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• • <br />A total of four unconsolidated-undrained direct shear <br />• tests were performed on the bulk samples provided for our use. <br />Representative samples were obtained for the direct shear <br />tests from each of the material types including each of the <br />two (2) overburden samples, a sample of the unweathered coal <br />refuse, and a sample of the weathered coal refuse. These <br />representative samples were then wet sieved through a 40 sieve <br />and the tests were performed on the material passing the <br />sieve after it was allowed to air dry to a moisture content <br />slightly above its plastic limit and then compacted by kneading. <br />The results of our sieve analysis tests are shown graph- <br />ically in Figures 3 through 6 included within this report. The <br />results of the Atterberg limits tests are tabulated below <br />along with the results of our direct shear tests. The direct <br />shear results are also shown graphically later in this report <br />in Figures 7 through 10. <br />• STABILITY ANALYSIS <br />[de analyzed a cross-section of the dispoal area using a <br />Bishop Method of Slices computer program and the data obtained <br />from our laboratory testing. The cross-section analyzed was <br />one of the least stable cross-sections which was provided for <br />our use. The cross-section used along with the presumed <br />highest phreatic surface possible is shown in Figure 2. <br />Included within this figure are the engineering properties <br />of the soils which were used in the analysis as well as the <br />resulting failure surface location. The location of the <br />phreatic surface Baas determined considering the worst conditions <br />possible for the soils tested and by also considerinc the <br />drainage conditions involved as well as the probable final <br />properties of the placed materials. Appendix A provides a <br />listing of the results of the computer run used for the <br />analysis of this problem. <br />• <br />-3- <br /> <br />