National Academy of Science Findings: At least 126,000 sites across the country have residual contamination at levels preventing site closure, and this number is likely an underestimate. About 10 percent of the 126,000 sites are estimated to be complex from a hydrogeological and contaminant perspective. No information is available on the total number of sites with contamination in place above levels allowing for unlimited use and unrestricted exposure, although the total is certainly greater than 126,000. Approximately ten percent of Superfund facilities affect or significantly threaten public water supply systems, but similar information from other programs is largely unavailable. The estimated "cost to complete" for sites that have not reached closure is $110-127 billion. This number is highly uncertain and likely to be an underestimate of future liabilities. For the suite of currently available remedial technologies, significant limitations persist that make widespread achievement of drinking water standards unlikely at most complex groundwater sites in 50-100 years. There are limited data with which to compare remedial technology performance.
Additional independent reviews of remedial technologies are needed to summarize their performance under a wide range of site characteristics. As our understanding of chemical toxicity and dose-response relationships evolves, there could be changes in drinking water and indoor air standards for important contaminants, such as the solvent TCE. Such changes could potentially lead to determinations that existing remedies at some hazardous waste sites are no longer protective of human health and the environment. Consideration of the vapor intrusion pathway is needed at all sites where volatile organic chemicals (VOCs) are present in the soil or groundwater aquifer. As a precaution, vapor mitigation could be built into all new construction on or near known VOC groundwater plumes.
The original URL: http://dels.nas.edu/Report/Alternatives-Managing-Nation/14668
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