The National Research Council, an arm of the National Academy of Sciences (NAS), recently released a report entitled, “Alternatives for Managing the Nation’s Complex Contaminated Groundwater Sites.” The report estimates there are more than 126,000 sites in the United States that are still in the process of being cleaned up and have not yet been removed from existing regulatory priority lists, and the estimate of the cost to complete remediation of these sites is between $110 billion and $127 billion. Further, the report estimates that 10% of these sites will not be restored in the next 50 to 100 years due to technological limitations.
These are not necessarily new revelations from NAS, but this report analyzes the future of groundwater remediation efforts and the challenges faced by responsible parties, including the U.S. Army which sponsored the report. The report concludes that when the effectiveness of site remediation reaches a point of diminishing returns (e.g., the reduction in concentration levels off, but the costs remain significant) prior to reaching groundwater cleanup goals, the site should be transitioned to monitored natural attenuation (MNA) or other passive or active long-term management. This determination will based on a formal, transparent evaluation entitled a “transition assessment.” Such an assessment would be similar to a feasibility study. Thus, for such sites, the committee recommends the focus of the remediation resources be on the management of the site to ensure protectiveness for as long as it is necessary (which may be a very long time).
It is helpful that the committee recognizes that in many cases, no existing or reasonably anticipated remedy can achieve groundwater cleanup goals, especially drinking water standards, and requiring additional work remedy that still will not attain groundwater cleanup goals is irrational. The presence of emerging contaminants such as perchlorate and 1,4 dioxane, coupled lowering of drinking water standards make the attainment of such goals even more improbable. Thus, at these sites, resources should be directed at institutional controls and long term management.
The voluminous report contains many other interesting findings. The report recommends that regulatory agencies should adopt new guidance explaining how to consider sustainability in the remedy selection process. The committee also recognized that the nomenclature for the phases of site cleanup and cleanup progress are confusingly inconsistent among public and private parties, including about what it means when a site is “closed.” The report also recommends increasing the role of risk assessment in the remedy selection process.
Michael Kavanaugh, chair of the committee that wrote the report and a principal with Geosyntec Consultants, Inc., stated:
“The central theme of this report is how the nation should deal with those sites where residual contamination will remain above levels needed to achieve restoration. In the opinion of the committee, this finding needs to inform decision making at these complex sites, including a more comprehensive use of risk assessment methods, and support for a national research and development program that leads to innovative tools to ensure protectiveness where residual contamination persists. In all cases, the final end state of these sites has to be protective of human health and the environment consistent with the existing legal framework, but a more rapid transition will reduce life-cycle costs. Some residual contamination will persist at these sites and future national strategies need to account for this fact.”