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1 <br />' PN: D9S263MT <br />December 21, 1995 <br />Page 2 <br />We performed random field density tests during the material <br />placement at the project site. All areas where the test results <br />indicated that the material placed did not meet the minimum project <br />' compaction requirements were re-rolled and retested until the test <br />results indicated that the required relative compaction in the <br />areas tested were achieved. The field density test results are <br />' presented in Appendix A. <br />We performed a Direct Shear test on the material placed to <br />determine the angle of internal friction (phi) and cohesion of the <br />material being placed. We performed the direct shear on a soil <br />sample with a dry density of 113.6 pounds per cubic foot, which is <br />about ninety two (92) percent relative compaction using the results <br />of the moisture-content-dry density (Proctor) test results for the <br />material tested. We obtained an angle of internal friction of <br />twenty (20) and a cohesion of 200 pounds per square foot from the <br />' direct shear test results. The nominal average wet density of the <br />material placed in the field, and the wet density of the direct <br />shear sample tested was about 130.0 pounds per cubic foot. <br />' The material at the Oak Ridge Energy site was placed on top of <br />and adjacent to an existing soil deposition area. We understand <br />that a drain system was placed below the existing pile near the toe <br />' of the slope. Long term stability of the deposition. area is <br />dependent, in a very large part, on the proper location and long <br />term performance of the drain system. <br />' The stability of any slope is dependent on many factors. <br />Typically the stability of a slope is analyzed by calculating the <br />anticipated gravitational forces that tend to drive the mass of <br />soil downhill and compare these forces to the internal strength <br />characteristics of the soil along the expected plane of failure <br />which tend to resist the potential movement. If the driving forces <br />' are greater than the resisting forces then failure of the slope is <br />likely. Slope failure can occur as slow deformation, creep, or as <br />a somewhat spontaneous and rapid movement. <br /> As requested we performed a simplified Bishops Method of <br /> slices to assess the theoretical slope stability of the material as <br /> placed. We understand that the steepest slope gradient of the <br />t material is about two horizontal to one vertical. The maximum <br /> height of the material above the adjacent toe is about seventeen <br /> (17) feet . We used the soil parameters, slope gradient, and <br />' material height in our analysis. We did not assess the in-place <br />support materials on the site. We understand that the stability of <br />1 <br />+!~:~irtl~rrt ;~izl ~ss~rri;~lrs <br /> <br />