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and-2013- values overall - slightly increased. The magnitude and timing of the-prior increase in sulfate <br />concentrations in well P -8 indicate that this is due to mining. The sulfate changes in wells GC-2' and <br />GP -9 are within the natural range of concentrations for this aquifer. Figure B -13 presents the sulfate <br />concentrations for well P -5. Well P -5 contained only a small amount of water for a sample in 2011. <br />The prior - sulfate concentrations in well P=5 were natural and show that relatively high values <br />naturally exist in this sandstone: <br />Figure B -14 presents the sulfate concentrations for alluvial wells GC -3, P -1, P -3, J -1 and <br />COY. The - sulfate concentrations -in alluvial well P -1 have been - variable but.within historical natural <br />values for this -well: The 2013- sulfate concentration for Johnson Gulch well J -1 was similar to recent <br />higher- values and- similar- to- the- natural levels in the Flume Gulch alluvium -at well COY. Sulfate <br />concentrations in the Flume Gulch wells (GC -3 and COY) have fluctuated from approximately 300 <br />to 1200 mg/l. <br />3.3 pH <br />Field pH is -an important parameter to monitor because-some -coal spoils have the potential to <br />increase acidity of the ground water, which increases the mobility of most heavy metals. A pH of <br />less than 5 would generally be needed to greatly increase the mobility of most heavy metals. <br />Available pH -data .is tabulated in Table B-1-of Appendix B. The field pH of water from the <br />GC wells has generally been slightly above 7.0 and has been at similar values since the initiation of <br />disturbance in this area. <br />Field pH from well GD -2 slightly decreased in 2005 and near neutral the last eight years. The <br />upgradient mining -in the QR seams has not significantly affected -the pH in- this area of the aquifer. <br />Trapper Minmg Company 3 -7 <br />10 13 Annual Report <br />