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<br /> <br />GROUND WATER MONITORING <br />LI <br />1 <br />BEDROCK <br />Sandstone Aquifers <br />Four sandstone aquifers are monitored at the site. They are, in <br />ascending order: Trout Creek Sandstone (2 wells), Middle Sandstone (6 <br />wells), Twentymile Sandstone (3 wells), and the lowermost sandstone bench <br />' of the White Sandstones (3 wells). The No. 5 Mine is between the Trout <br />Creek Sandstone and the Middle Sandstone. <br />' Water Levels <br />t Plots of the water levels in wells in the upper three aquifers are <br />presented in Figures 3 through 15. The water levels in the Middle, <br />Twentymile and White Sandstones generally are showing an upward trend. <br />For most wells, this trend began in 1983 or 1984. As discharges from the <br /> mines in the area where constant or increasing during this period, the <br />' water level changes appear to be the result of climatic factors. The <br /> years 1980 and 1981 were very dry years and the following two years were <br />' more <br />Years normal years. During this <br />1984 and 1985 were very wet period, water levels generally fell. <br />years and the spring runoff in 1986 was <br /> above normal. During this period, the water levels in the aquifers rose. <br />' Based upon the 1986 piezometric map (Figure 16), the ground water gradient <br /> in the Middle Sandstone ranges from 125 feet per mile to the southwest to <br /> 375 feet per mile to the west. A piezometric contour map of the <br /> Twentymile sandstone is presented on Figure 17. The indicated gradient is <br /> 525 feet per mile to the northwest. The high indicated gradient is <br /> probably a result of one of the wells, Well 259, being in a discharge area <br /> of the aquifer. Based upon the 1985 piezometric snap (Figure 18), the <br />' ground water gradient in the White Sandstone has not changed significantly <br /> and is approximately 100 feet per year to the northwest. <br />' Wat <br />alit <br /> er Qu <br />y <br /> The water quality data for the sandstone aquifers are summarized in Tables <br /> 5 through 17. Plots of field conductivity are presented in Figures 19 <br /> through 21. The data indicates that the water quality of all four <br /> sandstone aquifers is fairly constant over the whole period of <br />' measurement. The field conductivities seem to show a slight downward <br /> trend; however, the corresponding dissolved solids values do not show the <br /> same downward trend. The tables include all data collected through 1986. <br /> <br /> 2 <br /> <br />