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elevation of 6,340 feet above mean sea level (refer to figure I). Springs are cwre~tCy~iv°er[edociates <br />with gravel drains to a central collection point. <br />New Slone Geometry: The cut and fill profiles for the parking lot extension are show on figures <br />2 and 3, "Cross-Section ofthe parking lot extrnsion." <br />Soil Strrneth Properties: Two types of soils are used in the model. The strrngth parameters of <br />the soils are based on previous strength tests at the site, and are as follows: <br />• Native Colluvial Soil -Low plastic clay, cohesion 288 psf, intemal friction angle <br />21.6 degrees, moist trait weight l30 pcf, saturated wit weight I35 pcf. <br />• Rip Rap Gabion Wall -sandstone boulders, cohesion 0 psf, internal friction angle <br />35.0 degrees, moist unit weight 120 pcf, saturated unit weight 130 pcf. <br />The slope stability was evaluated Cuing PCSTABLS. This computer program was developed at <br />Purdue University and uses the simplified Janbu or simplified Bishop method of slices. It compares the <br />forces resisting slope failure to forces which cause slope failure along a specified failure surface. The <br />analysis utilizes a limit equilibrium procedure to calculate the factor of safety against failure. The input <br />information for the analyses includes, but is not limited to, slope geometry, groundwater conditions, soil <br />strengths, an loading conditions. <br />Results of the stability analysis for the parking lot extension are summarized as follows: <br />Profile A Profile B <br />(run 1) (run 2) <br />Original condition 2.45 1.43 <br />Parking Extension 2.32 1.30 <br />The calculated factors of safety for the proposed parking lot extension are above, or at the <br />minimum factor of safety of 1.3, as required by the State of Colorado Mined Land Reclamation Board, <br />1991. If you have any questions or require further assistance, please give me a call at (801) 363-4455. <br />Sincerely, <br />ARDiNC LAVA' O$ N ASSOCIATES <br />Loren A. Jalbert „~;a ~--0 !:.',~ ~ , <br />~JL i <br />Charlie Rehn . .~ <br />Project Manager <br />LAJ/klw <br />Attachments <br />