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2021 AIM Review: New Elk Mine <br /> monitoring. <br /> 20. Restoration of ground water recharge <br /> CDRMS regulation 4.05.12(3) <br /> Based on the information provided by the operator in the probably hydrologic consequences, PHC, <br /> section of the permit, 2.05,there is not a confined aquifer in the monitoring area. The geologic layers <br /> consist of interbedded sandstone and coal layers with permeability highest along the coal layers and lower <br /> between the bedding planes. Subsidence will increase permeability between layers at and above mined <br /> areas. <br /> 21. Prevention of adverse impacts to ground water systems outside permit area <br /> CDRMS regulation 4.05.11(1) <br /> Compliance with the Basic Standards for ground water, as in item 10,indicates the permittee is <br /> preventing adverse impacts to ground water quality outside the permit area. Monitoring data indicate <br /> the permittee is preventing impacts to water quantity outside the permit area. Hydrology reports <br /> indicate that water level at all wells fell within their historic ranges. <br /> 22. Prevention of impacts to ground water that adversely impact post-mining land use <br /> CDRMS regulation 4.05.11(2) <br /> As discussed in item 20 above,no material damage has occurred. The Reclamation Plan in the permit <br /> document addresses the protection of the Hydrologic Balance. Probable Hydrologic Consequences <br /> (PHC),predictions in section 2.05 and Exhibit 8 of the New Elk permit appear accurate. <br /> 23. Minimize disturbance to hydrologic balance within and adjacent to the permit area <br /> CDRMS regulation 4.05.1(1) <br /> Probable Hydrologic Consequences (PHC),predictions in section 2.05 and Exhibit 8 of the New Elk <br /> permit appear accurate. <br /> An increase in TSS is predicted for surface disturbances and is treated with settling ponds prior to <br /> discharge. The impact of backfilling a reach of the Middle Fork of the Purgatoire River with mine waste <br /> predicts increases of calcium, sodium, sulfate and TDS (Exhibit 8,pg 29). 2019 and 2020 sampling at <br /> PAW 2, downstream of the backfill, show lower contributions with the exception of Calcium in 2019. In <br /> 2020 all contributions were lower than predicted values, 2021 values were within historic ranges. <br /> Subsidence is expected and no surface water flow or water quality impacts are expected. Mining related <br /> subsidence will increase vertical permeability and wells above the zone of increased permeability are not <br /> likely to be impacted by mining(Section 2.05). <br /> PAW 9 is a shallow alluvial well, situated more than 400 feet above the planned mining horizon. NE 1-10 <br /> is designed to monitor impacts to groundwater in the mining horizon. Monitoring began in this well in <br /> 2019. <br /> Probable Hydrologic Consequences (PHC),predictions in section 4.8.3 of the permit appear accurate. <br /> Significant changes in surface water quality or quantity have not been observed for 2019, 2020 or 2021. <br /> 24. Prevention of material damage to the hydrologic balance outside the permit area <br /> CDRMS regulation 4.05.1(1) <br /> Probable Hydrologic Consequences (PHC),predictions in Section 2.05 of New Elk's permit appear to be <br /> accurate for both surface and ground water. <br /> Page 4 of 6 <br />