ABSTRACT
ABSTRACT: In accordance with Federal and State laws a former gold mine in Idaho is undergoing final closure. The closure criteria for the Heap Leach Pile (HLP) which contains 23 million tons (21 millions metric tons) of gold ore residues from cyanide leaching operations are the flow and quality of leachate released. Flows meeting the established chemical load criterion can be released to infiltrate without treatment. Combinations of soil and geosynthetic covers and long term treatment were evaluated. Financial life cycle costs analyses including consideration of risk and long term maintenance costs were performed to determine the least cost cover/treatment plant combination and assess the incremental costs of the other alternatives. Decision analyses were performed to evaluate which alternatives would best meet a set of closure objectives. The results were utilized by the Mining Company to select the cover type that best fit its financial goals, internal risk management approach and criteria for minimizing liability.
