Tailing storage at the Fort Knox Mine : an innovative expansion to continue a history of success

Fairbanks Gold Mining, Inc. (FGMI) owns and operates the Fort Knox gold mine and mill, which has been in production since 1996. Tailing are stored behind a cross valley dam. In the summer of 2006, the tailings storage facility (TSF) dam was raised to its originally designed final crest elevation. However, in January 2009, the mill ore reserve was increased above the remaining capacity of the TSF. A site wide optimization study identified a 52-foot raise to the TSF dam as the preferred alternative for expanded capacity, but this posed a challenge. How would the raise be configured to maintain the necessary level of stability and security for the TSF given its hazard consequence classification and other site specific conditions without adopting a conventional downstream raise? The solution was to construct the 52-foot raise with partial placement of the upstream random fill shell over tailings in lieu of a downstream raise as had been the practice through 2006. The 52-foot raise then bears largely on engineered fill on the crest and upstream face of the existing dam with a modest construction onto the tailings deposited immediately to the upstream. This paper presents the design of the 52-foot raise to the Fort Knox TSF together with construction and operational experiences to date, which represents another chapter in the success of the facility. [All papers were considered for technical and language appropriateness by the organizing committee.]Non UBCUnreviewedOthe