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GROUND WATER C The piezometers in the restablized mine bench were monitored monthly in 1986. The following table shows the average water level and elevation in each piezometer: Piezometer Average Water Level Average Elevation P-1 19.6 6,382.7 P-2 None Below 6,347.2 P-3 46.1 6,339.3 P-4 25.1 6,454.9 The average water level dropped in all but P-1. The water level in P-4 was expected to raise during the fall of 1986 due to standing water on top of the bench. The water level in P-4 dropped during that time but raised in P-1. Grading will be done on the bench in 1987 to allow proper drainage and to reduce possible impact on the bench. Monitoring was done monthly on the three underdrains. The north drain discharged 0.26 acre-feet of water with a mass average conductivity of 1603 µmhoslcm and an average pH of 7.9. The middle drain did not discharge enough to measure. The south drain discharged 1.11 acre-feet of water with a mass average conductivity of 3870 µmhos/cm and an average pH of 7.5. The flow from the north drain soaks into the ground before getting to the pond; therefore, a composite sample propor- tional to flows is taken for quality. MINE W~TFR C No mine water was pumped in 1986 and the mine was sealed prior to time for the 1986 mine inflows study. One water sample was taken during the year of water in the mine as it was filling. A map is included to show the water level when the mine was sealed. COIJSUMPTIVE USE OF WATER There was no consumptive use of water during the year. HYDROLOGIC IMPACTS Hubbard Creek showed little or no impact from the mining operation. The small increase in conductivity between the upper and lower sample points can be more than accounted for by the flow from the north draw. The discharge from the N1 and #5 Ponds would have increased the conductivity by 0.22 µmhos/cm. Assuming the maximum flow and conductivity during 1986 for the underdrains, 0.5 gpm @ 1946 and 1.6 gpm @ 4420, the mass average affect on the 10 year low flow in Hubbard Creek of 1.6 CFS would be to increase the conductivity by 10.8 µmhos/cm, assuming a creek conductivity of 130 µmhos/cm. Using the average flow and conduc- tivity for the underdrains discharging into the 1.6 CFS, the conductivity would be increased by 3.9 µmhos/cm. The standing water on the bench is not believed by Blue Ribbon Coal Company to have caused the increase in water level in piezometer P-1. If the water were seeping into the ground from the bench, a corresponding increase in flows from the underdrains and an increase in the water level of P-4 would have been ~~ expected. The hole for P-1 had a high clay content. Surface water near the hole may be seeping around the plug and into the hole. The clay content of the hole could then prevent the water from seeping out of the hole.