2013-02-21_REPORT - C2009087 - Laserfiche WebLink

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would bias the un- ionized results high. Any dissolved sulfides present in surface water should eventually oxidize to sulfates. No sites exceeded the ammonia standard this year. The aquatic life ammonia standard is dependent on pH and temperature. The detection limit for ammonia is 0.05 mg /1. All values above detection limit are compared to table standards, page 87, found on this website: http: / /www.epa.gov /waterscience /criteria /ammonia /99update.pdf NPDES Effluent Criteria (Permit No. CO- 0000221). Four excursions of effluent limits occurred this year, all of which involved the chronic selenium standard, 4.6 ug /1. Outfall 002 (NPDES2) values were 5 ug /1 in November 2011 and 4.7 in June 2012. Outfall 004 (NPDES4) values were 6.5 ug /1 in March 2012 and 5.7 ug /1 in June 2012. The Outfall 004 potentially dissolved selenium value was 6.5 ug /1 on a sample collected March 6, 2012. This value was obtained by ICP -MS. However, two other selenium test methods were performed on this sample, as we were investigating the differences in the methods. The potentially dissolved selenium value was <1 ug /1 on the same sample; this value was obtained by AA- Hydride. The total recoverable selenium value was 2 ug /1 on the same sample; this value was obtained by ICP -MS. The Outfall .002 potentially dissolved selenium value was 4.7 ug /1 on a sample collected June 6. This value was obtained by ICP -MS. However, one other selenium test method was performed on this sample. The total recoverable selenium value was 3.4 ug /1 on the same sample; this value was obtained by ICP -MS. The Outfall 004 potentially dissolved selenium value was 5.7 ug /1 on a sample collected June 11. This value was obtained by ICP -MS. One other selenium test method was performed on this sample. The total recoverable selenium value was 1.3 ug /1 on the same sample; this value was obtained by ICP -MS. 19