2008-04-15_REVISION - M1980244 (199)

Home Browse Search

January 9, 1996 -4- 943-2847.001 material had a peak cohesion of 920 psf and a friction angle of 18 degrees, and residual cohesion of 410 psf and a friction angle of 18 degrees. The failure surface for both tests noted the failure plane occurred in the Soil Liner Fi11 adjacent to the 100 mil textured HDPE geomembrane. From the interface shear strength testing performed for configurations 1 and 2, t.'te effect of placing a thin veneer of Carlton tailings o~•er 60 percent of the Ironclad Soil Liner Fill surface area which was in contact with the 80 mil smooth LLDPE~eomembrane, was to increase the interface shear strength properties. This was also observed for configurations 3 and 4, when a veneer of Carlton tailings was placed over the Ironclad Soil Liner Fill and in contact with the 80 mil smooth HDPE geomembrane. Based on these test results, Golder would expect that by placing a veneer of Carlton tailings over the surface of the Area No. 2 Soil Liner Fill and in contact with the textured 80 mil geomembrane, the interface shear strength would equal or exceed the interface shear strength results obtained with the testing. performed with no Carlton tailings. Interface testing was performed for the Low Volume Solution Collection FiII / 100 mil textured HDPE geomembrane /Area No. 2 Soil Liner Fill configuration. Based on the testing that has been performed to date, the interface shear strength for LLDPE has exceeded those for HDPE, when used in the same configuration. Therefore, Golder would expect the interface shear strength for Low Volume Solution Collection Fill / 100 mil textured LLDPE geomembrane /Area No. 2 Soil Liner Fill configuration to meet or exceed the strengths measured for the Low Volume Solution Collection Fill / 100 mil textured HDPE geomembrane /Area No. 2 Soil Liner Fill configuration. In addition, the test results for the Low Volume Solution Collection Fiil / 100 mil textured HDPE geomembrane /Area No. 2 Soil Liner Fill configuration indicated that the failure plane occurred in the Soil liner Fill, adjacent to the geomembrane. Therefore, the interface shear strength is a function of the shear strength of the Area No. 2 Soil Liner Fill and the test results would not be expected to differ significantly for a geomembrane with a thickness less than 80 mil. Therefore, Golder would expect that the interface shear strength for the Drain Cover Fill / 80 mil textured HDPE or LLDPE geomembrane /Area No. 2 Soil Liner FiII configuration would not differ significantly from that determined for the Drain Cover Fill / 100 mil textured HDPE geomembrane /Area No. ?Soil Liner Fill configuration. The interface shear strength test is performed by constructing the configuration in the laboratory, placing a normal load onto the confisuration, and shearing the sample at a rate of 0.04 inches per minute. Since the sample ~is not allowed to consolidate completely under the normal load applied and the excess pore water pressures generated from the } applied normal load are not allowed to dissipate, it is Golder's opinion that these tests J' provide relatively conservative results. The interface shear strength results that were ,~ obtained under these conservative conditions provided acceptable Factors of Safety (FOS) for the Ironclad material. In order to more closely model expected field conditions, Golder repeated the interface shear strength tests for the Low Volume Solution Collection Fill / Golder Associates -- ~