2514 RAINIER AVE Geotech Report 2022-10-25

2-it arnee foster wheeler The athletic field is a grass-covered surface. Vegetation in other unpaved landscaped areas around I the school building and in the parking lots consists primarily of grass, small trees, and shrubbery. The parking areas are asphalt-paved with concrete sidewalks near the school buildings for pedestrian access to buildings, parking areas, and the bus lane. A concrete walkway paralleling the City of Everett streets extends around the perimeter of the school property on all sides except the alleyway to the west. The parking lot and tennis court across 26th Street are paved surfaces. I At the time of our investigation in early September 2016, we did not observe any surface water on the site. 3.2 SOIL CONDITIONS According to published geologic maps, soil conditions at the site are characterized by Pleistocene Vashon Glacial Till with Advance Outwash deposits underlying the glacial till. Advance Outwash deposits are also exposed near the southern and southwestern perimeter of the project area (Minard, 2015). Our explorations confirm Advance Outwash deposits underlying the site. Advanced Outwash is characterized by moderately sorted sand and gravel deposits associated with an advancing glacier and compacted (over-consolidated) by the overriding glacier. Advance Outwash tends to be dense to very dense and exhibits high shear strength and low compressibility. Overlying the Advance Outwash, we encountered sandy silt or silt deposits which we interpret as Recessional Lacustrine deposits (referred to in this report as lacustrine silts).The lacustrine silts are characterized by poorly sorted silt, clay, sand, and gravel deposits associated with receding glaciers. Lacustrine silts range from very soft to very stiff and exhibit low to moderate shear strength and moderate to high compressibility, depending on depositional characteristics. The lacustrine silts we 111 encountered can become soft and unworkable when disturbed by excavation, stockpiling, and backfilling, especially when wet. ' The fill thickness for each boring was interpreted based on drilling action, SPT blow counts, and visual examination of samples collected during our exploration. We also reviewed pre- and I post-development site topographic maps. Table 2 summarizes the approximate thicknesses and depths of soil layers encountered in our explorations. I t Amec Foster Wheeler 4 Project No.6-917-18116-0 \\Sea-fsl\WordProc\ Projects\18000s\18116 Everett School District\Geotech Report\Revised\2017_10-19_Everett Middle School Geotech_Sx.docx