500 LAUREL DR 2016-01-01 MF Import

Geotechnical Engineering Study 00-2267 Three Story Addition - 500 January 31, 2001 Laurel Street, Everett Soil Description USCS Unit Friction Gohesi�n Symbol Weight Angle (Psfl (p� (ptai) Loose sitty SAND SM 118 32 0 SILT ML 130 28 100 SiItySAND SM �20 32 � Clayey SIL7 CL 130 28 2000 Silty SANL' SM 128 38 0 SILT ML '!28 28 150 Page 28 With these soil parameters, and the general slope configuration developed along an imaginary geometric profile at. about the point where the slope is closest to the existing residence, we ��nducted a computerized analysis of the slopes' stability usinq the SLOPE/W finite element program developed by GeoSlope Intemational of Canada. Our analyses were performed for the existing siope configuration, which is also expected to be the post construction geometry since there are no plans to generate any disturbance of the existing siopes. We analyzed a total of ten thousand five hundred and seventy-one (10,571) potential failure surFaces in an effort to find the potentially "critical" failure surface. That is, the surface with the lowest factor of safety for the slope. As irdicated earlier in this report we used a horizontal acceleration of 0.17g in our dynamic (earthquake) analysis. We develoFed two "minimum' factors of safety for static and dynamic conditions. The minimum factor of safety is that for the "most critical" plane of potential failure, and this typically does not �xtend back more than about seven io eight feet from the existing b�uff slope crest. The second "minirnum" factor of safety is for a potential plane of failure that extends back close to the northwestem corner of the existing residence. These fact��rs of safety developed in our analyses are tabulated below for your information. yG