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Section 2 <br />Potential for Adverse Impacts <br />from the piles. The MWMP testing indicates that the rock could release dissolved <br />constituents into pore water within the pile if sufficient water were present at the <br />mine. However, the mine is located within an and area and detailed analyses of <br />percolation from the piles using water balance estimates and unsaturated flow <br />modeling indicates that generation of significant quantities of leachate from the piles <br />is unlikely. These analyses show that water infiltrating into the piles would be <br />expected to be removed by evaporation in the arid environment at the Van 4 Mine. <br />This is validated by the absence of visual drainage from development rock stockpile, <br />which has been in place for decades. <br />Based on the evaluations of potential direct contact risks and risks related to <br />development of leachate from the piles summarized above, the development rock <br />piles are not considered acid- and toxic- forming materials. <br />2.2.3 Acid Mine Drainage <br />As defined in the HRMMR § 1.1 (2): <br />"Acid Mine Drainage" means contamination of water by low pH or heavy <br />metals that occurs from mined or disturbed materials as a result of the <br />chemical and biological oxidation of reactive sulphide minerals when exposed <br />to air and water. The possibility of generating Acid Mine Drainage exists <br />where the pH of any exposed or potentially exposed overburden, waste rock, <br />mill tailings, waste water treatment sludge or other mined, placed, disposed or <br />stockpiled material has the potential to develop a pH of 5.8 or less..." <br />As previously stated, development rock is unlikely to generate acid mine drainage. <br />Based on these conclusions, no designated chemicals or acid- or toxic-forming <br />materials are present at the Van 4 Mine. Additional details on these evaluations are <br />included in Attachment A - Environmental Geochemistry Evaluation of the.Van 4 Mine <br />(CDM 2009a) and Section 13 - Geochemical Data Analysis. <br />0 <br />2-3 <br />T:\64986-Denison Mines\Task Order 4 - EPP Sunday Mines Group-Van4\Van4\FINAL ReporITINAL - Environmental Protection Plan Van4.doc