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The Probable Hydrologic Consequences(PHC), Section 2.05 of <br /> New Elks mining and reclamation permit discusses the possibility <br /> increasing TDS. <br /> TDS/Sulfate levels in the alluvial wells have fluctuated <br /> significantly between the years 2019 and 2020 and appear to be <br /> within natural levels according to the report. <br /> T. Prevention of <br /> adverse impacts CDRMS Predicted impacts to ground water quality include increasing TDS <br /> to ground water regulation in the form of sodium and bicarbonate. <br /> systems outside 4.05.11 Elevated TDS levels in backfill aquifers are likely according to the <br /> the permit area PHC section of the New Elk permit. Well PAW 2 is completed in <br /> backfilled spoil. The elevated TDS levels in the backfill aquifers <br /> may be due to leaching from backfill material,reported levels are <br /> within their natural limits. <br /> The TDS and Sulfate levels are consistent with expectation in the <br /> PHC. Frequency and location of monitoring should be reevaluated <br /> with the mentioned incoming Permit Revision. <br /> Probable Hydrologic Consequences(PHC),predictions in Section <br /> 2.05 of New Elk's permit appear to be accurate for both surface <br /> and ground water. <br /> The frequency of monitoring was changed with TR73 to reduce <br /> U. Prevention of sampling during an inactive mining period. The data provided in <br /> material damage CDRMS AHR 2019 and 2020 is adequate for an inactive mine,however <br /> to the hydrologic regulation this will not be adequate for an active mine. <br /> balance outside 4.05.1(1) As previously noted by the Division in the adequacy review of <br /> the permit area TR73, historic data from NE-1-10 should be included in the AHR <br /> together with data from the current monitoring period. NE-1-10 <br /> is completed in the Allen seam, approximately 1000' from <br /> existing mine workings,down the projected potentiometric <br /> gradient. <br /> Overall,PHC predictions appear to be accurate, as illustrated by <br /> the following examples. <br /> New Elk does not anticipate recharge to shallow aquifer systems <br /> to be adversely affected by mining operations. Water levels in <br /> wells have remained stable during recent monitoring. <br /> V. Agreement of Per the PHC,constituent concentrations in backfill aquifers, <br /> observed CDRMS namely TDS and sulfate,are expected to be higher than pre- <br /> hydrologic regulation mining concentrations for an extended period of time after mining. <br /> impacts with 2.05.6(3) <br /> PHC projected in The data for TDS concentrations in wells in backfill aquifers have <br /> permit shown apparent impacts from mining. Sulfate concentrations <br /> exhibit similar trends as TDS. <br /> TDS/Sulfate levels in these wells should continue to be monitored <br /> in future years. <br /> Backfill aquifers will continue to have an impact on surface base <br /> flow water quality (TDS),conditions. <br /> Page 4 <br />