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fishery. Likewise, the water temperatures for Stations 27A and 1003 reflect higher temperatures than Station 1002. <br />• This would be considered normal given their location on lower Fish Creek. Again, the temperatures are not <br />conducive for maintaining acold-water fishery. Given the historic waning of the creek during the summer months, <br />no significant impacts aze anticipated to result from the undermining and subsiding of the vazious segments of <br />Fish Creek. Likewise, the TDS concentrations are low enough at this point to believe that there will be no impacts <br />to TDS concentrations in these pools. TCC is planning to recirculate underground water so that discharge to Fish <br />Creek is not increased over the historic level during the NMD permit year. Therefore, there should be no quality <br />impact to the streams due to the continued mining in the Northern Mining Districts. The exception to this is the <br />short-term impact associated with dewatering the reservoir in the western mining district. This is discussed in TR <br />99-32. <br />The mining in the NMD will result in subsiding aeeas where springs exist. TCC's experience is that there will be a <br />temporary disruption in flow and then recovery of the springs. The reader is referred to TCC's 1996 AHR for <br />further discussion of the recovery of springs SW 1 and SW2. No long-term impacts are anticipated to the springs in <br />this area. In reference to Foidel Creek, TCC is not anticipating any significant impacts to the creek due to the <br />mining of Panel 12 Right. TCC anticipates that the creek will react the same way it did previously. This reflects <br />the fact that there are no sandstone outcrops intersecting the channel. Therefore, the potential to dewater the <br />stream isnon-existent based on TCC's prior experience with Foidel Creek given this condition, i.e. no outcrop <br />channel. <br />The stream gradient for Foidel Creek is presented on Table 8, Exhibit 7e-3. TCC does not anticipate any <br />significant erosional processes be triggered by its' undermining and subsiding Foidel Creek. <br />GENERAL SUMMARY AND CONCLUSION <br />The above-discussed streamflow and water quality impacts of the expansion of underground mining into the EMD <br />at the Foidel Creek Mine are within the limits of impacts discussed by Kaman Tempo (1982) and by Parker and <br />Norris (I 983) relative to the study area. It is apparent that such hydrologic impacts are relatively greater in stream <br />reaches near mine discharges. Mine discharges may be subjected somewhat to treatment primarily to reduce levels <br />of total suspended solids, and possibly to settle out oxidized trace metals prior to dischazge to a stream. For the <br />most part, dissolved solids and major ionic solute concentrations associated with mine flows will be unaffected by <br />treatment, and will be mixed with receiving stream waters. Total Recoverable Iron will be removed by the FCB <br />treatment facility at Site 115. <br />Dissolution of soluble minerals will occur as a result of the process of dewatering and handling of dischazged <br />water from the underground mine. Because other ongoing underground and adjacent surface mine areas are <br />located in areas recharging groundwater to the overburden unit,. hydro-geochemical changes in water flowing <br />through this unit has already occurred and is expected to continue. The supporting analysis conducted to assess <br />these changes is included in the groundwater PHC section. <br />Changes in stream alluvial systems due to the proposed expanded underground mining in the EMD would vary <br />spatially. Supplemental mine-related flows to Foidel Creek during mine operations will alter the intermittent <br />nature of the stream and contribute to the adjacent alluvial system. Hence, some flows will occur in Foidel Creek <br />at times not normally observed under historical ambient conditions. In the case of mine dischazges to Fish Creek, a <br />perennial stream, mine-flow impacts would be minor compared to Foidel Creek due to the base flows occurring <br />under historical ambient conditions. Analogous conclusions could be made regarding water-quality impacts of <br />mine flows. Due to the smaller and intermittent flows in Foidel Creek, the relative water-quality impacts of mining <br />• would be more pronounced than for Fish Creek. <br />PR 03-06 2.05-164,1 05/07/03 <br />