2013-03-14_REPORT - C1981010 (7)

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RECEIVED 2012 Annual Hydrology Report for Trapper Mine MAR 14 2013 Division of Reclamation, Mining & Safety The 2012 National Weather Service Cooperative monthly summaries and the historical precipitation summary (1978 -2012) are included in Section 2.5. 2012 precipitation totaled 10.70 ", providing 79 percent of the established historical pre- mining (44 -YR) annual precipitation mean and 65 percent of the project - to -date annual precipitation mean (Figure 2 -1). The highest monthly precipitation amount was recorded in December (2.80 ") with the second and third highest totals occurring in September and February (1.73" and 1.21", respectively). 2.1 Climatological Data 2.2 Pit Dewatering and Consumptive Water Use for 2012 During 2012, Trapper dewatered approximately 50.59 acre -feet of water from four active pits and 49.63 acre -feet of water from G -Pit dewatering wells. (Table 1 -1 of Section 2.5 sub - section 1.0 shows the pumping volumes for each activity). The dewatering wells are expected to produce at approximately the same rates for 2013. All pit water was routed into the NPDES drainage system with resulting discharges monitored accordingly when pumped off site. The majority of pumped water was utilized on haulroads for dust suppression. Approximately 314 acre -feet of water was used for dust suppression on haul roads and topsoil handling operations in 2012. This value continues to rise during the past few years. The majority of this water was utilized from A -Pit where water has been stored in the inactive pit. Dust suppression water demands continue to be somewhat offset by the successful application of dust suppression chemical treatments on haulroads. Haul routes were similar in 2012 to 2011 routes. Life -of -mine Haulroad is still the primary route for coal delivery to the Craig Station. Continued activity in the eastern portion of the mine accounts for increased water usage also. This is due to heavy activity in the active stripping of the east panel with a truck and wheeled loader fleet. Total water volume used by Trapper Mine in 2012 was approximately 414 acre -feet, a significant increase over 2011 consumption at 333 acre feet. 2.3 Mining Advancement and Ash Disposal Sites The 2012 Annual Reclamation maps (see Trapper's 2012 annual report), the Water -Level Elevation maps 2 -1, 2 -2 and 2 -3 (included in this report) , and permit Map M52 (see mine permit) depict the following mining activities through year -end: a) Project to date utility waste disposal sites. b) Project to date pit advancement (toe of pit). c) Project to date monitoring wells, and natural and spoil springs and seeps. In the 2012 report, all applicable spring and seep sites within the permit area are depicted to provide location information for future reference. 2.4 Monitoring Points Refer to Map M52 in the mine permit for locations of all the operational hydrologic monitoring points. No new ground water monitoring wells were installed during 2012.