2010-03-16_REVISION - M1981185 (29)

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Mayday Mine and Mill Site, Wildcat Mining Corporation, 110(2) Permit Amendment Exhibit C • • Aero35 Xanthate -Fish LC50 = 10 -100 mg/L, Invertebrates EC50 1 -10 mg/L; • Dowfax 2al Solution Surfactant—LC50/EC50 1 -10 mg/L; and • Methyl Isobutyl Carbinol (MIBC) — Fish LC50 > 92.4 mg/L, Invertebrates EC50 100 -337 mg/L The maximum concentration of Xanthate and MIBC that will be present in the slurry can be calculated with the following assumptions: • application rates are described in Section (m); • water will be added to the tailings at 50% on a weight/weight basis, i.e. 0.5 ton of water will be mixed with one ton of waste rock; and • 1L of water weighs lkg, therefore 0.5 ton of water is equivalent to 500L. Based on the above assumptions, the following maximum concentrations are calculated The calculated maximum concentration for both chemicals are below the reported toxicological data for aquatic life and thus do not pose a threat to groundwater when the tailings are returned to the stopes. • The surfactant is reported to be used on an as needed basis and no application rates are provided. The surfactant is described in the MSDS as being moderately toxic to aquatic organisms on an acute basis. A combined LC50/EC50 of 1 -10 mg/L was reported. Using 1 mg/L as the conservative criterion, and using the same assumptions as above, an application rate of 1.1 lbs /ton would produce a chemical concentration of 1 mg/L. Thus the surfactant will not be used at rates greater than Ilb /ton of ore. (j) Protection of Existing Water Rights On October 10, 2007 Wildcat was granted a water right from Water Division #7 with an appropriated date of November 30, 2006. (See Water Rights discussion in Exhibit B — Site Description). The water right authorizes the Idaho Mill Diversion where surface water (tributary water to the La Plata River) is recharged from the Idaho - Mayday Mine. A conditional water right of 1 cfs (448 gpm) is granted where the water is authorized to be stored in Wildcat Augmentation Ponds #1 and Augmentation Pond #2 (to be built if necessary). Wildcat will consumptively use 10 gpm and is authorized to pump 40 gpm for use the mine and mill where no more than 10.8 acre feet per year can be diverted and cumulatively stored in a lined Wildcat Augmentation pond(s). Wildcat has an approved water right that is designed to mitigate injurious affect on owner or person entitled to utilize water under a vested water right or decreed conditional water right so long as the Idaho Mill Diversion is operated and administered in accordance with the approved Augmentation Plan. The water balance for the mine and mill is summarized on Table C -8. Additionally, Wildcat Mining Corporation is required to install, maintain and monitor measuring devises to measure instantaneous and cumulative flows being delivered to the Mayday Mill and the Idaho Mill Settling and Augmentation Pond(s). In addition Wildcat Mining Corporation is committed to install instruments recommended by the State or Division necessary March 12, 2010 Amendment M- 1981 -185 Fish Invertebrate Application Application Chemical Chemical Chemical LC50 EC50 Rate Rate Concentration Concentration (m ) (mg/L) lbs /ton kg/ton mg/500L m Xanthate 10 -100 1 -10 0.10 -0.15 0.045 -0.068 45 -68 0.09 -0.14 MIBC >92.4 100 -337 0.025 -0.05 0.011 -0.022 11 -22 0.022 -0.044 The calculated maximum concentration for both chemicals are below the reported toxicological data for aquatic life and thus do not pose a threat to groundwater when the tailings are returned to the stopes. • The surfactant is reported to be used on an as needed basis and no application rates are provided. The surfactant is described in the MSDS as being moderately toxic to aquatic organisms on an acute basis. A combined LC50/EC50 of 1 -10 mg/L was reported. Using 1 mg/L as the conservative criterion, and using the same assumptions as above, an application rate of 1.1 lbs /ton would produce a chemical concentration of 1 mg/L. Thus the surfactant will not be used at rates greater than Ilb /ton of ore. (j) Protection of Existing Water Rights On October 10, 2007 Wildcat was granted a water right from Water Division #7 with an appropriated date of November 30, 2006. (See Water Rights discussion in Exhibit B — Site Description). The water right authorizes the Idaho Mill Diversion where surface water (tributary water to the La Plata River) is recharged from the Idaho - Mayday Mine. A conditional water right of 1 cfs (448 gpm) is granted where the water is authorized to be stored in Wildcat Augmentation Ponds #1 and Augmentation Pond #2 (to be built if necessary). Wildcat will consumptively use 10 gpm and is authorized to pump 40 gpm for use the mine and mill where no more than 10.8 acre feet per year can be diverted and cumulatively stored in a lined Wildcat Augmentation pond(s). Wildcat has an approved water right that is designed to mitigate injurious affect on owner or person entitled to utilize water under a vested water right or decreed conditional water right so long as the Idaho Mill Diversion is operated and administered in accordance with the approved Augmentation Plan. The water balance for the mine and mill is summarized on Table C -8. Additionally, Wildcat Mining Corporation is required to install, maintain and monitor measuring devises to measure instantaneous and cumulative flows being delivered to the Mayday Mill and the Idaho Mill Settling and Augmentation Pond(s). In addition Wildcat Mining Corporation is committed to install instruments recommended by the State or Division necessary March 12, 2010 Amendment M- 1981 -185