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• Dedicated Monitoring Wells Immediately Down-Gradient <br />Wells utilized to establish baseline conditions are: <br />Well Aquifer <br />89-3 Perched <br />89-2 A-Groove <br />89-1 B-Groove <br />EX-2 Dissolution Surface <br />Down-gradient wells were completed in 1989, and samplers/pressure transducers installed <br />in February and March of 1990. Therefore, data (see Tables 6-2, 6-3, 6-4, and 6-5) was <br />obtained prior to ground water pumpage (water well 90-1), and 1991-2000 mining activities. <br />The data shown on the tables present a historical summary of water quality (WQ) data. <br />The WQ results for wells immediately down~radient from the injection/recovery well field <br />indicate three distinct water quality zones. The Perched aquifer is low in TDS (total <br />• dissolved solids), conductivity, fluoride, SAR (sodium absorption ratio) and moderate to <br />high in sulfate and pH. The A-Groove and B-Groove aquifers are similar in water quality <br />with moderate TDS, conductivity, SAR, but high fluoride. Although similar, the B-Groove <br />aquifer generally has slightly higher levels of TDS, conductivity, SAR and fluoride. <br />High TDS, conductivity, SAR, magnesium, potassium, and moderate pH characterize <br />the Dissolution Surface aquifer, and until 1993 fluoride levels were moderate. In late <br />1993, a significant increase in the concentration of fluoride was noted in the down-dip <br />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. <br />36 <br />