2010-03-15_REPORT - C1981010 (2)

Home Browse Search

pF-CEVVED ?U10 2009 Annual Hydrology Report for Trapper Mine MAR 15 2.1 Climatological Data Divisi0l7 ul r: ??t?maftOil, Ong and Suety The 2009 National Weather Service Cooperative monthly summaries and the historical precipitation summary (1978-2009) are included in Section 2.5. 2009 precipitation totaled 18.63", providing 137 percent of the established historical pre-mining (44-YR) annual precipitation mean and 113 percent of the project-to-date annual precipitation mean (Figure 2-1). The highest monthly precipitation amount was recorded in June (3.11") with the second and third highest totals occurring in April and March (2.23" and 2.07", respectively). 2.2 Pit Dewatering and Consumptive Water Use for 2009 During 2009, Trapper dewatered approximately 37.72 acre-feet of water from four active pits and 46.63 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 2010. All pit water was routed into the NPDES drainage system with resulting discharges monitored accordingly. Pit dewatering volumes were comparable to previous years. Approximately 123 acre-feet of water was used for dust suppression on haul roads and topsoil handling operations in 2009. This value appears to continue to rise during the past few years. 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 2009 as 2008. However increased activity in the eastern portion of the mine accounted for increased water usage. Total water volume used by Trapper Mine in 2009 was approximately 207 acre-feet, slightly more than 2008 consumption at 171 acre feet. 2.3 Mining Advancement and Ash Disposal Sites The 2009 Annual Reclamation maps (see Trapper's 2009 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 2009 report, all 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 2009. Well 81-03A will need further investigation for proper abandonment in the future as it is a flowing well. Cleaning of the channel below the flume at NPDES 011 resulted in a drastic change to the readings of this particular flume. Prior to this deaning operation, the flume had been providing inaccurate readings due to ponded water below the flume.