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RAG, Empire Corporation 1999 AHR <br />temporary cessation, the mine is being flooded and pumps are being run only <br />''~ <br />periodically for preventive maintenance. The minimal discharges recorded for 1999 <br />do not reflect changes of inflow into the mine. <br />WATER QUALITY <br />Summaries of the water quality data for the mine discharge are presented in Tables <br />17 through 20. The #5 Mine sump discharge is NPDES discharge point #003. The 7 <br />North Angle Discharge is NPDES discharge point #024. The #5 Mine discharge water <br />quality indicates a slight increase in dissolved solids concentrations over time which <br />has now stabilized at just under 1000 mg/L . The plot of dissolved solids presented in <br />Figure 18 shows that~tch-e average dissolved solids in the #5 Mine discharge water <br />~~ZS°Jo <br />have increased slightly from about 800 mg/I in 1982 and 1983 to almost 1000 mg/I in <br />• 1995. The average dissolved solids concentration for the 7 North Angle discharge <br />continued to hold stable at about 925 mg/I in 1999 as compared to 1285 mg/I in years <br />1991 and 1992. This trend is related to the accumulation of water in the North Angle <br />Sump location while the pump was out of order. This water was allowed to equilibrate <br />within old workings and subsided longwall panels. The maximum concentration of <br />1474 mg/I represents this equilibrium concentration and also provides an indication of <br />the expected post mining TDS concentrations in rubbelized zone of underground mine <br />workings. Likewise, this decrease illustrates the effects of flushing upon the TDS <br />concentrations with normal periodic discharge. <br />~ 4yy ~ 5 r `5Q a <br />• 5 (~S ~ ~~ `-Y ~~ Page 7 <br />Imo'" tea" <br />t,o <br />v/ ~ <br />