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lQJ u!11 ~ uu= <br />ii_~16~9i 11:1J F.~S YU1 J•9i 1-IJa EK~iRUI p\, ISC. ._ -_ <br />:~ ~ ' <br />ENVIROGON, INC. <br />705 WEST IROnw000 ORIVE <br />SOUTH SALT LAKE CITY, UTAH BII IS <br />TEIEPMONE (001 IBS-9565 <br />ENCi{ROCON, INC. <br />February 15, 1995 <br />Mrs. Kathy Welt <br />Mountain Coal Company <br />West Elk Mine <br />P.O. Box 591 <br />Somerset, CO 81434 <br />RE: SHEAR STRENGTH JTJSTli'ICATTON -LONE PINE ]7EVELOPD7ENT <br />WASTE PILE <br />Dear Kathy: <br />The following is the justification of the shear strength value used in the slope <br />stability analysis for the development waste pile previously submitted to Division oC <br />Minerals and Geology (DMG). The shear strength utilized was obtained from a <br />sample obtained from a former waste pile adjacent to the warehouse area. The <br />sample had a dry unit weight of 4S pcf which closely matches the coal unit weight at <br />Mountain Coal. The shear strength also closely matched strength values performed <br />by BBC&M Engineering, Inc. on coal samples whose data was used in the design of <br />the Phase III coal storage addition at Mountain Coal. The other samples listed in <br />Table 7 for coal waste all had unit weights in excess of 45 pcf which reflects a mix <br />of coal and sandstone. <br />Additional slope stability analyses were performed to determine the sensitivity <br />of the shear tests for coal waste as requested in the February i, 1995 DMG memo. <br />The following is the result of this ana]ysis. <br />A7/Ia ~CO mpenY ~\ \ <br />