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' United Companies, Inc. March 21, 1994 Page 4 ' feet distance is the existing residence and out building on the property which will be removed and an electrical line that feeds ' the existing residence which will be used for the pit operation. The existing electric line will be removed and relocated as the pit ' progresses. The electrical line is an overhead line that extends up the northeast side of the proposed gravel pit and along the north side of the roadway along the north side of the pit. In addition a telephone line exists along the north side. On the west side a water and telephone exists between the property and U.S. Highway 550. ' The mining operation consists of a relatively shallow excavation to remove the gravel layer to a depth of 25 to 30 feet. The drill ' logs did not encounter the shale bedrock to the maximum depth explored 25 feet. No water was encountered in the drill holes and ' is not expected to be a factor in the pit operation. ' The angle of repose is the angle from a horizontal plane that a dry, loose cohesionless granular soil is stable. For the existing ' granular material the angle of repose is on the order of 32 to 36 degrees. The angle of repose can be considered equal to the.angle of internal friction when the soils are in a very loose condition. However, the angle of internal friction increases with increased density and is dependent on particle size, shape, gradation and ' composition. The existing pit run material is medium dense to dense. Thus, an internal friction angle on the order of 40 to 44 ' degrees is reasonable for the pit run material. For a purely cohesionless material the slope stability equation reduces to: ' S.F.= tanPJ tan it Where p = internal friction angle ' i~ = angle of repose Using the above formula for the pit run material at a slope angle