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.
Intended land-use
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.
Demolition method
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.
Asbestos removal
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
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