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Tegre Corporation <br /> Job No. 3124JS057 <br /> would be indicative of the conditions encountered in Boring B-2, where the clay overburden <br /> was only about 2 feet thick and was underlain by the cobble and boulder layer. It was <br /> assumed that the maximum excavation depth would not exceed 80 feet. <br /> The second profile consisted of lean clay underlain by cobbles and boulders. It was assumed <br /> that the lean clay would be 34 feet thick, the maximum clay layer thickness that was <br /> encountered at the boring locations. This stratigraphic profile is indicative of the conditions <br /> encountered in Boring B-6. It was assumed that the underlying cobble and boulder layer <br /> would be 46 feet thick and would be underlain sandstone bedrock. It was assumed that the <br /> maximum excavation depth would not exceed 80 feet. <br /> The soil strength parameters used in the analysis were based upon the results of the field <br /> and laboratory tests, typical values presented published literature, and our experience in <br /> the area. It was conservatively assumed that the cobble and boulder layer would have a <br /> friction angle of 40 degrees. On the basis of the existing slopes present on the site, the <br /> friction angle of the cobble and boulder layer is most likely higher. <br /> It was assumed that the lean clay would have a cohesion value of 2,000 psf and a friction <br /> angle of 0 degrees for the short-term condition (total stress). It was assumed that the lean <br /> clay would have a cohesion of 100 psf and a friction angle of 18 degrees for the long-term <br /> condition (effective stress). <br /> It was assumed that material stockpiles, equipment, staging or storage would occur outside <br /> of the critical failure surfaces. A summary of the soil design parameters used in the stability <br /> analysis is provided in the following Table 2. <br /> TABLE 2 <br /> SOIL DESIGN PARAMETERS <br /> Parameter Lean Clay Cobbles and <br /> Boulders <br /> Total Unit Weight 110 pcf 120 pcf <br /> Cohesion (c) 2,000 psf N/A <br /> Friction Angle (0) N/A 40° <br /> Effective Unit Weight 110 pcf 120 pcf <br /> Cohesion (c') 100 psf N/A <br /> Friction Angle (0') 18° 40° <br /> 7 G <br />