1618 HOLBROOK AVE 2018-01-02 MF Import

Retaining Wall Letter Lyashuk Residence, Everett, WA I January 29, 2007 NGA File No. 755806 Page 2 SCOPE The purpose of this study is to evaluate the subsurface soil and groundwater conditions at the site and provide recommendations for design and construction of a temporary ultra block wall. Specifically, our scope of services includes the following tasks: I. Review geologic and soil maps of the area. 2. Measure and map the slope conditions using hand-held equipment. 3. Plot cross -sections of the existing site slope conditions. 4. Provide a design for a temporary ultra block wall up to 12.5 feet in height. 5. Provide a written geotechnical engineering evaluation letter with our findings, opinions, conclusions, and recommendations. SITE CONDITIONS Surface Conditions The site consists mainly of gently sloping ground oriented down to the north. A level pad has been Iexcavated into the sloping ground to construct the planned residence. resulting in cuts up to 10 feet high near the southern property line. On the adjacent lot to the south the slope rises roughly 50 feet at I inclinations of 15 to 35 degrees, as shown on Cross -Section A -A in Figure 3. The site is currently stripped of vegetation and the wall of the excavation is covered with plastic sheeting. The slope on the I adjacent lot to the south is covered by blackberry bushes, and signs of sloughing and erosion were observed on the slope. We also observed slight groundwater seepage emitting front the lower portion of the south wall of the building pad excavation during our site visit. Subsurface Conditions Geology: The geologic units for this area are shown on the Preliminary Geologic Map of the Evcrett 7.5- minute Quadrangle, Snohomish County, Washington. by .lances P. Minard, et al. (U.S.G.S., 1985). The site is mapped as advance outwash (Qva) with transition beds mapped near the site. Advance outwash is described as mostly gray, well -stratified unconsolidated sand with pebbles and some cobbles. The sand deposits encountered in our explorations were consistent with the description of advance outwash. NELSON GEOTECHNICAL ASSOCIATES, INC.