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Historic Allen Mine waste materials appear to be the major contributors to saline alluvial <br />ground water quality in the vicinity of the New Elk Mine (PAW-3 and PAW-4) (Figure <br />3.2-3). Saline conditions were anticipated in the PHC, and conductivities and TDS <br />is concentrations have been far lower than expected. During March and April of 1985, 500 <br />feet of the Middle Fork of the Purgatoire River was diverted to the north to create <br />additional room for the coal stockpile at the New Elk Preparation Plant. The original <br />channel was backfilled with mine waste, and two alluvial wells, PAW-3 and PAW-4, <br />were established to monitor water elevation and chemical parameters. Water quality does <br />not appear to deteriorate significantly due to the presence of refuse in the backfill <br />between PAW-3 and PAW-4 and measures of salinity, sodium, and sulfate are far lower <br />than predicted by the PHC. A threefold increase over historic values in iron quantities in <br />PAW -3 and PAW-4 may be due to the steel casing of the wells. No further monitoring is <br />required for PAW-3 and PAW-4. Data on PAW-8 (Table B-5) and the Stiff Diagram <br />indicate that seepage from the current refuse disposal area contains similar concentrations <br />of sodium, potassium and calcium to the pre-law mine waste (PAW-4). Leaching may be <br />a cause for lower values from the old materials. Data from PAW-9 downstream of the <br />New Elk facilities indicated dilution having an effect on concentrations. <br />3.2.4 New Elk Mine Water <br />During the third quarter of 1989, the New Elk Mine was sealed and access to the mine <br />workings terminated. Mine inflows are flooding the abandoned mine workings. Previous <br />studies and reports suggested an inflow of 177 gallons per minute (gpm) and calculated <br />inflows ranged from 142 to 468 gpm based on measurements taken at Station NEW-4. A <br />number of approximations were made in the calculation of rates of inflow. From mine <br />• maps, the dip of the mine floor was determined to be 5 percent, and the water line crosses <br />approximately 12,000 linear feet of mined areas. The available volume is based on an <br />average extraction of 60 per cent. The calculations assume that the entire mined area <br />below the water level measured in NEW-4 is flooded (i.e., no trapped air pockets). <br />Figure 3.2-4, Mine Water Levels, portrays a lineal increase in the mine water level in the <br />sealed New Elk Mine from 1994 through 2001. From mid-2001 through 2003, the rate of <br />increase in mine water level appears to have diminished, only to resume its previous rate <br />of increase during 2004. The water level at NEW-2 remained constant during 2006 with <br />a slight increase in 2007. It is thought that water was flooding the East Mains area as <br />water levels increased more rapidly at the Apache Canyon airshaft (NEW-3) during 2006 <br />only to stabilize in 2007. Continued monitoring will provide the information to clarify <br />the phenomena, and permit a more accurate projection of hydrologic consequences. The <br />surface elevation given for NEW-4 has been adjusted to the CF&I elevation system used <br />for NEW-2. Similarly, a GPS surface elevation determined for NEW-3 has been adjusted <br />to a CFI surface elevation. <br />Inflow water quality information is being obtained at the. sealed New Elk Mine (see NEW <br />-2, Table B-7; NEW-3, Table B-8; and NEW-4, Table B-9). Stiff diagrams of mine water <br />quality are provided in Figure 3.2.5. This water is of relatively high conductivity, and <br />high concentrations of total dissolved solids, bicarbonate, and sodium. None of this water <br />has been discharged from the sealed mine to date. <br />35