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NPDES Effluent Criteria (Permit No. CO- 0048275) . Three excursions of <br />effluent limits occurred this year, two of which involved the chronic <br />selenium standard, 4.6 ug /l and one total recoverable iron standard of <br />1.0 mg /1. <br />The Outfall 004 (NPDES4) exceeded the total recoverable iron standard of <br />1.0 mg /l with a value of 1.55 mg /l in January. This result was likely do <br />to minor debris in the discharge pipe that may have been causing some <br />constriction of flow. After the sample was collected a small amount of <br />vegetation was removed from the pipe, the accumulated vegetation may <br />have contributed to the high total recoverable iron value. The last <br />excursion of the total recoverable iron permit limit occurred in April <br />2005 more than seven years ago. The total recoverable iron values <br />measured at NPDES4 in February and March 2014 were well under the <br />effluent limit with values of 0.110 mg /l and 0.120 mg /l respectively. <br />The Outfall 004 (NPDES4) values were 8.8 ug /l and 9.7 ug /l in April and <br />May respectively for selenium. The selenium limit stated both on the DMR <br />and the discharge permit (issued 3/31/10) for Outfall 004 is 4.6 ug /1. <br />However, the acute receiving stream standard, 18.4 ug /l (potentially <br />dissolved), was not exceeded. Selenium analyzed in samples collected at <br />site SSC6, located at the lower end of the wetland established below <br />Outfall 004 on the same day of each excursion indicated the receiving <br />stream conditions of selenium were below the standard of 4.6 ug /1. The <br />seasonal snowpack and subsequent snowmelt runoff likely caused both of <br />these excursions. <br />On September 12, 2012, the CDPHE issued Notice of Violation #I0- 120912 -1 <br />to the PSCM for the selenium exceedances that occurred in 2011 and 2012. <br />The PSCM is working with the CDPHE to resolve this issue. Possible <br />remedies to the situation include (but are not limited to); indentifying <br />and isolating the source(s) of selenium, using downstream wetlands as a <br />treatment method, utilizing other treatment methods, and /or developing a <br />site - specific selenium standard for the respective receiving streams. <br />The PSCM has performed an extensive monitoring program this year to help <br />identify the sources of selenium. PSCM is in the process of evaluating <br />20 <br />