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saturation. The drainage from the top of the bench is adequate <br />so it did not contribute to the slump. <br />Two additional test holes were placed in the cover material in <br />the slump area. The first was dug adjacent to a vertical scarf <br />measuring 24-inches. The hole was dug 36-inches deep where coal <br />waste material was encountered. The hole was damp but dry. The <br />waste material being encountered 3-feet below the surface right <br />adjacent to s 2-foot deep scarf indicates that only the cover <br />material moved in this area. <br />The second teat hole was placed about 45-feet down the slope from <br />the center of the slump area. Salt deposits were located in this <br />area which indicates that this was an area where water had seeped <br />from the oover material. The hole was excavated 4-feet deep yet <br />no coal waste material was encountered. Free water returned to <br />within 2-feet of the surface in about one hour. The condition of <br />this hole indicates that the cover material was completely <br />saturated in this area at the time of the slump. <br />1989 REPAIR PLAN <br />The information presented above indicates the probable cause of <br />the bench slump was that the cover material became saturated <br />during the spring melt from water seeping into it from the sur- <br />face. Drainage above the slump area is adequate and the <br />piezometers show that the coal waste material is not saturated in <br />the area. The stability monuments also show that the coal waste <br />material is stable. <br />Blue Ribbon therefore plans to repair this slump like the 1988 <br />slump was repaired. The 1988 slump repair worked. The french <br />drains did relieve water from the 1988 slump area. <br />At least three french drains will be installed across the slump <br />area. They will be installed approximately at the interface be- <br />tween the cover material and the coal waste material. The french <br />drains will be placed through previously saturated areas <br />evidenced by salt deposits on the surface. The slump area will <br />then be regraded to blend in with the surrounding slope. <br />The french drains will surface on the out slope of the bench <br />south and below the slump area. Rocks will be placed over and <br />around the pipes to prevent localized erosion. If erosion does <br />become a problem, which is not expected because of the small <br />flows, stabilized channels will be provided for the water coming <br />from the drains. <br />ADDITIONAL MONITORING DBVICSS <br />During the repair process two piezometers will be installed in <br />the slump area. Both piezometers will be installed about 20-feet <br />3 <br />