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LJ <br />Cripple Creek & Victor Gold Mining Company November 13, 2003 <br />1 Mr. Ron Roberts -3- 003-2203 <br />Permeability Testine <br />Flexible-wall permeability testing was conducted on samples ALT-TP-l, ALT-TP-3, ALT-TP-6, <br />ALT-TP-8, ALT-TP-9 and ALT-TP-10. Results of the permeability testing conducted on the soils aze <br />summarized in Table 2. The samples were compacted according to project specifications to <br />approximately 95 percent of the standard Proctor maximum dry density. Though the target moisture <br />content for the permeability testing was 3 percent below optimum, representing the lower bound of <br />the SLF specification, the samples were compacted from 0 to 3 percent below the optimum moisture <br />content. The resulting permeabilities ranged from 5.8x10"~ to 4.0x10"5 cm/sec. With the exception of <br />one test (ALT-TP-9), all samples failed to meet the permeability requirements for the VLF project <br />specifications. <br />Of the samples that did not meet the project specifications with regazd to permeability, three <br />' (ALT-TP-I, ALT-TP-6, and ALT-TP-B) were retested to assess the potential reduction in <br />permeability by increasing the level of compaction. The samples were compacted to higher than the <br />project specifications (ranging from approximately 98 to 100 percent of the standazd Proctor density) <br />and retested. The permeability ranged from 2.1x10' to 2.9x10'5 cm/sec. Two of the four samples <br />' failed to meet the permeability requirements for the VLF project specifications. <br />An additional permeability test was conducted to evaluate the further reduction in permeability due to <br />increasing the level of compaction with use of the modified Proctor compaction test, in lieu of the <br />standard Proctor compaction test. This soil sample [ALT-TP-6 (Mod)] was compacted to <br />98.6 percent of the modified Proctor density at a moisture content approximately 1 percent below <br />1 optimum. The resulting permeability of 4.0x10$ cm/sec was approximately one order of magnitude <br />less than the same soil sample (2.1x10' cm/sec) tested at 100.4 percent of the standazd Proctor <br />maximum dry density. <br />Additional testing was conducted on samples from ALT-TP-1, ALT-TP-6, ALT-TP-8, and <br />ALT-TP-10 to evaluate the potential reduction in permeability by addition of 1 to 3 percent by dry <br />weight of bentonite. These samples were compacted according to project specifications to <br />approximately 95 percent of the standazd Proctor density and at moisture contents approximately <br />3 percent below the optimum moisture content. Prior to compaction, Wyo-Ben Envirogel bentonite <br />was added to each soil sample. The Material Safety Data Sheet for the Wyo-Ben Envirogel bentonite <br />is included as Appendix B. The soil was thoroughly mixed, moisture conditioned, and remolded to <br />the required density. Each sample was saturated for a period of 24 hours to hydrate the bentonite. <br />After the hydration period, the samples were tested. The resulting permeabilities for samples with <br />1 percent by weight of bentonite ranged from 5.3x10"s to 6.Sx10~ cm/sec, as summarized on Table 2. <br />Two of the five samples with 1 percent addition of bentonite failed to meet the permeability <br />requirements of the VLF project specifications. The permeability for samples with 3 percent by <br />weight of bentonite (ALT-TP-1 OA and ALT-TP-1 OB) ranged from 2.9x10'' to 4.6x10"' cm/sec, which <br />met project specifications with regazd to permeability. <br />Interface Shear Testine <br />In February 2003, single-point liner interface shear testing was conducted on sample ALT-TP-11 <br />from the East Cresson Mine. The liner interface shear test report is included in Appendix A. Single <br />point interface shear testing was conducted on samples amended with 3 percent bentonite and <br />moisture-conditioned to both 3 percent above the optimum moisture content, and the optimum <br />moisture content. Assuming zero adhesion, the resulting residual friction angle were 30.0° and 19.5° <br />for tests conducted at the optimum moisture content and at 3 percent above optimum moisture <br />content, respectively. <br />iswovxmwiornomxzm.otoo.ovoo~aEn'torrs[.f'nx Golder Associates <br />