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0 <br />slide, factors we believe caused the slide and repair recommendations. Based upon <br />our experience at the site and the results of previous investigations, we believe our <br />repair recommendations are a practical solution. We also believe additional <br />investigation, laboratory testing and analysis would result in similar <br />recommendations. <br />Based upon recent discussions wRh the Division of Minerals and Geology <br />(DMG) we recommend the following inspection, monitoring and performance criteria <br />for repair of the slide area: <br />1. During excavation of the slide mass and preparation of the base of the <br />repair (benching into the claystone or removal of the claystone area), <br />we should observe the excavation and seepage area to confirm <br />conditions are as anticipated in our analysis and recommend <br />modifications to procedures, as appropriate. <br />2. Montoring of the slide area can consist of installing a series of posts <br />along the south side of the access road. If the posts are installed on <br />a straight line, sighting down the posts will allow movement to be <br />detected if it occurs, and the line of stakes will provide a baseline for <br />measurements. We recommend monitoring be performed as part of <br />the quarterly inspections of the sedimentation pond. <br />3. Some settlement of the reconstructed area should be anticipated. A <br />single performance crfterion is difficult to specify. We recommend an <br />inRial requirement of more than 3 feet of lateral movement as a <br />definition of excessive movement. The monitoring will provide <br />indications as to the rate or continuation of movement, if it occurs, <br />which should also be considered when determining if additional repairs <br />or modifications are required. <br />Seepage Areas <br />Several seeps have developed between the slide and the excess spoil fill, <br />approximate locations are shown on Fig. 1. This area was previously stripped to <br />bedrock and covered with 18-inches of topsoil. Our observations of the slumps <br />which have developed at the seeps indicate the slumps are shallow and consist of <br />downslope sloughing of the saturated topsoil. At this time we do not believe <br />significant bedrock movement has occurred. <br />COLOWYO COAL COMPANY L P. <br />CM 2],001 't <br />