The ZVI-Clay technology is an in-situ method of treating source areas containing VOCs at high concentrations including DNAPL.  ZVI-Clay involves admixing reactive media (zero valent iron) and stabilizing agents (clay) into soils containing chlorinated compounds using conventional soil mixing equipment.  Through mixing, heterogeneous subsurface source zones are transformed into uniform low permeability bodies of soils, contaminants, reactive media, and stabilizing agents.  Soil mixing greatly reduces the need to rigorously delineate contaminant distribution within source zones and overcomes the challenge of delivering reactive media through complex geologic media.

Benefits of this technology include:

physically mixing the iron and clay into the source

    area overcomes many of the shortcomings of other

    remedial methods that arise from heterogeneities in

    the subsurface;

mixing clay into the subsurface physically reduces

    the flux of contaminants out of the source zone;

ZVI (granular iron) has been proven to be effective in

    degrading a wide range of VOCs;

ZVI is not hazardous to handle or use;

ZVI is benign in the environment; and

ZVI been shown to be reactive over long periods.

The ZVI-Clay treatment process is the same reductive dehalogenation process used in ETI’s permeable reactive barrier applications.  Chlorinated compounds in source zones are degraded through this process.  In soils treated by ZVI-Clay, the contaminant mass is reduced by 90 percent every few days to few months.

Stabilizing agents (typically clay) provide multiple benefits in the ZVI-Clay process.  First, admixing clay into the soil results in hydraulic conductivity values similar to those encountered in bentonite slurry walls (<10^-7 cm/s).  This provides source containment.  As such, ZVI-Clay is a “belt and suspenders” technology achieving both source depletion and containment.  Inclusion of stabilizing agents also:

facilitates drilling;

provides a high viscosity delivery fluid (necessary for suspension of the reactive media);

improves the uniformity of subsurface mixing;

reduces inflow of competing electron acceptors (e.g., dissolved oxygen and nitrate);

increases residence time for the reaction to proceed;

enhances capillary rise precluding air entry into treated material above the water table; and constrains adverse migration of dense non-

    aqueous phase liquids.

Tel.: 519.746.2204 · Fax: 519.746.2209 · E-mail: info@eti.ca

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