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CNAP'IERFOUR Enuironmenta~ conseuuences <br />' • Monitoring of water levels in the wells surrounding the mine panel and within the mine <br />panel. <br />• Comparison of water levels to attempt to determine if gradients have been influenced by fluid <br />' loss from the well. <br />• Sampling of the neazby upgradient and downgradient wells in the zone where well integrity <br />failure is suspected. <br />• Comparison of the groundwater analytical data from the baseline and well failure sampling. <br />'' • Should indications of a failure exist, a monitoring well should be drilled and installed into the <br />impacted zone. If elevated TDS levels aze detected, then delineation of the impacts and <br />mitigation of these impacts should be initiated. <br />The current monitoring plan proposed by American Soda has six of the ten monitoring wells <br />located in the first 5-year mining panel (Figure 2-10). No wells are currently located <br />downgradient outside the first 5-year mining panel. Four wells aze located outside the first <br />mining panel. Two of these wells, 19-2 and 20-10, are located cross-gradient to the panel within <br />the A-Groove and the Uinta Formation, respectively. Well 29-2 is located upgradient of the <br />panel and is screened at the Dissolution Surface, while we1121-2 is an alluvial monitoring well. <br />None of the wells are currently co-located. <br />Additional monitoring is necessary under the action altematives. To provide adequate detection <br />of potential loss of production fluids and to determine vertical components of the hydraulic <br />gradient, a network of nested or co-located monitoring wells would be necessary. These wells <br />should consist of installations in the Uinta Formation, A-Groove, B-Groove and Dissolution <br />Surface at one upgradient, two downgradient, and two cross-gradient locations of the first mining <br />panel. To determine the baseline conditions for the aquifers, monitoring of the wells should be <br />undertaken monthly over a 6-month period prior to any mining activity. The monitoring should <br />take place for the pazameters listed in the Mine Plan. Monthly results obtained should be <br />compared to the statistical means of the baseline parameter period, and criteria set for further <br />investigation based upon exceedances. This effort should also be undertaken at each mine panel <br />prior to mining that panel. These efforts should be performed under either action alternative. <br />However, the cross-gradient wells may not be necessary except at the first mine panel, depending <br />on what is teamed about potential groundwater flow and groundwater quality impacts from the <br />initial mining panel. <br />A potential mitigation measure that could be undertaken as a result of the loss of production fluid <br />and the subsequent elevation of TDS in any of the aquifers, would be the installation of <br />extraction wells in the impacted zone and the subsequent recovery of elevated TDS water. This <br />' action would apply to either of the action altematives, if a release of production fluid were to <br />occur. <br />The evaporation ponds at both sites also have the potential to release elevated-TDS fluids into <br />' the environment in the event of a liner failure. These ponds should also have periodic inventory <br />and measurement of the fluids to determine the potential for loss. In addition, monitoring wells <br />should be installed at both locations to determine if fluids containing elevated TDS <br />concentrations have been released from these facilities. <br />' Groundwater 4-17 <br />