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TR -18 to Permit M- 1977 -342 <br />Environmental Protection Plan <br />14. GEOCHEMICAL DATA AND ANALYSIS <br />14.1. Evaluation of Ore and Tailings Storage Facility <br />The Henderson ore body contains unoxidized sulfides that, in the presence of oxygen, water and <br />bacteria, have the potential to become an acid - forming material as defined in Rule 1, Section 1.1 <br />(1). Henderson concurred with this fact when it accepted the DRMS determination that the <br />Henderson Mine was a DMO under the amended rules. Thus, based upon discussions with <br />DRMS personnel, development of specific geochemical data are not necessary for mill tailing <br />material. <br />14.2. Evaluation of Overburden Properties <br />In stream monitoring data on file with the Division comparing metal concentrations above and <br />below the Henderson Mine provide demonstration that, after 40 years, the fill materials used to <br />construct benches and facility support at the Mine is not generating ARD that impact water <br />quality. Nonetheless, Henderson has managed this area as though it could potentially be acid - <br />forming, and has adequate controls in place to detect acid forming conditions and elevated <br />concentrations of key parameters through routine surface and groundwater monitoring (see <br />sections 8, 9, 10, and 11). <br />Furthermore, related to the development of the Groundwater Management Plan (TR -16), <br />Henderson performed a geochemical evaluation of the Mine site fill materials in June, 2010 with <br />the intent of identifying key parameters that have a reasonable potential of being transported <br />from mining materials to surface and groundwater systems and incorporating these parameters in <br />the scope of ongoing surface and groundwater monitoring. <br />The upper portion of the old railroad haulage route from the portal for approximately the first 2 <br />miles is constructed of rock excavated during construction of the haulage tunnel. This material <br />was tested for the potential to be acid producing. Acid -base accounting analyses were used to <br />test six (6) grab samples collected from this stretch of railroad in June of 1995, and are presented <br />in Appendix G. The data indicate that this fill material is non -acid producing. <br />Climax Molybdenum Company <br />Henderson Operations <br />October, 2012 <br />Page 35 of 40 <br />