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<br />the stream valleys of North and Middle Thompson Creeks. High <br />TDS inflows indicate longer residence time and reactive time <br />with soluble minerals in the transmitting aquifer. These <br />inflows represent the dewatering of overlying and underlying <br />aquifers whose ultimate source of recharge Cannot readily be <br />determined. <br />The impacts of depleting ground water in overlying and <br />underlying aquifers were predicted to be minimal as long as <br />these aquifers do not add significantly to the depletion of <br />springs and Stream flows. <br />The depletion of ground water from aquifers may impact the <br />discharge of over- and underlying aquifers by drying up springs <br />and seeps. The applicant has identified only two springs, SP-1 <br />and SP-Z, in the permit and adjacent areas. The drying up of <br />these springs will slightly reduce surface flow during high <br />flow periods and also improve water quality, as these springs <br />are intermittent and have poor water qualities. The net impact <br />of drying up these springs will be minimal and even beneficial, <br />because the water quality of these springs is poor. <br />The depletion of bedrock ground water in the mine area did not <br />impact any wells within the permit and hydrologically adjacent <br />areas. Water depleted from ground water aquifers was <br />replenished after closure of the mine. The depletion continued <br />until the mine workings filled and an equilibrium was <br />established between the mine workings and the overlying and <br />underlying strata. <br />All underground mines that induce subsidence have the potential <br />to increase mine inflows, particularly if the subsidence occurs <br />within a significant source of water (e.g., stream, pond, <br />alluvial aquifer). However, coal mine subsidence does not seem <br />to be a source of significant inflows into the North Thompson <br />Creek Mines. Areas which have undergone longwall and pillar <br />extraction (e.g., areas of controlled subsidence) do not <br />contribute significant inflows. This can be attributed to the <br />fact that these mine areas are not under perennial stream <br />valleys, but under the steep hillslopes. <br />The applicant has submitted analyses of the coals, roof, and <br />floor strata. The analyses of the roof and floor materials <br />performed by the Soils Laboratory of Colorado State University <br />(Appendix 3-I> indicate that these units contain insufficient <br />carbonate minerals to buffer the iron sulfide (e.g., pyrite) <br />contained in these strata. These analyses indicate that these <br />strata are acid-forming and potentially toxic. <br />The inactive North Thompson Creek No. 2 Mine contains both acid <br />and toxic mine waters (see laboratory analysis of Portal No. 2 <br />Mine, dated June 22, 1982). This analysis shows that mine <br />water in the No. 2 Mine exceeds receiving stream standards for <br />the following ions: aluminum, cadmium, chloride, copper, iron, <br />-.a_ <br />