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aquifer, but some of the individual strata do behave as aquifers. Generally, <br />the pressure conditions are different for each aquiferous stratum, and the <br />trend is such that the deeper aquifers generally have higher pressures. The <br />depth to crater is variable because of the irregular topography at the site. <br />Figure 2.7-29 shows that the head in the K -L -M aquifer is slightly greater <br />than the Below R aquifer. <br />At the pits that have been opened thus far at the Trapper Mine, it was <br />expected that the water table would be encountered at a depth of 90 feet. <br />Apparently, this projection was based on the static water level of wells <br />drilled deeper than the bottom of the pits. When the pits were opened, <br />the water table was actually encountered at a depth of 120 to 125 feet. <br />Water is encountered more in the northern (down -gradient) portion of the <br />pits than in the southern. Pumping for 16-20 hours is normally required to <br />remove the water in lower portions of the Ashmore pit after the pit has set <br />for a week. This relates to approximately 70 gpm of dewatering for the <br />Ashmore pit. The Derringer and Enfield are dry in the southern portion of <br />their pits and normally yield crater at the northern end of these pits. <br />In summary, the Upper Williams Fork includes perched, water -table, and <br />confined aquiferous strata. Depths to water (from the land surface) <br />are variable from about 120 to 250 feet. Pressures vary with depth, so <br />that increasing or decreasing pressures can be encountered at different <br />depths, even for the same well site. <br />2-520 <br />