The following conclusions and recommendations about this alternative approach are made.

At many complex sites, contaminant concentrations in the plume remain stalled at levels above cleanup goals despite continued operation of remedial systems. There is no clear path forward to a final end state embodied in the current cleanup programs, such that money continues to be spent, with no concomitant reduction in risks. If the effectiveness of site remediation reaches a point of diminishing returns prior to reaching cleanup goals and optimization has been exhausted, the transition to monitored natural attenuation or some other active or passive management should be considered using a formal evaluation. This transition assessment would determine whether a new remedy is warranted at the site or whether long-term management is appropriate.

Five-year reviews are an extremely valuable source of field data for evaluating the performance of remedial strategies that have been implemented at CERCLA facilities and could be improved. To increase transparency and allow EPA, the public, and other researchers to assess lessons learned, more should be done, on a national basis, to analyze the results of five-year reviews in order to evaluate the current performance of implemented technologies. EPA’s technical guidance for five-year reviews should be updated to provide a uniform protocol for analyzing the data collected during the reviews, reporting their results, and improving their quality.

Public involvement tends to diminish once remedies at a site or facility are in place. No agency has a clear policy for sustaining public involvement during long-term management. Regulators and federal responsible parties should work with members of existing advisory groups and technical assistance recipients to devise models for ongoing public oversight once remedies are in place. Such mechanisms may include annual meetings, Internet communications, or the shifting of the locus of public involvement to permanent local institutions such as public health departments.

Although the cost of new remedial actions may decrease at complex sites if more of them undergo a transition to passive long-term management, there will still be substantial long-term funding obligations. Failure to fund adequately the long-term management of complex sites may result in unacceptable risks to the public due to unintended exposure to site contaminants.

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