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comprised of timbers anchored into the side walls. The liner is comprised of geotextile <br />fabricated to prohibit water transport of any acid-generated erosion. <br />5. Page 1, First Paragraph "Exhibit C-Mining Plan (Rule 6.3.3) The placement of milled <br />sub-grade.... May require an underground injection permit... please state whether you <br />have inquired about the need for such a permit..". <br />RESPONSE: Mount Sneffels Mining Company personnel are familiar with the EPA <br />Underground Injection Control (UIC) permit program. The UIC Program works toward <br />protecting underground sources of drinking water from contamination by regulating the <br />construction and operation of injection wells. Underground injection wells are primarily <br />used to dispose of wastes into the subsurface and have the potential to adversely affect <br />USDWs (US EPA, 2010). Five classes of wells are defined according to the type of waste <br />that is disposed and where the waste is injected. As per conversation with Valois Shay of <br />the US EPA Region 8 UIC program, underground management of water in a mine site <br />setting can qualify as a 'Class V: Injection Wells Not Included in Other Classes (typically <br />Shallow Disposal Systems)' IF the 'produced fluids' are injected into a well that is deeper <br />than it is shallow' AND if the fluids inject into 'drinking water resources'. <br />The proposed subgrade ore repository does not meet any of the UIC definitions for the <br />following reasons; <br />The proposed repository occurs within an historic tunnel well above the <br />groundwater resource therefore there will be minimal to no contact (and no <br />injection) into the groundwater. <br />Any water in the subgrade repository will be re-circulated into the milling circuit. <br />The repository itself will be built and managed to contain any water and not <br />allow for it to percolate into underlying formations. <br />As stated within the initial amendment application, the repository occurs over <br />180 above the groundwater level and also occurs above the mined areas. If any <br />water were to infiltrate down through underlying formations it would likely <br />encounter the mine areas and be captured as part of the mine site Colorado <br />Discharge Permit System (CDPS) discharge point as defined by the Colorado <br />Department of Public Health and the Environment (CDPHE). <br />The area is not defined by the Colorado Division of Water Resources (CDWR) as <br />having a viable potable supply therefore there is no 'drinking water resource' L0 <br />an <br />Cz <br />a