How zero valent iron chemistry works in permeable reactive barriers — and a field case study where a direct-push mZVI PRB stopped a chlorinated solvent plume.
Zero valent iron (ZVI) has been used to treat contaminated soil and groundwater for more than two decades. Through research, development, and field experience, ZVI technology has become increasingly well understood and widely accepted for treating a broad range of contaminants. Since the installation of the first full-scale permeable reactive barrier in Sunnyvale, California in 1995, more than 200 PRBs have been installed across North America, Europe, and elsewhere.
ZVI treats contaminants through chemical reduction: as the iron corrodes, it donates electrons that break down susceptible compounds abiotically — degrading chlorinated solvents without producing the harmful daughter products (like DCE and vinyl chloride) that incomplete biological pathways can leave behind. The chemistry can be enhanced with carbon, sulfur, and other amendments, which extend and sharpen the treatment. ZVI has been proven against chlorinated solvents, pesticides, energetics, petroleum hydrocarbons, and metals.
The site. A former manufacturing facility with chlorinated solvent and oily waste contamination in shallow glacial till deposits. The chlorinated hydrocarbons — primarily cis-1,2-dichloroethene (cDCE) and vinyl chloride (VC) — continued to leach from the clay till into an underlying sand aquifer.
The problem. A CHC plume formed in the aquifer and extended off-site, moving toward a municipal drinking water supply well.
The solution. A microscale zero valent iron (mZVI) permeable reactive barrier, installed by direct-push technology (DPT), was implemented to intercept the plume and prevent further off-site migration. Direct-push installation allowed the barrier to be placed precisely in the flow path without large-scale excavation.
The takeaway. This is the pattern PRBs excel at: passive, long-term interception of a dissolved plume, with the reactive media doing continuous work as groundwater flows through — no pumps, no ongoing energy input, and treatment longevity measured in years.
Successful barriers come down to media selection, barrier geometry, and an honest accounting of iron demand and longevity. Hepure supports all three — see our PRB design guidance, the purpose-built Ferox PRB granular ZVI, and the fundamentals of ZVI remediation. More field results are in our case studies library.
Planning a barrier? Call 866-727-4776 or request more information — our team can help with media selection, quantity estimation, and design review.