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Mr. Maher <br /> Page 12 <br /> June 21, 2016 <br /> correlated to specific dates or to a general timeline. Please provide the Division with a timeline for <br /> completing the individual steps of the proposed plan. <br /> 4. The Operator has stated a visual inspection of the tailings liner would proceed upon removal of the <br /> tailings and mine dump material. Conducting a visual inspection is an acceptable step in determining <br /> whether the integrity of the liner has been compromised. However,the Division will require the <br /> Operator to utilize additional methodologies that are quantifiable. Please identify the other methods <br /> which will be used test the integrity of the liner. <br /> 5. The Operator is proposing to increase the frequency of groundwater sampling from monthly to <br /> quarterly. Presumably this change is being proposed in order to demonstrate the tailings <br /> impoundment is functioning as designed and is protective of groundwater quality. The approved <br /> groundwater monitoring plan for this operation is established on practice-based groundwater <br /> protection rather than through the establishment of numeric protection limits. Therefore, the primary <br /> purpose of the monitoring wells is to detect leaks in the tailings impoundment liner. As noted in the <br /> Inspection Report dated November 19, 2015,the Division has concerns about the construction of the <br /> monitoring wells. According to the data which were submitted to the Division,the monitoring wells <br /> have been dry during each sampling event. The Division is concerned that the Operator may not be <br /> able to retrieve a sample in the event there is water in the wells. In order to demonstrate the wells <br /> were properly constructed,please provide the Division with copies of the Well Construction Reports. <br /> This concludes the Division's preliminary adequacy review of this Technical Revision. Please remember <br /> that the decision date for this Technical Revision is July 4,2016. As previously mentioned, if you are <br /> unable to provide satisfactory responses to any inadequacies prior to this date, it will be your <br /> responsibility to request an extension of time to allow for continued review of this Technical <br /> Revision. If there are still unresolved issues when the decision date arrives and no extension has been <br /> requested,the Technical Revision will be denied. <br /> If you have any questions,please contact me at(303)866-3567 x8116. <br /> Sincerely, <br /> Michael A. Cun Ingham <br /> Environmental Protection Specialist <br /> CC: Wally Erickson, DRMS <br />