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Engineering Demonstration for Box Elder Holding Company Structures As can be seen on Map C-1 A, the Box Elder fences and outbuildings aze within 200 feet of the permit boundary. These structures will not be affected for the following reasons: 1) The closest edge of the mining pit is over 310 feet away from the permit boundary. 2) The pad area of the operation has been filled with 3-6 feet of overburden fill from the eastern edge of the mining azea. This further ensures that the natura12H:1 V slope cannot fail. There aze no springs or seeps along the slope which will be covered and back up water in the slope. Water is allowed to drain in a ditch as shown on Map C-2. 3) The mining pit excavation slope is 2H:1 V. The existing gravel material has few fines and the material does not get its strength from cohesion, but internal angle of friction. Partly rounded gravel of this type in place has an angle of repose of approximately 40 degrees. For non-cohesive soils, this is also the intemal angle of friction of the material. The overall slope of 2.OH:1.OV is an angle of 30.0 degrees; therefore, the factor of safety is 40/30 or 1.33. This is conservative since the in place gravel has usually increased forces over thousands of years. I, Greg Lewicki, P.E., with over 26 years of experience in mine slope safety analysis in Colorado, state that this is true and that this factor of safety is adequate to prevent failure of the slopes. Given this stability and the distance from the excavation to the pernut boundary, it is virtually impossible that a pit slope failure could damage any Box Elder structure. See Map C-5, showing cross section D-D' though the pit and the Box Elder structures. The cross section in plan view is best seen on Map C-lA. The damage waivers on the following pages show anExhibit A -Affected Land Description. This has only been reproduced for the 1 s` waiver. All aze identical. White River City Pit December 06 S-2