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<br />Ms. Connie Davis <br />January 4, 2001 <br />Page 3 <br />Inc <br />In addition, to simulate stockpiled overburden, we imposed a 1,200 pounds per square foot surcharge <br />load in a 2 i-foot wide zone extending from the top of the mine highwall. <br />Stability analyses were run on 100 randomly generated circles generated at the structure (30 feet from <br />the tap of the highwall) and highwall base using the simplified Bishop Method. The resulting minimum <br />factor of safety was 1.5. A copy of the Bishop stability analysis cross-section and the input file are <br />attached to this letter. <br />Based on our analyses, the aggregate mining, mine related disturbances, and subsequent reclamation <br />activities should not compromise the stability of permanent man-made structures in the area. <br />LLMITATL()NS <br />Our revieovis based on regional geologic mapping, present mining plans, bore hole data provided by <br />Aggregate Industries, and stability analyses using typical soil strength parameters based on our <br />experiencf~. No laboratory analyses for strength parameters were performed. Should the mining plans <br />change or subsurface conditions vary from those portrayed in this letter, we should be contacted in <br />order to re-evaluate the potential affects on permanent man-made structures. <br />If you have any questions or comments, please call. <br />Sincerely, <br />ROCKY ~ UNTAIN CONSULTANTS, INC. <br />nt/,~ <br />G ry Linden, R.G. <br />Engineering Geologist <br />r _ <br />Roy Spitzer, P.G. <br />Senior Engineering Geologist <br />GL:sp <br />Attachment <br />REFERENCES <br />Colton, R.B., 1978, "Geologic Map of the Boulder-Fort Collins-Greeley Area, Colorado, U.S.G.S. <br />Map I-855G. <br />D.VAyFiles\Depil9Nl Peuhel.rpi.v+ptl <br />