Project Summary

After ground breaking ceremony in August 2012, the project started with its first component which was to build a structure for thermal desorption application (IPTD). The project continued with excavation of contaminated soil and sediment and hauling to IPTD for treatment. The IPTD filled with contaminated material was then capped with insulating concrete and other layers as per designed. The final step of project operation was to remove all treated material from IPTD and demolish entire IPTD structure, returning the site back to the airbase.

The Project successfully treated over 94,000m3 of contaminated soil and sediment (from dioxin concentration of input level of above 1,200ppt to below 150ppt); securely landfilled over 68,000m3 of contaminated soil with concentration of below 1,000ppt.

In this project, Tri Viet in association with its partner provided the following services to the US main contractors:

• Construction of the IPTD structure with dimensions of 70m(W) x 105m(L) x 7m (H). The bottom, the wall and also the cap of the IPTD structure were constructed with different layers to ensure the thermal insulation as designed. The insulation layers include 60cm thickness of light weight insulation concrete. On the wall, there were other layers such as 1mm thickness HDPE, inter-locking metal panels. The entire IPTD structure was surrounded by over 28,000 Concrete Mason Unit (CMU) blocks of the dimension 60cm x 60cm x 132cm.
• Excavation, hauling and compaction contaminated soil and sediment: over 120,000m3 of contaminated materials were excavated following the design. Over 2/3 of this excavation volume was treated in IPTD and the rest was landfilled at a location to the southwest of the airbase.
• Support installation/ and removal of the heater cans
• Support the confirmation sampling of the in-pile soil during/post treatment

By the end of the project, a total of 32.4 hectares of “clean�?land was handed over back to the airbase for expansion of Danang International Airport and for other land-use purpose. The project helps minimize the risk of environmental and people exposure to dioxin and in the meantime, it helps “remove Danang out of the list of dioxin contaminated hotspots in Vietnam�? This project was one of the largest and most complicated in its kind with an initial estimation based on preliminary design. The actual volume of soil and sediment requiring removal (excavation) and treatment was higher than original estimate, from 72,900m3 to 162,500m3.

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Project Summary

US Department of Defense (Conference in Hanoi, August 2007) informed that the Phu Cat Airbase was used during
the operation “Ranch Hand�?from June 1968 to May 1970. Main activities undertaken at the airbase included: receiving of fuels, storing and loading of herbicides to aircrafts, and washing of the aircrafts after spraying. The quantity of herbicides used at the Phu Cat Airbase was reported to be 17,000 barrels of Agent Orange, 9,000 barrels of Agent White and 2,900 barrels of Agent Blue. Herbicides were transported by ship to Quy Nhon port, and then by truck to the Phu Cat Airbase. There was considerable spillage of herbicides during storage and use. In addition, used barrels with remaining chemicals were brought to residential areas by soldiers, and were used for various domestic purposes. The dioxin-contaminated area in the Phu Cat Airbase includes the former storage area, the former loading area, and the former washing area, etc. Over time, the chemical contamination has spread to the perimeter areas of the airbase

In Phu cat airbase, the contamination was divided into 4 zones: The storage area (Z3), the buffer zone, the sedimentation zone and Z9 (the southeast and southwest area). The total excavated volume of contaminated soil (5,400m3) was landfilled in a semi-subsurface area with covered with a cap. The landfill design was following all technical requirements of hazardous waste landfill. Especially, the landfill option was selected because it is a low cost solution, compared with other solutions and in the meantime, it still helps prevent dioxin exposure to human and environment.

The landfill is far away from residential area. It was built on an area of 5,600m2 and on an elevation of 30m. The landfill is on the northeast direction to the airbase and about 60m away from internal road. The Center for Environmental Remediation (under Chemical command- MND) was design contractor. Tri Viet and its partner was construction contractor for this landfill. The work that Triviet and its partner performed included not only construction of the lanfdill but also excavation of contaminated materials, hauling to the landfill, compaction and covering the landfill. The completion of this landfill in August 2012 helps remove Phucat airbase out of the list of dioxin contamination hotspot in Vietnam.

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