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Currently, the gradient in the lenticular sandstones and <br />• siltstones is approximately 6.5% or 6.5 ft of head loss <br />per 100 ft. on the flank of the anticline. The rate of <br />natural ground water flow through the sandstone is then <br />approximately .07 ft/yr and through the siltstone, flow <br />is approximately .04 ft~yr. This asses no significant <br />fracturing occurs in these sediments. <br />If systems of tension fractures related to folding of the <br />sediments are encountered on the flanks of the anticline, <br />they may contribute to the overall permeability of the <br />rock mass. If encountered, estimates of permeability <br />and flow may be increased by up to two orders of magnitude. <br />However, even increases in permeability of this amount <br />• result in extremely low natural flow velocities. <br />If fault systems are encountered in the proposed mine, <br />these systems could provide conduits for ground water <br />migration at accelerated rates. Although suggested by <br />Carpen (1957) no faulting has as yet been mapped on the <br />tract. <br />Ground Water Quality <br />Analysis of ground waters encountered in the 3 operating <br />test wells are presented on Figure 1 and plotted on the <br />trilinear diagram, figure 2. Water in Well No. 1, pene- <br />trating the upper sandy member of the Pierre Shale and <br />u <br />10 <br />