A treatability study (the Study) was conducted in 2008 to determine the effectiveness of either in situ chemical oxidation (ISCO) or in situ chemical reduction (ISCR) to reduce residual concentrations of organochlorine pesticides and xylenes in saturated soils at an industrial site (Site). Amendments to be studied included EHC(R) (an Adventus ISCR product based on zero-valent iron (ZVI)), iron-catalyzed sodium persulfate and base-catalyzed sodium persulfate (to study ISCO). Baseline analysis identified 12 organochlorine pesticides above screening levels in soils with the highest concentration being heptachlor at 310 mg/kg. Total xylenes concentrations were 565 mg/kg. The laboratory analysis of the contaminants in groundwater indicated that only 0.004% of total xylenes and only 0.0003% of heptachlor were in the dissolved phase. The disparity between the dissolved phase and adsorbed phase data is the reason that the Study was focused on the saturated soils. Based on the results of the treatability study, ISCR using EHC? Was not an effective treatment amendment for pesticides in saturated soil at the Site. However, the base-catalyzed persulfate showed a 90% reduction in the total xylenes and an 87% reduction in pesticides after the 20-day test period indicating that ISCO was successful for treatment of the saturated soils.
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