2011-07-28_HYDROLOGY - C1982057 (3)

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S ENECi4 Coal Company Colorado Department of Health WQCD -PE -B2 4300 Cherry Creek Drive South Denver, CO 80246 -1530 RE: Quarterly Discharge Monitoring Report for Permit CO- 0000221 Dear Sir or Madam: July 21, 2011 Furthermore, on page 75, third paragraph (31.22 SBP — 1987 Revisions) it states: Seneca Coal Company • P.O. Box 670 • Hayden, Colorado 81639 Telephone (970) 276 -5217 • FAX (970) 276 -5222 Seneca Coal Company A9rn ng ° and S�mat7 � � Pursuant to the quarterly reporting requirements contained in Colorado Discharge Permit CO- 0000221 for the Seneca Mine Complex, enclosed find the second quarter 2011 discharge monitoring reports for Outfalls 005, 006 and 008 to 017. In this quarter, intermittent discharges were observed at Outfall 009. All other Outfalls discharged continuously. Vehicle access to Outfalls 005, 008, 009, 010, 015, 016 and 017 was closed starting in November due to snow. Monthly visits (at all sites except 015) were performed by snowmobile or snowshoe. For Outfall 015, deep and light 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). One excursion of an effluent limit occurred this quarter. On June 6, a potentially dissolved selenium value of 4.8 ug/1 was observed at Outfall 006. The standard listed on the DMR is 4.6 ug/l. However, the total recoverable selenium value from the same sample was only 3.9 ug/1. Also, in Regulation 31 (Basic Standards for Surface Water) Footnote 4 to Table III, it states: "Both acute and chronic numbers adopted as stream standards are levels not to be exceeded more than once every three years on the average." "Footnote 5 to Table III states that standards based on these table values are not to be exceeded more than once every three years on the average. This provision is adopted based on evidence that aquatic life can recover from impacts if not exposed to exceedances more frequently than once every three years." The reference to `Footnote 5' (rather than Footnote 4) above is either a typo, or a result of a deleted footnote in a later revision. In any case, Outfall 006 has NOT exceeded 4.6 ug/1 for selenium (in any form) in the past SIX years. The attached water quality statistics report for this Outfall from 1/1/2005 to 12/31/2010 indicates no exceedances during that time frame. It is unknown as to why this exceedance occurred, although we suspect it may be due to the record snowfall and rainfall, and near - record snowmelt runoff that occurred in Routt County this winter and spring. Perhaps that unusually high runoff somehow mobilized the selenium. In any case, we hope that this excursion is transitory, and that the selenium values will drop in future months. The July 6 selenium value for this Outfall was 2 ug/1.