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<br /> <br />Requirement <br />Requirement <br />citation Require- <br />ment <br />complied <br />with ? <br />es/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, M13-1, M13-2R, RPE,and SG-1). The West Elk Mine appeared to not significantly degrade water <br /> in the North Fork in 2007 based on a comparison of samples taken from the North Fork immediately <br /> upstream from the mine (page C-1 of 2007AHR) and the North Fork immediately downstream from <br /> the mine (page C-2 of 2007 AHR). TDS in North Fork water showed negligible change where the <br /> stream passes the mine, remaining near 110 mg/l above and below the mine. This TDS concentration <br /> is well below a 700 mg/l threshold that may be considered a level of concern for irrigation water use. <br /> A 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 />U. Prevention of indicate seasonal precipitation fluctuations are a more likely cause of the reduced flows than mining. <br />material <br />damage to the CDRMS <br />regulation <br />yes <br />Bedrock ground water - Data from the down-gradient bedrock monitoring wells (03-11-1 and 01- <br />hydrologic <br />4.05.1(] ) 11-1) indicate there have been no significant impacts to bedrock ground water outside the permit <br />balance outside area. High TDS in one monitoring well appears anomalous and warrants further discussion. TDS in <br />the permit area B seam monitoring well SOM-129H increased from 2970 mg/1 to 8400 mg/1 in 2002, and since then <br /> has remained around 8400 mg/1. This increase appears to indicate water has flowed from the Rollins <br /> Sandstone into the well, based on the chemistry of water in the well that is similar to the Rollins (a <br /> sodium chloride/bicarbonate water type and the relatively high concentration). The Rollins likely is <br /> in hydraulic communication with the B seam where the intervening sequence is relatively thin. The <br /> change in water quality in the SOM-129H well does not threaten the water quality in bedrock units <br /> due to the low permeability of those units. (Discharge of this high TDS water to the alluvium or <br /> surface water of the North Fork through the B seam subcrop in the alluvium does not threaten alluvial <br /> water quality because such a discharge is not an increase above what would naturally discharge from <br /> the subcrop of the Rollins in the North Fork alluvium.) <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