Steam Line Project Boeing Everett Facility • Everett, Washington January 17, 2012 • Terracon Project No.: 81115085 surface of angular crushed aggregate to protect the moisture sensitive subgrade soils, provide a leveling surface for precast components, and provide more uniform support I characteristics for cast-in-place and precast utilidor foundations. • Subsurface Drainage: The utilidor should include a 6-inch diameter perforated PVC foundation/wall drain system. The perforated drain pipe should be embedded in at least an 18-inch wide envelope of clean, free-draining, well graded mixture of course sand. A non- woven filter fabric should envelope the free-draining granular material. • Exiting Foundations: In order to maintain adequate foundation support for existing structures, we recommend that temporary open cut excavations made near existing foundations be set back from the edge of existing foundation element. Based on the soil types encountered in our explorations, we recommend that all temporary open cuts made ' adjacent to existing shallow foundation systems include a level bench extending out from the edge of the existing footing a minimum distance of 3 feet. The elevation of the level bench should be above or equal to the base elevation of the existing footing. Soils beyond the 3-foot minimum setback distance may be cut at a maximum temporary slope angle of 45 degrees (1 H:1 V). If the foundation subgrade elevation for existing structures and the proposed utilidor location and foundation depth do not allow enough room for the recommended temporary open cut configuration, we recommend that temporary support for existing foundations be provided by structural means. Based on the current location and depth of the utilidor, temporary open cuts near Building 40-21 column foundations do not appear feasible from a geotechnical perspective. Structural support for the existing foundations could be provided by soldier pile underpinning. Terracon is available to provide I underpinning recommendations, at your request. Close monitoring of the construction operations discussed herein will be critical in achieving the design subgrade support. We therefore recommend that Terracon be retained to monitor this portion of the work. , This geotechnical executive summary should be used in conjunction with the entire report for design and/or construction purposes. It should be recognized that specific details were not included or fully developed in this summary, and the report must be read in its entirety for a comprehensive understanding of the items contained herein. The section titled General Comments should be read for an understanding of the report limitations. , I Responsive • Resourceful • Reliable ii