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' GROUND WATER MONITORING ' BEDROCK ' Sandstone Aquifers Four sandstone aquifers are monitored at the site. They are, in ascending order: Trout Creek Sandstone (2 wells), Middle Sandstone (6 wells), Twentymile Sandstone (3 wells), and the lowermost sandstone bench of the White Sandstones (3 wells). The No. 5 Mine is between the Trout Creek Sandstone and the Middle Sandstone. The No. 9 Mine is between the ' Twentymile Sandstone and the White Sandstone. Water Levels ~ Plots of the water levels in the upper three aquifers are presented in Figure 3 to Figure 12. The water level measured in the Twentymile Sandstone has continued to remain fairly constant. The plots indicate that the water levels in the Middle Sandstone stopped 1 declining. The water levels in most of the Middle Sandstone wells have been rising for the past year. Only Well 83-02 has experienced a recent decline in the last quarter of 1985. This change in the pattern of water ~ level changes in the Middle Sandstone was probably produced by the change ,2 in the location of the mining to the east in an area of lower head and therefore, lower inflow per unit area .7 Based upon the 1984 piezometric map (Figure 13) the ground water gradient in the Middle Sandstone ranges from 100 feet per mile to the southwest to 350 feet per mile to the west. The 1984 peizometric surface is a little different from the 1983 surface. This change is not due to any significant change in the piezometric levels but instead is due to the addition of three new monitoring wells in 1984 (Wells 83-10, 83-02 and 83-03) and the correction of an approximately 200 feet error in the datum of wAll TR-7a. The 1983 piezometric levels in the White Sandstone indicate that the No. 9 Mine may not be effecting the White Sandstone. The water level in Well ' 81-03a is rising while the water levels in Wells 81-04a and 81-19 are remaining steady. The rise in the water level in Well 81-03a, which is closest to the outcrop area, may be due to the last twc years of relatively high precipitation. As there has been no significant decrease in the discharge from the No. 9 Mine, the water level change in the Well 81-03a probably can not be attributed to the effects of mining. Based upon the 1984 piezometric map (Figure 14) the ground water gradient in the ' White Sandstone has not changed significantly and is approximately 100 feet per year to the northwest. ' Water Quality ' The water quality data for the sandstone aquifers are presented on Table 5 to Table 12. The data indicates that the water quality of all four 1 -2