4003 NASSAU PL 2016-01-01 MF Import

I. Geotechnical Engineering Report Kvemmo Single-Family Residence � 4003 Nassau Place, Evereit September 17, 2002 NGA File No. 35610? ' Page 5 to hard silt at the project site best fits the UBC description for Soil Profile Type Sp (Stiff Soil Profile) for 1 native coils. � Geotechnical seismic considerations include liquefaction potentisl and amplification of ground motions by soft soil deposits. Liquefaction potential is highest for loose sand beneath the ground water table. The � very stiffto hard soils interpreted to underlie the site are considered to have low potential for liquefaction or amplification of ground motion. Erosion Hazard The criteria used for evaluation of erosion harards include soil type, slope grsdient, vegetation cover, and Igound water conditions. The surface soil types (group classification) are related to the underlying geologic soil units. The Soil Survev of Snohomish Countv Area. Washin on, by the Soil Conservation �_ Service (SCS), wu reviewed to evaluete the erosion hazard of the on-site soils. � The surface soils at the site were mapped by the SCS and classified as Alderwood gravelly sendy loam. 'fhe su�cial site soils we observed are not consistent with the Alderwood gravelly sandy loam soils. T'he soils expected to be exposed during site development consist of loose silry fill material. The erosion potential of these fill soilt should be considercd moderate to high. The contact between +.i;e existing fill and the native soils is a potential slip surface. Recommendations for improving the stability of the fill material can be found in the Slope Stability subsection of this repott. CONCLUSIONS AND RECOMMENDATIONS General It is our opinion that the existing loose fill in the planned addition area is not suitable for support of a shallow foundation due to the substantial potential for future foundation settlement and cracking. Also, the fill was placed in an uncontrolled manner, making future fill movement and sliding a possibility. It is likely that the site was not properly suipped of topsoil material or benched prior to placing the fill. You plan to place up to 8 feet of fill material as a part of the site development. In our opinion the existing fill NELSON GEOTECHNICAL ASSOCIATES, INC.^ U