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i� p ® Climax Molybdenum A Freeport- McMoRan Company September 12, 2013 Via Email and UPS Tracking #: 1Z 804 847 03 7736 1878 Mr. Peter Hays Division of Reclamation, Mining and Safety 1313 Sherman St., Rm. 215 Denver, CO 80203 COLORADO OPERATIONS Henderson Mine 1746 County Road 202 Empire, CO 80438 Phone (303) 569 -3221 Re: /Mill Groundwater NPL Exceedance Notification, Permit No. M -1977 -342 Dear Mr. Hays: Henderson Mill is providing this written notification of an NPL exceedance for pH at groundwater point of compliance (POC) well MLGW -7, downgradient of the Henderson Mill 1 -Dam, in accordance with Section 5.3 of the Henderson Groundwater Management Plan. This written notification is subsequent to the verbal notifications that were made to you on August 7, 2013 and August 22, 2013. MLGW -7 was sampled during the normally scheduled triannual monitoring event on July 31, 2013, with a pH value of 6.1 standard units (s.u.). This exceeded the numeric protection limit (NPL) of 6.5 -8.5. A follow -up pH measurement was taken on August 14, 2013, resulting in a pH of 6.2 s.u. Henderson performed a trend analysis and the results did not appear to be anomalous, or obvious outliers. The monitoring frequency at this location for pH and a list of indicator parameters currently being developed will be increased to once per month in order to better evaluate pH trends and the underlying water chemistry that may be causing a low pH at this location. Henderson proposes to provide a follow -up report to the DRMS by March 31, 2014, where results of additional sampling at MLGW -7 will be provided, including a water quality assessment. The objective of the water quality assessment will be to provide an understanding of potential causes of reduced pH which can then be utilized to guide in further monitoring and /or develop a mitigation plan, as appropriate. RECEIVED ✓SEP 13 2013 DIVISION OF RECLAMATION MINING AND SAFETY