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~T~ V, Peabody Twentymile Coal~Company 29575 Routt County Road #27 Oak Creek, CO 80467 970.879.3800 January 31,2006 Mr. Clyde Sharp Colorado Department of Public Health and Environment Water Qualify Control Division -Permits and Enforcement 4300 Cherry Creek Drive South Denver. CO 80222-1530 RE: Dear 1vIr. Sharp: ~ N~ ~~ RECEIVED MAY 0 4 2006 pmson of Minerals and GeolapY Twentymile Coal Company (TCC) respectfully requests that the above-referenced permit be amended to eliminate or reduce the percent minimum removal requirement for BOD, to reflect the practical operating constraints of our wastewater treatment system, based upon applicable provisions of State "Regulation 62, Section 62.4 (2). It would be appreciated if you could pass this request on to the appropriate party within the CDPHE-WQCD. As we discussed in a recent phone conversation, TCC recently experienced a permit exceedance with ~ regards to the 85-percent minimum removal requirement for BOD for Outfall 002A. While our post- - treatment analysis values for BOD, TSS, and fecal coliform levels are consistently low (please refer to previously submitted DMR's), and well within our permit requirements, we have had an ongoing problem meeting the percent removal requirements, due to practical system operational constraints. Our primary operating constraint relative to percent BOD removal is a low influent BOD due to grey- water dilution in our system. Influent flows to our wastewater treatment system include significant grey-water dilution from aboot- wash station, showers, sinks, floor-drains, and roof-drains. In fact, the primary source of influent to the system is shower-water (with very low or no BOD), with approximately 300 mine employees showering at the end of their shifts. Influent BOD and TSS to the system are consequently much lower than for most conventional wastewater systems, making it very difficult to meet the minimum BOD percent removal limitation. It is also important to note that the treated wastewater effluent is not discharged to surface waters, but rather is discharged back to a sealed area of abandoned underground mine workings, where it is further diluted by natural groundwater. TCC is requesting that the current permit requirement for an 85-percent minimum BOD removal rate be eliminated or reduced, based on applicable provisions of State Regulation 62, Section 62.4 (2), which is appropriate as long as the provisions of 40CFR 133.103d aze met. The primary consideration relative to the applicable provisions is that the wastewater treatment facility (WWTF) must meet