2010-04-16_REPORT - C1982056 (3)

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into an enhanced wetlands before discharging to Foidel is being discussed. As of the first week in March 2010, there is approximately 48.5 feet of freeboard in the EMD. During the summer of 2009, a pilot study was conducted on water from the Area # 1 Pit using an electro- coagulation/Reverse osmosis hybrid system with nano filtration. The results were quite promising. A copy of the pilot study report is attached as Appendix to this AHR. This system is currently under consideration by TCC for installation and treatment of Pit water. If installed, this system may supply treated water for our potable water system, the new wash plant, and possibly for underground use. 3.7 Mine Water Discharge Sites Four mine water discharge sites associated with the TCC operations are monitored. Site 109 requires quarterly monitoring for flows, field parameters, and water quality samples (when flowing), and site 115 is monitored as a CDPS discharge point in accordance with the requirements set forth under CDPS Permit No. CO-0042161. Two other mine water discharge sites are discussed in greater detail under a subsection to Section 3.6 above. To dewater the old WMD and EMD, pumps and piping were installed to direct mine water from the Fish Creek Vent Shaft (FCVS) and TORT #1, to the Area # 1 Pit. Overflow from the Pit passes through site 7 to Pond D, and subsequently through CDPS Outfall 005A to Foidel Creek. Site 7 requires quarterly analyses when flowing per DRMS Permit No. C-82-056. Outfall 005A requires weekly, twice monthly, monthly, and quarterly water • quality sampling when flowing, under CDPS Permit CO-0027154. There has been no flow from site 109 to Foidel Creek for several years, and none in 2009. Site 115 had not discharged to Fish Creek since early 2005, but was reactivated in 2008. In 2009, site 115 discharged approximately from May to early August. Note that mine water is pumped from underground to the surface (from the former Western Mining District), and is treated via an electro-coagulation process at the surface, where water enters the 3 former treatment ponds that can be directed through site 115. However, the majority of this treated water is pumped directly back into the mine for underground dust suppression. Additional overflow piping was added, so the treatments ponds cannot overflow. Overflow water is directed back into the mine via a former pump well. Historically, when pumping mine water from the Fish Creek Borehole (mine discharge site 115) the flow becomes a contributor to sulfate levels in Fish Creek. Fish Creek in turn contributes to the sulfate levels in Trout Creek. Trout Creek currently had a secondary drinking water standard limiting sulfate concentrations above 250 mg/1. Section 3.7, under the Emergency Discharge Permit section, discusses the sulfate issues dealt with in 2009. The 2009 Water Year data for mine water discharge site 115 is presented on Table 53. Table 53a provides historical water quality data. Figures 110 and 111 present graphical data for this site. 0 15