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• 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 the average dissolved solids in the #5 Mine discharge water <br />have increased slightly from about 800 mg/I in 1982 and 1983 to almost 1000 mg/I in <br />1995. A minor reduction to approximately 850 mg/I is noted for 1996. The average <br />dissolved solids concentration for the 7 North Angle discharge continued to decrease <br />to about 850 mg/I in 1996 as compared to 1285 mg/I in years 1991 and 1992. This <br />trend is related to the accumulation of water in the North Angle Sump location while <br />the pump was out of order. This water was allowed to equilibrate within old workings <br />and subsided longwall panels. The maximum concentration of 1474 mg/I represents <br />• this equilibrium concentration and also provides an indication of the expected post <br />mining TDS concentrations in rubbelized zone and underground mine workings. <br />Likewise, this decrease illustrates the effects of flushing upon the TDS concentrations <br />with normal periodic discharge. <br />ALLUVIUM <br />Sediments in the Williams Fork River Alluvium are monitored. Three wells are in the <br />general area of the loadout facilities and underground discharge sediment ponds. <br />• <br />C-8t-044 1996 AHR. I.\EMPIREWHR\96AHR1EMPAHR96.DOC Page 8 <br />