2015-07-28_REPORT - C1982056

• Permit No: C1982056
• IBM Index Class Name: Report
• Doc Date: 7/28/2015
• Doc Name: Request for Extension to Submit Annual Hydrology Report, Including Draft Of Annual Hydrology Report
• From: Twentymile Coal, LLC
• To: DRMS
• Annual Report Year: 2015
• Permit Index Doc Type: Hydrology Report
• Email Name: JLE
• Email Name: DIH
• Media Type: D
• Archive: No

Also: about 130 feet below the Wadge seam is the Wolf Creek Coal Seam. TC began rampling down from the
Wadge to the Wolf Creek seam in October 2014. Following development of the ramp and an initial gate road,
mining of the Wolf Creek Coal Seam began in March 2015.
Wadge Overburden: Five Wadge Overburden wells (009-79-4, 006-82-74C, 91M006, 008-77-58, and
93M001) are currently monitored. Water quality sampling is required annually. All monitoring requirements
were completed at these sites. Tables 2 through 6 provide summaries of the 2015 Water Year data. Tables 2a
through 6a provide some historical statistical summaries of collected data at each site through 2015. Figures 3
through 11 provide graphical representations of water levels and selected water quality parameters recorded at
each site.
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 91M006. During
2015, 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 2000. Well 006-82-74C (Figures 5 and 6) water levels have been relatively stable since
1999, although 2008 did exhibit a slight drop, and has subsequently stabilized through 2015. TDS measurement
for 2005 indicated a new high and has generally dropped off to date, however the levels seen since are still 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. These levels have appeared relatively
stable over the last four years.
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 2015 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 TDS appears to be stable. 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 2015, as compared to historical results.
Twentymfle Sandstone: One well, 006-BRDH-7, requires 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 2015. Tables 7 through 9 provide summaries of
the 2015 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.
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