U.S. Department of Energy, Office of Environmental Management (DOE-EM), 13 Aug 2019

DOE-EM is using 760 tons of iron filings recycled from the automotive industry to treat groundwater contaminated by solvents in a section of an aquifer beneath the Savannah River Site (SRS). The filings will be mixed with a food-grade, starch-like material and injected into 22 wells installed at 12-ft intervals. High-pressure injection will create fractures in the subsurface rock, creating space to be filled by the mixture. Upon completion, a 23,000 ft² water-permeable wall consisting of iron filings will extend ~135 ft bgs at its deepest point and 264 ft long. As groundwater flows through metal wall, the iron filings neutralize the dissolved-phase solvents. This type of treatment wall can be installed at greater depths than the trench-emplaced permeable reactive barriers built at the site in the past. The technology also allows for precision placement, enabling SRS to intercept the contaminated groundwater plume in a narrow zone as it travels along an old subsurface stream-bed channel. The treatment wall is scheduled for completion in November 2019. https://www.energy.gov/em/articles/srs-uses-recycled-iron-treat-contaminated-groundwater