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A=COM <br /> Mr. Raymond Lazuk <br /> Climax Molybdenum <br /> February 20, 2017 <br /> Page 2 <br /> No significant issues were identified during observation that required notification to the DRMS by <br /> Climax. Identified maintenance issues were discussed with the Climax tailings operations staff during <br /> the site visit and corrective action plans were developed and implemented. <br /> The Tenmile and Mayflower TSFs appear to be functioning as designed and within the established <br /> design criteria. This judgment is based on observations made during site visits, as well as <br /> information provided and reported by Climax tailing operations staff such as deposition quantity, <br /> water surface elevations, and other parameters. <br /> The remote monitoring system provides continuous monitoring of piezometric elevations. The system <br /> incorporates alarms based on piezometric elevation changes identified as either action levels or <br /> threshold elevations. Action level alarms are triggered when predetermined elevation changes occur <br /> over a prescribed period of time.Action levels and threshold elevations are specific to individual <br /> piezometers. Threshold levels are established based on the results of slope stability analyses and <br /> provide redundant warnings should piezometric elevations rise above prescribed predetermined <br /> elevations. The monitoring system triggers alarms requiring immediate review. <br /> AECOM reviews the piezometric data monthly on both the Tenmile and Mayflower TSFs. <br /> Piezometers are tracking in accordance with the design. AECOM reviewed the annual movement <br /> monument data and found movement within the tolerance expected. <br /> The instrumentation is tracking in accordance with or below established action levels and threshold <br /> elevations. Continued diligence in monitoring embankment construction, decant pond levels, and <br /> instrumentation is essential to long term safety and performance of the structure. Correct operation of <br /> the tailing storage facility is essential and it is incumbent upon Climax to maintain proper training and <br /> personnel. AECOM will continue to work with the Climax team to monitor the performance of the <br /> TSFs. <br /> AECOM represents that our services are performed within the limits prescribed by the Client in a <br /> manner consistent with the level and skill ordinarily exercised by other consultants under similar <br /> circumstances. No representation to the Client, expressed or implied, and no other warranty or <br /> guarantee is included or intended. <br /> Closing <br /> Please do not hesitate to call us with any questions or comments. <br /> Sincerely, <br /> i Z. iiijA OV" <br /> t;-YJ <br /> Lisa R. Yenne, PE Richard R. Davidson, PE <br /> Project Manager Senior Principal Engineer <br /> MADCS\TEMPORARY\MELISSA\2016 TSF ANNUAL REVIEW.DOCX <br />