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EPA Introduces Comprehensive Web Site on Cleanup of DNAPLs
For the first time, comprehensive information about the cleanup of dense nonaqueous-phase liquids (DNAPLs) at hazardous waste sites is now available at a single place online (http://cluin.org/DNAPL). This Web site was developed as the result of a recommendation by the EPA Ground Water Task Force. This initial phase of the development of the DNAPL Web pages addresses the most common DNAPL contaminants: chlorinated ethenes (e.g., tetrachloroethene and trichloroethene) and multi-component wastes (creosotes, coal tars, and heavy oils). Future expansion of the Web site may include ethers, halogenated alkanes, polychlorinated biphenyls, and other chemicals that form DNAPLs.
DNAPLs are chemicals or chemical mixtures that are heavier than, and only slightly soluble in, water. Contamination by DNAPLs can be difficult to clean up, because they can move through soils and groundwater until they are blocked by a resistant layer that allows the liquid to pool. DNAPL soil residuals and pools become slowly dissolving sources of groundwater and soil vapor contamination. EPA estimates that DNAPLs are likely to be present at 60% of Superfund sites.
CLU-IN’s DNAPL pages are part of the CLU-IN Web site’s Contaminant Focus series. The DNAPL pages contain over 1,000 references related to DNAPL. For each individual contaminant, the material is organized in several categories: Policy and Guidance, Chemistry and Behavior, Environmental Occurrence, Toxicology, Detection and Site Characterization, and Treatment Technologies. The Web site will be continuously updated with new information as it becomes available.
The main focus of the Web site is on cleanup of DNAPL source zones. The site covers the full range of potential DNAPL remediation technologies: bioremediation, containment, direct and multiphase recovery, in situ flushing, in situ oxidation, in situ reduction, permeable reactive barriers, soil vapor extraction and air sparging, solidification/stabilization, source area excavation, in situ and ex situ thermal treatment, and in situ treatment trains. For more information about the Web site, contact: Linda Fiedler, U.S. EPA at fiedler.linda@epa.gov or (703) 603-7194 .
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