PERMFILE101682

• Permit No: C1981010
• IBM Index Class Name: Permit File
• Doc Date: 4/4/1997
• Doc Name: Annual Hydrology Report
• Section_Exhibit Name: Appendix W 1996 Report Section 2.0
• Media Type: D
• Archive: No

III I II I II I II IIII III Doc Date:12/11/2001
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SECTION 2.0 Annual Hydrology Report for Trapper Mine (1996)
•
2.1 Climatological Data
The 1998 National Weather Service Cooperative monthly summaries and the historical precipitation
summary (1978-1996) are included in Section 2.5. 1996 was 131 percent of the historical precipitation
mean (Figure 2-1).
2.2 Pit Dewatering and Consumptive Water Use for 19911
During 1996, Trapper dewatered approximately 84 acre-feet of water From three active pits and an addi-
tional 37 acre-feet from two dewatering wells in Derringer pit. Table 1-1 of Section 2.5 shows the pump-
ing volumes for each pit. All pit water was routed into the NPDES drainage system and for the most part
was lost to percolation and evaporation.
Pit dewatering volumes were higher than the 1995 total. Reasons for the high volume are attributed to
the continued higher than normal precipitation, resulting in higher pit dewatering activities. Additionally,
Ashmore pit advancement into the Pyeatt drainage area resulted in increased dewatering activities.
Also, the idle cut in Ashmore pit, left open for ash disposal purposes, was dewatered frequently.
Well dewatering in Derringer pit was higher than the 1995 level due to two wells being alive. One was
active in 1995.
Approximately 66 acre-feet of water were used for dust suppression on haul roads and topsoil handling
operations in 1998. This higher use of water for dust suppression is attributed to the expanded use of
., magnesium chloride treatments on haulage routes in 1996. Total water volume used by Trapper Mine in
1998 was approximately 188 acre-feet, slightly higher than the 1995 total.
2.3 Mining Advancement and Ash Disposal Sites
The 1996 Annual Hydrology Report maps depict the following mining activities through year end
a) Project to date utility waste disposal sites.
b) Project to date pit advancement (foe of pit).
c) Project to date monitoring and dewatering wells; and natural and spoil springs and seeps with
flows.
Two maps are provided to present this information, including the monitoring wells that are proximal to
alive mining and that could be affected in this permit tens.
2.4 Monitoring Points
Rather than submitting an additional map series, please refer to the current Map M52 showing all the
operational hydrologic monitoring points. No new ground water monitoring wells were installed during the
year. However, wells GA-1 and GA-2 were removed during the year by mining activities. Technical
Revision TR-75 was filed updating map M52 removing these wells.
NPDES point, Oak Gulch (NPDES 017) was completed during the year. The second pond and the par-
shall flume installation were completed.
~' Two dewatering wells (No 7 & 8) were alive in Derringer pit in 1996. Both wells were abandoned in
September. Two new wells were drilled in the Flintlock pit area but were not operational during the year.