1998-05-21_REVISION - M1983052 - Laserfiche WebLink

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Mr. Robert Ernst Page Two following this revised rinsing process, was collected and analyzed using SPLP. The SPLP testing method (EPA Method 1312) may be used to characterize waste material for the potential to release metals and other constituents into the environment in unacceptable amounts due to exposure to normal meteoric precipitation. In this procedure a minimum of 100 grams of solid waste is combined with 20 times that weight of slightly acidic, artificial rain water. Traditionally, the U.S. EPA recommends that concentrations of constituents in the resulting leachate be compared to 100 times drinking water standards as an indication of the material's toxic characteristics. This rationale assumes that a 100-fold dilution will occur prior to use of the leachate mixture as a drinking water source and follows from the practice of comparing Toxic Characteristic Leaching Procedure(TCLP) results to Maximum Concentrations of Contaminants for Toxicity Characteristics (MCCTCs) which are equivalent to 100 times drinking water standards. Table 1 presents the results of the SPLP procedure performed on the tailings and values equal to 100 times U.S. Primary and Secondary Drinking Water Standards, where available. None of the measured constituents exceeded the comparison values. Manganese was the only constituent to exceed a direct comparison to the drinking water standard. Manganese has a secondary drinking water standard of 0.05 mg/L. The level detected in the leachate sample was 0.321 or approximately 6 times the standard. To determine the probability of the manganese in the leachate affecting a drinking water source, we obtained a list of the nearest wells to the Joker Mine. According to the Colorado Division of Water Resources database, the nearest down-gradient well is approximately 5 miles from the site. This well is listed as a domestic use well. Another domestic use well is located approximately 1.5 miles east of the mine site, but based on topography is not down gradient from the mine. If leachate were to enter the ground water, by the time it reached the nearest well, manganese levels are expected to be undetectable due to the dilution from precipitation leaching the material and existing ground water. Five wells are located on the Joker Mine property and their listed uses include industrial and domestic. These wells are not likely to be used for domestic sources of water. The Elkhead Joint Venture proposes to monitor the ground water during operations. Quarterly monitoring of one up-gradient and one down-gradient well