2013-04-25_REPORT - C1994082 (2)

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The sulfide data presented in Appendix D are the total of both the ionized (S -) and un-ionized (H2S) forms of hydrogen sulfide. The un- ionized form is the potentially toxic form, and is what the CDPHE water quality standard is based upon. A procedure for calculating the un- ionized form may be found on the website: htt : / /www.mullal en ineerin .com.au /ima es/ roduct /file /Problem of H dr ogen Sulphide in Sewers.pdf page 5, Table 1. No excursions of the 0.002 mg /1 un- ionized sulfide standard occurred this year. The aquatic life ammonia standard is dependent on pH and temperature. The detection limit for ammonia is 0.05 mg /l. All values above detection limit are compared to table standards found on this website, page 87: http://www.epa.gov/waterscience/criteria/ammonia/99update.pdf No ammonia excursions occurred this year. SCC runs two different mercury tests, a high level test with a MDL of 0.2 ug /l (for streams and NPDES sites) and a low level test with a MDL of 0.0002 ug /l (for certain NPDES sites only). All high level test values this year were less than the detection limit, which is normally 0.2 ug /l. All low level tests were below the 0.01 ug /l stream standards. NPDES Effluent Criteria (Permit No. CO- 0000221). One excursion of NPDES effluent criteria occurred this year. On July 17, a pH value of 9.07 was measured at Outfall 013. The limit is 9.0. There was no discharge at this pond during a visit at 9:90 AM on July 16. A thunderstorm occurred later that day, caused the outfall to start discharging again. Discharge from the outfall stopped early in the morning of July 18, and did not discharge for the remainder of the year. The high pH is mostly likely due to the presence of algae in the outfall' s pond. The phenomenon of algae causing high pH values is well documented. One such article may be found on this website: https : / /srac.tamu.edu /index.cfm/ event /getFactSheet /whichfactsheet /205/ 13