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C: <br />Rio Tinto Energy America SIiANNC+N FtWII.SON, INC. <br />Arm: Mr. Tay Tonazzi <br />October 26, 2005 <br />Page 2 <br />PREVIOUS STUDIES <br />We reviewed the following reports which are referenced in this letter <br />~ Shannon & Wilson, Inc., "Geotechnical Study, South Taylor Excess Spoil Fills', <br />Project No. 23-1-01105-200, dated July 2006. <br />~ CTL /'fhompson, Inc. (CTL), 2003, "Geotechnica] Investigation, South Taylor, <br />Sedimentation Pond Embankments", Job No. 35,854, dated Apri12003. <br />SUPPLEMENTAL EXPLORATION <br />Excavation for highwall mining was in progress in the East Fork of the East Fork of Taylor <br />Creek (refer to revised Fig. 2). The soi]/bedrock profile was observed in a cut across the valley <br />at the location labeled TP-1. The soils observed in the cut consisted of about 2 feet of dark to <br />medium brown, medium dense, clayey sand, underlain by about 4 feet of tan, medium dense, <br />• clayey sand. Sandstone bedrock was at a depth of about 6 feet. The clayey sand is a <br />colluvial/alluvial soil fomted on the valley side slopes with short transport down valley. Gravel <br />to boulder size weathered bedrock fragments were observed in the exposed cut. <br />The results of classification testing of a bulk sample obtained from TP-1 aze presented on <br />revised Table B-] . The soil is similar to soils found in our previous explorations at the <br />Colowyo property. The subsurface conditions found in the East Fork of the East Fork of <br />Taylor Creek are similar to conditions found in the adjacent valley and in investigations to the <br />south of the South Taylor mine azea. Therefore, conclusions and recommendations regarding <br />the stability oCexcess spoil, as presented in previous reports for the area (SW 2006) are also <br />judged valid for this area, <br />The excavation for highwal] mining is expected to be on the order of 50 feet deep below the <br />proposed excess spoil fill, north of TP-1. This area will be backfilletl with spoil. Anew <br />sedintentatiort pond is not planned in this azea; the water will be routed down-valley to the East <br />Taylor sediment pond. <br />zaa-uuos-~w nex,m~mno~ ~oxaaa.e~~ 23-1-01705?00 <br /> <br />Etch. 21, Item 1 Revision Date: 11/14/06 <br />Intro. Letter-2 Revision No.: PR-02 <br />