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Peabody RECEIVED <br />�IIII ENERGY <br />Peabody Sage Creek Mining, LLC MAY 14 2013 <br />DviWon of m, <br />Miming & <br />Colorado Department of Public Health and Environment <br />Water Quality Control Division <br />Permits and Enforcement Section <br />4300 Cherry Creek Drive South <br />Denver, CO 80246 -1530 <br />36600 Routt County Rd. 27 <br />PO Box 250 <br />Hayden, CO. 81639 <br />(970) 276 -7001 <br />April 25, 2013 <br />RE: Quarterly DMRs for CPDS Permit No. CO- 0048275, Peabody Sage Creek Mine <br />Dear Sir or Madam: <br />Pursuant to the quarterly reporting requirements contained in Colorado Discharge Permit <br />CO- 0048275 for the Peabody Sage Creek Mine (PSCM), enclosed find the first quarter <br />2013 discharge monitoring reports for Outfalls 002 to 004. <br />One selenium (Se) value reported by PSCM's lab (ACZ Labs in Steamboat Springs, CO) <br />exceeded the 4.6 ug/L DMR limit. This occurred on a sample collected at Outfall 004 on <br />February 4, 2013. Additional analyses for selenium were performed by the lab as <br />described below. <br />The original potentially dissolved (PD) by ICP -MS selenium analysis was performed on <br />February 8, and yielded a value of 20 u L. The lab also performed a total recoverable <br />(TR) selenium analysis on the same sample on February 8 that resulted in a value of 1.0 <br />ug/L. Suspecting that water matrix interference caused the high PD selenium value <br />compared to the TR selenium value, the lab performed an additional digestion on the PD <br />sample on February 15 to remove the water matrix interference. The result of the <br />February 15 analysis on the PD selenium sample was 1.0 ug/L. In March, PSCM <br />requested the lab perform an additional selenium analysis on the PD sample using the <br />AA- Hydride method in order to confirm the February 15 PD analyses and the February 8 <br />TR analysis. This work was performed on March 15 and yielded a value of <1.0 ug/L. <br />The value reported on this DMR for Outfall 004 was 2.1 ug/L, which was the highest of <br />the three reliable monthly PD Se ICP -MS values for this quarter (1.8, 1.0 and 2.1 ug/L, <br />respectively). PSCM believes the 20 ug/L value noted above to be a false high value, <br />based on the other three Se analyses performed on that sample. As one would expect the <br />total recoverable method to result in the same, or higher, value than the potentially <br />dissolved method (the former involves a hot acid digestion, while the later involves a <br />cold acid digestion), we suspect that the 20 ug/L value to be in error. This may be due to <br />matrix interference in the sample that displays itself in the potentially dissolved ICP -MS <br />method. An additional TR digestion apparently removes that interference. The AA- <br />