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To: Chris Nyikos, Project Manager - Mountain Coal Company <br />Subject: Geotechnical Review of Updated PR-2 Conveyor Alignment <br />Date: July 17, 2009 <br />Project: 06/26-1004 <br />with cement grout. The concrete support blocks would float on un-reinforced concrete slabs that are not <br />connected to the piles. In this manner, the piles would provide lateral support should the lower slope <br />exhibit excessive deformation. If small movements occurred and the conveyor became misaligned, the <br />concrete blocks could be adjusted by sliding them back into alignment on top of the concrete slab. <br />The bents located from Stations 15+00 through 19+00 still require stabilization. Installing two piles below <br />each bent is recommended at these locations for conceptual design purposes. For cost estimation purposes, <br />piles very similar in depth and size to those installed to stabilize the concrete conveyor support blocks were <br />assumed. <br />LRP Stabilization Review <br />The proposed Screening and Preparation Plant facility is located atop the Lower Refuse Pile (LRP). The <br />Screening and Preparation Plant facility is positioned on the south end of the LRP, north of the access <br />road. For the LRP stabilization review, global stability was analyzed in the area of the proposed Screening <br />and Preparation Plant facility. <br />A previous series of analyses for critical slopes along the proposed Sylvester Gulch E-Seam Coal Handling <br />Facilities was completed in 1999. In the 1999 report, two critical slopes located on the LRP (denoted as <br />Cross Sections A and B) were evaluated including the then-proposed Screening and Breaker Building in a <br />location similar to that of the currently-proposed Screening and Preparation Plant facility. The previous <br />stability analyses were based on plans to widen the top of the LRP by removing refuse material down to <br />Elevation 6,120. Results of the 1999 analysis indicated a factor of safety of no less than 1.8 for both cross <br />sections under the then-proposed profile (denoted as construction condition in the previous report). The <br />original work included geotechnical parameters for the refuse material and bedrock, and they were <br />assumed based on those provided by Harding and Lawson (1985). Parameters for the native soil (i.e. <br />colluvium and alluvium) were estimated based on the results of laboratory testing presented in the 1999 <br />report. <br />A review of conceptual plans for the LRP with the Screening and Preparation Plant facility was conducted. <br />Two cross sections were evaluated for global stability. Cross Section A is located along the same <br />alignment (roughly oriented north-south) as old Cross Section A evaluated in 1999. Cross section C (in <br />-5-