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2010 Annual Hydrology Report for Trapper Mine <br />• 2.1 Climatological Data <br />The 2010 National Weather Service Cooperative monthly summaries and the historical precipitation <br />summary (1978-2010) are included in Section 2.5. 2010 precipitation totaled 17.80", providing 131 <br />percent of the established historical pre-mining (44-YR) annual precipitation mean and 107 percent of the <br />project-to-date annual precipitation mean (Figure 2-1). The highest monthly precipitation amount was <br />recorded in April (3.16") with the second and third highest totals occurring in December and October <br />(3.13" and 1.81", respectively). <br />2.2 Pit Dewatering and Consumptive Water Use for 2010 <br />During 2010, Trapper dewatered approximately 31.58 acre-feet of water from four active pits and 42.59 <br />acre-feet of water from G-Pit dewatering wells. (Table 1-1 of Section 2.5 sub-section 1.0 shows the <br />pumping volumes for each activity). The dewatering wells are expected to produce at approximately the <br />same rates for 2011. All pit water was routed into the NPDES drainage system with resulting discharges <br />monitored accordingly. Pit dewatering volumes were comparable to previous years. <br />Approximately 164 acre-feet of water was used for dust suppression on haul roads and topsoil handling <br />operations in 2010. This value appears to continue to rise during the past few years. Dust suppression <br />water demands continue to be somewhat offset by the successful application of dust suppression <br />chemical treatments on haulroads. Haul routes were similar in 2010 as 2009. Life-of-mine Haulroad is <br />still the primary route for coal delivery to the Craig Station. However increased activity in the eastern <br />portion of the mine accounted for increased water usage. This is due to heavy activity in the active <br />stripping of the east panel with a truck and wheeled loader fleet. Total water volume used by Trapper <br />Mine in 2010 was approximately 238 acre-feet, slightly more than 2009 consumption at 207 acre feet. <br />• 2.3 Mining Advancement 9 and Ash Disposal Sites <br />The 2010 Annual Reclamation maps (see Trapper's 2010 annual report), the Water-Level Elevation maps <br />2-1, 2-2 and 2-3 (included in this report), and permit Map M52 (see mine permit) depict the following <br />mining activities through year-end: <br />a) Project to date utility waste disposal sites. <br />b) Project to date pit advancement (toe of pit). <br />C) Project to date monitoring wells, and natural and spoil springs and seeps. In the 2010 report, all <br />spring and seep sites within the permit area are depicted to provide location information for future <br />reference. <br />2.4 Monitoring Points <br />Refer to Map M52 in the mine permit for locations of all the operational hydrologic monitoring points. No <br />new ground water monitoring wells were installed during 2010. Well 81-03A will need further <br />investigation for proper abandonment in the future as it is a flowing well. <br />A new flume was installed at East Pyeatt Spring during 2010 due to the prior piece rusting through. The <br />new flume will ensure accurate readings of the spring discharge.