Cleaning up Agent Orange residue in Vietnam

Published in the dossier of December 2019

Due to the use of Agent Orange during the Vietnam War (1955-1975) the soil in certain areas are still contaminated with herbicides and dioxin and represents a highly toxic element for the population and the environment. In 2012, the Vietnam Ministry of Defense and the United States Agency for International Development launched a project to treat 87,000 m3 of soils and sediments near Da Nang airport. The American company Cascade teaming up with Veolia was awarded the project using the only technology capable of meeting the cleanup standards with the least environmental impact: in-pile thermal desorption.

It involves heating the soil to 335°C for several months so that the dioxins are vaporized and thereby available for extraction and treatment.In concrete terms, a pile structure 100 meters long and 70 meters wide and 8 meters high was built on airport land. Initially, 50% of the soil was transported there by truck. Once the pile was filled, 1,252 heating wells were installed in the soil. The structure was then covered in order to be able to treat the gaseous effluent in situ. Liquid effluent was also collected for treatment. After ten months, the soil could be used as filler material for Da Nang airport. The process was repeated for the other half of the material. The objective was ultimately fulfilled and similar projects could be launched.

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Soil remediation: a second life