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PRELIMINARY ANALYSIS OF ALTERNATIVES FOR THE LONG TERM MANAGEMENT OF EXCESS MERCURY
Citation:
Kaiser, G., J. Vierow, J. DiMarzio, L. Brown, L. Deschaine, AND P M. Randall*. PRELIMINARY ANALYSIS OF ALTERNATIVES FOR THE LONG TERM MANAGEMENT OF EXCESS MERCURY. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-03/048 (NTIS PB2003-106599), 2003.
Impact/Purpose:
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Description:
This report describes the use of a systematic method for comparing options for the long term management and retirement of surplus mercury in the U.S. The method chosen is the Analytical Hierarchy Procedure (AHP) as embodied in the Expert Choice 2000 software. The goal, criteria, and intensities were established and inputted into the Expert Choice software. A limited scope decision-analysis was performed. Two(2) general types of treatment technologies were evaluated( stablization/amalgamation and selenide). These were combined with four(4) disposal options: a) disposal in a RCRA-permitted landfill; b) disposal in a RCRA-permitted monofill; c) disposal in an engineered belowground structure; and d) disposal in a mined cavity. In addition, there were three storage options for elemental mercury: a) storage in an aboveground RCRA- permitted facility; b) storage in a hardened RCRA-permitted structure; and c) storage in a mined cavity. Altogether, eleven(11) options were chosen for examination with the decision-making tool. Results were generated of a base-case analysis together with variations on the results assuming that only benefits(non-costs criteria) or only costs are important. Results show that the landfill options are preferred independent of the treatment technology. The storage options rank next followed by the treatment technologies combined with monofills, bunkers, or mined cavities. The landfill choice was the least expensive option and this clearly outweights the relatively unfavorable ranking if costs is a factor. If the costs are not an important factor, however, the three storage options occupy the first three places in the "non-costs only" ranking. The standard storage option ranks least favorably of all against risks (public, worker, and susceptibility to terrorism). Although it is considered that none of the options has a high risk, the fact that the standard storage option would have large quantities of elemental mercury in a non-hardened, aboveground structure suggested that the risks are somewhat higher than those for other options. Storage options also received unfavorable rankings because of high operating costs. This arises for two reasons: a) if storage continues for a long period, even relatively small per annum costs will add up; and b) storage is not a means for permanent retirement of bulk elemental mercury and it is assumed that ,sooner or later, a treatment and disposal technology will be adopted, which adds to the cost. This is enough to drive the storage options out of first place in the base-case rankings. However, the analysis would support continued storage for a short period (up to a few decades) followed by a permanent retirement option. This would allow time for the treatment technologies to mature.
This limited scope decision-analysis compared options for the retirement of surplus mercury. Future work could include: a) Involve additional experts or stakeholders in the process of assigning weights to the various criteria, b) the alternatives considered in this report were limited to elemental mercury.( additional alternatives could be considered for mercury-containing wastes), c) Revisit the available information periodically to determine if changes in criteria, or changes in intensities, are required, d) consider performing a formal uncertainty analysis utilizing Monte-Carlo-based techniques.