2012-03-12_REPORT - C1982056 (2)

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Mining related dewatering impacts were noted for the Fish Creek sandstone wells 91M001 and 91M004 (Figure 26), and the Ashley well (Figure 27). Wells 91M001 and 91M004 were undermined in 1995 and exhibited historic water level declines corresponding to mining activity. Water levels in these wells subsequently stabilized, exhibiting only seasonal fluctuations. Two springs (SW -1 and SW -2) are monitored in the same vicinity as 91M001 and 91M004. Minor flow was detected in SW -1 during May 2011. SW -2 exhibited no flow in 2011. The Ashley well was undermined in 1999 and exhibited water level declines corresponding to mining activity. This well appeared to be recovering in 2000, continuing through 2011. No unusual observations are noted with respect to Foidel Creek alluvium groundwater levels. The historical increasing conductivity trend in well 001 -S -5 (Figure 32) stabilized in 2004, and appears to be increasing again through the end of 2011. No unusual observations are noted with respect to Fish Creek alluvium groundwater levels. The general water level decline noted in well 006 -AY -1 (Figure 34) since 1995, appears to continue in 2011. Overall, fluctuations at this well are insignificant. No other notable water level observations are apparent based upon review of the 2011 data. Field conductivity readings at this well appear stable over the last few years. Surface Water: Recorded surface water flows for Foidel Creek, Fish Creek, and Trout Creek were generally high in comparison to TC's historic record because of a heavy snow year. Flooding of Fish Creek, Middle Creek, and Trout Creek was observed in areas from late March through May. A stream gage study was initiated by TC with the aid of a consultant in the fall of 2007, continuing through 2011. This study will continue in the spring, summer and fall of 2012. A discussion of this study, including results for re- evaluating stream rating curves will be included in the 2012 AHR. Conductivity concentrations at site 301, 69, and 1005 on Trout Creek appeared elevated during the spring runoff season in April. This may be the result of upgradient spring runoff flushing through the old P & M mine area. No other water quality impacts of concern were evident at any surface water sites monitored during 2011. Spoil Springs: Recorded 2011 spoil spring discharges remain minimal and, therefore, did not constitute a significant portion of discharge from the TC mine area with the potential to impact off -site areas. Discharges from sedimentation ponds predominately occurred in conformance with applicable CDPS permit limitations and therefore did not constitute significant impacts to receiving waters. Mine Discharge: Mine water discharge site 109 did not discharge to Foidel in 2011. In 2005, TC began redirecting electro - coagulation treated mine water pumped from the Fish Creek Borehole well, underground locations for dust control. Mine water from the Fish Creek Borehole well (which is treated by electro- coagulation) inadvertently discharged to Fish Creek over two days in January 2011 because of a cracked pipeline valve. No other discharge occurred in 2011. The mine pump at TORT began discharging to Foidel in September 2008 under an emergency discharge permit issued by CDPHE. In early 2009, TC experienced difficulties in consistently meeting WET and iron standards at the pipeline discharge source. In the second quarter of 2009, TC halted all discharge at the discharge source 18