Members of the Kwai Tsing District Council today (February 16) were briefed by an Independent Expert Assessor (IEA) on his report on monitoring the incineration of dioxin-containing residues at the Chemical Waste Treatment Centre (CWTC) in Tsing Yi from January 5 to 9, 2005.
"According to the report submitted by the IEA, Prof Jonathan W C Wong, analysis of samples taken on January 6 and 8 revealed that the concentration of dioxin in stack emission was 0.0004 ng/cubic metre on average, well below the prevailing international standard for incinerator dioxin emissions of 0.1 ng/cubic metre," a spokesman for the Civil Engineering and Development Department (CEDD) said.
Meanwhile, the IEA's monitoring result on the concentration of dioxin in kiln bottom ash was 1.53 ng/kg in average, far below the most commonly acceptable soil contamination criteria of 1,000 ng/kg.
"Given the very low concentrations of dioxins in the stack emission and kiln bottom ash during the incineration period, the IEA concluded that the incineration process at CWTC was effective and environmentally safe in destroying the dioxin-containing residues, with no additional dioxins loading to the environment," the spokesman said.
The IEA's monitoring results on average ambient dioxin concentration at five locations in Kwai Tsing areas ranged from 0.090 to 0.126 pg/m3, higher than the baseline monitoring results which were in the range of 0.010 and 0.100 pg/m3 obtained between November 2003 and October 2004. However, the result fell within the range of dioxin level of 0.035 and 0.345 pg/m3 recorded by the Environmental Protection Department in Tsing Yi, Central and Tsuen Wan during the past five years.
The IEA pointed out that the relatively higher dioxin level in ambient air was very likely due to the periodical increase in pollution levels in winter months, adding that the emission during the incineration process was not the cause.
"We agree with the IEA's recommendation that with the implementation of the stringent monitoring measures as being adopted in previous incinerations, it would be safe for the CWTC to proceed with the next incineration," the spokesman said.
"We will continue to maintain high transparency in the remaining transportation and incineration operations and will update the Kwai Tsing District Council on the progress from time to time," he stressed.
Since the trial incineration on November 26, 2004 complied with all stipulated requirements, approval was granted by the Director of Environmental Protection for incineration of the remaining dioxin-containing residues. About 22 tonnes of dioxin-containing residues were transported from To Kau Wan in Lantau to CWTC on January 4 for incineration from January 5 to 9, 2005.
The IEA's brief report can be viewed at CEDD's website at http://www.cedd.gov.hk/eng/topics/idcr/index.htm.
Ends/Wednesday, February 16,2005