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i <br />5.0 Basis for Variance from Ground Water Point of Compliance <br />CDPHE variance criteria provide the rationale why ground water associated with the Mine <br />should be exempted from ground water monitoring requirements. The criteria include: <br />• Technolo3;ica1 feasibility <br />• Economic reasonability <br />• Number, quantity, nature and persistence in the environment of the contaminants present <br />• Potential iEor vertical migration of contamination <br />• Upgradierrt levels of contamination <br />• Point of use <br />5.1 Technological Feasibility <br />Ground water monitoring methods as currently required are technologically infeasible to <br />implement because of the extreme depth required to establish such points of compliance. In <br />addition, it is technologically impractical and extremely problematic to establish a representative <br />point of compliance that might "reasonably (be) expected to detect evidence of violation of <br />applicable groundl water standards" within the site's highly fractured and faulted geological <br />system. <br />5.2 Economic Reasonableness <br />Ground water points of compliance as currently required are economically unreasonable. The <br />cost to permit, design, drill, complete, and develop a single ground water monitoring well at a <br />depth of 2,000 feet or greater could be in excess of $200,000 per well. In 2007, $1,000,600 was <br />spent on two exploration drill holes that were completed at a depth of 2,500 feet. The cost to <br />install multiple ground water monitoring wells will exceed $1,000,000.00. <br />5.3 Number, Quantity, Nature and Persistence in the Environment of the Contaminants Present <br />The potential water quality impacts from underground mining activities will be limited to <br />inorganic salts and metals such as sodium, sulfates, bicarbonates, carbonates, and iron where <br />TDS will typicall;~ be less than 5,000 mg/l. As water migrates down dip, TDS could exceed <br />10,000 mg/1. <br />5.4 Potential for Vertical Migration of Contamination <br />As previously discussed, the vertical migration of potentially contaminated water down gradient <br />is less than 0.02 g:pm per acre. All migrating water will move down dip to the northeast beneath <br />5 <br />