The Chairman suggested advancing agenda item 3 as a Member would leave the meeting early.
Agenda Item 3 :EIA for Demolition of Kwai Chung Incineration Plant
(ACE-EIA Paper 16/2001)
2. The Chairman welcomed Mr. David Bloomfield et. al. to the meeting. Dr. David Green gave a brief presentation on the highlights of the EIA findings.
3. In reply to the Chairman's enquiry, Mr. Bloomfield said that the future land-use of the site had not been decided yet. Mr. Brian Ashcroft supplemented that the site was presently zoned as "Government /Institution for Community". It was unlikely for the site to be used for residential purpose due to its proximity to the sewage treatment plant, trunk road and port activities.
4. The Chairman asked whether conventional demolition methods other than the top down method had been considered. In reply, Dr. Green said that they had considered the methods set out in the Draft Code for Demolition Practice in Hong Kong in which most of them were categorized as conventional as they had been tried out in Hong Kong. The blasting method was considered the last resort and it had only been used for the Tsing Yi Chimney which was located in a remote site without many constraints in the surroundings.
5. In response to a Member's question, Dr. Green said that because of the proximity of the sensitive receivers, the determining factor for choosing the demolition method was safety. They had also referred to the Draft Code for Demolition Practice for comparing the environmental impacts of different methods.
6. In reply to a Member's question on the procedures of demolition, Dr. Green said that it had been assumed that two crane shafts would be erected inside the chimney for hoisting and lowering tools and debris. A number of intermediate working platforms would be built within the structure for workers to take down the chimney in 2-meter sections. The bottom 10m would be removed by hydraulic breakers.
Safety of workers
7. A Member said that the number of accidents on work sites indicated a poor standard of safety for workers. He asked about the qualifications or experiences of the scaffolding inspectors. In reply, Dr. Green said that they should be registered inspectors working in accordance with the requirements set out in the Factories and Industrial Undertakings Regulation. A resident engineer would also base on site and, with experienced support staff, would carry out daily supervision of the demolition works, including the checking of the scaffolding.
8. A Member said that building a chimney would cost a lot and enquired about the reason for demolishing the chimney at the moment instead of after a decision on the land-use had been made. Mr. Bloomfield said that the chimney was due to be demolished. It would be too late to start the works when the land-use was determined because the demolition plus remediation works would take about three years.
9. A Member asked how the civil demolition contractor and the Registered Asbestos Contractor (RAC) would work as a team. He was concerned about the safety of the workers on site and enquired about the measures in place to prevent the leaking of the asbestos containing materials (ACM). In response, Dr. Green said the RAC would be responsible for supervising the asbestos removal contractor and would ensure that the demolition works were carried out according to the methods prescribed in the Air Pollution Control Ordinance and the relevant code of practice. Furthermore, the safety of the workers would be regulated by the Occupational Health and Safety Ordinance.
Disposal of soil contaminated with heavy metals
10. Dr. Green referred to a Member's question (at Appendix) and explained that the aim of the proposed Toxicity Characteristic Leaching Procedures (TCLP) test was to identify the correct mixture of cement to immobilize the heavy metals. It should be noted that the contamination evaluation standards adopted were very stringent and were similar to those adopted in Holland for ensuring the safety of groundwater for drinking purposes.
11. Regarding another question raised by a Member about the feasibility of thermally destroying the contaminants and re-using the cleaned soil as construction materials, Mr. Shorthose said that it was not possible to treat the soil by that method given the existence of other co-existing contaminants in the soil.
12. In reply to the Chairman, Dr. Green said that the proposed disposal method had been used in Hong Kong but not in a designated project.
13. In reply to a Member's enquiry, Dr. Green assured the meeting that after implementing the proposed treatment method, there would be no need for the future users of the site to treat the soil again.
14. The Chairman asked whether there were other treatment or disposal methods for soil contaminated with heavy metal. In reply, Mr. James Shorthose said that the idea was to retain on the site materials which could be left on-site after proper treatment and dispose in the landfills those materials which were harmful to retain. Mr. Brian Ashcroft supplemented that the level of contamination of the soil in question was not particularly high. The stringent standard to be adopted in the TCLP test would ensure the immobility of the contaminants before reusing the soil on site. In addition, re-using the treated soil on the site could help save the capacity of the landfill.
Disposal of dioxin contaminated ash
15. A Member noted in the EIA report that the dioxin contaminated ash would be placed in polythene lined steel drum and then disposed of in landfills. She asked whether there were any disposal procedures to follow and enquired about the practice in other countries. In reply, Dr. Green said that they could not find any specific experience in other countries in handling such materials. A TCLP test would be carried out to identify the correct mixture of cement to immobilize the dioxin before sealing it in polythene lined steel drum which acted as an extra precaution to prevent the ash from leaking. Mr. Shorthose supplemented that the contaminated ash would be further tested before they were disposed of in landfills. Also, EPD would monitor and check the results of the TCLP tests.
16. A Member was still concerned about the risk of potential leakage of dioxin and the possible hazards to the landfills. She said that there were specified disposal procedures for such materials in Japan and asked whether the proponent would consider shipping the contaminated ash to Japan for proper disposal. In response, Dr. Green said that the estimated amount to be handled was only 20 m3 which was considered insignificant. If the treated ash waste failed to meet the TCLP tests, it would be delivered to the Chemical Waste Treatment Centre in Tsing Yi for treatment. Mr. Ashcroft said that since the proposed method was a practicable and robust solution, they did not consider it a better option to transfer the materials to other countries.
17. A Member asked whether the project proponent had any idea about the way the ash previously generated by the incinerator was handled. Mr. Michael Tsing replied that it might have been landfilled.
18. A Member felt that more stringent standards should be set for treating dioxin contaminated ash waste and means other than disposal in landfills should be explored to ensure the safety and health of the community.
Landfill gas hazard
19. In response to a Member's question, Dr. Green said that they had carried out a standard qualitative assessment that was adopted in all other landfill gas assessment. On the basis of the assessment, various protection and precautionary measures would be adopted. As regards the assessment of the quantity of gas, it would be undertaken by on-site monitoring.
20. A Member enquired about the "acceptable level" of risks after the proposed site safety practices had been complied with. In reply, Mr. Shorthose said that the assessment of risks was done in accordance with procedures prescribed by EPD. It would be regarded as "dangerous" if the volume of methane would exceed 20% of the lower explosive limit in the ambient air. Mr. Ashcroft emphasized that the landfill gas was not generated by the incinerator and therefore the quantity was unpredictable. Nonetheless, the extent of risks had been assessed.
Follow-up consultancy study
21. A Member asked whether the same consultant could be employed for follow-up consultancy studies of a project. In reply, Mr. Bloomfield said that contracts of infrastructure development would have to go through normal government tender procedures. Mr. Elvis Au explained that the consultant undertaking environmental monitoring and audit would be different from the independent environmental checker. He also said that it was mandatory for project proponents to set up websites for their projects. The EM&A reports and the findings of the independent environmental checker would be made available to the public through the Internet.
22. A Member brought to the attention of the Subcommittee and EPD that her representing organization had noticed a case in which the consultancy study and the environmental checking were done by two teams under the same consultant firm. The Chairman said that that Member's concern was noted.
Recommendation of the Subcommittee
23. The Subcommittee agreed to recommend the EIA report to the Council for endorsement without conditions while noting a Member's urge for more caution in the treatment and disposal of dioxin contaminated waste and that treatment by other chemical waste treatment methods should be actively explored.
Agenda Item 1 : Confirmation of Minutes of 64th Meeting held on 5 November 2001
24. The minutes were confirmed subject to the amendments raised by Miss Alex Yau and Mr. Otto Poon. Agenda Item 2 : Matters ArisingPara. 15: Para. 27 of EIAO GN004/200125. Regarding the agreement at the last meeting that AFCD should revise the wordings in para. 27 of EIAO GN004/2001, Mr. C C Lay reported that the Department would take into account the views of Members and other parties represented in the liaison groups and would circulate the revised draft to the Subcommittee for consideration.