4501 COLBY AVE 2016-01-01 MF Import

GeoTest Services,Inc. January 5, 2007 4501 Colby Avenue.Everett.WA Job No 07-J02B areas of hummocky topography, scarps, tension cracks, sag ponds, excessivety curved or knocked-over tree trunks, or unexplainable vegetative anomalies. Suhsurface Conditions I During our site visit, we explored the subsurface soil conditions at six locations. Three locations were hand dug test pits and three locations were explorations using a Dynamic Cone Penetrometer (DCP) adjacent to the test pits. See Figure 1 for approximate exploration locations. A DCP probe includes recording the number of blows necessary to advance a pointed steel rod into the ground with a 35•pound drop hammer. The blows necessary to advance the rod ir.to the soil have been correlated with the density of granular soil deposits and the consister�cy of cohesive soils. SubsuAace soil condi!ions at TP-1, TP-2 and TP-3 consisted of brown, moist, silty sand with occasional cobbles, overlying hard, glacial till. All explorations ended in the glacial tiil. TP-1 and TP-2 were terminated at a depth of 4.5 feet and 2.5 feet below existing ground surface, respectively, while TP-3 v✓as terminated at 1 foot below ground surface. No groundwaler was encountered within the hand dug test pits at the time of our investigation. Results of the DCP anaiysis indicate that very loose to loose soils were encountered to deplhs of approximately 4.25 to 3.5 feet. Below these depths, all of the explorations encountered what was interpreted to be the underlying, haro, glacial tiil. All of the DCP tests terminated on the encountered till. The hard, till soil and should provide adequate bearing support for the proposed shallow foundations with a design bearing pressure of 2,500 psf. Discussion The subject property is listed in the Snohornish County Cede as � geologically hazardous area, due to the presence of siopes with inclinations greater than 33%. In general, it is our opinion that the subject lot slope is stable in its present condition and configuration. Due to the hard glacial till interpreted to underlie the site, a deep seated rotational type failure is unlikely to occur. Evidence of a larc�e deep•seated rotational type failure was not observed on the property or in the immediate vicinity. Rotational failures can extend down into lhe subsurfar.e substantial depths. These tailures 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 subsurface exploration for this assessment, we focused on tra�ersing the accessible site slope for visual evidence of past failures. No obvious visual indications of large-scale siope instab�lity, such as lhose reterenced above or signs of shallow sliding or excessive erosion were observed on the lot or in the immediately surrounding vicinity. i Based upon the above information, it is our opinion that the proposed 30 foot setback from the top ot the steep slope wiil provide protection equal to or grealer than that provided by Snohomish County Code Section 30.6i..210, whir,h would be approximalely 6 feet. The daylight basement design of the proposed residence would mitigaie any slope related issues. Page 2 oi 5 � \ �,�� ) ��