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<br /> <br />Requirement <br />Requirement <br />citation Require- <br />ment <br />complied <br />with ? <br />(yes / no) <br /> <br />Comment <br /> There is no known impairment of water use caused by the mine outside the permit area. <br /> North Fork Gunnison River. The West Elk Mine discharges surface water into the North Fork at <br /> two mine water discharge points (outfalls 017A and 018A) and at five sediment control ponds ( MB- <br /> 3, MB-1, MB-2R, RPE,and SG-1). As previously explained, the West Elk Mine appeared to not <br /> significantly degrade TDS in the North Fork in 2009 based on a comparison of samples taken from <br /> the North Fork upstream and downstream from mine inflows. The TDS concentrations were well <br /> below a 700 mg/l threshold that may be considered a level of concern for irrigation water use. A <br /> mass-balance analysis attached to DRMS's review summary of the 2004 annual hydrology report <br /> indicated that in an extreme worst-case scenario, TDS in the North Fork would remain well below the <br /> 700 mg/l threshold. <br /> Natural springs - Monitoring showed a continuation of reduced spring flows for many springs <br /> compared to previous years, although some springs showed increased flows. Spring hydrographs <br /> indicate seasonal precipitation fluctuations are a more likely cause of the reduced flows than mining. <br />U. Prevention of Bedrock ground water - Data from the down-gradient bedrock monitoring wells (03-11-1 and 01- <br />material 11-1) indicate there have been no significant impacts to bedrock ground water outside the permit <br />damage to the CDRMS <br />regulation <br />regu regu do yes area. High TDS in one monitoring well appears anomalous and warrants further discussion. TDS in <br />hydrologic B seam monitoring well SOM-129H increased from 2970 mg/1 to 8400 mg/l in 2002, and remained <br />balance outside around 8400 mg/l through 2008. The TDS increase from 2002 through 2008 may have resulted from <br />the permit area water flowing into the well from the Rollins Sandstone into the well, based on the similarity in water <br /> chemistry between the well and the Rollins (sodium chloride/bicarbonate water type and a relatively <br /> high concentration). The Rollins likely is in hydraulic communication with the B seam where the <br /> intervening sequence is relatively thin. The change in water quality in the SOM-129H well would not <br /> have threatened the water quality in bedrock units due to the low permeability of those units. <br /> (Discharge of this high TDS water to the alluvium or surface water of the North Fork through the B <br /> seam subcrop in the alluvium would not have threatened alluvial water quality because such a <br /> discharge is not an increase above what would naturally discharge from the subcrop of the Rollins in <br /> the North Fork alluvium.) TDS in well SOM-129H dropped to less than 500 mg/1 in 2009 after a <br /> casing repair, and the source of the water in this well is uncertain. <br /> Alluvial ground water - A mass-balance analysis attached to DRMS's review summary of the 2004 <br /> annual hydrology report indicates that in an extreme worst-case scenario TDS in the North Fork <br /> alluvium would not increase to a level that impairs the use of the water. <br /> Page 6