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errors in obtaining an accurate measurement of equilibrium artesian pressures within the well. The long term <br />• decline could be a pressure response due to the overall drop in potentiometric levels in the Middle <br />Sandstone In the vicinity of Mines 5 and 6. On the other hand, there was no apparent relationship between <br />the fluctuations observed in Well 13.3-03 with the fluctuations observed in other Middle Sandstone wells due <br />perhaps to the combined influence of apparent errors in pressure measurements and the further distance <br />to the well. <br />Monitoring results through year 1991 still show no apparent change in the water levels in the Twentymite <br />Sandstone that could be attributable to mining activities. Water level plots indicate essentially no change <br />except, perhaps, for a slight increase in the levels in Well 84-01. <br />Based upon the 1991 piezometric map (Figure 14), the groundwater gradient in the Middle Sandstone <br />ranges from 120 feet per mile to the southwest to 60 feet per mite to the southwest. The drop in <br />potentiometric levels in the Middle Sandstone unit above the subsided longwall mine panels in the F and <br />• E coal seams has created a potentiometric gradient to the south in the vicinity of the longwall panels. A <br />piezometric contour map of the Twentymile Sandstone is presented in Figure 15. The map indicates that <br />the gradient is 220 feet per mile to the northwest and shows essentially no change from 1990. <br />WATER DUALITY <br />The water quality data for the two Trout Creek Sandstone Wells do not indicate any water quality impacts <br />related to mining. The water quality data for the two Trout Creek Sandstone Wells are summarized on Table <br />5 through 8. A plot of field conductivity measurements is presented in Figure 16. <br />The data for the three Middle Sandstone Wells which are monitored for water quality show no adverse <br />impact or trend. Water quality data are summarized in Tables 9 through 14. Plots of field conductivity for <br />these Middle Sandstone Welts are presented in Figure 17. Wells TR-7A and TR-4 indicate slight reduction <br />• 4 <br />