2012-03-12_REPORT - C1982056 (2)

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The potentiometric surface in the Wadge Overburden generally slopes from south to north in monitored wells in the vicinity of the TC facilities, as shown by water levels in wells 009 -79 -4, 006- 82 -74C, and 91 M006. During 2011, the water levels in well 009 -79 -4 (Figure 3) continue to be comparable to previous years going back to 1984. Well 009 -79 -4 (Figure 4) had exhibited a general decline in total dissolved solids since 1995, which has stabilized since about 2003. Well 006 -82 -74C (Figures 5 and 6) water levels have been relatively stable since 1999, although 2008 did exhibit a slight drop, and subsequently stabilized through 2011. TDS measurement for 2005 indicated a new high, however the levels seen since are within historic ranges. Well 91M006 (Figure 7) has exhibited a steady decline in water level beginning in 1992, which relates to dewatering impacts from the underground mining operation. Well 008 -77 -58 (Figure 8) has been unaffected by mining and exhibits seasonal water level fluctuations. During 1998, this well experienced an unusually long seasonal decline, and subsequently an established recovering water level trend resumed. In 2011 TDS concentrations (Figure 9) remain at consistent levels seen since the mid 1990s. The potentiometric surface reflected by well 93M001, has generally been observed to slope from southwest to northeast. Well 93M001 (Figure 10) has exhibited a steep decline in water level from 1994 through 2002. From 2002 to date there was a gentle decline which appears to have stabilized from 2005 through 2011. These earlier declines were associated with underground mining of the Eastern Mining District (EMD). TDS concentrations (Figure 11) in this well remain very stable. No anomalous water quality impacts attributable to mining were evident in data collected from Wadge Overburden wells during 2011, as compared to historical results. Twentymile Sandstone: During 2011, one well, 006 - BRDH -7, required monitoring for water levels and field parameters on a semi - annual basis, and two wells, FBR -2, and 97013TM, required monitoring for water levels, field parameters, on a semi - annual basis, and water quality parameters on an annual basis. Water quality frequency is annual. All monitoring requirements were completed at these sites during 2011. Tables 7 through 9 provide summaries of the 2011 Water Year data collected at each site. Tables 7a through 9a provide historical statistical summaries of collected data. Figures 12 through 17 provide graphical representations of water levels and selected water quality parameters recorded at each site. The potentiometric surface in the Twentymile Sandstone generally slopes from southwest to northeast. The Water levels and conductivity at well 006 - BRDH -7 (Figures 12 and 13, respectively), remained relatively consistent with that of previous years, with no mine impacts apparent. There was about a five foot drop in water level in mid -2007. Water levels continued to decline through 2008, stabilizing in 2009 and 2010. In 2011 water levels began to decline again. The drop may relate to increased dewatering activities in the Eastern Mining District initiated around this time period. Water levels in well FBR -2 (Figure 14) were consistent through the late 1990s, however, in 2003 water levels dropped by approximately 56 feet, based upon a measurement in April of 2003. Through 2005, the water level dropped an additional 84 feet. In May and June of 2003, work on the eastern end of the 16 Right panel was approaching the general vicinity of FBR -2. This anomaly may be related to work on the 16 right panel and the 5