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

2.0 SITE CONDITIONS This section discusses the general geologic setting of the project area and the surface, subsurface and groundwater conditions observed at the project site at the time of our field investigation. Interpretations of the site conditions are based on the results of our review of available information, and the results of our site reconnaissance,subsurface explorations,and laboratory testing. (During preparation of this interim draft report, additional previous explorations by others were presented to us by the design team. The conditions reported on logs of those explorations have not been fully incorporated into the discussion and conclusions presented in this interim draft report) 2.1 GENERAL GEOLOGIC CONDITIONS General geologic information for the project area was obtained from the Preliminary Surficial Geologic Map of the Mukilteo and Everett Quadrangles, Snohomish County, Washington (Smith 1976), published by the Washington Department of Natural Resources. According to this source, near-surface deposits in the vicinity of the project site consist of modified land overlying glacial till and advance outwash. Soil defined as modified land is associated with past cut/fill grading activities related to the construction of the existing manufacturing and office buildings. Soils remaining in cut areas typically consist of glacial till, as described below. Soils in filled areas generally consist of excavated glacial till, topsoil, and various imported backfill. This fill unit exhibits variable levels of compaction and permeability. Soil defined as glacial till typically consists of a heterogenous,non-sorted mixture of subrounded boulders, cobbles, gravel, and sand in a matrix of silt and clay. The heterogeneous nature of the till is a result of it being mixed and transported before being deposited, overridden, and compacted by the weight of an advancing glacier. This unit typically exhibits very low permeability and high shear strength. Soil defined as advance outwash typically consists of clean sand with an increasing gravel content higher in the geologic unit. Fine-grained sand and some silt are common in the lower part of this unit. Sorting, cross and horizontal stratification, and cut and fill structures are distinctive features of outwash. Advance outwash is transported by melt water and deposited in streams and pools emanating from the face of an advancing glacier. This unit has been glacially overridden, typically exhibits moderately high permeability,and is susceptible to erosion,especially when exposed on steep slopes. 2.2 SURFACE CONDITIONS The proposed Building 40-58 will be located within the Boeing Everett manufacturing facility in Everett, Washington. Building 40-58 will be situated to east of the existing Building 40-56 and north of 5/16/14 P:\1423\002\010\FileRm\R\Draft Bldg 40-58 Report\Bldg 40-58_draft rpt.docx INTERIM DRAFT 2-1