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1 <br />5.0 CHARACTERIZATION <br />' S.1 HYDROGEOLOGIC FIELD CHARACTERIZATION <br />' Given the current understanding of the hydrogeology of the West Pit area and the associated <br />geochemical responses that appear to be occurring as a result of the post-mining establishment <br />of [he West Pit water table, several technical issues need to be evaluated to allow the <br />development of appropriate long-term response actions. The principal issues requiring further <br />' characterization and evaluation include: <br />(1) characterization of the ground water outflow from the West Pit to evaluate changes <br />in water quality downgradient of the pit; <br />(2) characterization of the ground water flow direction, volume of storage within the <br />pit, volume of unsaturated material, and water quality within the West Pit backfill <br />materials; <br />' (3) evaluation of the area downgradient of the West Pit to assess the areal extent of <br />alluvial waters with elevated water quality constituents; <br />' (4) incorporation of these characterizations and evaluations with possible long-term <br />strategies to allow BMRI selection of an appropriate and effective long-term <br />implementation plan; and <br />' (5) continued monitoring of ground water and surface water quality. <br />t In addition to changing from quarterly to montlily sampling for the required TR-15 ground <br />water monitoring, BMRI has initiated monthly water quality monitoring at monitoring wells <br />' PW-1, BF-1 and BF-2. Monthly monitoring of these wells will be conducted for the listed <br />parameters shown on Table 3. <br />' 5.1.1 Characterization of the West Pit Outflow <br />Based on conceptualized flow paths from the West Pit to the Rito Seco alluvium, it appears <br />' that the primary flow pathway from the pit is through the pit wall contact with the Rito Seco <br />alluvial materials, rather than the area in contact with the Santa Fe Formation. Therefore, it <br /> <br /> 17 <br /> <br />