BHP maintains inactive copper mines in Arizona. BHP recently started a formal evaluation forpermanent closure of these inactive mines. The evaluation included development of a wide range ofclosure options for tailings facilities including embankment slope, spillway channel, and tailingsimpoundment in an effort to account for the global paradigm shift in how tailings facilities should beoperated and closed.The study team used two-staged Multi-Criteria Decision Analysis (MCDA) to evaluate closureoptions based on environmental, technical, social and cost differentiators and to select a preferredsource remediation and engineering design option for the detailed closure design phase. The studyteam developed a range of technical and non-technical variables to characterize the relativeperformance of each reclamation option. The inputs for each variable were calculated and normalizedto an index scale. Each variable (i.e., decision parameter) was then assigned a relative importancebased on a workshop exercise. The final MCDA calculation and sensitivity analyses ranked theclosure options to guide final decision-making.
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