2012-02-28_REVISION - M1980244 (69)

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October 11, 1999 2.1 Test Apparatus The testing apparatus for this program consisted of a 10 -inch inside diameter (ID) aluminum load cell, approximately 18 inches in height. Figure 3 shows the assembled testing cell. The cell was clamped to the base plate and the tie -down rods anchored to the cell base plate. A porous loading plate was placed in contact with the material and a hydraulic jack was used to apply the force to the sample against the top plate. A digital pressure transducer was used to monitor the applied load and dial gauges measured deformation. The load from the hydraulic jack is adjusted to maintain desired loading stress throughout the test. 2.2 Test Configuration 3.0 TESTING RESULTS -2- 993 - 2075.002 Figure 4 shows the Drain Cover Fill used for this program. The Drain Cover fill was placed in the testing cell (Fiore 5), the initial sample height was recorded and the loading plate was secured. The sample was loaded in approximately 150 psi increments up to 450 psi. Vertical displacement values were recorded at each load beginning at 153 psi. The sample was saturated at 153 psi and additional consolidation was allowed to occur before permeability testing. After the consolidation of the sample stopped, the permeability of the material was tested. The sample was loaded further to consolidation pressures of 305, and 450 psi; and the permeability measured at these increments. A summary of the load - permeability test results is presented on Table 2 and presented in Figures 6 through 8. The average coefficient of permeability of the material at the 153, 305 and 450 psi loads was found to be .15, .15, and .11 centimeters per second (cm/sec), respectively. In general, the minimum acceptable permeability of ore and drain cover fills is in the range of 10 cm/sec (Van Zyl, 1988). Therefore, the load- permeability test results indicate that the Drain Cover mill material permeability exceeds the minimum acceptable value by three orders of magnitude even under a heap load of 450 psi (an equivalent heap height of 590 feet based on an average ore density of 110 pcf). It is important to note that previous tests conducted on the Drain Cover Fill material yielded similar results. - The test results also show that the Drain Cover Fill material undergoes approximately 16 vertical strain (change in sample height/original sample height) during loading. The vertical strain results in a densification of the material from 109.1 pcf (dry density) at 153 psi to 115 pcf (dry density) at 450 psi. Additionally, the Drain Cover Fill void ratio decreases from 0.44 at 153 psi to 0.36 at 450 psi. After completion of the test program, a post -test gradation was conducted on the material to evaluate the potential for mechanical degradation of the Drain Cover Fill material under