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process. These monitoring plans are adequate to monitor for the development of impacts, if any <br /> should develop. Well GP-09 has been designated the groundwater point of compliance for the <br /> Third White Sandstone aquifer, and the Coy well is the point of compliance for the Flume Gulch <br /> alluvium. <br /> No new or revised water monitoring is being proposed under RN8. <br /> E. Probable Hydrologic Consequences <br /> The model for leachate formation and migration at the Trapper Mine is based on <br /> a study conducted by the U.S. Geological Survey at the Seneca 11 Mine in Routt <br /> County, approximately 14 miles east of the Trapper Mine (U.S. Geological <br /> Survey Water Resources Investigations Report 92-4187). The model is described <br /> in the probable hydrologic consequences of the permit application (Section 4.8). <br /> No drawdowns have been detected in aquifer wells within one mile from the <br /> permit boundary. Observed drawdowns have been temporary and are limited to <br /> the immediate vicinity of the pits. The operator expects such limited drawdowns <br /> to continue with future mining. <br /> The proposed mining operation will have little if any effects on the post-mining <br /> recharge capacity. The applicant's studies concluded that the recharge capacity of <br /> the reclaimed spoils will actually be slightly higher than the pre-mine condition. <br /> The mine activities should not impact any regional aquifers except the Third <br /> White Sandstone. Mined strata dip far beneath the Yampa River alluvial aquifer <br /> and communication between these strata and the alluvial aquifer is negligible. <br /> Permit section 4.8.2.2 discusses potential drawdown impacts to adjacent wells. A <br /> groundwater monitoring program is discussed in section 4.8.3.2 of the permit. <br /> Point of compliance wells are in place. <br /> Surface Water Impacts <br /> The most noticeable change in surface water quality resulting from mining <br /> activities constitutes increased levels of total dissolved solids (TDS). TMI expects <br /> higher TDS in some surface water runoff for a few years after reclamation in <br /> an area. The higher TDS levels will occur periodically when the contribution <br /> from precipitation and snowmelt is at a minimum(base flow conditions). <br /> Conductivity, TDS and major constituents tend to increase as the ground water <br /> contribution comprises a larger portion of flow. For a detailed analysis of surface <br /> water impacts,the 2021 Annual Hydrology Report, Section 2.5 of the permit <br /> presents the most current information. <br /> Leachate that may discharge from the toe of the Horse Gulch Fill probably will <br /> cause an increase in the dissolved solids content of natural stream flows in <br /> Horse Gulch. Rain or snowmelt provides most natural surface water flows in <br /> Horse Gulch. Although loading of Horse Gulch surface flows with dissolved <br /> 17 <br />