1205 50TH ST SW 2020-07-02 - Laserfiche WebLink

Geotechnical Engineering Evaluation NGA File No. 1033518 Larsen Property Garage May 8,2018 Everett,Washington Page 2 SITE CONDITIONS Surface Conditions The site consists of a roughly rectangular-shaped parcel covering approximately 0.48 acres. The site is currently occupied by a single-family residence within the central portion of the property. The ground surface within the site is relatively level to gently sloping from the southeast to the northwest throughout the site. Along the very eastern property line,the ground surface slopes'moderately,to steeply down from the eastern property line to a gently sloping area along the eastern side of the existing residence at a gradient of approximately 23 degrees (42 percent) as shown on Cross Section A-A' in Figure 3. Immediately above the sloping area along the eastern property line is an existing concrete rubble retaining wall supporting the yard area associated within the neighboring property above and to the east of the subject property. The rubble wall ranges from approximately four to seven feet in exposed height and appears to be in disrepair. The site and slopes are generally vegetated with spars grass,landscaping plants and trees. The property is bordered to the north, east, and west by residential properties and to the south by 50th Street SW. We did not observe any standing water within the site or groundwater seepage within the site slopes during our site visit on April 3, 2018. We also did not observe significant signs of recent slope movement during our site visit. The existing site conditions and proposed development areas are shown on the Schematic Site Plan in Figure 2. Subsurface Conditions Geology: The geologic units for this area are shown on the Geologic Map of the Everett 7.5-Minute Quadrangle, Snohomish County,Washington,by James P. Minard(U.S.G.S., 1985). The site is mapped as Glacial Till (Qvt). The glacial till is described as a non-sorted mixture of silt, sand, and cobbles. Our explorations within the site generally encountered surficial undocumented fill underlain by medium dense to dense fine to medium sand with varying amounts of silt and gravel that we interpreted as glacial till deposits. Explorations:_The subsurface conditions within the site were explored on April 3, 2018 by excavating five hand auger explorations to depths in the range of 3.0 to 4.5 feet below the existing ground surface. The approximate locations of our explorations are shown on the Schematic Site Plan in Figure 2. A geologist 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. The soils were visually classified in general accordance with the Unified Soil Classification System, presented in Figure 4. The logs of our hand augers are attached to this report and are presented as Figures 5 and 6. We present a brief summary of the subsurface conditions in the following paragraph. For a detailed description of the subsurface conditions,the hand auger logs should be reviewed. NELSON GEOTECHNICAL ASSOCIATES,INC.