Laserfiche WebLink
immediately upstream from the sedimentation pond to monitor <br />the impact, if any, on the alluvial ground water system down- <br />stream from the refuse diapoeal azea. <br />3. Construction: All vegetation sad topsoil located within the <br />diapoeal site is to be removed prior to refuse diapoeal. <br />Refuse material will be placed in 2-foot vertical lifts and <br />compacted with a sheep's-foot compactor Cif aeceasazy) to <br />achieve 90 percent of the maximum dry density o! the refuse <br />material. Following compaction and grading of the refuse <br />disposal site to its design configuration, the area is to be <br />reclaimed by placing 3.5 feet of overburden material over the <br />compacted and graded refuse material, replacing 0.5 feet of <br />topsoil material and revegetatiag the site. <br />4. Stability: At the time of the initial permit submittal, <br />physical chazacteriatice of the refuse were not available~ao <br />as estimation of the expected embaal~ent strength character- <br />iatica was made using the Bureau of Mines Report of Inveati- <br />• gatioa 7964 titled Physical Property Data on Coal Waste <br />Embanl®eat Materials. The pazametere used to estimate the <br />slope stability of the refuse diapoeal embanlweat aze ae <br />follows: <br />1. Placement density 89.5 lbe/cu. ft. <br />2. Internal angle of friction 33.4° <br />3. Cohesion 3.1 psi <br />Based upon these assumed physical properties and the embank- <br />ment size and configuration described above, the factor oP <br />safety wan calculated utilizing the methods outlined is the <br />Buresu of Yinee Report of Investigation 8684 titled Factor of <br />Unsaturated Tailines Poad Embanl~ente to be 3.2. A aenaiti- <br />vity analysis was performed oa the !actor of safety by vazy- <br />iag cohesion, angle of friction and overall embanl~ent elope. <br />The result of this sensitivity analysis iadlcated that the <br />factor of safety varied under all reasonable conditions from <br />. 1.75 to 3.2, indicating that under any condition that could <br />463 <br />Revised 1/88 <br />