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The leaching study also established a predicted high level of <br />salinity in spoils aquifer leachate. During the leaching <br />experiment, electrical conductivity (EC) measurements of the <br />leachate reached a high value of approximately 3,000 umhos/cm <br />before gradually declining towards baseline levels. Electrical <br />conductivity measurements were compared with laboratory TDS <br />analyses of the same samples to establish an TDS/EC ratio, <br />which was found to be 0.7339. This value when multiplied by <br />the measured high EC of 3,000 umhos/cm, yields an estimated TDS <br />concentration of 2,200 mg/L. <br />The Division feels that this estimated TDS concentration is too <br />low, based on empirical data that has been collected from the <br />area. The TDS concentration of spoils leachate water from the <br />Energy Mine No. 1, located five miles southwest of the <br />Energy Mine No. 3, has been measured at 3,200 mg/L or greater <br />(Proposed Decision and Findings of Compliance, Foidel Creek <br />Mine, CMLRD, April 18, 1983). For conservative purposes, the <br />Division will assume an estimated concentration of leachate <br />from spoils of 3,600 mg/L, which is the value used for solute <br />transport analysis in the Energy Mine No. 1 and 2 and <br />Eckman Park permit document (CMLRD Permit 79-177). <br />Solute Transport <br />Solute leaching from the backfilled spoils pits at Energy Mine <br />No. 3 is predicted to contribute additional dissolved solids to <br />ground water in the adjacent undisturbed Wadge Overburden <br />Aquifer downgradient from the mine. A solute transport <br />analysis has been performed by the applicant using the <br />Plume Management Model (Sandberg, et al, 1981). The leachate <br />solute concentration used in the analysis is 2,200 mg/L, as <br />determined from the results of the column leaching study. <br />Estimated solute concentrations above the baseline level were <br />computed for several distances downgradient from the mine site <br />after 50 years of solute transport. The results of this <br />analysis indicate an estimated increase in dissolved solids <br />concentration of 250 mg/1 at 2,500 feet, and 0 mg/1 at <br />6,200 feet from the mine site (page 2.05-172a). <br />_ 27_ <br />