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~~ Twentymlle Coal 29515 Routt County Road #27 Oak Creek, CO 80467 970.879.3800 Dear Water User/Owner: The purpose of this letter is to provide a routine notification of an unanticipated accident discharge of slurried coal material to Foidel Creek, which was detected on September 11`h. The slurried coal discharge consisted of fine coal and rock particles suspended in water, and a benign chemical flocculant. None of the materials contained in the discharge are considered hazardous, toxic, or harmful to aquatic life, and do no[ represent a known health risk to downstream users. Twentymile Coal Company (TCC) took immediate steps to stop the discharge, limit the downstream movement of the slurried material, evaluate any impacts, and notify appropriate authorities, and is now proceeding with clean-up efforts. Due to the fine-grained nature of the rock and coal materials, some of this material may be picked-up and carried downstream by normal or storm flows, appearing as black or cloudy streamflows, however, water quality is not affected and remains suitable for all designated human, livestock, and recreational uses. The following summarize relevant information about the accidental discharge and TCC's related mitigation and clean-up efforts. Relevant Information on Accidental Discharee and Mitisation and Clean-ua Actions • TCC operates an on-site coal-washing facility which removes rock material from low-quality coal so that the clean coal product can be shipped and sold as a usable energy source, rather than disposed of as an unusable waste material. • The discharge from the coal-washing facility is a slurry composed of finely crushed rock material, coal fines, water, and a chemical flocculant. The flocculant is anon-hazardous, non-toxic powder which causes the fine rock and coal particles to agglomerate (the solid particles aze attracted to each other and form "flocs") and settle-out of the discharge slurry. • The discharge slurry from the coal-washing facility flows through a buried pipeline from the coal- washing facility into an abandoned and sealed portion of the underground mine workings, where the solids settle-out and the resulting decant water flows to an underground sump, where it is available for recycling in the mine water system. • At some time prior to September 1 l`", a break in the buried slurry line resulted in discharge of slurried material to TCC's Sedimentation Pond E. This Pond is designed to intercept and control surface runoff from mine disturbance areas to allow any sediment to settle-out prior to discharge to Foidel Creek. • Slurried material discharged from Pond E into Foide- Creek. • The accidental discharge was detected at about 10:00 AM on September 1 I`h. TCC immediately took steps to seal the Pond E discharge structure to prevent further release of the slurried material. • TCC Environmental Staff immediately obtained water quality samples at the discharge point, and proceeded downstream on Foidel Creek to determine how far downstream the slurried material had migrated with normal seasonal low-flows. Containment booms were placed at several locations to limit downstream migration of the slurried material and to filter coal and rock solids from the slurry mixture.