Integrated DNAPL Source Strategy
	Team Leader Naji Akladiss 207-287-7709 naji.n.akladiss@maine.gov

Dense, nonaqueous-phase liquids (DNAPLs), which are chlorinated organic compounds, are one of the most widespread and high-risk types of subsurface contamination. Chlorinated organic solvents were produced on an industrial scale beginning in the 1930s. They were widely used for cleaning and degreasing in a number of industries, including chemical manufacturing, aerospace, semiconductors, electronics, commercial and retail dry cleaning, and pest control. The same properties that led to their use in industry also led to their widespread use at Defense and Energy department facilities. By the 1970s scientists began to recognize the exposure risk posed by chlorinated organics.

Chlorinated solvents share certain characteristics that combine to produce a lingering problem even when present in small amounts (liters). They are chemically stable; thus, they do not degrade under typical subsurface conditions. They have low solubility, causing them to persist for decades or centuries. They are immiscible with water, so they form separate “phases,” and they have relatively high densities, so they migrate downward, polluting a large thickness of an aquifer. They are also very toxic.

As a result, many sites—industrial facilities, Superfund sites, military bases, DOE facilities, and dry cleaners—are contaminated with chlorinated solvent DNAPL. The exact number of DNAPL sites is unknown but is undoubtedly very large. At one time DNAPLs were seen as an almost unsolvable problem; however, several technologies to deplete DNAPL sources have been developed and successfully demonstrated. Unfortunately, even when using these methods, a single technology cleanup typically cannot achieve regulatory criteria, and the benefits of removing only a portion of the source contamination remain uncertain. Efforts to address DNAPL contamination continue within the regulatory community, and decision makers are faced with costly attempts to achieve reasonable cleanup goals.

An “Integrated DNAPL Source Strategy” (IDSS) is needed to address the technical and regulatory issues involved in a strategic approach to DNAPL source zone remediation. The ITRC Integrated DNAPL Source Strategy Team, formed to develop an IDSS, expects to publish a technical and regulatory document by the end of 2010 . The IDSS will assist decision makers in determining the site conditions that are conducive to source zone cleanup. It will also facilitate strategies for selection of technologies (or combinations of technologies) to deplete the contamination and accelerate remediation. Equally important, the IDSS will also help establish realistic expectations for cleanups and in measuring progress towards achieving expectations. The IDSS will assist decision makers in understanding the challenges faced and the tools available to meet those challenges, in overcoming the regulatory and public perception hurdles that often make source cleanups more difficult and contentious than necessary, and in making informed remedial decisions based on established performance and desired results.