2011-10-31_REPORT - C1981010

• Permit No: C1981010
• IBM Index Class Name: REPORT
• Doc Date: 10/31/2011
• Doc Name: DRMS Review of 2010 AHR Report
• From: DRMS
• To: Trapper Mining, Inc
• Annual Report Year: 2010
• Permit Index Doc Type: Hydrology Report
• Email Name: RDZ
• Media Type: D
• Archive: No

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Overall, PHC predictions appear to be accurate, as illustrated
by the following examples.
Per the PHC, TSS values in the surface water runoff are
expected to increase a few years after mining and then decline.
Data for NPDES sites 001 and 002 illustrate this trend.
Per the PHC, elevated TDS levels will be detected in base
flows derived from backfill aquifers. During 2010, relatively
high TDS concentrations were reported for NPDES sites in
several gulches: Johnson, No Name, East Pyeatt, and Flume.
All four of these sites are downgradient of potential spoil
springs from the A Pit and East A Pit. In general, the data
reflect the inverse relationship between TDS and flow.
X. Agreement of
observed
hydrologic
CDRMS
Per the PHC, post -mine values of pH in surface water runoff
are not expected to be significantly lower or higher than
present or pre -mine levels. Field pH values for all sites in
2010 were similar to previous data collected.
impacts with
regulation
Yes
Per the PHC, Trapper does not anticipate recharge to the
PHC projected in
permit
2.05.6(3)
shallow aquifer systems to be adversely affected by mining
operations in the Third White Sandstone. Water levels in
wells GC -2, GP -9, and P -8 (used to monitor the Third White
Sandstone) did not rise or fall considerably between 2009 and
2010. Previous analysis has indicated good recharge with
above average precipitation over the last few years.
Per the PHC, constituent concentrations in backfill aquifers,
namely TDS and sulfate, are expected to be higher than pre -
mining concentrations for an extended period of time after
mining. The data for TDS concentrations in wells in backfill
aquifers have shown apparent impacts from mining. TDS
concentrations in GD -3 and GF -5 are somewhat higher to
those of native aquifers in these areas. TDS values for wells
GF -7 and GF -11 were much higher than the naturally
observed concentrations in the 1990s and 2000s, but have
declined in recent years. These trends have continued in 2010.
Sulfate concentrations exhibited similar trends as TDS for
wells GF -7 and GF -11. Sulfate concentrations increased in
GD -3 in 2010 and should be watched closely in future years.
Y. Adequacy of
CDRMS
groundwater
monitoring
program
regulation
4.05.13 (1)
yes
Z. Adequacy of
CDRMS
surface water
monitoring
regulation
yes
program
4.05.13(2)
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