2013-03-14_REPORT - C1981010 ‎(7)‎

• Permit No: C1981010
• IBM Index Class Name: REPORT
• Doc Date: 3/14/2013
• Doc Name: 2012 Annual Hydrology Report
• From: Trapper Mining, Inc
• To: DRMS
• Annual Report Year: 2012
• Permit Index Doc Type: Hydrology Report
• Email Name: JLE
• Email Name: SB1
• Media Type: D
• Archive: No

water -level elevations. Table A -1 in Appendix A presents a tabulation of the water -level elevations
for each of the monitoring wells. Figure 2 -1 presents the total annual precipitation at the Trapper
Mine from 1978 through 2012. Precipitation declined from a high in 1983 to a low in 1988 and had
increased again to a peak in 1993 with a below average value in 1994. The years 1995 through 1997
had above average precipitation relative to the Trapper Mine record, while 1998 through 2004 were
below. The precipitation in 2005 through 2011 was above or near normal while precipitation in
2012 was slightly below the 1988, 1994 and 2002 low precipitation years. Water levels in many of
the wells reflect the natural variations in recharge. These changes may lag the actual precipitation
events due to the time it takes the head change to move through the aquifer to the monitoring well.
Figure A -1 presents water levels versus time for wells GF -5 and P -5. The wells are
completed in the HI backfill and 2nd White Sandstone aquifers, respectively. Water levels in well
GF -5 slightly rose in 2007 and 2008 and were steady in 2009 and 2010 and a small overall rise and
decline in 2011 and 2012 respectively. Well P -5 went from being dry in early 2010 to recovering
four feet in late 2010 and 2011 but was dry in 2012 except for the 4th quarter.
The GC wells (GC -1, GC -2, GC -3, see Figure A -2) are located near the northeast corner
of the permit area (PA) slightly more than 1100 feet from mining activity in 2012. These wells are
completed in the HI, 3rd White and alluvial aquifers, respectively. The water -level changes in these
wells may not still be good indicators of natural recharge impacts on these aquifers due to the
upgradient mining. Water levels in well GC -1 have been overall steady from 2003 to 2009. In 2010
and 2011 the water level rose while a decline was observed in 2012. Water levels in well GC -3 show
some seasonal effects. Water levels in well GC -2 were overall steady from 1999 to 2005, while
gradually increasing 2006 through 2011 prior to becoming steady in 2012. Changes in these three
wells are probably natural. The alluvial aquifer response indicates continuation of above average
Trapper Mining Company 2-4
2012 Annual Report