4704 HARBOR LN 2018-01-02 MF Import

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. The samples obtained from the split-harrel 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. Subsurface Soil Conditions AESI identified three distinct soil types during our subsurface exploration program. Near - surface soils consisted of previously placed fill materials to a depth of about 7 feet below existing site grades at EB-1. It should be noted that the ground elevation at exploration boring EB-1 is estimated to be several feet higher than the elevations within the crawl space of the house. Furthermore, it did not appear that the subsurface soils observed in the crawl space consisted of fill material identified in LB -I. Below the fill material, AESI encountered medium dense sands with varying silt and gravel contents to a depth of approximately 34 feet below existing site grades. The material appeared disturbed and was interpreted to be landslide debris. The amount of silt observed in recovered samples, as well as depositional pattern, suggest that the parent material is likely a lodgment till, which has been mapped in the vicinity of the site. Below the fill :utd the landslide debris, at a depth of approximately 34 feet below existing site grades, AESI encountered very deme sands with relatively low silt and gravel contents interpreted to be pre-Vashon, coarse -grained deposits. Pre-Vashon deposits are part of older sand and gravel deposits that pre -date the Vashon Stade of glaciation into the Puget Sound region. These soils are typically very strong, have low compressibility, and are not particularly sensitive to moisture. Ground water seepage was no' -ountered in exploration boring EB-1 at the time of our field studies in September 2009. quantity and duration of ground water flow can vary with topography, soil grain size, sca anal precipitation, and off -site land use. 2 Z/b