2008-07-30_HYDROLOGY - C1980007 (2)

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Ms. Lynette Myers Colorado Department of Public Health and Environment July 30, 2008 Page 2 divisional level (Environmental Coordinator, Arch Western Bituminous Group), as well as MCC environmental staff located at the mine (Manager of Engineering and Environmental Affairs and staff Environmental Engineer). The voluntary self-evaluation for the West Elk Mine is still in progress and is expected to be completed within sixty (60) days of the date of this letter. Several potential deficiencies have been identified during the evaluation to date. MCC is submitting to CDPHE this disclosure of the potential deficiencies discovered to date, even though the self- evaluation is not yet complete. Specific Information on Each Deficiency The following is specific information on each deficiency discovered as a result of the voluntary self-evaluation of the West Elk Mine at this time: 1. Incomplete Discharge Monitoring Reports ("DMRs"): Although MCC submitted DMRs to CDPHE as required by CDPS Permit No. CO-0038776, Part I.E.1, it was discovered during the self-evaluation that the DMRs prepared by the West Elk Mine for Outfall 017A were incomplete. In particular, potentially dissolved iron and total recoverable iron analytical results were inadvertently excluded from the reporting in the DMRs for Outfall 017A. Other parameter values were occasionally omitted from the DMRs, as summarized in the attached Table 1, Preliminary List of Potential Deficiencies. With respect to whole effluent toxicity ("WET") testing, laboratory results were attached rather than being entered onto the DMR forms. The required information for certain outfalls (e.g., Outfalls 004A, 007A, 008A, 014A, 016A, and 018A) was inadvertently not included in the submittal as indicated in Table 1. MCC is continuing to assess the accuracy of the outfall flow monitoring devices as part of the ongoing voluntary self- evaluation (see CDPS Permit No. CO-0038776, Part I.E.5). MCC will provide CDPHE the necessary amended DMRs and any relevant discoveries regarding the flow monitoring devices within 60 days of the date of this letter. 2. Exceedances of Permit Limits: The inadvertent exclusion of potentially dissolved iron and total recoverable iron from the DMRs for Outfall 017A resulted in exceedances of the permit limits for these parameters not being reported to CDPHE, as required by CDPS Permit No. CO-0038776, Part II.A.4. These two parameters were not included in the previous permit, but were added to CDPS Permit No. CO-0038776 (Parts I.A. Lc and I.B. Ld) that became effective on June 1, 2004. Those quarters and months with potentially dissolved iron and total recoverable iron exceedances at Outfall 017A are itemized in Table 1. As part of the voluntary self-evaluation, the company began to investigate certain data anomalies and potential interferences associated with the results reported for all forms of iron by the commercial laboratory used to analyze water samples collected at Outfall 017A in connection with CDPS Permit No. CO-0038776. This investigation is still underway, but there may be evidence that the complex nature of the effluent at Outfall 017A may have contributed to laboratory interference resulting in potentially inaccurate results. MCC is investigating the source of the potential exceedances and will provide CDPHE additional information on this effort within 60