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2. Acid-Base Accounting, including analysis for forms of sulfur, using the EPA <br />methods due w Sobek. Acid Generation Potential (AGP) was calculated using bout <br />the Total Sulfut and the Pyritic Sulfur values, and ratios of Acid NeutraiiZation <br />Potential to Acid Generation Potential were calculated for each sample using both <br />AGP values <br />3. Static leaching of samples using EPA Method 1312, the Synthetic Precilritation <br />Leaching Procedure. <br />RESULTS <br />The results of the ;eochentical characterization of the five new, deep tailings samples <br />from the Lower Impoundment are summarized in Tables 1 through 4. The hull <br />analytical report from Core Laboratories is provided as Attachment 1. <br />Table 1 presents the pH and conductivity data for the sequential rinses of tailings <br />samples from each interval. <br />Table 2 presents the chemistry of the five pore-water samples. <br />Table 3 presents dte acid-base accoutttin; data for the five samples. <br />Table 4 presents the results of the EPA Method 1312 leaching of un-rinsed tailings <br />samples fi•om the five new locationslin[ervals. <br />DISCUSSION <br />Sequential rinsing of the tailings samples shows that the soluble components of the <br />tailing are rinsed ratl~cr rapidly front the samples: by Cycle 3 of each sample, the <br />conductivity of the leachate had fallen to about 10% of the value in the initial rinse <br />cycle, and there was little additibttal change in cycles after Cycle 3. The <br />conductivities at Cycle 3, ranging from 23 uS to 42 uS with a mean value of 31 uS, <br />are very low conductivities, indicating [hat the total dissolved solids load of long- <br />term leachates will be extremely low. <br />The pH of leachates remained in the distinctly alkaline range for all rinse cycles. In <br />fact, the pH rises over sequentia'1 rinsing to values somewhat greater than pH 9, <br />indicating that the low-term pHl of effluents from the tailing will be buffered at <br />distinctly alkaline values. There appears to be tto possibility that rinsing by <br />meteoric waters will produce an acidic leacha[e. <br />2. Table 2 includes standard descriptive statistics for each tested parameter f'or [he five <br />pore-water samples. Most of the parameters have narrow ranges of values, as <br />Geochimica, Inc. 3 26 Sep7ember, 1996 <br />