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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 />• concentrations have been faz 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 appeaz 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 faz 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 concentratons. <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 aze 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 lineaz 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 NE W-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 <br />(flooding of) in the sealed New Elk Mine through from 1994 through 2001. From mid- <br />2001 through 2003, the rate of increase in mine water level appears to have diminished, <br />only to resume its previous rate of increase during 2004. The water level at NEW-2 <br />remained constant during 2006. It is thought that water is now flooding the east mains as <br />water levels are increasing more rapidly at the Apache Canyon airsha8 (NEW-3). <br />Continued monitoring will provide the information to clarify the phenomena, and permit <br />a more accurate projecfion of hydrologic consequences. <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 aze provided in Figure 3.2.5. This water is of relatively high conductivity, and <br />high concentrations of total dissolved solids, bicazbonate, and sodium. None of this water <br />has been dischazged from the sealed mine to date. <br />L J <br />35 <br />