Permeable reactive barriers are rapidly emerging as a new way to treat mobile contaminants in the subsurface, particularly for containing the spread of contaminated groundwater. The technology has experienced an exponential growth in interest and R&D activity in the past few years as the true cost and limitations of pumping and treating groundwater have come to light.

As envisioned, permeable barriers may be emplaced through wells, in trenches, in fractures, or by innovative means such as soil mixing or grouting technologies. The wide spectrum of possible barrier-based treatment includes degradation, sorption, and chemical precipitation. A notable example of the concept is the iron filings "funnel and gate" system that has received wide interest for chlorinated solvent treatment. However, various other applications are being studied in addition to "chlorocarbon" plumes, including petroleum hydrocarbons, metals, and radionuclides.

An overview of the technology will be presented, including a discussion of potential advantages and limitations of the concept, information on engineering and costs, and a summary of experience to date in DuPont and elsewhere.

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