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Geotechnical Engineering Evaluation NGA File No.961916 Mason Residence Addition and Deck August 24,2016 Everett,Washington Page 4 I f2_S The soils were visually classified in general accordance with the Unified Soil Classification System presented in Figure 5. The logs of our borings and hand holes are attached to this report and presented as Figures 6 through 9. We present a brief summary of the subsurface conditions in the following paragraphs. For a detailed description of the subsurface conditions,the boring and hand hole logs should be reviewed. In all of our borings,we encountered approximately 7.5 to 10.0 feet of surficial topsoil and very loose/soft to loose/soft dark brown/black to brown-gay silty fine to medium sand with varying amounts of gravel and organics and silt with varying amounts of sand organics that we interpreted as undocumented fill and buried topsoil soils. Underlying the fill and buried topsoil in the borings,we encountered loose to dense, brown-gay to gray fine to medium sand with varying amounts of silt and gravel we interpreted as granular advance outwash deposits. Underlying the granular advance outwash deposits in Borings B-1 and B-2, we encountered medium dense/hard to very dense/very hard, brown to blue-gray silt with trace fine sand and silty fine sand that we interpreted as native transitional bed deposits. Boings 1 and 2 were terminated within the native transitional bed deposits while Boring B-3 was terminated within the native advance outwash soils at depths in the range of 11.5 to 26.5 feet below the existing ground surface. In Hand Hole HIM we encountered very loose to loose, dark brown silty fine to medium sand with varying amounts of gravel and organics that we interpreted as undocumented fill soils. In Hand Hole HH- 2, we encountered approximately 1.0 feet of surficial topsoil underlain by very stiff, brown-gray silt with fine sand and gravel that we interpreted as native transitional bed deposits. Hand Hole HH-1 was terminated in the undocumented fill soils while Hand Hole HH-2 was terminated in the native transitional bed deposits at depths of 3.0 and 2.0 feet below the ground surface,respectively. Hydrologic Conditions Minor to moderate groundwater seepage was encountered in Boring B-1 and B-2 at approximately 11.0 and 8.0 feet below the existing ground surface, respectively. We interpreted this groundwater to be a perched water condition. Perched water occurs when surface water infiltrates through less dense, more permeable soils, such as the undocumented fill soils, and accumulates on top of a relatively low permeability material such as the transitional bed deposits. Perched water does not represent a regional groundwater "table" within the upper soil horizons. Perched water tends to vary spatially and is dependent upon the amount of rainfall. We would expect the amount of perched groundwater to decrease during drier times of the year and increase during wetter periods. NELSON GEOTECHNICAL ASSOCIATES, INC.