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from both wells indicate mining has not caused adverse impacts to the quality of ground <br />water at these locations. <br />Basic Standards (Interim Narrative Standard) for Ground Water (CWQCC <br />Regulation 41.5(C)(6)) <br />The Edna Mine's alluvial ground water point of compliance is well TR -3, located <br />approximately 600 feet north of the permit boundary. This well is completed in Trout Creek <br />alluvium. In accordance with Colorado Water Quality Control Commission (CWQCC) <br />regulation 41.5(C)(6)(b)(iii), sample data collected after January 31, 1994 is presumed to <br />represent existing ambient quality because no new disturbances have occurred since that <br />date; therefore, currently prevailing water quality is the applicable standard and monitoring <br />data indicate the operation is in compliance with the Basic Standards for Ground Water <br />(Colorado Water Quality Control Regulation 41.5.C.6). <br />The Edna Mine does not have a ground water point of compliance for ground water in <br />bedrock stratigraphic units, based on the absence of the potential for the mine to negatively <br />impact the quality of bedrock ground water (memorandum in the hydrology file for permit <br />C -80 -001, by Byron Walker of DRMS, dated October 5, 2006). This conclusion was based <br />on the likely head differential between spoil leachate and bedrock ground water, and the <br />lack of hydraulic communication between the leachate- saturated pits and permeable <br />bedrock stratigraphic units. <br />Surface Water Impacts <br />Instream Numeric Standards (CWQCC regulation 33) <br />The west side of the Edna Mine discharges surface runoff and spoil leachate into Segment <br />13c (Trout Creek above Fish Creek) of CWQCC's Region 12 of the Yampa River basin. <br />The CWQCC Regulation 33 lists numeric standards for 26 parameters in Segment 13c. <br />Chevron Mining Inc. has sampled discharges from two outfalls in Segment 13c that are <br />monitored under the Colorado Discharge Permit System (CDPS). A parameter is chosen <br />for CDPS sampling based on its potential for occurring in coal mine runoff and leachate, <br />and its potential for degrading instream water. Only one parameter in Edna's CDPS <br />sampling program, pH, has an instream standard. The Edna Mine's CDPS samples have <br />not exceeded the 6.5 to 9.0 pH instream standard applicable to Segment 13c of Region 12. <br />As part of Trout Creek surface water monitoring required in the DRMS mine permit <br />application, the mine has also sampled instream quality for two additional constituents <br />(NH3 and NO2) which have Trout Creek instream standards. Discharges from the Edna <br />Mine have not exceeded the greater than 0.03 mg /l instream standards for these <br />constituents. Edna's samples usually contain less than 0.01 mg /l of these two constituents. <br />Comparison of sample data from Trout Creek surface water sites TR -B (upstream from the <br />Moffat Pond discharge) and TR -C (downstream from the Moffat Pond discharge) indicates <br />the Moffat Pond and /or spoil springs in this area probably contribute a significant sulfate <br />Edna Mine Page 23 April 12, 2013 <br />Phase II. and III Bond Release <br />