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MountRoyaleVenturesCashMineHydrology AdrianBrown <br />I = hydraulic gradient (0.26) <br />A = flow area (1750 ft x 1 ft = 1750 square feet) <br />Thus, the hydraulic conductivity is computed to be: <br />K = 292 cu.ft./yr / (0.26 x 3500 sq.ft.) = 0.32 ft/yr = 3x10-7 cm/sec <br />Based on these data, the computed hydraulic conductivity of the rockmass to prevent the mountain from <br />draining is approximately 0.3 feet per year (3x10"7 cm/sec). This is a low permeability, typical of a <br />sparingly fractured igneous rock (which this is). <br />2.2.2 Hydraulic conductivity based on mine inflow <br />A test of mine inflow was performed on August 8 through August 15, 2006. The recharge rate of the <br />mine was measured, and thena total of 6,344 gallons was pumped from the mine. The water level was <br />measured as the mine recharged after pumping, and it was observed to take 68 hours for the water level <br />in the mine to recover to the level that it had reached prior to pumping. The inflow rate to the mine was <br />computed to be 1.56 gpm. At the time of the test the depth to water in the mine from ground surface was <br />approximately 312 feet, and assuming that the original water level in the vicinity of the mine was <br />approximately 50 feet below ground surface, the drawdown at the time of the test was 262 feet. <br />The inflow to the mine is the equivalent of the contribution from infiltration of 15.1 acres. Assuming <br />that the contributing infiltration area is located above and below the mine and that the mine is 600 feet <br />long, the contribution area extends out to a distance of 550 feet from the mine. The mine is 618 feet deep <br />below the original water table to Level 9. With this information, the hydraulic conductivity of the rock <br />around the mine can be estimated using Darcy's Law: <br />Q=KIA <br />K=Q/(I A) <br />where: Q = flow to one side of the mine (1.56 gpm /2 = 0.78 gpm = 54,808 cubic feet/year) <br />K hydraulic conductivity <br />I = hydraulic gradient (262/550 feet = 0.476) <br />A = flow area (600 ft x 618 ft = 370,800 square feet) <br />Thus, the hydraulic conductivity is computed to be: <br />K = 54,808 cu.ft./yr / (0.476 x 370,800 sq.ft.) = 0.31 ft/yr = 3x10"7 cm/sec <br />This value is similar to that obtained from the infiltration analysis above. <br />2.2.3 Groundwater. Table <br />The groundwater table at present, with the mine dewatered to a depth of approximately 300 feet below <br />ground. surface, and the draw,down cone (computed using the above hydraulic conductivity and <br />infiltration values) is shown in Figure 2. This has been used to compute the.current groundwater table in <br />the vicinity of the Cash Mine, also shown in Figure 2, by subtraction from the pre-mining groundwater <br />levels (approximately 50 feet below ground surface on the hillside). This groundwater table will <br />fluctuate with the level of water in the mine; the current level is approximately half way between the <br />proposed mining level and the level of the dewatering pump, so is generally representative. <br />1601A-20060911 2