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• Exchan~eeable Sodium Percentage The values for exchangeable sodium percentage ranged <br />from 11.6 to 74.9. These values were high, as would be expected given the high SAR values. <br />Lime The relative lime values were slight or moderate for all the overburden samples taken <br />within the permit area. Although no guidelines for mining have been established for lime <br />as related to overburden, none of the samples reflected potential problems. <br />Selenium The values for selenium ranged from less than 0.05 to 0.21. These concentrations <br />were well below the levels set forth in the Wyoming Guidelines. No selenium problems with <br />respect to toxicity or groundwater quality were encountered. <br />Boron The values for boron within the permit area ranged from 0.27 to 1.96. These values <br />were well below the 5 ppm set forth in Wyoming's Guidelines. No boron toxicity problems <br />were encountered. <br />Molybdenum Values for total molybdenum ranged from 0.2 to 2 ppm, and the average <br />value was 0.84 ppm. Although Wyoming has established no limit with respect to <br />molybdenum, several researchers have concluded that there are no recorded instances of a <br />field occurrence of molybdenum toxicity to plants. With respect to leaching, the molybde- <br />num values are low and molybdenum is fairly insoluble. Therefore, there were no toxicity <br />problems as a result of molybdenum in the overburden. <br />• Arsenic The value for arsenic in permit area overburden ranged from less than 0.1 to 49.4 <br />ppm. The mean value for arsenic is 12.8 ppm. No limitation for arsenic has been estab- <br />lished by the Wyoming Guidelines, but research indicated that concentrations of approxi- <br />mately 40 ppm of arsenic would have no damaging effect on plant growth. Only two values <br />of arsenic in the permit area were above 40 ppm. Therefore, there were no arsenic <br />problems related to toxicity or groundwater quality. <br />Lead Values for lead within the permit area ranged from 1.06 to 4.86 ppm. Wyoming has <br />no guidelines with respect to lead, but the Montana Guidelines indicate that lead below 20 <br />ppm will not cause a toxicity problem. No problems with lead were encountered within the <br />permit area. <br />2.04.7 Hydrology Information <br />Groundwater <br />Groundwater quantity and quality have been greatly influenced by the presence of old mine <br />openings in and adjacent to the permit area. The workings serve as conduits for <br />groundwater transport, resulting in the formation of "valleys" and "ridges" in the water table <br />surface. In addition, the presence of sulfide minerals and unsaturated mine openings result <br />in sulfide oxidation and resultant chemical degradation of groundwater quality. In the long <br />run, the mining operation resulted in improved water quality as a result of the removal of <br />• many of these unsaturated mine openings. <br />2.04-34 <br />