Laserfiche WebLink
6/16/2016 State.co.us Executive Branch Mail - Fwd: Twentymile Coal -Use of Flocculant to Settle Coal Fines Prior to Discharge to Fish Creek <br />Bill Atkinson <br />Aquatic Biologist <br />Colorado parks and Wildlife <br />925 Weiss Dr. <br />Steamboat Springs, CO 80487 <br />office: 970-871-2868; cell: 970-846-9381 <br />e-mail: bill.atkinson@state.co.us <br />On Tue, Jun 7, 2016 at 7:16 AM, Nettleton, Jerry <JNettleton@peabodyenergy.com> wrote: <br />ZZI <br />We have an existing water treatment facility on Fish Creek that has been used for years to treat mine water prior to <br />discharge in order to meet the effluent limits and requirements of our Colorado Discharge Permitting System (CDPS) <br />industrial discharge permit. Originally, this facility used sodium -hydroxide (caustic soda) to change the pH of the <br />mine water discharge, causing iron and other suspended solids to agglomerate and drop-out in a three cell (in <br />series) settling pond system prior to discharge. Sodium hydroxide is a strong alkaline material with certain handling <br />hazards, and the system was fairly expensive to operate, so in 2006 Twentymile converted our treatment system to <br />an electro -coagulation system, where the mine water is directed over a series of charged electric plates causing <br />suspended solids in the water to pick-up an electrical charge, adhere to other particles, and drop-out in the settling <br />pond system prior to discharge. <br />While this system remains in-place, we have not used it for a number of years because our extensive mine water <br />recycling system has allowed us to balance mine water use with mine inflow and recycling such that both our water <br />withdrawals and discharge have been minimal. We are moving into a new coal seam which is underneath the <br />previously mined seam. In order to safely develop and mine this lower seam, we need to drain some of the water <br />which has accumulated in the previously mined and sealed areas of the upper seam. This additional water volume <br />means that we need to discharge some of the water. <br />The water that we need to discharge has elevated coal fines from pumping operations, elevated iron, and elevated <br />electrical conductivity (EC). In consultation with water treatment professionals, we have determined that the coal <br />fines and iron can most effectively be treated with a polymer flocculant. The flocculant would be metered into the <br />flow stream in the existing Electro -Coagulation Building prior to a mixing tank, with the discharge into the first cell of <br />the three -cell settling pond system, and progressive movement through the pond system to the discharge point. <br />The selected flocculant (SOLENIS Amerifloc 490 — Safety Data Sheet attached) is approved for use in drinking <br />water systems, and at the proposed feed rate of 20 mg/I will be consumed in the reaction with suspended solids, <br />with little or no residual in the discharge to the stream. The SDS sheet (Section 12) indicates an LC50 for Daphnia <br />magna (most sensitive aquatic species) of 10 — 100 mg/I, with an exposure time of 48 hours. Based on this <br />information, our testing, and the consultants recommendations, we are confident that we can meet our permit <br />effluent limits (which include WET testing) while using this treatment method. Consistent with past practice, we <br />propose to limit discharge to high flow periods (typically during spring runoff) in order to take advantage of the <br />resulting mixing and dilution so that we can meet a relatively stringent 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 a <br />sample CPW consultation letter as a template to facilitate your response. Please feel free to contact me with any <br />questions, or to discuss. Thanks for your consideration and assistance — <br />Best regards, <br />hftps:Hmail.google.com/mail/u/O/?ui=2&i k=e29129fcb5&view= pt&search=i nbox&th= 1 55594dffe2d6c2d&sim 1= 155594dffe2d6c2d 2/4 <br />