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1.0 INTRODUCTION <br />The Bowie Mine No. 2 is a subsurface coal mine owned and operated by Bowie Resources <br />Limited (Bowie). The Bowie Mine No. 2 is located north of Colorado State Highway 133B, <br />approximately 3.5 miles northeast of Paonia, Colorado. The mine produces approximately 5 <br />million tons of coal per year. Coal waste from the preparation plant as well as some high ash <br />coal is disposed of at a coal waste disposal area located immediately north of Colorado State <br />Highway 133B. Buckhorn Geotech, Inc. ( Buckhorn) was retained by Bowie to evaluate stability <br />of the coal waste disposal stockpile ( "gob pile ") and provide recommendations for a stable <br />stockpile configuration (i.e., slope angle). We are pleased to present this report summarizing our <br />field investigation, laboratory testing, and analysis to date. <br />1.1 Scope of Services <br />As part of the stability evaluation for the coal waste disposal stockpile, Buckhorn conducted a <br />geotechnical site investigation, installed geotechnical instrumentation to monitor pore pressures <br />and ground movement, conducted laboratory testing, and conducted limiting equilibrium stability <br />analyses. The site investigation included: (i) drilling eleven boreholes at the existing stockpile; <br />(ii) collection of bulk and in -situ samples of coal waste; (iii) installation of five vibrating wire <br />piezometers to monitor pore pressures within the compacted coal waste; and (iv) installation of <br />three inclinometers to monitor ground movement within the coal waste stockpile. Laboratory <br />testing included index testing to characterize the coal waste, natural moisture and density, and <br />triaxial testing to characterize strength parameters of the coal waste. <br />Monitoring of installed geotechnical instrumentation is underway and on -going at the writing of <br />this report. This report describes our site investigations to date, laboratory testing results, to date <br />instrumentation monitoring, stability evaluations, and provides recommendations for gob <br />stockpile stacking slopes and practices and on -going instrumentation monitoring. <br />2.0 SITE DESCRIPTION <br />The coal waste ( "gob ") stockpile is located immediately north of State Highway 133B near the <br />bottom of an unnamed drainage designated "D- Gulch" in the permit documents. The coal waste <br />primarily consists of refuse from the preparation plant and some high ash coal. Originally, some <br />of the native soils from the foundation and slopes adjacent to the disposal area had been blended <br />with the coal waste to reduce the moisture content and improve workability. The ultimate <br />capacity of the coal waste disposal area desired by Bowie is 2,000,000 cubic yards. <br />Two foundation underdrains were constructed from upgradient ephemeral drainages to a <br />sedimentation pond, Pond "I"', located near the southeastern toe of the stockpile. Surface water <br />diversion ditches have also been constructed along the ultimate lateral edges of the stockpile. <br />The diversion ditches discharge into the sedimentation pond. The current configuration of the <br />waste stockpile consists of- <br />Bowie No 2 Gob Pile Stability Dec2005 <br />Project #05- 126 -GEO <br />Page 4 of 18 <br />