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<br />the river by 187 mq/1 to a total value of 391 ml/1, Based on average <br />values of Na, CA, and Mq available for river samples at Station PRS-1 and <br />for mine discharge at Station MSNE, an SAR value of 16.7 was computed for <br />the combined waters, The TDS value of 391 mq/1 is less than the drinking <br />water standard of 500 mg/1; the SAR value of 16,7, however, exceeds the <br />standard value of 12 for irrigation water. Both of these values would be <br />reduced, as a result of mixture with water from the North Fork of the <br />Purgatoire River before reaching the adjacent Golden Eagle Mine. Using <br />the apparent additional Q7-10 low flow value of the North Fork, i.e., <br />10.9-1.6 or 9.3 cfs, the Purgatoire River below the confluence of the <br />North and Middle Forks would have a TDS Value of 236 mg/1 and a SAR value <br />of 4, Asa result, the downstream use of this water for either domestic <br />or irrigation purposes should not be affected. <br />At the New Elk Mine site, several historic and existing coal refuse piles <br />are located on the alluvial flood plain of the Middle Fork of the <br />Purgatoire River. None of these is now being used by the mine. As a <br />result of Permit Revision 1, a new refuse disposal area was established <br />north of the mine across Highway 12. Processing waste is carried to this <br />facility by means of a conveyor system from the prep plant. This is the <br />only coal waste disposal facility currently in use at the New Elk Mine. <br />Runoff and seepage from the new refuse disposal facility is contained by <br />Pond 8. This pond has never discharged since its constuction, <br />Consequently, except in a rare case of pond discharge, no impact on water <br />quality in the Middle Purgatoire should be made by runoff and seepage <br />from this facility. <br />Seepage from the refuse piles located in the alluvial flood plain, <br />however, does enter the stream-alluvial aquifer system where it can <br />affect water quality. An analysis of leachate from the estimated 16.6 <br />acres of this refuse shows the water to be a sodium sulfate-bicarbonate <br />type with a total dissolved solids concentration of 2599 mg/1 and a pH of <br />8.0 (Exhibit 6, Table 13 ). Trace metal concentrations are low. <br />A water balance study was conducted for the New Elk Mine development <br />waste pile site and is contained in Exhibit 6 of the New Elk permit <br />application, In this study, the applicant has calculated the average <br />annual precipitation at the New Elk Mine to be 16.92 inches. Sublimation <br />of snow during winter, and evaporative losses were calculated to be 3.77 <br />inches. During a normal year, runoff from the refuse piles is calculated <br />to account for all of the remaining available precipitation, Rased on <br />the calculations included in the application, deep percolation in most <br />years will be essentially zero; that is, all precipitation will evaporate <br />or runoff from the soil. During wet years, as much as .72 inches of <br />water may be attributed to subsurface runoff (See Exhibit 6, pages 44-50 <br />of the permit application). <br />-2 4- <br />