2009-05-12_REVISION - C1981025 (8)

Home Browse Search

Metals Arsenic (As) There has been no continuous or recent monitoring for arsenic at the downstream monitoring location on North Thompson Creek, thus there is no direct information to determine the relationship of downstream concentrations of arsenic with the Numeric Standard. However, baseline monitoring suggests that downstream arsenic is below the Numeric Standard. The Numeric Standard for arsenic (As) is 50 ug/1 (acute, total recoverable). Arsenic was undetected in baseline upstream, downstream, and Mine No. 1 and Mine No. 3 inflow samples. Cadmium (Cd) There has been no continuous or recent monitoring for cadmium at the downstream monitoring location on North Thompson Creek, thus there is no direct information to determine the relationship of downstream concentrations of cadmium with the Numerical Standard. However, monitoring results suggest that downstream levels of cadmium are below the Numeric Standard, and that there is no contribution of cadmium to North Thompson Creek from Outfall 001 discharges. The Numeric Standard for cadmium (Cd, chronic, total recoverable) is 3.38 ug/l. Cadmium was undetected in baseline upstream, downstream, Mine No.I and Mine No. 3 samples, and, as might be expected, has been undetected in Outfall 001 discharges. Chromium III and Chromium VI (Cr) There has been no downstream or Outfall 001 monitoring for chromium. Baseline monitoring results indicate that there may be an effect on chromium in North Thompson Creek from Outfall 001 discharges, but that the Numeric Standard for chromium is not exceeded in downstream flows. The Numeric Standard for chromium III (chronic) is 117 ug/1 (water hardness of 175). The Numeric Standard for chromium VI (chronic) is 11 ug/l. Total chromium was detected in baseline upstream samples up to 1 ug/l. Chromium was undetected in six locations in Mine No. 1, and was detected at 6 ug/1 at one location. Chromium was undetected in samples from Mine No. 3. Outfall 001 discharges have not been tested for chromium, but as chromium was detectable in a baseline Mine No. 1 grab sample, chromium may be present in Outfall 001 discharges. If so, the concentration would be less than the Numeric Standard of 6 ug/l. Copper (Cu) The Numeric Standard for copper is 14.42 ug/l. Monitoring results suggest that there is an increase in the concentration of copper in North Thompson Creek and that levels of copper in downstream flows exceed the Numeric Standard; however, not as a result of Outfall 001 discharges. The measured concentrations of copper at outfall 001 ranged from 11 ug/1 to 100 ug/l, with an average of 62 ug/l. North Thompson Creek C-1981-025 Permit Renewal 05 12 May 2009 26