4330 HOYT AVE Geotech Report 2022-10-25

Geotechnical Engineering Evaluation—REVISED NGA File No.1148519 Staniford Residence Remodel June 23,2020 Everett,Washington Page 3 Subsurface Conditions Geology: The geologic units for this site are shown on the Geologic map of the Everett 7.5 minute quadrangle, Snohomish County, Washington, by James P. Minard (USGS, 1985). The site is mapped as advance outwash (Qva). Advance outwash is described as clean, well stratified, unconsolidated sand with pebbles and some cobbles. During our explorations we encountered approximately 7.5 to 10.5 feet of undocumented fill soils and peat underlain by fine to coarse sand with gravel which we interpreted as native advance outwash. Explorations: We visited the site on November 13, 2019 and November 21, 2019 to explore the subsurface conditions around the existing residence with three track hoe excavated test pits. The approximate locations of our explorations are shown on the Schematic Site Plan in Figure 2. A geologist from Nelson Geotechnical Associates, Inc. (NGA) completed the explorations, examined the soils and geologic conditions encountered,and maintained logs of the explorations. The soils were visually classified in general accordance with the Unified Soil Classification System, presented in Figure 3. The logs of our explorations are presented in Figure 4. The following paragraph contains a brief description of the subsurface conditions encountered in the explorations. For a detailed description of the subsurface conditions,the hand auger and boring logs should be reviewed. At the surface of Test Pit 1 and 2 we encountered approximately 6.0 and 4.3 feet, respectively, of dark gray,fine to medium sand and silty fine to medium sand with varying amounts of gravel, silt, roots, and organics which we interpreted as undocumented fill soils. Underlying the fill soils we encountered approximately 3 to 4 feet of dark brown to black organic rich silty fine to medium sand with varying amounts of wood debris, roots,and organics, which we interpreted as peat. Underlying the peat in Test pit 1 and 2 we encountered gray,fine to coarse sand with varying amounts of gravel in a medium dense or better condition which we interpreted as native advance outwash soils. Both Test Pit 1 and 2 were terminated within the native advance outwash material at respective depths of 11.5 and 8.0 feet. At the surface of Test Pit 3 we encountered roughly 6.5 feet of dark brown to black silty fine to medium sand with gravel, organics, and anthropogenic debris which we interpreted as undocumented fill soils. Underlying the fill soils we encountered 1.5 feet of dark brown to black organic rich,silty fine to medium sand with wood debris which we interpreted as peat. Test Pit 3 was terminated within the peat material at a depth of 8 feet. NELSON GEOTECHNICAL ASSOCIATES,INC.