2007-03-16_REPORT - C1981010 (12)

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6.2 SURFACE WATER Peak flows for the surface water sites at Trapper Mine in 2006 were normal. The precipitation in 2006 was 17.18 inches, or 0.8 inches above the 29 -year average for the Trapper Project. The previous seven years of annual precipitation to 2005 had been below normal precipitation prior to the larger precipitation in 2005 and 2006. No failures or monitoring site problems were encountered during 2006 and no compliance limits were exceeded in 2006. Values of total suspended solids (TSS) were generally on the low side of ranges observed in previous years. Total dissolved solids ('1'DS) were generally in an indirect relationship with flow rate when adequate flow occurred at a site to determine the relationship. The TDS of the surface water from the mine area is similar to the TDS from the non-mined area and, therefore, an increase has not been defined, except for an increase in TDS during low flow conditions at NPDES sites 001 and 011. The TDS, conductivity and major constituents varied over expected ranges with an increase in values as ground -water flow to the stream becomes a larger portion of the total flow. The SAR values measured in 2006 were within the natural ranges for this site. Other chemical constituents analyzed from samples collected from the surface water sites showed little change. The variations and magnitude in iron concentration observed in 2006 were typical of natural values for these sites. The total aluminum concentrations observed in 2006 were slightly above the range of concentrations observed in previous years but likely still in the natural range of concentrations. The remainder of the minor constituents measured in 2006 are low and within natural ranges. Monitoring data indicates that Trapper Mine sediment control structures prevented any significant impacts on the surface water systems downgradient of the mine in 2006. Trapper Mining Company 6-6 2006 Annual Report