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Page 4 Mr. Eric Scott <br />November 3, 2014 Colorado DRMS <br />Weathered Shale 120 50 15 <br />The Ditullio slope liner design was modeled with a general section developed from the most <br />conservative conditions encountered at the site, more conservative than those utilized for <br />Veldman property, including 4 feet of overburden overlying a 14.4 foot thick layer of sand <br />and gravel. Beneath the sand and gravel, a 2.5 foot thick layer of weathered, residual <br />strength bedrock. Beneath this layer of residual strength bedrock we modelled undisturbed <br />shale bedrock. <br />The closest structure to mine excavation limits is listed in Table 2. Only the closest structure <br />was modeled, per DBMS suggestion. It is assumed any structure beyond this distance will <br />have a higher factor of safety. Thus, this closest permanent structure is the critical, lowest <br />stability value. The general cross - section is shown on Figure 5. <br />Table 2: Structures and Entities within 200 Feet of Excavation Limits <br />Structure <br />Structure Owner <br />Distance to Structure <br />Power line pole <br />Poudre Valley REA <br />29 feet from excavation <br />Stability analyses were run on randomly generated circles generated through the mine <br />excavation and highwall intersecting the location of only the closest permanent structure. <br />The Slope/W program calculated the Factors of Safety (FOS) using the ordinary, Bishop, <br />Janbu, and Spencer Methods. The Spencer FOS correlates more closely with observations of <br />actual slope failure, providing a realistic and more rigorous FOS. On the annotated cross <br />sections (Attachment A), the Spencer FOS is listed. The results of the analyses are listed in <br />Table 3. <br />Table 3: Stability Results for Excavation in Proximity to Utilities <br />Structure <br />Distance to Structure <br />Factor of Safety <br />Power line pole <br />29 feet <br />1 1.2 <br />GEI <br />