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CG <br />April 14, 2011 <br />Mr. Michael Cunningham <br />Division of Reclamation, Mining and Safety <br />1313 Sherman St., Room 215 <br />Denver, Colorado 80203 <br />RE: Varra Great Western Sugar Project <br />Response to Division Letter <br />DRMS File No. M-2010-049 <br />CGRS No. 1-135-12539aa <br />Dear Mr. Cunningham: <br />ENVIRONMENTAL SERVICES <br />This letter addresses your comments regarding what water level criteria will be used to <br />when an adverse affect to groundwater has occurred. <br />We propose that the trigger point be a measured water level of 4 feet below the <br />predicted drawdown midway between the mine face and the effective radius of influence <br />(-x400 feet) based on two pit pumping simulations. This level provides accommodation <br />for typical seasonal fluctuations which has been measured to be on the order of four <br />feet. At a point were the predicted drawdown is 6 feet if a drawdown of 10 feet is <br />measured the Division will be contacted and an appropriate action plan generated based <br />on available data. <br />If you have any questions regarding this letter, please contact me at 970-493-7780. <br />Sincerely, <br />CGRS, Inc. <br /> <br />Joby L. Adams, P.G. <br />Principal/Hydrogeologist <br />P.O. Box 1489 Fort Collins, CO 80522 T 800-288-2657 F 970-493-7986 www.cgrs.com