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May Day Idaho Mine Complex 112 (d) Permit Application <br />(d) Fate of Material <br />A detailed geochemical analysis of the mine rock material is provided in Attachment T-7. <br />The results are summarized below: <br />SiO2 and A12O3 dominate the oxides, indicating that the sample is felsic in nature, <br />with Ca and K the dominate alkali and alkaline earth metals. Sulfur <br />concentrations as determined by XRF (1.10%) is similar to that determined by <br />combustion (1.75%). Zinc was the dominate trace metal (684 ppm). <br />The pH of the mined rock is 7.5. The Neutralizing Potential (62.2 kg/ton) is <br />greater than the Acid Potential (54.6 kg/ton) producing a positive Acid-Base <br />Potential (7.55 kg/ton). <br />SPLP analytical results were compared to both groundwater and surface water <br />basic standards. For surface water, the Chronic Aquatic Life Standard was used <br />as it was assumed that the leaching of any rock would occur over long periods of <br />time rather than an immediate release. The only analyte above any of the Basic <br />Standards was Arsenic (0.0151 mg/L) which was 10% above the Domestic Water <br />Supply -Human Health Standard (0.01 mg/L). However, as described in <br />Section 6.4.20(8), there is no pathway to drinking water. <br />Surface water analytical results are presented in Section 6.4.20(11). Two surface water <br />samples are located immediately down gradient of either a mine rock deposit (Location <br />DG-2) or an historic tailings deposit (Location SW-2). The results are summarized <br />below: <br />Surface water sample DG-2 was collected from Little Deadwood Gulch <br />immediately below mine rock on the out slope below the bench at the May Day <br />No.2 Operational Area. Concentrations of dissolved and total metals are below <br />Chronic Aquatic Life Standards. <br />Surface water sample SW-2 is collected from the La Plata River immediately <br />down gradient of historic tailings deposited within the floodplain of the La Plata <br />River. Two samples collected from this location indicate that Total <br />Recoverable Aluminum may be a potential contaminant of concern from historic <br />tailing leachate. <br />Results indicate that when tailings are in direct contact with surface water, <br />elevated concentrations of Total Recoverable Aluminum may be encountered. <br />The weathering of mine rock, however, does not appear to have any direct impact <br />to surface water. Additionally, no run of mine rock or tailings will be disposed <br />of in locations in direct contact with surface water. <br />The geochemical characterization is in agreement with what would be predicted from the <br />general geology of the area. Sulfide minerals have been reported in several of the ore- <br />bearing porphyry veins (Christensen, 2007) and would account for the acid-potential. <br />The presence of ore within calcite replacement veins accounts for the greater neutralizing <br />potential. Thus while there is the potential for acid generation, the naturally occurring <br />May Day Idaho Mine Complex 112(d) Permit Application <br />September 21, 2010 <br />14