A pilot scale test for a process combining in-situ chemical oxidation using H2O2 solution with biodegradation was performed to remove TPH from a diesel contaminated military site. In batch experiments, when 20% H2O2 solution was used for TPH contaminated soil, TPH removal efficiency was 63.5%. Batch experiments investigating biodegradation by adding indigenous microorganisms in pre-H2O2-treated soil were also performed, and TPH removal efficiency of biodegradation was 48.5%, showing an improvement of 19.4% by biodegradation even after chemical oxidation. For a pilot scale feasibility test, a site contaminated with diesel (2.5 m x 2.7 m x 1 m) in Korea was selected, and five injection wells and one extraction well were installed in the site. After 0.3 pore volumes of 17.5% H2O2 solution flushing for 15 days, TPH removal efficiency of the site was 51.5%. Seven days after the H2O2 solution flushing was finished, a mixed indigenous microorganism cultured solution (43 L) was injected into the wells two times. After the injection of the cultured solution, the average concentration of TPH in the site decreased to 777 mg/kg, showing that an additional 19.6% of TPH was removed by biodegradation (total TPH removal efficiency: 71.1%). (C) 2012 Elsevier B.V. All rights reserved.