2013-05-14_HYDROLOGY - C1982057 (2)

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SE/VECA Cos/ Company Colorado Department of Health WQCD -PE -B2 4300 Cherry Creek Drive South Denver, CO 80246 -1530 Seneca Coal Compan April 25, 2013 RE: Quarterly Discharge Monitoring Report for Permit CO- 0000221 Dear Sir or Madam: Pursuant to the quarterly reporting requirements contained in Colorado Discharge Permit CO- 0000221 for the Seneca Mine Complex, enclosed find the first quarter 2013 discharge monitoring reports for Outfalls 005, 006 and 008 to 017. In this quarter, no discharges were observed at Outfalls 005, 009, 011 and 014. Intermittent flows were observed at Outfalls 010, 013 and 016. Vehicle access to Outfalls 005, 008, 009, 010, 015, 016 and 017 was closed this winter due to snow. Monthly visits (except at 015) were performed by snowmobile or snowshoe. For Outfall 015, snow on this long, narrow road prevented safe access, even with a snowmobile, for the entire quarter. Winter time monitoring exemptions exists for all these sites (CPDS permit, Part I, page 20). Two selenium (Se) value reported by PSCM's lab (ACZ Labs in Steamboat Springs, CO) exceeded the 4.6 ug/L DMR limit. These occurred on a samples collected at Outfall 010 on February 4 and March 5. Additional analyses for selenium were performed by the lab as described below. For the February 4 sample, the original potentially dissolved (PD) by ICP -MS selenium analysis was performed on February 8, and yielded a value of 55 u L. The lab also performed a total recoverable (TR) selenium analysis on the same sample on February 8 that resulted in a value of 0.4 u L. Suspecting that water matrix interference caused the high PD selenium value compared to the TR selenium value, the lab performed an additional digestion on the PD sample on February 15 to remove the water matrix interference. The result of the February 15 analysis on the PD selenium sample was 0.4 u L. In March, PSCM requested the lab perform an additional selenium analysis on the PD sample using the AA- Hydride method in order to confirm the February 15 PD analyses and the February 8 TR analysis. This work was performed on March 15 and yielded a value of <1.0 u L. For the March 5 sample, the original potentially dissolved (PD) by ICP -MS selenium analysis was performed on March 7, and yielded a value of 41 u L. The lab also performed a total recoverable JR) selenium analysis on the same sample on March 8 that resulted in a value of 0.3 u L. Suspecting that water matrix interference caused the high PD selenium value compared to the TR selenium value, the lab performed an additional digestion on the PD sample on March 29 to remove the water matrix interference. The result of the March 29 analysis on the PD selenium sample was 0.3 u L. PSCM also requested (when the sample was submitted) that the lab perform an additional selenium analysis on the PD sample using the AA- Hydride method in order to confirm the other Se analyses. This work was performed on March 8 and yielded a value of <1.0 u L. Seneca Coal Company • P.O. Box 670 • Hayden, Colorado 81639 Telephone (970) 276 -5217 • FAX (970) 276 -5222