The National Research Council (NRC) has issued a report which concludes that for 10 percent of sites in the United States that require groundwater remediation, work is unlikely to be completed within the next 50 to 100 years. The report determines that at least 126,000 sites have contaminant levels in groundwater above those that would allow unlimited use and unrestricted exposure. It estimates that about 10 percent of those sites are complex from a hydrogeological and contaminant perspective. These include Department of Defense and Department of Energy sites as well as sites addressed under the Comprehensive Environmental Response, Compensation, and Liability Act and the Resource Conservation and Recovery Act. The report states that an estimated “cost to complete” of up to $127 billion for these contaminated groundwater sites “is likely to be an underestimate of future liabilities.”

The report also finds that despite significant efforts to remedy contaminated groundwater across the country, some sites, especially complex sites, cannot be remedied to drinking water standards using current technology or technology that appears to be on the horizon. It recommends using more risk assessments to determine when active remediation has reached a plateau and implementing other mechanisms such as ongoing monitoring for those sites that cannot reach drinking water levels.

The report supports fuller exploration of flexible approaches like site-specific risk assessment, incorporation of sustainability factors, determining a reasonable timeframe to reach remedial goals, and choosing the point of compliance for monitoring of groundwater-contaminated sites. It proposes broadening risk assessments to include consideration of short-term risks that result from remediation activities. NRC also suggests that risk assessments consider the potential change of residual risk over time, such as those that may result from future changes in land use, and that risk assessments consider both individual and population risks. Stating that implementation of institutional controls at complex sites may be difficult, the report suggests establishing a “national, searchable, geo-referenced institutional control database” to notify the public of such controls.