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Geotechnical Engineering Evaluation Miller Property Slope Stabilization Everett, Washington NGA File No. 1333322 July 1, 2022 Page 5 At the surface of each boring, we generally encountered approximately 5- to 7.5-feet of loose to medium dense, silty sand with varying amounts of gravel and organic debris, which we interpreted as undocumented fill soils. Below the undocumented fill soils in Borings 2 and 3 we generally encountered gray to gray -brown, interbedded sandy silt and silty sand with varying amounts of gravel in a medium stiff or better condition, which we interpreted as a fine-grained native glacial deposit. At depth, in Borings 1 and 3 we generally encountered yellowish brown to gray, fine to medium sand with silt and varying amounts of gravel in a dense or better condition, which we interpreted as native glacial outwash. Boring 2 met refusal within the upper fine-grained soils at approximately 21.2 feet below the existing ground surface, while Borings 1 and 3 terminated within the granular outwash deposits at depths of 31.5- and 51.5-feet, respectively. Hand Augers 1 through 4 focused on delineating the soil conditions within the slide mass, between the crown of the slide and the southern fence line. At the surface of each exploration, we generally encountered approximately 7.5- to 12.5-feet of sandy silt to silty sand with varying amounts of gravel and organic debris in a very loose to medium dense condition, which we interpreted as undocumented fill soils. Underlying the fill soils, we encountered gray -brown to light brown, silt with fine sand in a medium stiff or better condition, which we interpreted as a native glacial fine-grained outwash deposit. Hydrogeologic Conditions During our work at the site beginning late February, we observed moderate groundwater seepage from slope faces within and in proximity to landslide activity on the site. We understand that seepage conditions may be ephemeral depending on seasonality. It was unclear where stormwater runoff from the residence was directed, however, we anticipate at least some of the house runoff may be directed towards the slope, based on observed drains within the landslide head scarp. Localized seepage zones were encountered within the upper approximately 15- to 20-feet of Borings 2 and 3. Localized seepage zones were generally encountered in sandy lenses within the upper fine-grained deposits, as interpreted from observation and classification of the split spoon samples. Within the granular outwash deposits at depth, we noted a significant increase in moisture content at approximately 50-feet below the ground surface within Boring 3, which we anticipate is indicative of a soil contact and transition to a lower relatively impermeable soil unit. Groundwater was also encountered in Hand Augers 1 through 4 at depths in the range of approximately 4.5- to 5.5-feet below the existing ground surface. We installed a 1- inch diameter perforated PVC pipe within Hand Auger 1 to a depth of approximately 13-feet below the existing ground surface to monitor groundwater levels within the slide mass. The water level appeared to stabilize at approximately 5-feet below the ground surface during our two days on site. Groundwater observed within the soils at depth is interpreted to represent a permanent perched groundwater condition. NELSON GEOTECHNICAL ASSOCIATES, INC.