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DESIGN ANALYSIS AND CRITERIA <br /> The proposed mining slopes were analyzed using the XSTABL v5.105a computer <br /> program. XSTABL was designed to analyze the slope stability of earth embankments <br /> subjected to several critical situations that may occur during the life of the embankment. <br /> For this project, four cases were identified as critical during the mining operation. Static <br /> and pseudo-static conditions were analyzed in each case. <br /> Pseudo-static peak acceleration factors were taken from USGS information for the <br /> western United States. The 2% probability of exceedance in 50 years (the most <br /> conservative) was used. <br /> Surface loading equivalent to an HS 20 highway load was applied adjacent to each area <br /> to simulate heavy equipment loading that could be present at that location for <br /> maintenance or construction activities. <br /> All mining side slopes will be 3H:1V. <br /> Case 1 — South Property Line (SOUTH 1). The mining operation is adjacent to <br /> a private property on the south side of the site. The proposed setback for mining <br /> is 50 feet from the property line. The mining depth was assumed to be 85 feet in <br /> this area based on bore log information in the geotechnical reports. <br /> Case 2 — Existing Balsam Avenue ROW (WEST 2). The mining operation is <br /> adjacent to Balsam Avenue on the west side of the site. The mining depth was <br /> assumed to be 75 feet in this area based on bore log information in the <br /> geotechnical reports. The proposed mining setback was set 40 feet from the <br /> existing ROW. <br /> Case 3 — North Property Line (NORTH 3). The mining operation is adjacent to <br /> a private property and some minor electric utilities for a portion of the north side <br /> of the site. The mining depth was assumed to be 85 feet in this area based on <br /> bore log information in the geotechnical reports. The proposed mining setback <br /> was set 127 feet from the property line. <br /> Case 4 — Existing Gas Well (WELL 4). An existing gas well is located in the <br /> center of the proposed pit. The mining depth was assumed to be 85 feet in the <br /> area based on bore log information in the geotechnical reports. The proposed <br /> minimum mining setback was set 150 feet from the gas well. <br /> The cross-sections located in Appendix B show the estimated phreatic surface <br /> associated with each case as well as the geometry used in the mining. <br /> Broken Arrow Investments,LLC-Derr Pit Project <br /> ' J&1 Consulting, Inc. Slope Stability Analysis <br /> Page 3 <br />