3610 W MUKILTEO BLVD Geotech Report 2022-10-25

Geotechnical Engineering Evaluation NGA File No. 1129119 Zahier Residence Development October 14,2019 Everett,Washington Page 2 5. Qualitatively map conditions on site slopes, perform shallow hand angered explorations, and develop geologic cross-sections. 6. Provide recommendations for earthwork,foundation support, and slabs-on-grade. 7. Provide recommendations for temporary and permanent slopes. 8. Provide recommendations for pavement subgrade preparation and subsurface utility installation. 9. Provide recommendations for site drainage and erosion control. 10. Provide recommendations for temporary or permanent shoring measures,as needed. 11. Determine feasibility of on-site storm water infiltration. 12. Document the results of our findings, conclusions, and recommendations in a written geotechnical report. SITE CONDITIONS Surface Conditions The site consists of a rectangular-shaped parcel covering approximately 0.44 acres within the Edgewater neighborhood of Everett. The site is currently undeveloped and vegetated with grass-covered yard areas and few young to mature trees bordering the site. A gravel access driveway extends into the site from the northern property line. Topography within the site consists of a broad northeast-southwest trending ridgeline plateau area within the central portion of the site bound by gentle north- and southeast-facing slopes that descend to the property lines at gradients in the range of 10 to 13 degrees(18 to 23 percent),as • shown on Cross Section A to A' in Figure 3. The site is bound to the north by West Mukilteo Boulevard and to the west, east, and south by other residential properties. We did not observe surface water on the site during our visit on September 19,2019. Subsurface Conditions Geology: The site is mapped on the Distribution and description of geologic units in the Mukilteo quadrangle, Washington, by James P. Minard (US Geological Survey, 1982). The site is mapped as Transitional beds (Qtb). Transitional beds are described as glacial and non-glacial deposits that consist primarily of thick beds of gray clay, silt, and"fine- to very-fine sand. Our explorations typically encountered undocumented fill underlain by silty fine to medium sand with gravel consistent with the description of transitional bed deposits. Explorations: The subsurface conditions within the site were explored on September 19, 2019 by monitoring the excavation of six trackhoe excavated test pits. The approximate locations of our explorations are shown on the Site Plan in Figure 2. A geologist from NGA was present during the explorations, examined the soils and geologic conditions encountered, obtained samples of the different soil types,and maintained logs of the test pits. NELSON GEOTECHNICAL ASSOCIATES, INC.