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INTRODUCTION AND SCOPE <br />• Sultan Mountain Mine (formerly P & G Mining Inc) proposes to <br />resume operation of the Pride of the West flotation <br />concentrator to treat base and precious metals ore in the <br />spring of 1986. W T Cohan PE Inc. was retained to evaluate <br />the hydraulic integrity of the tailings ponds and to <br />inititate such water quality monitoring as would be <br />appropriate to to permit the resumption of pond operation. <br />Field work commenced on September 5, 1985 and terminated on <br />October 3,1985. The program included the construction of <br />seven additional permanent monitor wells about the new pond <br />(3 on the dam and 4 near the toe of the dam), implementation <br />of a dye injection program and the sampling of surface and <br />subsurface waters at 23 sites on and adjacent to the <br />tailings ponds. All wells and sample sites were surveyed at <br />the completion of the program. <br />The excellent cooperation of P & G personnel, in particular <br />Bob Nelson, greatly aided the progress of the work. The <br />geotechnical studies performed by Sutherland, Ricketts and <br />Rindahl in 1980 and made available by P & G were of great <br />benefit. <br />CONCLUSIONS <br />• The new pond is in hydraulic communication with the <br />underlying ground water, which contains I <br />In addition low concentrations of were <br />found at several locations under and adjacent to the ponds. <br />The tailings in the west 300 feet of the new pond are <br />considered impermeable as no evidence of leakage was <br />observed. However, the tailings pond dikes are permeable and <br />have conducted tailings fluids into ground waters below and <br />adjacent to the new and old ponds; not unlike the chimney <br />drains of an earth fill dam. <br />The sources of the of the anomalous <br />values are believed to include comprising the <br />"old" tailings pond and upstream source tailings which have <br />been redeposited in the Animas River flood plain west of the <br />"new" tailings pond. The sources of the anomalous>~ <br />concentrations are believed to include <br />leaking through the dilres as well as the previously <br />mentioned sources. This contaminated ground water is moving <br />southward and discharging into the Animas River south of the <br />old pond. Additional contaminated water is seeping out of <br />• -1- <br />