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i) ? N Adlp? Adsp? <br />r RWGLWK? <br />NORTHERN (0109ADO (ONMULT0H, IN(, <br />9075 WCR 10 * Fort Lupton, CO 80621 <br />303-857-1754 <br />FAX: 303-857-2933 <br />June 16, 2011 <br />"Michael Cunningham <br />Environmental Protection Specialist <br />Colorado Division of Reclamation, Mining and Safety <br />1313 Sherman Street - room 215 <br />Denver, Colorado 80203 <br />RE: NCCI Pit #1, Technical Revisfon No. 5, Updated Moni <br />Data, Established Bench Marks, and Adequacy Review <br />Tresponse o etter Dated May 20, 2011, To Address G <br />File No. M-2001-107 <br />Dear Mr. Cunningham: <br />RECEIVED <br />J N 2 0 2jil <br />Civilian of Redamagon, <br />mining & safety <br />Wells, Groundwater Monitoring <br />As Required <br />NCCI offers the following response to the five (5) items that the Division requires be addressed for <br />our request for Technical Revision No. 5. <br />Item No. 1 - NCC began monitoring the wells as per Technical Revision No. 3 in January, 2007. <br />Item No. 2 - Establishing base line monitoring well levels based on standard deviation calculations <br />for each monitoring well using the data collected from January, 2007 through December, 2010. <br />Attached you will find NCC's established standard deviations for monitoring well No. 1 through No. <br />10. The standard deviation for the minimum and the maximum probability is as follows: <br />MW No. 1 Min. 159 - Max 191 <br />No. 2 Min. 6 - Max 166 <br />No. 3 Min. 171 - Max. 237 <br />No. 4 Min. 229 - Max. 343 <br />No. 5 Min. 110-Max. 188 <br />No. 6 Min. 55 - Max. 127 <br />No. 7 Min. 36 - Max. 90 <br />No. 8 Min. 15 - Max. 51 <br />No. 9 Min 1 - Max. 97 <br />No. 10 Min. 22 - Max. 100 <br />Item No. 3 - NCC will notify the Division in writing within 48 hours in the event the monthly <br />averages of any of the monitoring well exceeds the upper and lower baseline levels by 24 inches for <br />three consecutive months.