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represents the spoil water. Table 2.05.6.(3) -2 in the permit application package <br />shows the chemistry of these waters sampled at the same time. <br />If the pyrite breakdown were occurring without any neutralization, the pH of the <br />spoil water would be lower than overburden water. This has not occurred; <br />however, the replacement of sulfate ion by carbonate ion from the calcite should <br />be seen as an increased carbonate or bicarbonate in solution. This is exactly what <br />is seen between the overburden water and the spoil water for each sampling <br />period except for the August 1998 sample, which must have had outside <br />influence of surface water flows since its total dissolved solids is much less than <br />any other sample. All other ions in solution are more or less proportional to the <br />level of TDS in the sample. Bicarbonate, on the other hand, has consistently <br />increased by approximately 33 %. <br />There is no significant trend in TDS differences from the overburden water to the <br />spoil water, although averaging the samples from 1995, 1996, 2000 and 2001 <br />shows a difference of 200 ppm or a 6.6% increase. Overall, water quality of the <br />spoil water may be only slightly higher in TDS than the undisturbed overburden <br />water. The quality of both waters is relatively poor. However, the spoil water <br />quality is affected to a significant degree by the time of year when irrigation is <br />occurring on the surface. Table 2.05.6.(3) -3 in the permit shows the TDS levels <br />and flow rates for various samples taken from 1987 to the present for the Spoil <br />Spring and the NPDES 001 discharge. TDS for wells GW -N9 and GW -N15, <br />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 <br />direct correlation between TDS and flow rate. As the flow rate gets lower, the <br />TDS gets higher. <br />It is important to understand what is truly different from the pre -mine condition <br />to the spoil condition. In the pre -mine condition, very good quality water from <br />precipitation and from the irrigation ditches infiltrates through the soil and <br />through the more permeable strata and picks up dissolved solids. The water <br />quality becomes poor (approx. 3000 ppm TDS), but this process takes a very <br />long time since the water moves very slowly through the tight strata with low <br />hydraulic permeabilities, which are in the range of 3.5 to 5.5 ft /day. <br />In the case of the spoil, the hydraulic permeability is increased to 40 ft /day and <br />much more irrigation water is recharged rapidly through the permeable, broken <br />spoil material. This good quality water picks up dissolved solids as in the case of <br />the overburden, it simply does it much more rapidly. Water infiltrating into the <br />spoil at the upper end of the New Horizon #1 spoil may only spend 15 -45 days in <br />the spoil before the water is discharged at the spring. Yet, during this short time <br />it has managed to become approximately the same quality as the overburden <br />water. The average TDS of the irrigation ditch water is only 100 to 280 ppm. <br />Due to the increased porosity and higher level of oxygen in the rapidly <br />37 <br />