Laserfiche WebLink
immediately upstream from the sedimentation pond to monitor <br />,._., the impact, if nay, on the alluvial ground rater system down- <br />{~~~' stress from the refuse dispoeal area. <br />3. Construction: All vegetation and topsoil located within the <br />dispoeal site is to be removed prior to refuse dispoeal. <br />Refuse material will be placed in 2-coot vertical lifts sad <br />compacted with a sheep's-foot compactor <if necessary) to <br />achieve 90 percent of the maximum dry density of the refuse <br />material. Following compaction and grading of the refuse <br />disposal site to its design configuration, the area ie to be <br />reclaimed by placing 3.5 feet of overburden material over the <br />compacted sad graded refuse material, replacing 0.5 feet of <br />topsoil material and revegetating the site. <br />4. Stability: At the time of the initial permit submittal, <br />physical characteristics of the refuse were not available so <br />an estimation of the expected embaalaaent strength character- <br />ietica was made using the Bureau of alines Report of Inveati- <br />r -• <br />~ gatioa 7964 titled Physical Property Data on Coal Neste <br />Emban]®ent Materials. The parameters used to estimate the <br />elope stability of the refuse dispoeal emban]®ent are as <br />follows: <br />1. Placement density 89.5 lbe/cu. !t. <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 of <br />safety was ealcnlated utilizing the methods outlined in the <br />Bureau of Mines Report of Investigation 8584 titled Factor of <br />SafetT Charts !or Estimating the Stability o! Saturated and <br />Unsaturated Tailings Pond Embanlaaents to be 3.2. A sensiti- <br />vity analysis wan performed on the factor o! safety by vary- <br />ing cohesion, angle of irietioa and overall embanlaaent elope. <br />The result of this sensitivity analysis indicated that the <br />!actor of safety varied under all reasonable conditions from <br />;~: 1.75 to 3.2, indicating that under any condition that could <br />483 <br />Revised 1/88 <br />