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GEOTECHNICAL STABILITY EXHIBIT(CONT) Page 2 the Permit Line and the Baily House is 159 feet from the dig line (Section N-S - 1/ to 1V Existing Slope) . When the mining face in this area reaches the floor, the toe of the mine face will be 165 feet from the closest point on the house The cross section shows In the past, Mr. Alan Sorenson reviewed Slope Stability Reports prepared for the mine in Colorado and he suggested that an appropriate friction angle could be found in Table 1 of a Federal Highway Administration paper Rock Slopes: Design, Excavation and Stabilization, Publication No. FR WA-TS-89-045, Table 1 - Typical Soil and Rock Properties and used when non-site-specific information was available of a gravel deposit . So for this analysis a 35' friction angle and a near vertical mining face of %: 1 is used for the pre reclamation calculations . For the reclamation calcula- tion a 3 : 1 slope was used (Section N-S - 3H to 1V Reclaimed Slope) . The material in the mine wall will be in-place sand and gravel and assumed to be cohesionless and having an assumed natural friction angle (0) of 350 (z1 . 43 : 1) . This is consistent with observations made along the north side of the permit area where the old mine face has remained undisturbed many Using the measured angles from the cross section ns, the safety factors for each slope was calculated using the 35o (0) as the base angle . The safety factors are shown in the following table using the formula FS = TanO =Tan6, where 6 is the slope angle from the toe of the created slope to the closest structure. I have also calculated the Factor of Safety for the �5: 1 and the 3 : 1 slopes . SLOPES EVALUATED CALCULATED FACTOR OF SAFETY SLOPE ANGLE FOR NATURAL SLOPE O ANGLE 0=35° PROPOSED MINING 63.40 0.35 SLOPE (Y2:1) SLOPE FROM MINING 4.200) 9.54 TOE TO HOUSE FINAL SLOPE 3H TO 1V SLOPE FROM TOE TO 3.60 11.13 OUSE 4.2° angle is calculated from 12 feet slope height and 165 feet horizontal (2) from the toe of mine face to the Baily House 3.6° angle is calculated from 12 feet slope height and 190 feet horizontal from the toe of reclaimed slope to the Baily House The safety factor for the Baily house 9 . 54 when the mining face is mined near vertical and 11 . 13 when the final slope is constructed. Both numbers exceed the 1 . 5 normally used.