8110 LARIMER RD 2016-01-01 MF Import

GeoTest Services, Inc. March 22, 2007 8110 Lanmer Road, Everett, WA Job No. 07-0153 below the surface, where the unweathered glacial till was encountered. TP-2 was terminated at a depth of 10 feet. Surface soil conditions at the site and in the vicini;y consisted of a thin topsoil cover overlying what has been mapped as Aldenvood-Everett Gravelly Sand;� Loams - 25 to 70 Percent Slopes on the Soil Survey of Snohomish County Area, Washington (1978). Visual observation of the soils in the test pits tend to confirm the mapped soil type was present beneath the subject site. Groundwater was not encountered in the test pits at the time of our investigation. Discussion The subject property is listed in the Snohomish County Code as a geologically hazardous area, due to the presence of slopes with inclinations greater than 33% (-18°). In general, it is our opinion that the subject lot slope is stable in its present condition and r.onfnuration. Due to the hard glacial till interpreted to underlie the site, a deep seated rotational type failure is unlikely to occur. Evidence of a large deep-seated rotational type failure was not observed on the property or in the immediate vicinity. Rotational failures can extend down into the subsurface substantial depths. These failures leave typical geomorphic evidence of their existence on the slope. Typical indicators are head scarps, tension cracks, sag ponds, seepage zones, hummocky ground surface and slump blocks. As we did not perform a detailed s�bsurface exploration for this assessment, we focused on traversing the accessible site slope for visual evidence of past failures. No obvious visual indications of large-sr.ale slope instability, such as those referenced above or signs of shallow sliding or excessive erosion were observed on the lot or in the immediately surrounding vicinity. Based upon the above information, it is our opinion that the proposea 60 foo; �•,etback from the top of the steep slope will provide protection equal to or greater than that provided by Snohomish County Code Section 30.62.210, which would be approximately 8 feet. No evidence of groundwater was encountered in the test pits. Because of the lack of groundwater, and the medium dense granular soils and hard, impermeable, fine grained soils encountered at the proposed residence location, the potential for liquefaction at lhis site is very unlikely. Allowable Bearing Capacity mtinuous or isolated spread footings founded directly on suitably prepared native, �n dium dense, weathered till, may be proportioned using a maximum net allowable soii i= :3ring pressure of 1,500 pounds per square ft(ps�. F^� t.`�� •`•�rd, �nweathered till, a n,�.eimum net allowable soii bearing pressure of 2,500 p�r may be used. The term "net allowable bearing pressure" refers to the pressure that can be imposed on the soil at foundation level resulting from the total of all dead plus live loads, exclusive of the weight of the focting or any backfill placed above the footing. The net allowable bearing pressure may be increased by one-third for transient wind or seismic loads. Page 2 0� 5