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Minrec, Incorporated Water Quality Assessment <br />CO- 0048233 <br />Note that although data from Division Station 133 are based on samples collected at a downstream <br />location, they are comparable to data representative of upstream water quality as total recoverable and <br />dissolved arsenic, dissolved copper, dissolved cadmium, dissolved lead, total mercury, and dissolved zinc <br />are not present at detectable levels. For manganese, downsteam water quality was deemed representative <br />of upstream water quality as downstream ambient values are very low. A summary of these data is <br />presented in Table A -6. No data was available for chromium, sulfide, boron, and nickel. <br />Table A -6 <br />Ambient Water Quality for North Thompson Creek <br />Parameter <br />Number <br />of <br />Samples <br />15th <br />Percentile <br />50th <br />Percentile <br />85th <br />Percentile <br />Mean <br />Maximum <br />Chronic <br />Stream <br />Standard <br />Notes <br />As, TR(µg /1) <br />2 <br />0 <br />0 <br />0 <br />0 <br />0 <br />0.02 <br />1 <br />As, Dis (µg /1) <br />1 <br />0 <br />0 <br />0 <br />0 <br />0 <br />340 <br />1 <br />Cd, Dis (µg /1) <br />2 <br />0 <br />0 <br />0 <br />0 <br />0 <br />2.8 <br />1 <br />Cu, Dis (µg /1) <br />3 <br />0 <br />0 <br />0 <br />0 <br />0 <br />11 <br />1 <br />Fe, TR (µg /1) <br />16 <br />163 <br />595 <br />830 <br />575 <br />unk* <br />1000 <br />Pb, Dis (µg /1) <br />4 <br />0 <br />0 <br />0 <br />0 <br />0 <br />3.4 <br />1 <br />Mn, Dis (µg /1) <br />3 <br />4 <br />4 <br />5.4 <br />4.7 <br />6 <br />1814 <br />Hg, Tot (µg /1) <br />2 <br />0 <br />0 <br />0 <br />0 <br />0 <br />0.01 <br />1,2 <br />Ni, Dis (µg /1) <br />0 <br />0 <br />0 <br />0 <br />0 <br />0 <br />66 <br />Se, Dis (µg /1) <br />3 <br />0 <br />0 <br />0 <br />0 <br />0 <br />4.6 <br />1 <br />Ag, Dis (µg /1) <br />3 <br />0 <br />0 <br />0 <br />0 <br />0 <br />0.12 <br />1 <br />Zn, Dis (gg /1) <br />4 <br />0 <br />0 <br />0 <br />0 <br />0 <br />159 <br />1 <br />B, Tot (mg /1) <br />0 <br />0 <br />0 <br />0 <br />0 <br />0 <br />0.75 <br />Chloride (mg /1) <br />8 <br />3.4 <br />5.6 <br />7 <br />5.9 <br />12 <br />NA <br />Sulfate (mg /1) <br />16 <br />13 <br />21 <br />34 <br />23 <br />unk* <br />NA <br />Sulfide (mg /1) <br />0 <br />0 <br />0 <br />0 <br />0 <br />0 <br />0.002 <br />*This data point not provided in the previous water quality assessment <br />Note 1: When sample results were below detection levels, the value of zero was used in accordance with the Division's standard approach for summarizing <br />and averaging. <br />Note 2: The minimum detection limit (0.3 ug/1) exceeds the stream standard. <br />V. Facility Information and Pollutants Evaluated <br />Facility Information <br />The North Thompson Creek Mines are located 8 miles south of Carbondale on North Thompson <br />Creek Road in Pitkin County; Latitude 39° 19 0.05 N, Longitude 107° 31 0.067 W. The current <br />design capacity of the facility is 0.058 MGD (0.09 cfs). Wastewater treatment is accomplished using <br />three passive sedimentation ponds. The technical analyses that follow include assessments of the <br />assimilative capacity based on this design capacity. <br />Appendix A (WQA v 7.0) Page 11 of 25 Last Revised Sept 14, 2009 /ES <br />