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Peabod <br />ill! ENERGY <br />Twentymile Coal, LLC 29515 Routt County Road 27 <br />Oak Creek, CO 80467 <br />970.879.3800 <br />Mr. Jared Ebert, Environmental Protection Specialist .June 2, 2016 <br />Division of Reclamation, Mining, and Safety <br />13 13 Sherman Street, Room 215 <br />Denver, Colorado 80203 <br />(303) 866-3567 X 8120 <br />RE. Twentymile Coal, LLC - Foidel Creek Mine (Permit No. C-82-056), Minor Revision <br />(MR16-298) — Fish Creek Borehole Flocculant System <br />Dear Mr. Ebert: <br />Twentymile Coal, LLC (TC) requests CDRMS approval of a Minor Revision to our existing approved <br />Permit to reflect the addition of a flocculant delivery system and use of flocculant at the fish Creek <br />Borehole and Water Treatment installation to drop-out coal fines and enhance water duality prior to <br />discharge. In order to safely complete initial development activities and initiate longwalll mining in <br />the Wolf Creel: Coal Seam, TC is proceeding with dewatering of nearby flooded mine workings in the <br />overlying Wadge Coal Seam. Sone of the water from the mine dewatering activities is being <br />transferred to sealed and abandoned mine workings in the Western Mining District, however, the <br />overall water balance dictates that some of the water be discharged, as development and mining <br />proceed. TC has analyzed the nine water and determined that it can be safely discharged while. <br />meeting applicable CDPS effluent discharge standards. <br />Due to the increased volume of water being moved, pumping from the existing underground discharge <br />points may result in re -suspension of coal fines in the discharge stream. TC has worked with a <br />professional water treatment firm (SOLENIS) to identify a practical and cost-effective means of <br />capturing and settling the coal fines out prior to discharge. Testing has identified an organic polymer <br />flocculant the can be introduced into the mine water flow stream, which is very effective in attracting <br />and facilitating rapid settling of the coal fines prior to discharge. The flocculant would be supplied in <br />poly totes which can be stored inside of the existing Electro -Coagulation (EC) Building, and metered <br />into the flow stream prior to the existing EC mix tank. The treated flow would then discharge from the <br />mixing tank using the existing piping into the existing three -cell settling basin system. Testing has <br />identified an effective application rate of 20mgll, which will result in effective settling, with no <br />nntieipated flocculant residual once the flows reach the third cell in the treatment system. p side <br />benefit of the proposed flocculant use for dropping -out the coal fines identified during testing is a <br />significant reduction in iron levels, because much of the potentially available iron is associated with <br />settleable solids. TC plans to limit discharge to high flow periods in order to maximize mixing and <br />dilution, and will continue monitoring water quality in the receiving stream (Fish Creek) under the <br />existing monitoring schedule, which includes expanded downstream monitoring whenever discharge is <br />occurring at this location_ <br />It should be noted that the proposed change is limited to an additional option for water treatment, <br />specifically to address reduction of suspended coal fines prior to discharge, and does not replace or <br />supersede existing approved treatment methods. It is also limited to water treatment and does not <br />involve the construction or installation of any addition structures or equipment (with the exception of a <br />