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ANALYSIS OF ALTERNATIVES FOR THE LONG TERM MANAGEMENT OF EXCESS MERCURY
Randall*, P M. ANALYSIS OF ALTERNATIVES FOR THE LONG TERM MANAGEMENT OF EXCESS MERCURY. Presented at 7th International Conference on Mercury as a Global Pollutant, Ljubljana, Slovenia, 6/27-7/2/04.
This paper describes a systematic method for comparing options for the long-term management of surplus elemental mercury in the U.S., using the Analytic Hierarchy Process (AHP) as embodied in commercially available Expert Choice software. A limited scope multi-criteria decisionanalysis was performed. Two (2) general types of treatment technologies were evaluated (stabilization/amalgamation and selenide), combined with four (4) disposal options: a) hazardous waste landfill; b) hazardous waste monofill; c) engineered below-ground structure; and d) mined cavity. In addition, three storage options for elemental mercury were considered: a) aboveground structure; b) hardened structure; and c) mined cavity. Alternatives were evaluated against criteria that included costs, environmental performance, compliance with current regulations, implementation considerations, technology maturity, potential risks to the public and workers, and public perception.
Considering non-cost criteria only, the three storage options rank most favorably. If both cost and other criteria are considered, then landfill options are preferred, because they are the least e:xpensive ones. Storage options ranked unfavorably on cost because: a) even relatively small per annum costs will add up over time; and b) storage is a tempoary solution and, sooner or later, a treatment and disposal technology will be adopted, which adds to the cost. However, the analysis supports continued storage for a short period (up to a few decades) followed by permanent retirement when treatment technologies have matured.
Suggestions for future work include: a) involving additional stakeholders in the process, b) evaluating alternatives for mercury-containing wastes rather than for elemental mercury only, c) revisiting the analysis periodically to determine if changes are required, d) conducting uncertainty analyses utilizing Monte-Carlo-based techniques.