Environmental Cleanup of Navy Facilities: Adaptive Site Management (NRC, 2003) developed the concept of adaptive site management (ASM) to deal with sites where remedial goals have not been reached after some significant amount of time operating the remedy (the so-called asymptote effect). The hallmark of ASM is doing things while a remedy is ongoing that will inform the process if the remedy fails. The report describes several management decision points at which new information from parallel activities could be incorporated to allow site remedies to be reconsidered over time.
Contaminants in the Subsurface (NRC, 2005a) responded to another trend in hazardous waste remediation—the use of aggressive source removal. Source removal via such technologies as in situ chemical oxidation, thermal treatment, and surfactant-enhanced flushing was often attempted without a clear understanding of whether those actions would in fact remove mass or lead to substantial changes in contaminant concentration in groundwater. The report defined five hydrogeologic settings, based on the degree of heterogeneity and permeability found in subsurface soils. In addition, it created a table for each source remediation technology discussing the extent to which that technology could meet five different goals in each of the five hydrogeologic settings. The goals included mass removal, concentration reduction, mass flux reduction, reduction of source migration potential, and a change in toxicity. The report concluded that available data from field studies do not demonstrate what effect source remediation is likely to have on water quality.
a Although sometimes used synonymously, there is an important difference between the terms remediation and cleanup. Remediation is the “removal of pollutants or contaminants from environmental media such as soil, groundwater, sediment, or surface water for the general protection of human health and the environment” (http://sis.nlm.nih.gov/enviro/iupacglossary/glossaryr.html); it does not imply removal or destruction of all contaminants. Cleanup is the restoration of the affected site to a condition allowing for UU/UE which generally implies meeting drinking water standards in the case of contaminated groundwater. This report primarily uses the term remediation to avoid confusion.
Key Challenges for Subsurface Remediation at DoD Facilities
The DoD has invested over $30 billion to address contamination of the soil and groundwater at military bases in the United States and abroad (OUSD, 2011). Under the Installation Restoration Program, many individual sites have been closed with no further action required. However, at complex sites characterized by multiple contaminant sources, large past releases of chemicals, or highly complex geologic environments, meeting the DoD’s ambitious programmatic goals for remedy in place/response complete seems unlikely and site closure almost an impossibility. The recent