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III I II I II I II IIII I+I Doc Date:12/11/2001 <br />sss <br />• SECTION 2.0 Annual Hydrology Report for Trapper Mine (1993) <br />Trapper Mine is providing the Division with an Annual Hydrology Report required by our approved <br />mining permit (Section 4.8.5). <br />2.1 Climatological Data <br />The 1993 National Weather Service Cooperative monthly summaries and the historical precipitation sum- <br />mary (1979-1993) are included in Section 2.5. 1993 was 138 percent of the historical mean and was the <br />highest annual precipitation year since 1986 (Figure 2-1). <br />2.2 Pit Dewatering and Consumptive Water Use for 1993 <br />During 1993, Trapper dewatered approximately 72 acre-feet of water from four active pits and an addi- <br />tional 7 acre-feet from two dewatering wells in Derringer pit and one well in Browning pit. Table 1-1 of <br />Section 2.5 shows the pumping volumes for each pit. All pit water was routed into the NPDES drainage <br />system and for the most part was lost to percolation and evaporation. <br />Pit dewatering volumes were down considerably from 1992 totals. Reasons for the low volumes were: 1) <br />• No new dewatering wells were installed in 1993, 2) the B pit well was disconnected March, 1993 as <br />mining in the area was complete and final reclamation in progress, and 3) the Derringer pit wells were <br />disconnected for four consecutive months. <br />Approximately 98 acre-feet of water were used for dust suppression on haul roads and topsoil handling <br />operation in 1993. Total water volume used by Trapper in 1993 was approximately 177 acre-feet. <br />2.3 Mining Advancement and Ash Disposal Sites <br />The 1993 Annual Hydrology Report maps depict the following mining activities through year end: <br />a) Project to date (PTD) utility waste disposal sites. <br />b) PTD pit advancement (Toe of pi[). <br />c) PTD monitoring and dewatering wells; and all spoils seeps with flows >5 gallons per minute <br />(gPm)~ <br />Two maps are provided, since mining has expanded into the East Panel, to include monitoring wells that <br />are now proximal to active mining and that could be affected in this permit term. <br />2.4 Monitoring Points <br />• Rather than submitting an additional map series, please refer to the current Map 52 showing all the opera- <br />tional hydrologic monitoring points. No new ground water monitoring wells were installed during the <br />year. <br />