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<br />During operations, water quality in the stream/alluvial aquifer system <br />would be affected by the discharge of water from the underground workings <br />and by seepage from existing and proposed coal refuse piles. At the New <br />Elk Mine site, existing and proposed coal refuse piles and maximum mine <br />water discharge add approximately 180 mg/1 to the total dissolved solids <br />concentration during Q7-10 low flow conditions in the Middle Fork of the <br />Purgatoire. This would add approximately 32 mg/1 during the low flow in <br />the vicinity of the Golden Eagle Mine due to dilution by the North Fork. <br />Maximum anticipated mine water discharge at the Golden Eagle Mine would <br />add another 58 mg/1 to low flow total dissolved solids concentrations in <br />the Purgatoire. The cumulative effect of the mine discharges and the New <br />Elk refuse pile is to increase the total dissolved solids concentrations <br />by 90 mg/1 in the Purgatoire River at Golden Eagle under low flow <br />conditions. Added to baseline concentrations of approximately 200 mg/1, <br />this increase would not limit the use of water for either flood <br />irrigation, livestock watering, domestic or municipal purposes downstream. <br />The proposed Ciruela Canyon refuse pile at the Golden Eagle Mine is less <br />than one-third the size of the refuse piles in the alluvial plain at the <br />New Elk Mine. Seepage from these piles is anticipated to result in a <br />negligible increase in TDS values for a tdiddle Purgatoire Q7-10 low flow <br />less than 15 percent of that occurring in the Purgatoire River at Golden <br />Eagle. Precipitation and infiltration values should be similar for these <br />adjacent mines. Consequently the Ciruela Canyon refuse area has little <br />potential to raise TDS or SAR values in the Purgatoire River nearby. <br />Following mining, mine water would no longer be discharged to the river. <br />Only seepage from the coal refuse piles would potentially continue to <br />affect water quality in the stream-alluvial aquifer system. Continued <br />seepage from the New Elk and Golden Eagle piles would, however, not add <br />significantly to either TDS or SAR values of the Purgatoire River. <br />As required by Rule 2.07.6(2)(c), the Division has assessed the probable <br />cumulative impacts of all anticipated coal mining in the general area on <br />the hydrologic balance. These impacts cannot include those that result <br />from secondary or retreat mining under Santistevan Canyon, since adequate <br />data for such evaluation has not been supplied by the operator. As a <br />result, secondary or retreat mining under Santistevan Canyon cannot be <br />approved at this time. Excluding that aspect of the proposed operation, <br />the Division finds that the operations described in the application have <br />been designed to prevent damage to the hydrologic balance outside the <br />proposed permit area. <br />Hydrologic Monitoring <br />Stipulation No. 12 to the original permit delineated the monitoring plan <br />for the New Elk t4ine. This plan was subsequently modified by Technical <br />Revision No. 2. The present monitoring requirements are detailed in <br />Tables 27 and 28 of the New Elk permit application. As the operator has <br />committed to this program, Stipulation No. 12 is no longer in effect. <br />_28_ <br />