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t f Geotechnical Engineering Evaluation NGA File No. 959616 Watson Residence Addition July 6,2016 Everett,Washington Page 2 SITE CONDITIONS Surface Conditions The property is a rectangular-shaped parcel covering approximately 0.25 acres, as shown on the Site Plan in Figure 2. The site is generally situated on a relatively level upper bench within the southwestern and central portion of the site. An existing single-family residence structure is located within the central portion of the site with an attached deck structure on the northern portion of the residence. A steep northeast-facing slope is located below and to the northeast of the upper bench area. The steep slope descends from the upper bench area to the toe of the slope along Forgotten Creek Trail at gradients in the range of approximately 30 to 35 degrees (58 to 70 percent) as shown on Cross-section A-A' in Figure 3. The overall height of the steep slope is approximately 70 feet. The existing deck and residence are setback approximately 20 and 30 feet from the top of the steep slope, respectively. The site is generally vegetated with grass, young to mature trees, underbrush and landscaping plants. The property is bounded to the northeast by the steep slope and Forgotten Creek Trail,to the southwest by Tulalip Avenue, and to the east and west by existing residential properties. We did not observe surface water on the site or seepage on the slope during our site visit on June 13, 2016. We also did not observe signs of recent movement on the site slopes or obvious settlement of the existing residence foundation. Subsurface Conditions Geology: The geologic units for this area are shown on the Distribution and Description of the Geologic Units in the Everett Quadrangle, Washington, by James P. Minard, (USGS, 1981). The site is mapped as Undifferentiated Vashon Glacial to Non-Glacial deposits (Qvn) with Advanced Outwash (Qva) mapped in the near vicinity. The intermixed glacial and non-glacial deposits are described as clay, silt, and fine sand with areas along Port Gardner described as very firm medium to coarse sand. The Advanced Outwash is described as unconsolidated clean sand with pebbles and some cobbles. Our explorations generally encountered medium dense to very dense, brown-gray to gray, fine to medium sand with silt and gravel at depth. We interpreted these soils as native Advanced Outwash soils. Explorations: We visited the site on Monday, June 13, 2016 to observe the existing site conditions and to explore the subsurface conditions within the planned improvement areas and the steep slope with hand-augered holes. The approximate locations of our explorations are shown on the Schematic Site Plan in Figure 2. A geologist from Nelson Geotechnical Associates, Inc. (NGA) was present during the NELSON GEOTECHNICAL ASSOCIATES, INC.