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Mr. Jim McFarland <br />November 19, 2002 <br />Page 5 <br />Inc <br />Pod 5 -Four feet of overburden clay, overlying eight and one-half feet of sand and gravel, <br />over five and one-half feet of clay lens, over 16 feet of sand and gravel, on top of claystone <br />bedrock. A slurry wall was modeled 50 feet from the highwall and 20 feet from nearby <br />structures and the cliff on the north side of the valley. <br />Stability analyses were run on 100 randomly generated circles generated at the mine excavation and <br />highwall, as well as the nearby permanent structure. The Simplified Bishop Method was used to <br />estimate the factor of safety on the most critical surface. Input files and graphic profiles of each analysis <br />are attached. The results of the analyses are listed below: <br />Pod Distance to Nearest Factor of Safety <br /> Permanent Structure <br />1 55 1.6 <br />2 <br />( erimetetl 70 1.5 <br />2 <br />interior at well access roads) 55 1.5 <br />3 50 1.5 <br />4 70 1.8 <br />5 70 1.9 <br />The mine plan incorporates minimum setback distances for each pod. The minimum setbacks are equal <br />to the distances in the table above. Mining, following these minimum setbacks, should not pose a <br />hazard to nearby structures. <br />LIMIATIONS <br />Our review is based on regional geologic mapping, present mining plans, bore hole data, and stability <br />analyses using typical soil strength parameters. Should the mining plans change or subsurface <br />conditions vary from those portrayed in this letter, we should be contacted in order to re-evaluate the <br />potential affects on man-made structures. <br />Please call with any questions or comments. <br />Sincerely, <br />ROCKY/MOUNTAIN CONSULTANTS, INC. <br />(/NI <br />Gary Linden, R.G. <br />Engineering Geologist <br />RG:sp <br />H.\06J6 IJTBemhaNt S~abiluy Irc doc <br />