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4 <br />of deep bedrock groundwater in the vicinity of the CV Glory Hole is approximately neutral or slightly <br />basic (Whetstone, 2010). Uranium leaching potential is generally minimized under near neutral <br />conditions (EPA, 2008). The mine pool has remained approximately neutral throughout its existence. <br />Two small seeps on the Steve Level near the Illinois and Washington Faults were found to be somewhat <br />acidic (Whetstone, 2010), but this has had no effect on the vast buffering capacity of the mine pool. <br />Colorado Hard Rock Mining Rule 6.4.21(19) indicates that underground disposal in the mine workings is <br />acceptable provided that groundwater is protected in accordance with the provisions of Rule 3.1.7. <br />Regardless of whether or not mineralized waste rock from the alluvial fill is disposed within the mine, <br />Cotter is committed to protecting waters of the State from potential impacts associated with the mine <br />pool. Several strategies that are consistent with accepted scientific principles and the provisions and <br />intent of Rule 3.1.7 can be utilized to meet this objective including: <br />1) Highly engineered water tight bulkheads to permanently seal mine portals having any reasonable <br />potential to become inundated with mine refill water in the foreseeable future. This measure was <br />approved by the Division and was implemented under TR -9. <br />2) A comprehensive grouting program to seal any potential historic exploration core holes or natural <br />faults /fractures through which mine pool water could migrate to Ralston Creek. This program <br />will be aggressively pursued during alluvial fill excavation activities as concurrent isolation and <br />conveyance of the creek past the mine site in a temporary pipeline is expected to dry out alluvial <br />groundwater tables, maximizing access and ability to identify and seal any potential migration <br />pathways. <br />3) In -situ treatment of mine pool water has been proposed to greatly reduce potential impacts to <br />groundwater or Ralston Creek in the event that migration of mine pool water was to occur. <br />To summarize, disposal of waste rock inside of the mine would not significantly change water chemistry <br />of the mine pool, nor would it increase any potential for migration of mine water that could impact local <br />ground or surface water resources. Multiple measures to protect waters of the State from potential <br />migration of mine pool water can be implemented regardless of whether or not waste rock is disposed in <br />the CV Glory Hole. In terms of long -term isolation and stability, there is no better place for containment <br />of mine waste rock than inside the mine, deep underground in stable rock formations where uranium and <br />other metals have been immobilized through geologic time. This reclamation strategy is consistent with <br />accepted scientific and regulatory principles for maximizing long -term protection of human health and <br />the environment. <br />As previously indicated, there is a possibility that the amount of material that will need to be removed <br />from the alluvial fill could be underestimated by this TR -14 characterization study. If so, there may not <br />be sufficient capacity in the CV Glory Hole to accommodate all solid source term materials excavated <br />from the alluvial fill. In this case, an engineered waste rock pile or offsite disposal would be necessary <br />for any excess material. <br />20 <br />