2019-06-17_REPORT - C1982056 - Laserfiche WebLink

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the 2018 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 at well 006-BRDH-7 (Figures 12), show a mild decrease over the past years, in 2017 and 2018 there has been a slight increase in the water level. The drops and inclines may relate to increased dewatering activities in the EMD (10 RT dewatering well) initiated around these time period. There was also drop in the conductivity in 2017 to an historic low (Figure 13). The reason for this drop is unclear at this time. TC will continue to monitor this. 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 continued through 2017 but dropped approximantly 60 feet in 2018. TDS values for FBR-2 (Figure 15) went up from typical values in the upper 900's to 1170 in 2006, and were stabile through 2016 and had a drop in 2017 but recovered back to the stable line in 2018. Well 97013TM (Figure 16) water levels appeared to be relatively stable with a downward trend since 2004 but is now trending with a mild upwards trend.. The decrease in water levels in 2001 may be related to dewatering from nearby faulting. Water levels since 2012 appear more stable. TDS values in O 2011 dropped to a historic low of 540 mg/l. Since then, TDS concentrations have been rebounding (Figure 17). Trout Creek Sandstone: During 2018, five Trout Creek Sandstone wells, 001-83-106, 001-83-107, 95M001, FBR-2-E, and 97013TC. Note that per TR0342, 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, monitoring was conducted in the 2018 cycle year. Also per TR0342, Trout Creek Sandstone wells 008-75-EFC and 97012TC were deactivated. 2018 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 2018 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 l0a 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 until 2017. 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 006-83A8C routinely exhibited water levels in the 7100 ft elevation range while replacement well FCM#2 exhibited levels around the 6520 ft 6