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J <br /> <br />~~ Golder Associates <br />a CONSULTING GEOTECHNICAL AND MINING ENGINEERS <br />October 13, 1986 <br />Colorado Westmoreland Inc. <br />P.O. Box E <br />Paonia, Colorado 81928 <br />Attention: Ms. Kathleen A. Welt <br />Environmental Specialist <br />__ Q_t . <br />III IIIIIIIIIIIIIIII <br />sss <br /> <br />Our Ref: 863-2032 <br />RE: FOUNDATION DESIGN CRITERIA FOR PROPOSED 200,000 GALLON <br />WATER-STORAGE TANK - ADDITIONAL ANALYSES FOR <br />FOUNDATION SLOPE STABILITY <br />Dear Kathy: <br />This letter summarizes additional stability analyses, re- <br />quested by the CMLRD, that evaluate the change in slope <br />stability caused by installation of the 200,000-gallon water <br />tank near drill hole 81. <br />The bedrock surface contour was estimated from nearby drill <br />holes. The location and configuration of the tank and asso- <br />ciated cuts and fills were determined from the attached <br />telecopy prints received on October 8, 1986 from CWI. The <br />stability analyses were performed with the Golder program <br />CSLOPE using a modified Bishop's analysis for circular <br />failure and a Sarma analysis for colluvium/bedrock contact <br />failure. The ground-water elevation was conservatively <br />chosen to correspond with the ground surface. <br />Results of the stability analyses are on the attached Figure <br />1. Failure planes with minimum safety factors are shown for <br />both a circular failure and colluvium/bedrock failure paths. <br />Factors of safety corresponding to these two failure planes <br />are greater than 1.50 and are considered acceptable. <br />These results are based on the assumptions set forth above <br />and on the assumption that soil strength properties in the <br />slope coincide with those derived from the soil testing <br />program. Although the analysis was performed assuming satu- <br />ration, it is recommended that measures be taken to prevent <br />leakage of the tank and recharge of the colluvium tank foun- <br />dation. As recommended earlier, the tank should be placed <br />COLDER ASSOLIAiES. INL ~ ~%J01 Y/ WLFAN AYENUF. SUITE 2P. GOLDE410ENVE RI COLORADO BOaO~ U 5 A • TELEPHONE IJWI 219~B66P <br />OFFICES IN CANADA ~ UNNED STATES • UNITED KINGDOM • AUSTRALIA <br />