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Johnson Gulch well while a declining trend has been observed in the <br />Flume Gulch well (Coy). Additional monitoring is :needed to establish <br />any long-term trends for either of these aquifers. <br />3.2 pH <br />Field pH is an important parameter to measure because some coal <br />spoils have the potential to increase acidity of` the ground water <br />which increases the mobility of most heavy metals. A pH of less than <br />5 would generally be needed to greatly increase tt~e mobility of most <br />heavy metals. <br />Available pH data is tabulated in Table B-1 oi: Appendix B. Field <br />pH data for well GA1 is presented on page B-29 of Aippendix B. Field pH <br />has varied from 6.4 to 7.9 since 1974 for water from this well. These <br />variations are well within the natural range of fluctuation. Similar <br />variations have also been observed for well GA2. <br />The September of 1985 pH for well GB1 of 11.7 is above the <br />natural range and is probably influenced by cement contamination. <br />water from well GB2 has generally been slightly below neutral while <br />the values from well GB5 have been above neutral. The pH values for <br />well GB5 have been higher than normal since June of 1984. The bailed <br />sample, after air producing the well in September of 1985, was <br />significantly below the remainder of the recent values. This <br />indicates that the well bore is influencing the pH water in the well. <br />Cement contamination is likely in this well. <br />The field pH of water from the GC wells does not show a trend and <br />are within expected limits, except for some high pH values in 1976 and <br />1977 from well GC3. <br />Twenty Mile Sandstone well GD1 had a significant increase in pH <br />in 1984. Field pH values are presently back to levels that are <br />expected and that were present for the first several years from this <br />well. Field pH from well GD2 does not demonstrate a trend while <br />values from GE1 gradually declined for several years and seem to have <br />stabilized at approximately 7.7. The pH of water from well GE2 has <br />varied from slightly less than 7 to approximately 9. A similar pH has <br />been observed for well GE3. <br />Twenty Mile Sandstone well GF1 generally contains water with a pH <br />near neutral while the U aquifer well (GF2) and RLM aquifer well (GF3) <br />at this site contain water with a pH of approximately 8.5. A slightly <br />higher pH (near 9) has been observed for the HI aquifer at well GF4. <br />Data from backfill well GF5 indicates that the backfill water will <br />initially be slightly alkaline with a pH of 8. Well GF6 contains <br />3-4 <br />