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• i <br />Sliding during the shearing was observed between the liner cover fill and geomembrane in all 01 <br />the normal stress ranges with the exception of the 50 psi normal stress using 30 percent of the <br />Goldstar tails. This is consistent with previous test results and indicates that use of the tailings <br />as a thin smoothing layer does not significantly reduce the frictional strength of the soil liner <br />fill/geomembrane interface. Results of the large scale direct shear tests are presented in draft form <br />as Attachment A. The pending results will be forwarded to MLRD in draft form as soon as they <br />are completed. A copy of the final report will also be forwarded to MLRD once it has been <br />completed by GeoSyntec. <br />The previous slope stability analyses were evaluated using engineering strength parameters of 24° <br />for the angle of internal friction and 100 psf for the cohesion intercept. The critical failure surface <br />was a wedge type failure that occurred along the geotexiile/geomembrane interface. The critical <br />failure surface did not occur along the composite liner section. The results of the previous slope <br />stability analyses are presented in the Responses to Comments by Technical Reviewer, D. P. <br />Engineering, lnc., March 1994. <br />Since the input parameters that were used in the referenced work are still valid and the theoretical <br />critical failure surface did not occur through the composite liner, additional stability analyses are <br />not required. <br />If you have any questions or comments, please don't hesitate to contact either me or Dr. Van Zyl. <br />Respectfully, <br />GOLDER ASSOCIATES INC. <br />~~q.~~ <br />David A. Kidd, P.F. <br />Project Manager <br />Geotechnical Engineering <br />Attachment A: Draft Test Results <br />