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Dames ~ Moore <br />• Flatiron Companies <br />May 17, 1982 <br />Page 6 <br />existing wells of other users in the vicinity of the Bourg property, recharge <br />to downgradient wells, particularly if they were in alluvium, would be in- <br />creased due to the existence of the East Dump. <br />GEOTECHNICAL IMPACTS OF THE EAST DUMP <br />PREDIIMP CONDITIONS <br />The area to be occupied by the East Dump is typical of geomorphic and <br />topographic conditions in the region. It is a shallow draw of low relief with <br />stratigraphy consisting of shallow sandy silts and clays overlying sandstones, <br />siltatones and shale of the Coalmont Formation and the Pierre Shale. Land <br />forms in the region and specifically in the East Dump area vary from cuestas <br />(formed by the stratigraphic folds of the synclinal structure where the mine <br />• is located), to gently sloping and undulating eastward and northeastward <br />slopes around the dump area itself. Drainage in the dump area flows north to <br />northwest and is marked by a broad gentle channel. The drainage density in <br />the dump area is sparse and consists only of the one channel. Natural slopes <br />are gentle, on the order of 5 to 10 percent with occasional .localized zones of <br />15 [0 20 percent. These natural elopes are generally quite stable. One minor <br />slide zone (identified in a previous study) is located northwest of _t he dump <br />area. The slope of the slide zone is approximately 10 to 15 percent. <br />DUMP CONSTRUCTION PROCEDURES <br />The East Dump is being constructed of overburden materials from the <br />mine excavation. These materials are being excavated from [he mine by two <br />dual engine scrapers working in tandem. As the excavation deepens toward the <br />coal zones some ripping is necessary before the scrapers can pick up the <br />materials efficiently. <br />C J <br />