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� ARCADIS <br />MEMO <br />To <br />Mr. Ron Thompson <br />New Elk Coal Company, LLC <br />From <br />Jerry Koblitz <br />ARCADIS US, Inc. <br />Date <br />February 27,2014 <br />Subject <br />Copies <br />Monica Heintz, ARCADIS <br />ARCADIS Project No <br />C0001572.0003.00001 <br />Assessment of the Influence of Mining Activities at New Elk Mine on Surface Water <br />Quality in the Purgatoire River <br />1. Introduction <br />ARCADIS U S, Inc <br />630 Plaza Drive <br />Suite 200 <br />Highlands Ranch <br />Colorado 80129 <br />Tel 720 344 3500 <br />Fax 720 344 3535 <br />On behalf of New Elk Coal Company, LLC (NECC), ARCADIS U.S. Inc. (ARCADIS) presents this <br />memorandum Assessment of the Influence of Mining Activities at New Elk Mine on Surface Water Quality <br />at the Purgatoire River (memo). This memo summarizes geochemical data analysis and modeling <br />conducted in support of assessing potential effects to surface water quality from mine dewatering activities <br />at the New Elk underground coal mine and preparation plant (New Elk Mine). Background information <br />presented here and the data used in analysis and modeling were previously reported in the New Elk Mine <br />Annual Hydrologic Monitoring Report 2012 (NECC 2012). <br />Production from the Allen Seam at the New Elk Mine occurred intermittently between 1952 and 1988. In <br />1988, the mine was temporally sealed and was allowed to flood. Between February 2001 and November <br />2008 depth to water in the mine and mine water quality were monitored. In December 2008, active <br />dewatering of the mine began in order to prepare for mine rehabilitation. Mining activities were resumed in <br />late 2011 with mining of the Blue Seam, and in January 2012 mining in the Allen Seam was resumed. <br />Additional details regarding past and current facility operations, as well as environmental monitoring and <br />compliance programs at the New Elk Mine are presented in the Annual Hydrogeologic Monitoring Report <br />2012 (NECC 2012) and in National Pollution Discharge Elimination System (NPDES) permit <br />documentation. <br />Page. <br />cWsersVonlhanpson\appdaWbcarvnivosAwndoft-tmrporay nkxnet filestmientmODoklk6utti'ne"walsufacewaWrdluenceassessmenhnemo.docx 1/8 <br />