Dense Nonaqueous Phase Liquids

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The DNAPLs Team began in 1999 to foster a better understanding of the applicability, cost, and limitations of technologies for characterizing and remediating dense non-aqueous phase liquids. DNAPLs are a significant problem to groundwater supplies when released as discarded industrial solvents or waste. Once released into the subsurface, DNAPLs exist as residual droplets, or ganglia, in the unsaturated zone and, depending on the nature of the release, can form insoluble pools in the saturated zone. Because of these characteristics, conventional remediation and characterization technologies have been mostly unsuccessful in removing substantial amounts of these contaminants.

As its first major task, the team produced a technology overview that includes descriptions of current technologies and parameters for their use, limited cost and performance data, case studies, and related regulatory issues. The team next produced a regulatory overview "DNAPL Source Reduction: Facing the Challenge (DNAPLs-2)" that examines the current regulatory climate for deploying technologies to efficiently treat DNAPL source zones. The report outlines the pros and cons of partial source removal and challenges assumptions about the infeasibility of removing DNAPLs from certain geological settings where recent advances have made significant source reduction more feasible and cost-effective. Facing the Challenge acknowledges the technical difficulties and uncertainties surrounding DNAPL source zone reduction and supports further research to study the impacts of partial source zone mass reduction on groundwater quality and remediation timeframe.

The DNAPLs Team produced two technical/regulatory guidance documents on DNAPL characterization and surfactant/cosolvent flushing called “An Introduction to Characterizing Sites Contaminated with DNAPLs (DNAPLs-4)“ and “Technical and Regulatory Guidance for Surfactant/Cosolvent Flushing of DNAPL Source Zones (DNAPLs-3)”. They also produced a case study/overview document on thermal treatment technologies. Internet-based training courses based on the two technical/regulatory guidance documents were also developed by the team.

The ITRC DNAPLs Team operated from 1999-2004.