Impacts of DNAPL Source Treatment: Experimental and Modeling Assessment of the Benefits of Partial DNAPL Source Removal
NATIONAL RISK MANAGEMENT RESEARCH LAB ADA OK
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Once released into the subsurface environment, dense nonaqueous phase liquids DNAPLs serve as long term sources of groundwater contamination, and are a significant risk to water resources. Containment or removal are the two basic strategies that can be used in the management or restoration. Restoration can be pursued either through in-situ destruction or extraction, and a number of aggressive DNAPL remediation techniques have been developed for these purposes. Complete DNAPL removal may be possible at some sites, but because of technology limitations and financial restrictions, partial mass depletion may be the most likely end result of aggressive source treatment at most DNAPL contaminated sites. When it is not practical or economically feasible to achieve complete DNAPL mass depletion, it must be determined if the aggregate benefits of partial DNAPL mass depletion are sufficient to reduce risks to an acceptable level, and if the costs associated with this partial depletion are justified by the benefits received. This report summarizes research conducted to address these issues with the primary objective of the research being the development of a scientifically defensible approach for assessing the long-term environmental impacts benefits of DNAPL removal from source zones. The technical approach used to achieve this objective was to 1 characterize the relationships between DNAPL mass reduction, contaminant mass flux, and plume behavior, and 2 to use this information to develop a strategy for assessing the benefits of DNAPL source remediation. As discussed in Section 3, three lines of investigation were employed in our technical approach field site demonstrations Section 3.1, laboratory experiments Section 3.2, and numerical and analytical modeling Section 3.3. Using a combination of these applications allowed evaluation of varied hydrogeological settings and remediation scenarios.
- Physical Chemistry
- Hydrology, Limnology and Potamology
- Water Pollution and Control
- Environmental Health and Safety