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Mr. Jeff Gregg ~~~ October 23, 2000 Page 3 An AT&T buried cable located on the west side of the side approximately 60 feet from the mine excavation. The closest known structure to the actual mine excavation is the buried Sinclair gas pipeline which will be 50 feet from the actual mine excavation. STABILITYANALYSIS We performed stability analyses in order to evaluate the potential for damage to structures. The most critical mining situation potentially affecting structures will be the near vertical perimeter face of the mine excavation. Two different stability scenarios occur at the perimeter of the mine excavation. In the first scenario, no stockpiles or overburden/topsoil are present. In the second scenario, such stockpiles are present. We performed stability analyses for both scenarios using the XSTABL computer program. For both stability analyses, we analyzed the worst case potential soil profile based on the borings and slurry wall construction details immediately south of the site. The soil profile analyzed consisted of eight feet of clay overburden overlying 17 feet of sand and gravel on top of claystone bedrock. The face of the excavation was drawn at %<:1 (horizontal to vertical). No laboratory tests were performed on soils at the site. The soil strength parameters used were based on typical values for the anticipated soils and our experience at other sites in the area, and are summarized as follows: Material Tota/ Unit Weight (pcf) Saturated Unit Weight (pcf) Effective Cohesion (pcf) Effective Friction Angle (degrees) Overburden Clay 114 126 200 28 Sand and Gravel 130 137 0 35 claystone 124 134 100 28 The stability analyses were initially run on 100 randomly generated circles generated at the subject structure and mine excavation utilizing the simplified Bishop Method. The most critical surface was then analyzed using the Spencer Method.