Abstract: During In situ chemical oxidation (ISCO) oxidant solutions are typically delivered into the subsurface for contaminant destruction. Contaminants available to the oxidants, however, are limited by the mass transfer of hydrophobic contaminants into the aqueous phase. ISCO treatments therefore often leave sites with temporarily clean groundwater which is subject to contaminant rebound when sorbed and free phase contaminants leach back into the aqueous phase. Using a combined oxidant-surfactant solution, contaminant delivery to the oxidants can be optimized via desorption and emulsification of the contaminants by the surfactants. EthicalChem’s patented Surfactant Enhanced Product Recovery (SEPRTM) and Surfactant-enhanced In Situ Chemical oxidation (S-ISCO®) are green-chemistry technologies developed to address the source of contamination and effectively treat sorbed, hydrophobic, and free phase contaminants. SEPR is implemented for bulk NAPL (Non-Aqueous Phase Liquid) removal by extraction, where surfactants are injected with low doses of hydrogen peroxide. S-ISCO implementation addresses residual NAPL and soil sorbed contamination by significantly enhancing contaminant contact with the oxidant. This presentation will provide an overview of the SEPR and S-ISCO technologies, followed by an implementation case studies at a coal tar contaminated site in Queens, New York and a creosote site in Delaware.