2014-03-18_REPORT - C1981010 (5)

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2013 Annual Hydrology Report for Trapper Mine 2.1 Climatological Data The 2013 National Weather Service Cooperative monthly summaries and the historical precipitation summary (1978 -2013) are included in Section 2.5. For the year of 2013 precipitation totaled 16.50 ", providing 122 percent of the established historical pre- mining (44 -YR) annual precipitation mean and 100 percent of the project -to -date annual precipitation mean (Figure 2 -1). The highest monthly precipitation amount was recorded in September (3.36 ") with the second and third highest totals occurring in April and October (2.91" and 2.58 ", respectively). 2.2 Pit Dewatering and Consumptive Water Use for 2013 During 2013, Trapper dewatered approximately 0.0 acre -feet of water from four active pits and 41.93 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 2014. 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 205 acre -feet of water was used for dust suppression on haul roads and topsoil handling operations in 2013. This value declined this year compared to rising consumption 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 offset by the successful application of dust suppression chemical treatments on haulroads. Haul routes were similar in 2013 to 2012 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 the majority of dust suppression water usage. Reduction in temporary haul routes through the slide, and reduced production overall in 2013 may account for the reduced water usage after several years of increased consumption. Precipitation was also higher compared to record drought from 2012. Total water volume used by Trapper Mine in 2013 was approximately 248 acre -feet, a significant decrease over 2012 consumption at 414 acre feet. 2.3 Mining Advancement and Ash Disposal Sites The 2013 Annual Reclamation maps (see Trapper's 2013 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 2013 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 2013.