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• To determine the effects of phreatic surface on the refuse piles, <br />several cases were analyzed. One case models the foundation <br />materials becoming thoroughly saturated. Another case involves a <br />buildup of the phreatic surface to a height of 10 feet above the <br />existing foundation elevation with the phreatic surface exiting <br />at the toe of the slope. A third case involved a phreatic <br />surface 10 feet above the existing foundation elevation with the <br />phreatic surface exiting along the slope face 5 feet above the <br />toe. A fourth case assumed an extreme phreatic surface. The <br />location of these various phreatic surface assumptions are shown <br />on Figures 4 and 5. Theoretically, based upon our field <br />investigation, none of these phreatic surfaces should occur. <br />• With proper diversion of the runoff above the refuse piles and <br />proper grading of the refuse piles themselves to ensure that no <br />ponding occurs as the coal waste is placed, the coal waste piles <br />should remain unsaturated. <br />6.5 ANALYTICAL TECHNIQUES <br />The circular failure mode for the slope stability analysis was <br />performed using a computer-assisted limit equilibrium method of <br />slices. This particular program utilizes Spencer's method of <br />analysis. This program is capable of analyzing stability <br />conditions under circular and randomly specified shear surfaces. <br />• Three conditions of slope failures were analyzed for Refuse Pile <br />No. 3 while four cases were analyzed for Refuse Pile No. 2. <br />12 <br />