PRB: Technology Update
	Team Leaders John Doyon 609-633-0713 jdoyon@dep.state.nj.us Kimberly Wilson 803-896-4087 wilsonka@dhec.sc.gov

Permeable reactive barriers (PRBs) have been installed to intercept and treat contaminated groundwater at polluted sites throughout the country. In 2005, ITRC published Permeable Reactive Barriers: Lessons Learned/New Directions (PRB-4) to update previous guidance prepared by the ITRC PRBs Team regarding new development and innovative approaches in the application of PRBs to treat a variety of groundwater contaminants. Since that publication, advances in the PRB field have continued. Iron material PRBs are now widely accepted as a conventional treatment technology, but the evolution of new reactive materials will help the marketplace become more accepting of these more innovative techniques. Proper use of reactive materials technology in PRBs can result in time and cost savings as well as add another technology to the environmental remediation arsenal.

The PRB: Technology Update Team is developing a technical and regulatory guidance document on these advances in PRBs, including the increased use of non-iron reactive materials. For example, biowalls and in situ bioreactors are increasingly employed as a PRB approach to in situ bioremediation. Both are typically installed using mulch and compost materials combined with sand or gravel and may be modified to include amendments to stimulate degradation processes. Biowalls are typically installed as a trench to intercept passive groundwater flow, and in situ bioreactors are located in source zone areas that allow for recirculation of groundwater for greater residence times.

The PRB: Technology Update Team will focus on PRBs that require physically removing subsurface material to install a reactive material that may be used to treat chlorinated aliphatic hydrocarbons (chlorinated solvents), oxidizers (perchlorate and chlorate), explosive and ordnance compounds (RDX and TNT), dissolved metals (hexavalent chromium), nitrates, and sulfates.

The goal of the PRB: Technology Update Team is to provide a technical and regulatory guidance document which discusses advances in these technologies along with additional prove-outs and lessons learned since the previous update (PRB-4). The efforts and output of the PRB: Technology Update Team will help the regulatory community become more familiar with the treatment applicability, installation, performance, and mechanisms of reactive materials PRBs. The PRB technology update will also provide much needed guidance to help regulators and environmental practitioners implement and evaluate plans for reactive materials technology at appropriate sites.