615 75TH ST SE Geotech Report 2022-10-25

Subsurface Exploration, Geologic Hazard, and Boardwalk Condominium, Building C Geotechnical Engineering Report Everett, Washington Project and Site Conditions variations beyond the field exploration may not become fully evident until construction. If variations are observed at that time, it may be necessary to re-evaluate specific recommendations in this report and make appropriate changes. 3.1 Exploration Boring The exploration boring was completed by advancing a hollow-stem auger with a hand-portable, Acker-type drill rig. During the drilling process, samples were generally obtained at 2.5- to 5-foot-depth intervals. The exploration boring was continuously observed and logged by an engineering geologist from our firm. The exploration log presented in the Appendix is based on the field log, drilling action, and inspection of the samples collected. Disturbed but representative samples were obtained from the exploration boring by using the Standard Penetration Test (SPT) procedure in accordance with American Society for Testing and Materials (ASTM):D 1586. This test and sampling method consists of driving a standard 2-inch, outside-diameter, split-barrel sampler a distance of 18 inches into the soil with a 140-pound hammer free-falling a distance of 30 inches. The number of blows for each 6-inch interval is recorded and the number of blows required to drive the sampler the final 12 inches is known as the Standard Penetration Resistance ("N") or blow count. If a total of 50 is recorded within one 6-inch interval, the blow count is recorded as the number of blows for the corresponding number of inches of penetration. The resistance, or N-value, provides a measure of the relative density of granular soils or the relative consistency of cohesive soils; these values are plotted on the attached exploration boring log (Appendix). The samples obtained from the split-barrel sampler were classified in the field and representative portions placed in watertight containers. The samples were then transported to our laboratory for further visual classification. 4.0 SUBSURFACE CONDITIONS Subsurface conditions at the project site were inferred from the field exploration accomplished for this study, visual reconnaissance of the site, and review of applicable geologic literature. As shown on the exploration log, the exploration boring generally encountered approximately 12 feet of loose to medium dense fill material and weathered native soils. Below a depth of approximately 121/2 feet, we encountered medium dense to very dense native soils interpreted as Vashon ice contact deposits. The following section presents more detailed subsurface information organized from the shallowest (youngest) to the deepest (oldest) sediment types. September 12, 2012 ASSOCIATED EARTH SCIENCES, INC. FSM11d—EE120288A8—Projects1201202881EFNP Page 3