7818 LARIMER RD B Geotech Report 2022-10-25

! 0 • City of Everett GIS • Snohomish County GIS • Soil Survey Maps • Washington Geologic Hazards Explorer Landslides: Our review of available geologic maps and landslide hazard maps did not indicate that landslides had occurred in the proposed construction area, and the site is not located within any existing known slide area as illustrated in Figure 3 through Figure 5. During our site reconnaissance and in the available geologic and geologic hazards maps. landslide features were not mapped within the site boundary area. In general, the site and the vicinity area is not close to the zone designated as having landslide potential. The site itself and the immediate vicinity area has not been subjected to the deep-seated landslides or slope failures. The closest landslide hazard area and geologic landslide deposits of concern are located several hundred feet away from the site as shown in Figure 3 and Figure 5. Our site reconnaissance did not reveal any significant potential for slope failures, shallow slumps, or severe erosion at the site. At present, there are no visual signs of slope failures such as tension cracks, bent trees, unusual drainage patterns and vegetation, leaning retaining walls, or significant settlements or movements in any existing structures. However, considering the site topography, the presence of high moisture, the presence of perched water conditions, and clayey/silt soils, in our opinion, there is a potential for soil creep and/or slope instability at the site during unusual natural events or excessive grading operations in . the site vicinity area. Historically, construction in such site conditions and slope areas, there is an inherent risk associated with landslides. The owner should understand and assume this risk. No warranty is expressed or implied in terms of the landslide hazards present at the site, without performing a detailed and comprehensive landslide hazards assessment for the site and the vicinity area. Slope Stability Evaluation: Using the results of subsurface exploration, laboratory evaluation, and site reconnaissance data, we analyzed on -site slopes by performing preliminary slope stability analyses. We used the software SLOPE/W to model on -site slopes, subsurface soil conditions, and the impact of proposed construction on the stability of the site. Based on the results of our preliminary evaluation, we make following recommendations. • There is a low to moderate potential for shallow slumps or soil creep in the upper 4-6 feet in steep slope areas and within 10 feet of the steep slopes of the site, unless proper geotechnical design and well -monitored construction activities are used to develop the site. Provided proper geotechnical design is done, and all our recommendations are strictly followed, the site will remain stable after proposed construction. Although the potential is low, minor localized and shallow slumps may occur in the steep slope areas, however, their occurrence will not impact Proposed Construction Project No: 0470-WA18 January 24, 2019 Page No: 3 of 17