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Letter to Bryce Romig -2- November 6, 1995 <br /> Management Plan be provided at this time, as part of the ground water <br /> technical revision review. <br /> Tenmile Creek Valley <br /> Hydraulic conductivity data of the bedrock and overlying material in the <br /> Tenmile Creek valley are presented in Table 1 of the technical revision <br /> application. These data indicate that the Paleozoic Sedimentary Bedrock <br /> that underlies the tailing impoundments exhibits hydraulic conductivity <br /> that range from very low to moderately high (as high as 5. 8x10-4 cm/sec) . <br /> It is the Division's understanding that the paleozoic bedrock referred to <br /> in the technical revision application is the arkosic to conglomeritic <br /> sandstones of the Minturn Formation. Depending on a number of factors, <br /> such as nature and degree of cementation and intensity of fracturing, this <br /> rock type could be expected to provide an environment for ground water <br /> flow. In the stream bed below the tailing impoundments, the Minturn <br /> Formation bedrock gives way to Precambrian basement rock at*the trace of <br /> the Mosquito Fault. If the Minturn Formation is transporting ground <br /> water, and if the Mosquito Fault presents an impermeable barrier to ground <br /> water flow at this location, then ground water could be forced to the <br /> surface at the intersection of Ten Mile Creek and the Mosquito Fault, or <br /> possibly at the intersection of Graveline Gulch with the Mosquito Fault. <br /> Given this potential ground water pathway to a surface stream, it is the <br /> Division's view that the potential for contamination of ground water in <br /> the Minturn Formation should be investigated. This topic will be further <br /> developed under the Ground Water Monitoring Program Heading below. <br /> Arkansas River Valley <br /> Rule 3 . 1.7 (7) (b) (vi) of the Mineral Rules discusses the need to identify <br /> potential sources of ground water contamination. The most significant <br /> potential source of ground water contamination on the Arkansas River side <br /> of the operation would be the mine pool in the flooded underground <br /> workings. The Division was notified near the end of 1994 of Climax's <br /> intention to flood the 600 level of the underground mine, and to <br /> reestablish a dewatering pump station approximately 80 feet below the No. <br /> 5 Shaft collar. At that time, it was established that the Mosquito Fault <br /> would provide an impermeable barrier to ground water flow from the <br /> underground workings to the Arkansas River Valley to the west, and as <br /> such, contamination of the Arkansas River by subsurface migration of mine <br /> pool water would be unlikely. As noted in the ground water technical <br /> revision application, seepage and water table level monitoring related to <br /> the mine pool are a requirement of the Climax Reclamation Permit. In <br /> order to evaluate the effectiveness of the protection afforded ground <br /> water quality by the presence of the Mosquito Fault as an impermeable <br /> barrier to ground water flow, it is the Division's view that a monitoring <br /> well should be established on the west side of the Mosquito Fault at the <br /> latitude of the underground mine workings, and should be screened in <br /> bedrock in such a manner that any significant quantity of mine pool water <br /> transmitted across the Mosquito Fault would be detected. <br />