The dioxin contamination of soil in Da Nang was worse than expected, experts said at a conference reviewing the cleanup on Tuesday.
The event, organized by the National Steering Committee for Post-war Clearance of Ordnance and Toxic chemicals and USAID, shared some details on dioxin cleanup at the Da Nang International Airport, a U.S. air base during the Vietnam War.
Pham Quang Vu, head of the Air Force and Air Defense’s Military Science Division, said earlier calculations had underestimated the actual contamination at the airport.
He said the actual amount of contaminated soil is 162,500 cubic meters and not 72,900 cubic meters as earlier estimated.
Anthony Kolb, chief of USAID’s environmental remediation unit, explained that experts only took soil samples from the surface and from that determined the depth to which the dioxin could have penetrated.
The dioxin had percolated three meters deeper than expected, he said at the conference in Da Nang.
Vu said the miscalculation could be attributed to the fact this was the first time this particular technology was used to remove dioxin from the soil on such a large scale. It involves heating the contaminated soil while covering it in concrete.
The finding could help make future dioxin assessments more accurate, especially at another ongoing cleanup project at the Bien Hoa Air Base in the southern province of Dong Nai. Bien Hoa is considered one of the worst dioxin-contaminated spots, with some 850,000 tons of soil feared contaminated.