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Table 1. <br />Calculated Drawdown Versus Time in Twentymile Sandstone Aquifer <br />at Gertie #1 and Livestock #2 Springs. <br />t Drawdown in Springs Areas(ft) <br />, years Gertie #1 Sp. Livestock #2 Sp. <br />10 0.0 0.0 <br />30 0.0 0.0 <br />50 0.0 0.0 <br />70 0.1 0.0 <br />90 2.5 0.0 <br />100 6.7 0.0 <br />110 13.9 0.1 <br />120 24.5 0.4 <br />140 55.5 2.4 <br />160 96.2 8.1 <br />180 142.3 19.0 <br />200 190.2 35.5 <br />Because the Twentymile Sandstone is separated from the Wadge Coal Seam by 670 feet <br />of low-permeability, primarily marine shale overburden, and because subsidence-related <br />fracturing of overburden rocks is unlikely to extend more than about 200 feet upward <br />from the mined part of the Wadge Coal, there is little potential for hydrologic connection <br />between the mine and the Twentymile Sandstone. Additionally, it is unlikely that faulting <br />would provide a hydrologic connection between the mine and the Twentymile Sandstone.