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mining areas (89-1, 89-2, 89-3, and EX-1; Figure 3). Additional groundwater monitoring wells <br /> were established up-gradient and down-gradient from mining areas to monitor water quality <br /> and piezometric levels (Figure 3). <br /> The monitoring schedule takes into account the abundant historical data set established over <br /> three decades. Sampling activities are concentrated around current mining areas and proposed <br /> areas of operations. Any potential anomalies are anticipated to be detected in the DS Aquifer. <br /> The EPA considers all or part of the DS Aquifer an Underground Source of Drinking Water <br /> (USDW) due to density stratification; however, the EPA has issued an aquifer exemption for the <br /> DS Aquifer within the NS lease area. Any significant departure in the sample parameters <br /> exceeding two standard deviations from a given well's baseline or sample parameters <br /> exceeding normal variations shown with well trend analysis will result in a detailed analysis of <br /> the suspect data. Following detailed analysis any unresolved data concerns may require sample <br /> reanalysis, resampling, or more focused monitoring until resolution is achieved. As warranted, <br /> the cause of the departure and the appropriate remedial action will be determined when data <br /> concerns are encountered. <br /> NS is aware of historical and potential natural gas drilling activities that are in proximity to NS's <br /> existing and planned wells. NS understands that drilling for oil and gas in the area of mining <br /> activities may have an adverse impact on solution mining operations and water quality. <br /> Groundwater monitoring will be adjusted, as necessary, to ensure that the natural gas drilling <br /> does not affect solution mining intervals and the local groundwater system. This may include <br /> specific monitoring in select NS monitoring wells for tracer dyes (typically uranine, a sodium <br /> fluorescein dye), which are used to monitor annular fluid and drilling mud. However, studies <br /> have indicated that: "Uranine and Pyranine sorption is increased at higher salinities; therefore <br /> they can be used as tracers in moderately saline groundwater only. Na Naphthionate was <br /> found to be the best tracer for fresh and saline water, with minimal sorption in all casesi'. <br /> '(Magal, E., et. al., The use of fluorescent dyes as tracers in highly saline groundwater, Journal of Hydrology, <br /> August 2008) <br /> Daub&Associates, Inc. Page 2 Natural Soda LLC 2022 EMP <br />