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To establish a pre mining baseline, groundwater monitoring wells were established six <br />months prior to the onset of mining. These wells were located immediately down -gradient <br />of planned mining areas (89-1, 89-2, 89-3, and EX -1). They are shown in Figure 3. <br />Additional groundwater monitoring wells were established up -gradient and down -gradient <br />from mining areas to monitor water quality and piezometric levels (Figure 3). The maps will <br />be updated as necessary when monitor wells are installed, converted, no longer needed, or <br />plugged and abandoned. Groundwater monitoring has been ongoing for over 25 years with <br />long term credible baseline conditions established for all active groundwater monitoring <br />wells. 1 <br />The current monitoring schedule incorporates the NS plans for future mining operations <br />which include proposed monitor wells and surface subsidence monuments. The monitoring <br />schedule takes into account the substantial historical data set. Sampling activities are <br />concentrated around current mining areas and proposed area of operations. Any potential <br />anomalies are anticipated to be detected in the DS aquifer. The DS aquifer is not an <br />Underground Source of Drinking Water (USDW). Any significant departure in the sample <br />parameters exceeding two standard deviations from a given wells baseline or sample <br />parameters exceeding normal variations shown with well trend analysis will result in a <br />detailed analysis of the suspect data. Following detailed analysis any unresolved data <br />concerns may require sample reanalysis, resampling, or more focused monitoring until <br />resolution is achieved. As warranted, the cause of the departure and the appropriate <br />remedial action will be determined when data concerns are encountered.2 <br />NS is aware of historical and potential natural gas drilling activities by WPX Energy (WPX) <br />that is in proximity to the existing and planned wells. NS understands that drilling for oil <br />and gas in the area of mining activities may have an adverse impact on solution mining <br />operations and water quality. Groundwater monitoring will be adjusted, as necessary, to <br />ensure that the natural gas drilling does not affect solution mining intervals and the local <br />groundwater system. This may include specific monitoring in select NS monitoring wells for <br />tracer dyes (typically uranine, a sodium fluorescein dye), which are used by WPX to monitor <br />annular fluid and drilling mud. However, studies have indicated that: "Uranine and <br />Pyranine sorption is increased at higher salinities; therefore they can be used as tracers in <br />moderately saline groundwater only. Na Naphthionate was found to be the best tracer for <br />fresh and saline water, with minimal sorption in all cases". (Magal, E., et. al., The use of <br />fluorescent dyes as tracers in highly saline groundwater, Journal of Hydrology, August 2008). <br />Daub & Associates, Inc. <br />1 Revised: 9/18/2015 <br />2 Revised: 9/18/2015 <br />Page 2 Natural Soda LLC 2015 EMP <br />