2012-02-28_REVISION - M1980244 (69)

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October 15, 1999 of 110 pounds per cubic foot] and measured for compression, settlement and maximum percolation rate at select load increments. The maximum test pressure of 432 psi is the maximum capacity of the testing apparatus. 2.1 Test Apparatus The testing apparatus consisted of a 12 -inch nominal inside diameter (ID) aluminum tube (testing 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 a dial gauge measured deformation. The load from the hydraulic jack is adjusted to maintain the desired loading stress throughout the test. 2.2 Test Configuration Figure 4 shows the Cresson ore sample prior to testing. The Cresson ore material was placed into the test testing cell (Figure 5), the initial sample height was recorded and the loading plate was secured. The sample was loaded in five increments to approximately 27, 54, 108, 216, and 432 psi. The load increments correspond to ore depths of 35, 70, 140, 280, and 565 feet, respectively, assuming a bulk ore density of 110 pounds per cubic foot (pcf). Vertical displacement values were recorded at each load increment. The sample was loaded to the next increment only after consolidation had ceased. The sample was saturated with water and allowed to drain prior to the first load being applied. The percolation rate of the material was measured by applying tap water with an electromagnetic pump to simulate various solution application rates. The initial application rate was 0.0045 gallons per minute per square foot (gpmisf). At each load increment, the application rate was increased to a maximum rate of 0.045 gpm/sf or until ponding was observed on sample. The application rate of 0.045 gpmisf is ten times greater than the initial application rate and is the maximum flow rating for the testing frame. The sample was allowed to equilibrate (i.e. inflow equals outflow) before increasing the application rate. During the entire testing period, the surface of the sample was observed for ponding, which would indicate failure of the sample to percolate water at the given application rate. ne...... crct,..,,y -2- 993- 2075.003 Golder Associates •