A recent feature article in Environmental Science & Technology (ES&T) highlights the important practical lessons learned for improving dense non-aqueous phase liquid (DNAPL) source zone remediation based on a decade of work supported by SERDP and ESTCP. Chlorinated solvents, in the form of DNAPLs, are widespread groundwater contaminants that are difficult to remediate and represent a significant environmental liability for DoD.

Written by Dr. Hans Stroo, a technical advisor to SERDP and ESTCP, with support from SERDP and ESTCP staff, as well as several leading experts in the field, the article discusses the advances in source zone characterization and remediation that have occurred. Research, including studies funded by SERDP and ESTCP, has produced a better understanding of the physical, chemical, and biological constraints to achieving complete restoration. Key lessons learned are outlined in the article. Research also has shown that different technologies are needed for different times and locations and that deliberately combining technologies may improve overall remedy performance. Guidance is now available to help site managers select technologies and develop reasonable expectations for treatment.

Challenges, however, still remain, particularly at sites with complex sources zones and geologic settings. The article finds that “the most important idea to arise from the past decade of research, and the most contentious, has been the recognition that the scientific community may not currently have the ability to develop technologies to restore all contaminated groundwater sites.” Long-term management of these subsurface contaminants may be the reality for many DNAPL sites.

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