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Dedicated Monitoring Wells Immediately Down-Gradient <br />• Wells utilized to establish baseline conditions and continuing operations are: <br />Well A uifer <br />89-3 Perched <br />89-2 A-Groove <br />89-1 B-Groove <br />EX-2 Dissolution Surface <br />90-1 A-Groove Water Well <br />Baseline data (see Tables 6-2, 6-3, 6-4, 6-5, and 6~) was obtained prior to ground water <br />pumpage from water well (90-1 ), and from mining activities from 1991-2003. The data shown on <br />the tables present a historical summary of water quality (WO) data. The WO results for wells <br />immediately down-gradient from the production well field indicate three distinct water quality <br />zones. The Perched aquifer is low in TDS (total dissolved solids), conductivity, fluoride, SAR <br />(sodium absorption ratio) and moderate to high in sulfate and pH. The A-Groove and B-Groove <br />aquifers are similar in water quality with moderate TDS, conductivity, SAR, but high fluoride. <br />• Although similar, the B-Groove aquifer generally has slightly higher levels of TDS, conductivity, <br />SAR and fluoride. High TDS, conductivity, SAR, magnesium, potassium, and moderate pH <br />characterize the Dissolution Surface aquifer, and until 1993 fluoride levels were moderate. <br />In late 1993, a significant increase in the concentration of fluoride was noted in the down- <br />dip Dissolution Surface well. Figure 6-2 illustrates fluoride results of WQ sampling. <br />Sodium and boron WQ results indicated a similar increase but at a lesser rate. Alkalinity, <br />bicarbonate and TDS data indicated an increase late in 1993. See Figure 6-3 for illustration <br />of bicarbonate results. Other WO parameters indicated increased concentrations in late <br />1993 but lower than the period of record highs, i.e. magnesium, chloride and hardness. For <br />example Figure 6-4 illustrates chloride results. <br />35 <br />