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RULE 2 PERMITS <br />Potential Impacts From Minim - Water Ouali <br />Groundwater <br />General Area <br />The quality of the groundwater which exists in the general area will not be affected by the Colowyo Mine. <br />Impacts on the quality would only occur as a result of extreme changes in the (1) recharge rate, which is <br />presently minimal; (2) lithology; or (3) chemistry of the geological formations. This is highly unlikely as <br />the Colowyo Coal Company intends to only mine the area within the permit boundaries. <br />Permit Area <br />No significant changes will occur in the quality of the groundwater in or adjacent to the mine as a result <br />of mining. The chemical characteristics of the overburden and leachate, presented earlier, will not <br />seriously affect the quality of the limited groundwater present. Minimal amounts of water within <br />backfilled spoil areas are expected to show temporary increases in TDS owing to rapid dissolution of <br />relatively soluble minerals such as gypsum, calcite, thenardite and various clay minerals. The increase in <br />surface area of freshly exposed, broken backfill material is readily leached. Resulting temporary increases <br />in Ca, Mg, Na, S04 and C03 will subsequently increase TDS and conductivity over time until the readily <br />available minerals are leached out. <br />Compared to the undetectable effects of the mining operation, the effects on groundwater were much <br />greater due to natural conditions of high precipitation, infiltration and runoff during 1984 and to a lesser <br />extent 1985. Concentrations for the major ions mentioned above increased during 1984 and 1985, <br />however, there was a decrease at all sites for 1986 which indicates the natural system was responsible for <br />the temporary increase in concentration. Documentation for this observation is found in the 1984, 1985 <br />and 1986 Annual Reports. Note that two additional groundwater monitoring wells have been completed to <br />obtain background information for the proposed single seam operation in Section 16. Groundwater <br />monitoring locations are shown on Map 37. <br />As further evidence to support this conclusion, the reader is referred to the document by Skogerboe and <br />others (1979) entitled "Environmental Effects of Western Coal Surface Mining, Part III: The Water <br />Quality of Trout Creek, Colorado". The authors examined the effects of a surface mine on the <br />groundwater and surface water quality. They concluded that changes in groundwater quality are a <br />function of spoils age, area disturbed, contours and local precipitation. Chemical data presented in the <br />quality section for drainage water showed levels of constituents consistent with the values of the other <br />quality samples at the mine. Their report also points out that the increases in surface water quality values <br />were due to non-control of spoils drainage. This is not a factor at the Colowyo Mine, since Colowyo <br />grades the spoils to a final grade that drains to a designed drainage system. Concentrations of heavy <br />metals in groundwater should not be affected further, because of the extremely limited groundwater <br />supplies and the role that alkalinity plays in containing soluble concentrations. <br />Rule 2 Permits 2.04.7-31 Revision Date: 6/23/08 <br />Revision No.: MR-91