5001 23RD AVE W Geotech Report 2022-10-25

• Environmental Critical Areas Maps. • City of Everett GIS • Snohomish County GIS • Soil Survey Maps • Washington Geologic Hazards Explorer • Geologic Information Portal, USGS Landslides: Our review of available geologic maps and landslide hazard maps indicated that landslides had occurred in the close proximity of the site, and the site area in general is located within landslide hazard area as illustrated in Figure 5. Our site reconnaissance revealed the potential for shallow slope failures, shallow slumps, soil creep, or severe erosion at the site. At present, there are some visual signs of slope failures such as broken/cracked driveways, settlements, bent trees, leaning retaining walls, or significant settlements or movements in any existing structures related to landslide movement and/or soil creep or localized settlements. It is also possible that some of these features are related to utility leakage and/or global landslide instability impacting entire neighborhoods. Notwithstanding, a detailed global slope stability evaluation of the site and vicinity area was beyond our scope of services. Evaluation of ancient landslide analysis was beyond our scope of services. In general, any ancient landslide mass (If present) or landslide deposit (if present) or mapped geologic hazard areas are more likely to become unstable, relatively, compared to the areas that are not mapped as geologically hazardous. It is possible that there have been historic landslides, deep-seated landslides, or recently developed landslides (however inactive) present within or in the immediate vicinity of the site boundaries. Historically, for sites located within such critical slope areas, there is an inherent higher risk associated with future ground movement and associated structural distress. The owner/client should be aware of this inherent risk and should assume the entire risk. Considering the site topography, site geologic conditions, and current surface and subsurface conditions, it is our opinion that the immediate site and the vicinity area have some `inherent' risk associated with slope instability and structural impact from local slope movements. Moreover, historically, with construction in such areas, there is always an inherent risk associated with ground movement and/or settlements and related structural damage. The owner should understand these inherent risks. If the owner wants to better understand the risks and to eliminate the site-specific landslide hazard risks, then a detailed and comprehensive geotechnical evaluation including deep drilling, detailed slope stability modeling, and a detailed geologic hazards assessment (including global landslide hazards evaluation) should be performed to quantify the abovementioned risks and to provide detailed geotechnical design recommendations for comprehensive mitigation measures. Unless these recommended studies are performed, the Project No:0314-WA19 5\ August 07,2019 Page No:-4-ef-2