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NELSON GEOTECHNICAL ASSOCIATES, INC. April 10, 2020 Mr. Stepan Lyashenko VIA Email: Iyashenkostepan0gmail.corn_ Geotechnical Engineering Evaluation Lyashenko Accessory Dwelling Unit Development 5801 South 2"d Avenue Everett, Washington NGA Project No. 1165620 Dear Mr. Lyashenko: 17311-13511, Ave. N.E. Suite A-500 Woodinville, WA 98072 (425) 486-1669 www.nelsongeotech.com We are pleased to submit the attached report titled "Geotechnical Engineering Evaluation — Lyashenko Accessory Dwelling Unit Development — 5801 South 2"d Avenue — Everett, Washington." This report summarizes our observations of the existing surface and subsurface conditions within the site, and provides general recommendations for the proposed site development. Our services were completed in general accordance with the proposal signed by you on March 3, 2020. The rectangular -shaped parcel is approximately 0.81 acres and currently occupied by an existing single- family residence. Topography within the site is generally relatively level to gently sloping from west to east. The ground surface is covered with mostly grass yard areas and young to mature trees around the perimeter of the site. We understand that the proposed development will likely include constructing an Accessory Dwelling Unit (ADU) within the northern to northeastern portions of the property. We have been requested to provide a geotechnical evaluation of the proposed development. We performed four test pit explorations throughout the property, one of which we utilized for our small-scale pilot infiltration testing (PIT). Our explorations indicated that the site was underlain by surficial topsoil/undocumented fill with competent, native glacial soils at depth. It is our opinion that the proposed site development is feasible from a geotechnical engineering standpoint, provided that our recommendations for site development are incorporated into project plans. In general, the native glacial soils underlying the site should adequately support the planned structures. Conventional shallow spread foundations should be advanced through any loose soils down to the competent native bearing glacial material interpreted to underlie the site, for bearing capacity and settlement considerations. These soils should generally be encountered approximately 4.0 to 7.5 feet below the existing ground surface, based on our explorations. However, deeper areas of loose soils or undocumented fill could be encountered in unexplored areas of the site. If encountered, these soils should be removed and replaced with structural fill for foundation and pavement support. Due to the significant depth of fill, as an alternative we recommend the proposed ADU foundations be supported on 4-inch diameter pin piles to advance structure loads through the undocumented fill soils down to competent native soils. NELSON GEOTECHNICAL ASSOCIATES, INC.