2015-07-28_REPORT - C1982056 - Laserfiche WebLink

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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 2009, and stabilizing since 2012. The drops may relate to increased dewatering activities in the EMD (10 RT dewatering well) 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 well's close proximity to an adjacent fault zone. In 2005 water levels began to recover, and continues through 2015. TDS values for FBR-2 (Figure 15) went up from typical values in the upper 900's to 1170 in 2006, and appears to stabile through 2015. This may be related to the increase water levels seen in 2005. Well 97013TM (Figure 16) water levels appear to be relatively stable since 2004, with a slight downward trend. The decrease in water levels in 2001 may be related to dewatering from nearby faulting. Water levels since 2012 appear stable. TDS values in 2011 dropped to a historic low of 540 mg/l. Since then, TDC concentrations have been rebounding (Figure 17). Trout Creek Sandstone: During 2015, five Trout Creek Sandstone wells, 001-83-106, 001-83-107, 95M001, FBR-2-E, and 97013TC. Note that per TR03-42, monitoring frequency for water levels and field parameters were reduced to an annual basis, and water quality sampling to a bi-annual (every other year) basis. As such, no monitoring was conducted in the 2015 cycle year. Also per TR03-42, Trout Creek Sandstone wells 008-75-EFC and 97012TC were deactivated. 2015 data is presented in Tables 10 through 14. Well FCM#2 was replaced in the fall of 1995 by monitoring well 95M001, with semi-annual monitoring during 2015 occurring at well 95M001 in lieu of FCM #2. Summaries of the Water Year data collected at each site can be found in previous AHRs. Tables 10a through 14a provide the historical statistical summaries of collected data at wells 001-83-106, 001-83-107, 95M001, FBR-2-E, and 97013TC, respectively. Figures 18 through 25 provide graphical representations of water levels and selected water quality parameters recorded at active sites. The pumping of TC domestic water well 001-83-106 (Figure 18) complicates the potentiometric surface in the Trout Creek Sandstone. Water levels in well 001-83-106 were showing a slight increase since 1998, which appears to have stabilized back in 2003. The water pump was replaced in late 2011, at which time the electrical and support cables presented an obstruction to being able to obtain a water level reading. The potentiometric surface trends prevalent in the Twentymile Sandstone and Wadge Overburden aquifers are not evident in the monitored Trout Creek wells. The previously monitored well 006-83-48C routinely exhibited water levels in the 7100 ft elevation range while replacement well FCM#2 exhibited levels around the 6520 ft elevation during 1995. In the fall of 1995, well 95M00l was established in part to address the apparent discrepancy in water levels between wells 006-83-48C and FCM#2. Water levels from well 95M00l confirm that levels recorded from well FCM #2 were accurate (Figure 20). Mining in the northern mining district began in 1995, which is down dip of this well. Water levels in well 95M00l declined since 1994, appeared to stabilize since 2002, and again declined C,