An innovative three step remediation approach has been applied to successfully treat soil and groundwater at a site with a very tight soil matrix. The first step is to pre-condition the tight soil in order to increase its treatability by the second and third treatment steps. The second step utilizes chemical oxidation reactions created by the generation of in-situ free radicals through a sequential application of chemical amendments to the soil matrix. The exothermic reactions not only treat the contaminated groundwater but also desorb contaminants from the tight soil matrix. The third step is a bioremediation polishing step applied to the remaining desorbed contaminant mass. This break through approach avoids Traditional Fenton’s free radical chemical oxidation fate and transport limitations. Fenton’s free radicals are typically not applied in very tight soils since their fate (shelf life) is very limited (minutes and hours). A case history is presented describing the successful field application of sodium persulfate solution (first remediation step), which was subsequently activated by an in-situ application of a Fenton’s Free Radical Process (second remediation step). This break through approach allowed the sodium persulfate sufficient time, which has a fate (shelf life) of about a month, to transport to the source of the groundwater contamination within the tight soil matrix. Bioremediation (third remediation step) was then applied to augment natural attenuation through groundwater recirculation and stimulation of indigenous biological organisms.
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