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1 <br />1 <br />COAL <br />' FLOWS <br /> Plots of the measured discharges for the two #5 Mine discharge <br />' points are presented in figures 19 and 20. The flows are measured <br /> at the discharges by totalizing flow meters on the dewatering sump <br /> pumps. The mean flow rate did not exceed the predicted values of <br />760 to 890 combined gpm for the #5 Mine. The 1990 average <br />discharge was 463 gpm from the #5 Mine sump, and 154 gpm from the <br />7 North Angle. The combined average discharge was 617 gpm. The <br />' water produced in the #6 Mine is pumped underground to the #5 Mine <br />sump and is accounted for at the discharge from that point. <br />The decrease in the discharge from the 7 North Angle Sump at the <br />' end of 1990 was due to the deterioration of the pump. The <br />discharge from this sump is expected to increase when the pump is <br />repaired. <br />' WATER QUALITY <br />~ , Summaries of the water quality data for the mine discharge are <br />presented in Tables 19 through 22. The #5 Mine sump discharge is <br />NPDES discharge point #003. The 7 North Angle pischarge is NPDES <br />discharge point #024. The mine discharge water quality has been <br />generally constant through time. A plot of dissolved solids is <br />presented in Figure 21. It does indicate that the average <br />' dissolved solids in the discharge water have increased from about <br />790 mg/1 in 1982 and 1983 to approximately 890 mg/1 in 1986. This <br />increase may be due to the longwall mining, which was initiated in <br />May of 1985. This increase in dissolved solids leveled off in <br />' 1986. Other than one relatively high reading in 1987, the <br />dissolved solids are still at approximately 920 mg/1 in 1990. The <br />average dissolved solids concentration for the 7 North Angle <br />' discharge was 940 mg/1 in 1990. The flow weighted average <br />dissolved solids concentration for the combined discharge from the <br />#5 Mine is 925 mg/1. Since the dissolved solids level is still <br />within the range used in the low flow mass balance prediction, it <br />will not be significantly affected. The only NPDES violations in <br />1990 where for pH from the 7 North Angle discharge. This was due <br />to algal growth in the treatment ponds in the summer. This was not <br />' considered a serious problem by the Department of Heath (DOH) and <br />is a common problem in this type of system. A modification to the <br />NPDES permit to allow higher pH levels has been submitted to the <br />' DOH. <br />ALLUVIUM <br />Sediments in the Williams Fork River Alluvium are monitored. Three <br />wells are in the general area of the loadout facilities and <br />' underground discharge sediment ponds. <br />' -2- <br />