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6/7/2016 State.co.us Executive Branch Mail - Fwd: Twentymile Coal -Use of Flocculant to Settle Coal Fines Prior to Discharge to Fish Creek <br />The water that we need to discharge has elevated coal fines from pumping operations, elevated iron, and <br />elevated electrical conductivity (EC). In consultation with water treatment professionals, we have determined <br />that the coal fines and iron can most effectively be treated with a polymer flocculant. The flocculant would be <br />metered into the flow stream in the existing Electro -Coagulation Building prior to a mixing tank, with the <br />discharge into the first cell of the three -cell settling pond system, and progressive movement through the pond <br />system to the discharge point. The selected flocculant (SOLENIS Amerifloc 490 — Safety Data Sheet attached) <br />is approved for use in drinking water systems, and at the proposed feed rate of 20 mg/I will be consumed in the <br />reaction with suspended solids, with little or no residual in the discharge to the stream. The SDS sheet (Section <br />12) indicates an LC50 for Daphnia magna (most sensitive aquatic species) of 10 — 100 mg/I, with an exposure <br />time of 48 hours. Based on this information, our testing, and the consultants recommendations, we are <br />confident that we can meet our permit effluent limits (which include WET testing) while using this treatment <br />method. Consistent with past practice, we propose to limit discharge to high flow periods (typically during spring <br />runoff) in order to take advantage of the resulting mixing and dilution so that we can meet a relatively stringent <br />EC limit. <br />We have applied to the Colorado Division of Reclamation, Mining, and Safety for a permit revision to allow use of <br />this additional treatment method, and they have requested consultation with Colorado Parks and Wildlife. Given <br />that we are already into the runoff season, we would like to process this request as soon as possible in order to <br />discharge this year, so we would very much appreciate your timely consideration and response. I have attached <br />a sample CPW consultation letter as a template to facilitate your response. Please feel free to contact me with <br />any questions, or to discuss. Thanks for your consideration and assistance — <br />Best regards, <br />Jerry <br />Jerry M. Nettleton <br />Manager Environmental Affairs <br />Twentymile Coal, LLC <br />29515 RCR27 <br />Oak Creek, Colorado 80467 <br />970.870.2712 <br />jnettleton@peabodyenergy.com <br />https://mail.google.com/mail/u/0/?ui=2&ik=e29129fcb5&view=pt&search=inbox&th=1552b6lcedlae9f9&siml=1552b6lcedlae9f9 2/3 <br />