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If the pyrite breakdown were occurring without any neutralization, the pH of the spoil water would <br />be lower than overburden water. This has not occurred; however, the replacement of sulfate ion <br />by carbonate ion from the calcite should be seen as an increased carbonate or bicarbonate in <br />solution. This is exactly what is seen between the overburden water and the spoil water for each <br />sampling period except for the August 1998 sample, which must have had outside influence of <br />surface water flows since its total dissolved solids is much less than any other sample. All other <br />ions in solution are more or less proportional to the level of TDS in the sample. Bicarbonate, on the <br />other hand, has consistently increased by approximately 33 %. <br />There is no significant trend in TDS differences from the overburden water to the spoil water, <br />although averaging the samples from 1995, 1996, 2000 and 2001 shows a difference of 200 ppm <br />or a 6.6% increase. Overall, water quality of the spoil water may be only slightly higher in TDS than <br />the undisturbed overburden water. The quality of both waters are relatively poor. However, the <br />spoil water quality is affected to a significant degree by the time of year when irrigation is occurring <br />on the surface. Table 2.05.6.(3) -3 shows the TDS levels and flow rates for various samples taken <br />from 1987 to the present for the Spoil Spring and the NPDES 001 discharge. TDS for wells GW- <br />N9 and GW -N15, which are located in undisturbed overburden, are also included in the table. <br />The monthly flows and TDS values from the NPDES 001 discharge show a direct correlation <br />between TDS and flow rate. As the flow rate gets lower, the TDS gets higher. <br />Revised August 2010 (PR06) 2.05.6(3) -29 <br />