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• anions in meq/1 divided by their sum times 100. BALNC is also a <br />good indicator of accuracy of major constituents and values between <br />-10 and 10 are considered good. The TDS concentrations from the <br />Trapper Mine ground-water quality generally compared favorably to <br />the corresponding conductivity values. The TDS (March 1989) values <br />from wells GB2 and GB5 are significantly lower than the values <br />indicated by the conductivity and also lower than adjacent values. <br />These TDS values are likely in error. <br />3.3 pH <br />Field pH is an important parameter to measure because some <br />coal spoils have the potential to increase acidity of the ground <br />• water which increases the mobility of most heavy metals. A pH of <br />less than 5 would generally be needed to greatly increase the <br />mobility of most heavy metals. <br />Available pH data is tabulated in Table B-1 of Appendix B. <br />Field pH has varied from 7.0 to 7.4 in 1990 for water from well <br />GA1. These variations are well within the natural range of <br />fluctuation. A similar range of variation has been observed for <br />well GA2 in 1990 but well within its historical variation. <br />Water from well GB2 has generally been near or slightly below <br />neutral through 1988. Values for this mine year are very similar <br />except for the September value of 6.6. The pH values from well GB5 <br />have been above neutral. The pH values for well GB5. have been <br />higher than normal since June of 1984. The bailed sample, after <br />air producing the well for the third quarter for the last three <br />3-9 <br />