2400 33RD ST GEOTECHNICAL INVESTIGATION 2018-01-02 MF Import

SC 130 MilborPita = 0+c Along, the East and South portions of the site, the topography is relatively flat and ranges in elevation from approximately 60 to 62 feet above sea level. At the west end of Pacific Avenue, the alignment rises gradually upyill reaching an elevation of approximately 70 feet at McDougall Avenue There are several existing buildings on the site (refer to Figure 2). A!, of these are to be demolished as part of this project. The ground surface varies from asphalt (around the O'Day Petroleum Building and Champion Bolt Supply) to dirt with very deep potholes. Paine Avenue between 32nd and 33'd Street is concrete with at least two feet of ballast on the eastem side between the street and Hogland Transfer's office building. 4.2 Subsurface Conditions 4.2.1 Regional Geologic Conditions The project site is located between Possession Sound and the Snohomish River Valley near downtown Everett, Washington. Everett is located in the Eastern central portion of the Puget Lowland, an elongated topographic and structural depression bordered by the Cascade Mountains on the East and the Olympia Mountains on the West. The Puget Lowland is characterized by North-NorthWest trending ridges with deep, wide sediment - filled valleys. The Puget Lowland has been repeatedly occupied by a lobe of the Cordilleran ice sheet, a massive glacier that repeatedly advanced and retreated in the Quarternary period. The most recent advance ended approximately 15,000 years ago, leaving ridges parallel to the movement of the ice. The glacier was at least 3,000 feet in thickness in the vicinity of Everett. The glacier extended from British Columbia South to the Black Hills South of Olympia, Washington. As it advanced, the glacier blocked the Straits of Juan de Fuca, which impounded many of the drainage basins from the Cascades and Olympics. This created massive lakes that may have persisted for hundreds of years prior to being overridden by the ice. As the glacier approached the silt and clay of the lake bottom, the latter was covered by sand, then gravel, and finally till as the ice moved south. This sequence is characteristic of glaciated regions, and is repeated in reverse as the ice retreated. The materials carried from the front of the glacier by meltwater are referred to as "outwash". 4.2.2 Site Soils Based on the results of our investigation, previous work, and our experience in similar geologic settings, the site appears to be underlain by the following materials: fill from the surface to approximately five feet (absent in some areas), lacustrine (lake) clays from the surface to approximately 20 feet, recessional outwash sand from approximately 18 to 20 feet (absent in some areas), glacial till from approximately 20 feet to 30 feet, and advance outwash sand (30 feet to unknown depth). The native soil is overlain by fill from I to perhaps 8 feet in thickness. Geotechnical, Tunnel end I:nvironmentai Engineers 3090 125° Ave Nr. Phone (425) 969-5778 lkllnw, WA98005 Page Fax (425)961-0677