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1 <br />5.1.3 Monitoring Wells <br />Per regulatory requirements, dedicated monitoring wells have been constructed to <br />monitor four water - bearing zones; Perched, A- Groove, B- Groove, and the Dissolution <br />Surface aquifers. The aquifers are monitored at several locations across the solution <br />mining area; down - gradient, up- gradient, remote down - gradient, and east in panel 2. <br />Refer to Figure 3: Plant and Well Location Map for well locations. <br />Baseline data were obtained prior to ground water pumping from water well (90 -1), and <br />from mining activities from 1991 through the present. Within NSI's lease boundaries, <br />there are three aquifers defined by US EPA as underground sources of drinking water: <br />the Perched, A- Groove and B- Groove Aquifers. The Dissolution Surface Aquifer is not <br />designated as an underground source of drinking water (USDW). <br />The Perched Aquifer is characteristically low in total dissolved solids (TDS), <br />conductivity, fluoride, SAR (sodium absorption ratio) and moderate to high in sulfate and <br />pH. The A- Groove and B- Groove aquifers are similar in water quality with moderate <br />TDS, conductivity, SAR, but high fluoride. However, the B- Groove aquifer generally has <br />slightly higher levels of TDS, conductivity, SAR and fluoride. The Dissolution Surface <br />Aquifer is characterized by very high TDS and conductivity, high SAR, magnesium, <br />potassium, and moderate pH. <br />Water quality results are carefully monitored to detect anomalies and address them to <br />prevent negative impact on USDW's. The results from 2011 indicate that solution <br />mining is not impacting the Perched, A- Groove or B- Groove aquifers regionally. One <br />anomaly noted in 2011 and addressed through the appropriate agencies. <br />The 90 -1 water supply well chemistry values have been rising since summer of 2009. <br />As of December 2011, the 90 -1 chemistry seems to have plateaued at somewhat higher <br />levels. The BLM and DRMS were notified and an investigation was undertaken. Until <br />the exact cause is known, NSI will decrease pumping from the 90 -1 and the new WSW - <br />2 will be utilized for the majority of plant make up process water. The decrease in <br />pumping from the 90 -1 should allow the A- Groove Aquifer to relax and return <br />groundwater chemistry to baseline levels. The 90 -1 anomaly is not impacting any other <br />surrounding monitoring wells. An investigation is ongoing. <br />Daub & Associates, Inc. 18 NSI Annual Report 2010 <br />