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—� January 9, 1996 -4- 943-2847.001 <br /> t <br /> material had a peak cohesion of 920 psf and a friction angle of 18 degrees, and residual <br /> cohesion of 410 psf and a friction angle of 18 degrees. The failure surface for both <br /> tests noted the failure plane occurred in the Soil Liner Fill adjacent to the 100 mil <br /> textured HDPE geomembrane. <br /> From the interface shear strength testing performed for configurations 1 and 2, the effect <br /> of placing a thin veneer of Carlton tailings over 60 percent of the Ironclad Soil Liner Fill <br /> surface area which was in contact with the 80 mil smooth LLDPE geomembrane, was to <br /> increase the interface shear strength properties. This was also observed for configurations <br /> 3 and 4, when a veneer of Carlton tailings was placed over the Ironclad Soil Liner Fill and <br /> in contact with the 80 mil smooth HDPE geomembrane. Based on these test results, <br /> Golder would expect that by placing a veneer of Carlton tailings over the surface of the <br /> Area No. 2 Soil Liner Fill and in contact with the textured 80 mil geomembrane, the <br /> interface shear strength would equal or exceed the interface shear strength results obtained <br /> with the testing performed with no Carlton tailings. <br /> Interface testing was performed for the Low Volume Solution Collection Fill / 100 mil <br /> textured HDPE geomembrane / Area No. 2 Soil Liner Fill configuration. Based on the <br /> testing that has been performed to date, the interface shear strength for LLDPE has <br /> exceeded those for HDPE, when used. in the same configuration. Therefore, Golder would <br /> expect the interface shear strength for Low Volume Solution Collection Fill / 100 mil <br /> textured LLDPE geomembrane / Area No. 2 Soil Liner Fill configuration to meet or <br /> exceed the strengths measured for the Low Volume Solution Collection Fill / 100 mil <br /> textured HDPE geomembrane / Area No. 2 Soil Liner Fill configuration. <br /> In addition, the test results for the Low Volume Sclution Collection Fill / 100 mil textured <br /> HDPE geomembrane / Area No. 2 Soil Liner Fill configuration indicated that the failure <br /> plane occurred in the Soil liner Fill, adjacent to the geomembrane. Therefore, the <br /> interface shear strength is a function of the shear strength of the Area No. 2 Soil Liner Fill <br /> and the test results would not be expected to differ significantly for a geomembrane with a <br /> thickness less than 80 mil. Therefore, Golder would expect that the interface shear <br /> strength for the Drain Cover Fill / 80 mil textured HDPE or LLDPE Qeomernbrane / Area <br /> No. 2 Soil Liner Fill configuration would not differ significantly from that determined for <br /> the Drain Cover Fill / 100 mil textured HDPE geomembrane / Area No. 2 Soil Liner Fill <br /> configuration. <br /> The interface shear strength test is performed by constructing the configuration in the <br /> laboratory, placing a normal load onto the configuration, and shearing the sample at a rate <br /> of 0.04 inches per minute. Since the sample is not allowed to consolidate completely <br /> under the normal load applied and the excess pore water pressures generated from the <br /> } applied normal load are not allowed to dissipate, it is Golder's opinion that these tests <br /> provide relatively conservative results. The interface shear strength results that were <br /> obtained under these conservative conditions provided acceptable Factors of Safety (FOS) <br /> for the Ironclad material. In order to more closely model expected field conditions, Golder <br /> repeated the interface shear strength tests for the Low Volume Solution Collection Fill / <br /> Golder Associates <br />