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GEOTECHNICAL STABILITY EXHIBIT EXHIBIT U <br />There are no buildings or any structures outside the permit area which could be affected by the <br />excavation. A minimum twenty foot buffer will be maintained from the permit boundary line to <br />all excavations. All reclaimed areas will be restored to relatively flat (<3.5%) slopes except for <br />the side slope, which be mined and reclaimed to a 3H:1 V slope. The surface material of these <br />slopes will be topsoil, but the majority of the slope is unmined gravel. <br />It is extremely unlikely that a slope failure would occur, but if the slope failed up to the Fence <br />Line (the closest man made structure to the operation), Figure U-1 shows the slope angle that <br />would occur. The horizontal distance from the edge of the excavation to the fence line is 20 feet. <br />The failure angle would be 10 degrees, or 5.6H:1 V. This angle is far less than normal failure <br />angles in material that gets strength from internal angle of friction. Figure U-2, from Huang, <br />shows typical internal angles of friction for various materials. Assuming that the gravel is <br />classified as GC (clayey gravels, poorly graded gravel-sand-clay), this material has an internal <br />angle of friction of approximately 34 degrees. <br />Moonscape Pit, July 2009 U-1