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P EnviroGroup Limited <br />The Environmental Solutions Company <br />CLIENT MEMORANDUM <br />Date: March 20, 2009 <br />To: Ryan Sweetwood, Mountain Coal Company <br />Doug Nolte, Mountain Coal Company <br />From: John Rahe, P.E. <br />Bence Close, P.E. <br />Cc: Chris Hansen, AWBG <br />Scott Lewis, Arch Coal, Inc. <br />Project: AR-0615 <br />• Subject: Geotechnical and Slope Stability Analyses: Sylvester Gulch Facilities Area <br />Mountain Coal Company - West Elk Mine <br />This memorandum summarizes the geotechnical work and slope stability analyses performed to <br />evaluate a potential site for constructing a second settling pond at the Sylvester Gulch mine <br />dewatering facility at the West Elk Mine. The second pond would be located east and adjacent to <br />the existing Pond 017. <br />During 2008, test pits were excavated within the footprint of the proposed pond, and samples <br />collected for geotechnical analysis (Figure 1). A geotechnical program performed in 1997 for the <br />initial construction of dewatering and treatment facilities at the Sylvester Gulch area also <br />included data pertinent to the design of the Second Pond. This included six borings to bedrock <br />and several other shallow boreholes within and near the footprint of the Second Pond (Figure 1), <br />along with associated soil characterization, strength and consolidation data. During the 1997 <br />study, most soils were described as very dense to very stiff sandy to gravelly clays. In addition, <br />inclinometer data were reviewed from a device installed near the edge of the steep hillside (I-13) <br />just east of the Second Pond. <br />0 <br />Rev. 04109-TR116