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<br />• SCOPE <br />This report presents the results of our Initial Stability Analysis and <br />Geotechnical Recommendations regarding the proposed Excess Spoil Disposal <br />Areas planned at the Lorencito Coal Mine in Las Animas County, Colorado. The <br />purpose of our evaluation was to assess geotechnical conditions, stability conditions <br />and construction procedures on a preliminary basis to assist in mine planning and <br />permitting. Conditions will need to be evaluated in more detail at each disposal site <br />to confirm stability analysis assumptions and to refine construction <br />recommendations. The work was performed in accordance with our Proposal No. <br />96-997, dated November 4, 1996. Our evaluation included: <br />1. Characterizing soils, bedrock and geologic conditions based upon a <br />review of information provided by Greystone and our experience at the <br />nearby New Elk/Golden Eagle Mines. Technical publications, previous <br />investigations by CTLIThompson, Inc. and available geologic/soil <br />information were reviewed to develop preliminary estimates of <br />• engineering properties for the spoil, foundation soils and bedrock. <br />2. Evaluation of the proposed fills to characterize and group the types of <br />fills according to relevant engineering and regulatory crkeria. <br />3. Performing parametric stability analyses for typical sections. <br />Engineering properties (density and strength), water, earthquake and <br />foundation conditions were varied to develop an understanding of <br />minimum requirements for stability and the sensitivity to the various <br />factors. <br />4. Developing recommendations regarding proposed configurations, <br />slope angle, and proposed drain systems. Discussions of anticipated <br />investigations, laboratorytesting and design procedures are presented <br />to develop specific plans for each disposal area prior to construction. <br />Proposed construction procedures (site preparation, placement and <br />compaction procedures, drain requirements) along with inspection <br />procedures are also discussed. <br />Analysis or design related to permanent surface water control or evaluation <br />of potential acid or toxic properties of the spoil was not within the scope of this <br />investigation. <br />• <br />LORENCITO COAL COMPANY <br />cTLrr ss,ssi 1 <br />