Laserfiche WebLink
<br />These terraces support typical hydrophytic vegetation characteristic of <br />floodplains and contain ground water hydrologically connected to the <br />river. Absolute dates on the alluvial deposits are not available; <br />however, in analogous areas of the Rocky Mountain Region, the strath <br />terraces are, of Pleistocene age and the alluvial terraces of Holocene age. <br />B. Ground Water - Bedrock Aquifers <br />The Trinidad Sandstone is a significant regional aquifer, given its <br />250 feet thickness and regional extent. This sandstone is the first <br />major aquifer below the lowest coal seam to be mined and is separated <br />from the coal seam by up to 900 feet of interbedded and lenticular <br />shales, siltstones, and sandstones. The Trinidad Sandstone, however, may <br />be impacted by the Golden Eagle Mine. Early in 1988, a substantial <br />artesian flow of water was encountered in conjunction with a fracture <br />zone in the Second Right entry area of the mine. The source of this <br />water is uncertain, but the Trinidad Sandstone is a possibility. The <br />coal seams and most of the overburden in the permit area are part of the <br />Raton Formation. Sandstones in the formation are interbedded and <br />lentiaiar. These Characteristics of the formation inhibit the vertical <br />and horizontal flow of ground water through it. <br />Little or no ground water has been encountered in the Raton Formation <br />during the exploration phases at the New Elk and Golden Eagle Mines. <br />Smell amounts of water are encountered in the coal seams during mining. <br />Minor amounts of water were encountered within minor coal beds that were <br />intersected during mine development. Small amounts of ground water may <br />generally be found in the sandstone units and fractures occurring in the <br />formation. <br />The applicant has conducted laboratory permeability and porosity tests on <br />twenty-three samples of selected sandstone intervals collected from <br />cores. Because of the lack of correlation, core samples were selected <br />from those intervals that appeared to be the most permeable. Measured <br />values of the vertical intrinsic permeabilities of the sandstones of the <br />Raton Formation fell within a narrow range of 0.12 - 1.65 millidarcies. <br />Horizontal intrinsic permeabilities were determined for five samples. <br />Their values ranged from 0.08 to 2.4 millidarcies. The test results <br />indicate that the channel sandstones in the Raton Formation in the <br />vicinity of the New Elk and Golden Eagle Mines are quite uniform with <br />respect to permeability, even though these sandstones are vertically and <br />horizontally discontinuous. <br />The applicant has also provided the results of three pump tests conducted <br />at: the Golden Eagle Mine, In two wells (LA 221A and LA 218A) the <br />open-interval available for water entry included the Maxwell seam, and <br />various thicknesses of shale, siltstone, and sandstone immediately above <br />and below the coal seam. No significant water was encountered in either <br />hole until the Maxwell Coal Seam was penetrated. Therefore, the <br />permeability values determined are for the coal. <br />TFie tests found permeabilities of 0.02 and 0.04 ft/day, transmissivities <br />oi' 0.56 and 1.98 ft2/d, and storage coefficients of 1 x 10-5 and <br />8 x 10-5. The permeability and transmissivity values are low and the <br />sl:orage coefficients are indicative of confined aquifers. <br />_11_ <br />