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Mr. Mark Johnson <br /> January 2 , 2014 <br /> Page 3 <br /> Therefore, prior to submitting the final stability run, at least 288 failure surfaces were analyzed to determine the <br /> lowest factor of safety. <br /> The six cross-section locations were selected to analyze proposed setbacks for stability of structures using <br /> appropriate surcharge loads for the mining limits. Cross sections A, B, C, E, and F are modeled with a 3:1 (H:V) <br /> highwall and include a slurry wall. Cross sections A, B, and C are modeled to include the relocation of the Last <br /> Chance Ditch. Section C is also modeled to include the relocation of the Rural Ditch Return. Cross section D is <br /> modeled with a 3:1 highwall but without a slurry wall. Cross section D was modeled to represent the Rural Ditch <br /> Return in its existing location and also for when the Rural Ditch Return will be relocated to the eastern side of the <br /> project site. All mining slopes are modeled to be no steeper than 3:1 (HY). Phase 3 was modeled to include a <br /> soil-bentonite slurry wall (Sections B and E). The locations are described below and shown on Figure 1. <br /> ► Section A-A': This section considers the closest distance to the farm structures,WCR 11.25, and the <br /> relocated Last Chance Ditch. A high phreatic surface was included to model the maximum water surface <br /> from the ditch, a surcharge of 250 psf was included to model the live load of the road and a surcharge of <br /> 2000 psf was included to model the dead load from the building. <br /> ► Section B-B': This section considers WCR 26,the overhead power line, and the relocated Last Chance <br /> Ditch. A high phreatic surface was included to model the maximum water surface from the ditch; a <br /> surcharge of 250 psf was included to model the live load from the road, and a surcharge of 100 psf was <br /> included to model the dead load from the power line. <br /> ► Section C-C': This section considers The Rural Ditch and relocation of the Rural Ditch Return along the <br /> eastern margin of the site. A high phreatic surface was included to model the maximum water surface <br /> from the ditches. <br /> ► Section D-D': This section considers the Kerr-McGee Burch 3-1A well located between phase 1 and <br /> phase 2. A surcharge of 500 psf was included to model the live load from the access road and dead loads <br /> from the well and associated tanks. <br /> ► Section E-E': This section considers Kerr McGee's gas line, access road, and the relocation of the Rural <br /> Ditch Return to the south boundary of the site. A high phreatic surface was included to model the <br /> maximum water surface from the ditch. <br /> ► Section F-F': This section considers Kerr McGee's gas line, access road, and the relocation of the Rural <br /> Ditch Return to the south boundary of the site. A high phreatic surface was included to model the <br /> maximum water surface from the ditch. A surcharge of 300 psf was included to model the live load from <br /> the access road and dead load from the gas line. <br /> The material index and engineering strengths assumed in this slope stability report are discussed below. <br />