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RAG. Empire Corporation 2000 AHR • ] 6. Figure 17 is a monthly tabulation of meter readings for 2000. While mining is in temporary cessation, the mine is being flooded and pumps are being run only periodically to maintain appropriate mine water levels. WATER QUALITY Summaries of the water quality data for the mine discharge are presented in Tables 17 through 20. The #5 Mine sump discharge is NPDES discharge point #003. The 7 North Angle Discharge is NPDES discharge point #024. The #5 Mine discharge water quality indicates a slight increase in dissolved solids concentrations over time which has now stabilized at just under 1000 mg/L . The plot of dissolved solids presented in Figure 18 shows that the average dissolved solids in the #5 Mine discharge water have increased slightly from about 800 mg/1 in 1982 and 1983 to almost ] 000 ntg/I in 1995, moderating back to 880 in 2000. The average dissolved solids concentration for the 7 North Angle were around 1150 mg/1 in 2000 which is a return to values common in 1994 and 1995. This trend is related to the accumulation of water in the North Angle Sump location while [he pump was cut of order. This ~~~ater was allowed to equilibrate within old workings and subsided longwafl panels. The maximum concentration of 1474 mg/1 represents this equilibrium concentration and also provides an indication of the expected post mining TDS concentrations in rubbleized zone of underground mine workings. Likewise, tlus decrease illustrates the effects of flushing upon the TDS concentrations with normal periodic discharge. • ALLUVIUM Sediments in the Williams Fork River Alluvium are monitored. Three wells are in the general area of the loadout facilities and underground discharge sediment ponds. WATER LEVELS Groundwater levels in the alluvium have remained fairly regular, with notrnal seasonal fluctuations, apparently related to changes in river levels. Groundwater levels in the alluvium are plotted in Figure 19. A piezometric map for the Williams Fork Alluvium is presented as Figwe 20. The data indicates no impact on alluvial water levels related to mining. WATER QUALITY Sttmmaries of the water quality data for the alluvial wells are presented in Tables 21 through 26. A plot of field electric conductivity versus time is presented in Figwe 21. There is no conclusive evidence of seasonal variation of water quality in the alluvium. The field conductivity of Well AVF-5 was above normal in late 1983 and early ]984. The laboratory • measwements did not show the same high levels dwing that period. Well AVF-3 has shown a long term variabiliq~ in field conductivity, from below 2000 umhos/cm in 1993 and 1994, 1:\Environmental\EMPIREWHR\2000\Text\Empire2000AHR.doc Page 4