7818 LARIMER RD B Geotech Report 2022-10-25

The Legend and Notes necessary to interpret our Exploration Logs are also included in an appendix. Data obtained from site observations, subsurface exploration, laboratory evaluation, and previous experience in the area was used to perform engineering analyses. Results of engineering analyses were then used to reach conclusions and recommendations presented in this report. The subsurface exploration results are shown on the individual Boring Logs included in an Appendix. The Legend and Notes necessary to interpret our Boring Logs are also included in an appendix. SUBSURFACE CONDITIONS Soil classification and identification is based on commonly accepted methods employed in the practice of geotechnical engineering. In some cases, the stratigraphic boundaries shown on Boring Logs represents transitions between soil types rather than distinct lithological boundaries. It should be recognized that subsurface conditions often vary both with depth and laterally between individual boring locations. The following is a summary of the subsurface conditions encountered at the site: Topsoil: Clayey silt to silt with organics is present in upper up to 12 inches throughout the site. Native Clays and Silts: Bellow topsoil, the site is primarily underlain by about 10 feet of medium stiff to very stiff silts (in upper 6 feet) and clays (below 6 feet) that are typically present as 'Transitional Beds' in the site vicinity area. Groundwater: Stable groundwater table was not encountered during explorations; However, perched groundwater conditions exist at depths of about 5-6 feet below existing ground surface during heavy rains, throughout the site. This observation may not be indicative of other times or at locations other than the site. Some variations in the groundwater level may be experienced in the future. The magnitude of the variation will largely depend upon the duration and intensity of precipitation, temperature and the surface and subsurface drainage characteristics of the surrounding area. GEOLOGIC HAZARDS EVALUATION Based upon the results of our site exploration, engineering analysis, and literature review of following documents, we evaluated geologic hazards at the site. • Washington Division of Geology and Earth Resources, Open File Reports • U.S. Geological Survey Maps • Environmental Critical Areas Maps. Proposed Construction Project No: 0470-WA18 January 24, 2019 Page No: 2 of 17