GENERAL30126 - Laserfiche WebLink

Home Browse Search

Under the definition of "designated mining operation" (DMO), the Act at 112.5(2) provides for exemption from DMO status for the following reasons: (2) If an operator demonstrates to the board at the time of applying for a permit or at a subsequent hearing that toxic or acidic chemicals are not stored or used on-site and that acid- or toxic-producing materials will not be used, stored, or disturbed in quantities sufficient to adversely affect any person, any property, or the environment, the board shall exempt such operations whether conducted pursuant to section 34-32-110 or otherwise. The board may promulgate rules governing the conduct of mining operations which are exempted pursuant to this subsection (2). The "Mineral Rules And Regulations of the Colorado Mined Land Reclamation Board for Hard Rock, Metal and Designated Mining Operations" (the Rules) at 1.1(2) define "acid mine drainage" as follows: (2) "Acid Mine Drainage" means contamination of water by low pH or heavy metals that occurs from mined or disturbed materials as a result of the chemical and biological oxidation of reactive sulphide minerals when exposed to air and water. The possibility of generating "Acid Mine Drainage" exists where the pH of any exposed or potentially exposed overburden, waste rock, mill tailings, waste water treatment sludge, or other mined, placed, disposed or stockpiled material has the potential to develop a pH of 5.8 or less. Such determination may be based upon acceptable accelerated weathering and leaching tests of a representative sample of the overburden, waste rock, mill tailings, or other mined, placed, disposed, or stockpiled material. In determining whether a potential for acid mine drainage generation exists, the Office will consider natural pre-mining acidity and metals occurrence in bedrock, soil, groundwater and surface water where such information is available to the Office. Mined and stockpiled material does not include ore or other mined product that is or will be processed within one hundred eighty (180) days of being stockpiled and removed from the permit area. However, the area affected by such stockpiled material may require the appropriate measures pursuant to Rules 3, 6 and 7, to prevent off-site impacts due to drainage or leaching, and for reclamation of the affected stockpile area. Acid or toxic substance releases are to be measured at a groundwater wmpliance point or points per Rule 3.1.7(5) and gauged according whether the release, after reaching groundwater, protects the existing and reasonably potential future of such groundwater, as described in Rule 3.1.7(c). For discharges to groundwater, the quality of the groundwater is measured at the compliance point(s) and compared with groundwater quality standards as established by the WOCC or numeric protection levels as permit conditions as established by the Division. Consideration is given to the ambient conditions per Rule 3.1.7(2)(c)(ii), and discharges, as measured at the point of compliance point(s) may not exceed the higher of either the pertinent standard or ambient condition, whichever is higher. Permit conditions for the protection of groundwater may be in the form of numeric protection levels as established by the Division, practice-based permit conditions, or both, per Rule 3.1.7(2)(a). Testing Procedure: Ore and waste rock from the targeted U-V mines were evaluated under astep-wise procedure for their potential to release acid or toxic substances. Division and company personnel were aware from mining history and geological reports that U-V ores in the Colorado Plateau may contain sulfide minerals including pyrite (FeS2), galena (PbS), clausthalite (PbSe), or copper sulfides such as chalcopyrite (CuFe SZ) and some of its Cu-Fe-S and Cu-oxide derivatives. 2