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Ms. Christina Kamnikar <br /> Page Three <br /> times that weight of slightly acidic, artificial rain water. Traditionally, the U.S. EPA <br /> recommends that concentrations of constituents in the resulting leachate be compared to 100 <br /> times drinking water standards as an indication of the material's toxic characteristics. This <br /> rationale assumes that a 100-fold dilution will occur prior to use of the leachate mixture as a <br /> drinking water source and follows from the practice of comparing Toxic Characteristic Leaching <br /> Procedure (TCLP) results to Maximum Concentrations of Contaminants for Toxicity <br /> Characteristics (MCCTCs) which are equivalent to 100 times drinking water standards. <br /> Table 2 (attached) presents the results of the SPLP procedure performed on the tailings and <br /> values equal to 100 times U.S. Primary and Secondary Drinking Water Standards, where <br /> available. <br /> None of the measured constituents exceeded the comparison values. <br /> Manganese was the only constituent to exceed a direct comparison to the drinking water <br /> standard. Manganese has a secondary drinking water standard of 0.05 mg/L. The level detected <br /> in the leachate sample was 0.321 or approximately 6 times the standard. To determine the <br /> probability of the manganese in the leachate affecting a drinking water source, we obtained a list <br /> of the nearest wells to the Joker Mine. According to the Colorado Division of Water Resources <br /> database, the nearest down gradient well is approximately 5 miles from the site. This well is <br /> listed as a domestic use well. Another domestic use well is located approximately 1.5 miles east <br /> of the mine site but based on topography is not down gradient from the mine. If leachate were to <br /> enter the ground water, by the time it reached the nearest well, manganese levels are expected to <br /> be undetectable due to the dilution from precipitation leaching the material and existing ground <br /> water. Five wells are located on the Joker Mine property and their listed uses include industrial <br /> and domestic. These wells are not likely to be used for domestic sources of water. <br /> The Elkhead Joint Venture will monitor the ground water during operation of the mine. A plant <br /> for quarterly monitoring of one up gradient and one down gradient well will be implemented. <br /> Ground water sampling will be conducted prior to backfilling the pit with tailing material to <br /> determine existing ground water quality. <br />