1921 W MUKILTEO BLVD 2018-01-02 MF Import

Preliminary Geotechnical Engineering Evaluation 1919 Mukilteo Boulevard October 20, 2005 NGA File No. 718805 Page 3 ■ drill rig. Hand auger and hand hole explorations were excavated during slope mapping at the site on August 18, 2005. The approximate locations of our explorations are shown on Figure 2. An engineer 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 explorations. A Standard Penetration Test (SPT) was performed on each of the samples during drilling to document soil density at depth. The SPT consists of driving a 2-inch outer -diameter, split -spoon sampler 18 inches using a 14U-pound hammer with a drop of 30 inches. The number of blows required to drive the sampler the final 12 inches is referred to as the "N" value and is presented on the boring logs. The N value is used to evaluate the strength and density of the deposit. The soils were visually classified in general accordance with the Unified Soil Classification System, [ presented in Figure 4. The logs of our borings are attached to this report and are presented as Figures 5 through 7. The logs of our hand tool explorations are attached to this report and are presented as Figures 8 and 9. We present a brief summary of the subsurface conditions in the following naragraphs. For a detailed description of the subsurface conditions, the boring logs should be reviewed. Each of the borings exposed loose, silty fine sand with abundant organics extending to one foot below the existing surface. We interpreted this material to be topsoil. Belov, the topsoil each of the borings I: encountered loose fine to medium sand with silt and varying amounts of gravel extending between five to ten feet below the existing surface. Below the loose sand, each of the borings encountered medium dense, silty fine to coarse sand and sand with silt and varying amounts of gravel extending to depths of approximately 15 to 20 feet. Underlying the medium dense soil, each of the explorations encountered I'• dense to very dense fine to coarse sand with silt and gravel. All three of the borings were terminated in f dense to very dense sand at depths between 29.0 and 48.0 feet below the existing ground surface. I; Hand Auger 1, located along the top of the steep slope in the eastern portion of the site, encountered (, loose, silty fine to medium sand extending to 3.0 feet below the existing surface. Below the silty sand, f HA-1 encountered loose to medium dense, fine to coarse sand with varying amounts of silt and gravel extending to the depth explored at 8.2 feet. NELSON GEOTECHNICAL ASSOCIATES, INC.