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TAILINGS POND #2 <br /> GEOTECHNICAL STUDY <br /> Western Technologies Inc. , was employed by San Juan County Mining <br /> Venture to perform a geotechnical study of Tailings Pond Number <br /> Two during the summer of 1990 . The study included field <br /> sampling, laboratory testing, and stability analyses for several <br /> different pond configurations . These analyses were performed on <br /> two slope cross sections both of which are adjacent to Boulder <br /> Creek. The slopes were analyzed for stability under the four <br /> following slope configurations. <br /> 1 . Existing slopes. <br /> 2. Slopes excavated to 2: 1 slope . <br /> 3 . Slopes excavated to 2 : 1 slope and 15 ' of fill placed on <br /> top of the pond. <br /> 4 . Slopes excavated to 2. 5 : 1 slope with 20 ' horizontal <br /> bench ten feet above Boulder Creek and 20 ' of fill <br /> placed on top of the pond. <br /> The resultant factors of safety against slope failure are <br /> presented in the table below. <br /> Slope Cross Section #3 Cross Section #5 <br /> Configuration Static Pseudo-Static Static Pseudo-Static <br /> 1 1 . 24 1 .06 1 . 38 1. 17 <br /> 2 1 . 55 1 . 25 1 . 59 1 . 29 <br /> 3 1 . 54 1 . 25 1 .62 1. 30 <br /> 4 1 . 54 1 . 20 1 . 89 1 . 47 <br /> The current minimum factors of safety for the pond <br /> indicate that is is stable however the factors of <br /> safety are unacceptably low. <br /> The proposed reclamation plan incorporates slope <br /> configuration number four . As illustrated in the table <br /> the minimum static and pseudostatic factors of safety <br /> for this configuration are, respectively, 1 . 54 and <br /> 1 . 20. <br /> -6- <br />