In response to media enquiries, a spokesman for the Civil Engineering Department (CED) said today (February 5) that all the tender bids for the decontamination of dioxin-contaminated soil at To Kau Wan were for incineration at the Tsing Yi Chemical Waste Treatment Centre (TYCWTC) and none of them included any other treatment method.
"In June 2002, all the six prequalified tenderers had submitted their designs in accordance with the tender requirements for the decontamination of dioxin-contaminated soil at To Kau Wan and the associated collection and disposal of residue for incineration at the TYCWTC," the spokesman said.
"The tenderers were also allowed to elect to submit an alternative design in the tender. However, no alternative designs were submitted by any tenderers," he stressed.
On Greenpeace's suggestion of using non-incineration technology, the spokesman said such technology like Based Catalyzed Dechlorination (BCD) was evaluated but not adopted because of its lower destruction efficiency in comparison with incineration. BCD would also generate five times more by-product residues requiring further treatment, and would result in double-handling and potentially more secondary environmental impacts.
BCD is an emerging technology, that is, one that is in the development and demonstration phase, without a long-standing performance track record.
"Incineration is a proven and very effective technology to treat residues containing dioxin. The residue, after the thermal desorption of the dioxin-contaminated soil in To Kau Wan, will be transported to the TYCWTC for high temperature treatment in a controlled environment in a facility properly designed and equipped to treat such wastes. This method of treatment is internationally recognised as the most effective means based on technology that is well-proven," the spokesman said.
"This treatment method was recommended in the relevant Environmental Impact Assessment Report, which was endorsed by the Advisory Council on the Environment and also approved by the Director of Environmental Protection under the Environmental Impact Assessment Ordinance, following extensive public consultation in early 2002," he said.
During the EIA study for the decommissioning of the former Cheoy Lee Shipyard, CED had assessed various options for treatment of dioxin residues that were generated after the dioxin-contaminated soil went through the thermal desorption process. Both incineration and non-incineration technologies were examined for treatment of the residues.
With adequate spare capacity and state-of-the-art technology including effective air pollution control devices, CWTC can effectively and safely decompose dioxins into harmless carbon dioxide and water vapour.
The CWTC adopts the most stringent international standard for dioxin emission, that is, less than 0.1 nanogramme per cubic metre. The dioxin concentrations of the flue gas from the chimney will be subject to vigorous monitoring to ensure stringent emission standard is met.
Ends/Thursday, February 5, 2004
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