Use of the inorganic wood preservative chemical chromated copper arsenate (CCA) has resulted in several documented cases of soil and ground water contamination at wood treatment plants due to spills or releases of the treatment chemical. The most significant impact from releases of CCA to the environment is related to hexavalent chromium contamination of ground water. This is due to the relative solubility of the hexavalent form of chromium in ground water and its toxicity. The other metals associated with CCA, copper and arsenic, are generally less soluble and therefore not as mobile as hexavalent chromium under typical environmental conditions. Although hexavalent chromium is readily reduced to less soluble and less toxic trivalent chromium, and natural attenuation of hexavalent chromium in the environment has been documented (Palmer and Puls, 1994), often the volume of CCA released exceeds the natural reducing capacity of the soil. Under this scenario, a plume of ground water contamination by hexavalent chromium develops. This paper discusses various approaches to remediation (clean up) of hexavalent chromium associated with CCA releases to the environment, and focuses on an innovative in-situ (in-place) approach that saves significant time and money.

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