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August 10, 2000 <br />Mr Erich J. Bower <br />Environmental Engineer <br />Climax Molybdenum Company <br />Henderson Mill <br />19302 County Road <br />Parshall, Colorado 80468 <br />Subject: Response to Technical Revision No. 9, Stipulation No. 4 Tailing Dam No 3 <br />Decant Grouting, Henderson Mill, near Parshall, Colorado <br />Project No. 6800044400 00 -9407 (T- G2000) <br />Dear Erich: <br />We have prepared this letter in response to Technical Revision No. 9 (TR -09), Stipulation No 4 <br />prepared by the State of Colorado Divisions of Minerals and Geology (DMG) dated April 21. <br />2000. Presented below is a summary of the request, a brief project history and a brief discussion <br />of our opinion. <br />SUMMARY OF REQUEST <br />We were requested by the Climax Molybdenum Company (Climax) to prepare a response to a <br />letter received from DMG. The DMG letter provides Climax conditional approval for grouting <br />the existing decant structure closed and is designated as Technical Revision No. 9 (TR -09) to <br />Permit No. M -77 -342. Conditional approval was given provided that four stipulations are met <br />We have been requested to provide a response to Stipulation No. 4, which reads as follows <br />The penetration of No. 3 -Dam by the abandoned No. 2-Dam decant system could create a <br />pat way for seepage and piping which are potential dam stability issues. Within 61) days <br />of date of technical revision TR -09 approval, Henderson must provide the Division with a <br />report on this potential, which may comprise recordi on the construction a / 3 -Dam <br />as they relate to the decant system penetrations, or if adequate historical records are <br />unavailable Henderson must provide the Division with a proposal to investigate the <br />nature and condition of the decant system penetrations <br />PROJECT HISTORY <br />Construction of the Henderson tailing dams began in the early 1970's. Two dams were <br />constructed and are referred to as the Lower and Upper Tailing darn or Tailing Dam No I and <br />No. 2, respectively Both dams are constructed using the upstream method of Tailing <br />deposition. <br />J VA Ox argiato013 l: 'M, <br />