Advisory Council on the Environment

Report of the 60th Environmental Impact Assessment Subcommittee Meeting

(ACE Paper 29/2001)
For discussion


At its 60th meeting held on 9 July 2001, the Subcommittee considered three papers, namely, the Strategic Assessment and Site Selection Study for Contaminated Mud Disposal, Penny's Bay Development-EIA Study for Decommissioning of Cheoy Lee Shipyard and the Status Report on Sand Dredging at West Po Toi Marine Borrow Area.


2. Members are requested to note the comments and recommendations of the Subcommittee on the three subjects, particularly the recommendation that the paper on Strategic Assessment and Site Selection Study for Contaminated Mud Disposal be discussed at full Council meeting on 23 July 2001.


Strategic Assessment and Site Selection Study for Contaminated Mud Disposal
(ACE-EIA Paper 6/2001)

The Study

3. The contaminated mud pit at East Sha Chau will be exhausted by late 2007. At present, there is too much uncertainty to identify a management option for the long term (post 2010) but planning for the intermediate period of 2007 to 2010 should start now. The Strategic Assessment and Site Selection Study for Contaminated Mud Disposal (the Study) was commissioned to (a) provide an analysis of viable methods of disposal of contaminated mud and (b) to identify and evaluate suitable sites on the basis of the characteristics and constraints of the viable options as an intermediate measure for 2007 to 2010.

Disposal options

4. Contaminated mud disposal options include contained aquatic disposal (CAD), confined disposal facility (CDF) and special treatment/disposal. CAD, the system currently in use in Hong Kong involves filling a seabed pit with contaminated mud and capping it with uncontaminated material such that the contaminated mud is isolated from the surrounding environment. CDF are near shore or artificial island diked containment facilities which serve to isolate contaminated dredged material but extend up to and possibly above sea level. For materials requiring special treatment, they will go through a process of physical or chemical stabilization and will subsequently be disposed at either a CAD or CDF.

Site options

5. The Study identifies a total of 20 sites within Hong Kong waters which have the potential to locate one of the contaminated mud disposal options. Although a CDF has potential in the long term, it is not considered suitable for the 2007-2010 period. After a series of screening with regard to the sites' suitability against environmental, engineering and planning considerations, the number of strategies/sites is reduced to seven CAD strategies in North Brothers, East Sha Chau, Airport East, Airport West, Hei Ling Chau, Shek Kwu Chau and Southern Waters. The potential constraints at the seven strategies are further evaluated and the strategy of developing a CAD at Airport East is considered to be less constrained and, in terms of environmental ranking, is regarded as the most suitable option. For details, please refer to ACE-EIA Paper 4/2001 attached.

Views and Recommendations of the EIA Subcommittee

6. At the Subcommittee meeting, Members' discussion focused mainly on the reason for adopting an intermediate measure instead of a long-term strategy; the present position of a long-term strategy; whether there are other engineering methods that will reduce or even avoid dredging of contaminated mud; whether marine disposal is commonly adopted in overseas countries and, if an intermediate CAD for 2007-2010 is required, the reason for selecting Airport East instead of East Sha Chau.

7. Members had reservation on the intermediate measure and considered it not only unsustainable but might incur adverse environmental impacts in the long run. They preferred to leave contaminated mud in place as far as practical. Furthermore, Members considered that more options such as a low growth option and a high growth option on mud arising should be provided in the analysis.

8. As far as the intermediate measure is concerned, the proponent clarified that changes had taken place that had considerably reduced the certainty of the forecast of contaminated mud arising. It is therefore not prudent at this time to commit to a disposal option for the long term. While there should be sufficient information in one or two years' time to identify a long-term strategy, there is now a pressing need to identify an intermediate disposal facility for the years 2007 to 2010 because the implementation of a CAD, including the EIA process, design and construction will take about five years. Early planning is required otherwise fast tracking of the project will be required later.

9. On the question of a CDF as a long-term strategy, the proponent pointed that CED was conducting a study on the feasibility of co-disposing dredged and inert construction and demolition materials. An artificial island CDF would be examined under this study.

10. As far as reduction of dredging of contaminated mud is concerned, the proponent indicated that Works Bureau Technical Circular 3/2000 was being revised to require even more justification for dredging of mud, especially contaminated mud. However, there were projects such as tunnels, navigation channels, river training and maintenance dredging for which removal of the seabed is unavoidable. Such projects contributed to about 50% of the contaminated mud arising.

11. On the method of marine disposal in overseas countries, the proponent indicated that CAD is used in the US while CDF is used in the Netherlands.

12. Members were unclear about the environmental benefits of Airport East in comparison with East Sha Chau. The project proponent clarified that Airport East was much less frequented by the Indo-pacific Humpbacked Dolphin. Strong resistance would be expected if further expansion were planned in the areas more commonly used by the Dolphins.

13. To sum up, the project proponent explained that the purpose of the submission was to seek Members' view on the proposal to conduct an EIA on a short-term CAD at Airport East. While Members did not consider an intermediate CAD option at the Airport East site a non-starter, they did have reservation on an intermediate strategy as against a long-term strategy. In addition, they considered it inappropriate to endorse a specific site for the conduct of an EIA. Members recommended that the subject be referred to the full Council for consideration.

EIA Study on the Decommissioning of Cheoy Lee Shipyard
(ACE-EIA Paper 5/2001)

14. Decommissioning of Cheoy Lee Shipyard (CLS) is a designated project under the EIA Ordinance. When the Council considered the EIA report on the Northshore Lantau Development Feasibility Study in April 2000, Members were concerned about the possible land contamination of the CLS site. Against this background, the Administration made a commitment that no works within CLS, except for investigation works necessary for the decommissioning of the EIA study, should commence before completion of the decommissioning EIA study and an environmental permit obtained from Director of Environmental Protection.

15. Asbestos surveys conducted in December 2000 and April 2001 confirmed the existence of asbestos-containing materials (ACM) on the building superstructures of CLS. As asbestos is hazardous to health, it is essential that asbestos removal and abatement works at CLS be carried out at the earliest opportunity. It is assessed that the asbestos abatement works would not affect the ground soil and if it is carried out with appropriate mitigation measures is unlikely to cause adverse environmental impacts.

16. The project proponent would apply to Director of Environmental Protection under section 5(11) of the Ordinance for permission to apply permit direct for the proposed asbestos removal work. The proposed work will need to comply with all relevant environmental standards and guidelines.

17. As for the decommissioning EIA study, it is progressing on schedule. It is expected that the study will be completed in November 2001 and will be submitted to the Council at the end of the year or the beginning of next year. Decommissioning work will likely commence in mid 2002.

Views and Recommendations of the EIA Subcommittee

18. At the Subcommittee meeting, Members supported the proposal to undertake ACM abatement and removal works ahead of the completion of the decommissioning EIA study. The discussion focused mainly on whether the removal works would affect the ground soil of the shipyard and the surrounding environment, whether the buildings of the shipyard will be removal or not and how the works would be carried out.

19. The project proponent indicated that the ACM abatement and removal works would not affect the ground soil of the shipyard. The floor slabs of the buildings would be covered with a heavy-duty impervious membrane to prevent soil contamination. Removal of ACM is controlled under the Air Pollution Control (ACO) Ordinance. A contractor registered under the ACO Ordinance will undertake the necessary works. The contractor will need to comply with relevant environmental standards and safety guidelines so that the workers concerned will be protected and that the dust and particles generated during the work process will not affect the outside environment. The project proponent also confirmed that only the roofing and ACM would be removed. The buildings concerned would not be affected.

Status Report on Sand Dredging at West Po Toi Marine Borrow Area (WPTMBA)
(ACE-EIA Paper 6/2001)

20. In November 2000, the Marine Fill Committee allocated West Po Toi as a supplementary sand source to the Penny's Bay project (WPTMBA had been used before between 1993 and 1995). The allocation was made with a condition that a focused assessment should be carried out to establish whether there would be adverse cumulative impact related to other concurrent works.

Impacts during the first two weeks of dredging

21. The major concern of the sand dredging work has been the potential impact of sedimentation on some high ecological and conservation value table coral community which are about two kilometres east from the WPTMBA. Results of the EM&A from 28 May up to 4 June 2001 indicated no adverse impacts resulting from the dredging. On 5 June, a high level of turbidity and suspended solids were recorded at North East Po Toi. Sedimentation and bleaching on some table corals at the same site was recorded on 7 June. Dredging work stopped on 8 June. On 18 June, a dive survey jointly conducted by AFCD and the EM&A team confirmed that the sedimentation of corals recorded on 7 June had disappeared and except for about 3% of the previously sedimented area, there had been no damage.

22. The proponent indicated that despite a thorough review of all available data it was not possible to draw definite conclusions as to cause of the sedimentation. The Independent Environmental Checker employed by the proponent has recommended that dredging can be resumed with the control provided by EM&A and its event and action plan.

Views and Recommendations of the EIA Subcommittee

23. At the Subcommittee meeting, Members raised questions on the ecological value of the table coral; the basis of the decision graphs and action limit level; the risk of relying on the EM&A to monitor the impact of dredging, the effectiveness of the EM&A Manual; in addition to dive survey whether it is possible to install automatic under-water device to provide quick monitoring; what triggers the cessation of dredging and resumption of dredging.

24. On the ecological value of table coral, representative from AFCD said that according to literature, table coral had a restricted Indo-Pacific range and was considered a high-latitudinal coral, being relatively rare in lower tropical locations.

25. As regards the decision graphs and action limit level, the proponent said that they were based on protocols adopted for the Great Barrier Reef. However, as such protocols were not previously applied to local coral community and more precautionary criteria had been adopted.

26. Members considered that despite the EM&A Manual, there were still elements of risk because by the time the impact was detected, damage might have been done to the corals. On this point, the proponent clarified that the EM&A Manual included a step-by-step action plan and there were different event levels so that mitigation measures could be made progressively. In fact, the proponent had further improved the standards in the Manual and all parties involved in the project, including the relevant enforcement authorities had accepted the EM&A Manual dated 9 July. The proponent agreed to provide the updated Manual to Members for reference.

27. The AFCD representative supplemented that they had offered advice/suggestions in drawing up the EM&A Manual, in particular the event action plan for monitoring table corals. Subject to the implementation of the measures and the event and action plans, they were satisfied that EM&A Manual dated 9 July would be adequate and effective. The coral event action plan would be subject to review and revision throughout the EM&A process as more data were gathered. In addition, because of the specialist nature of the assessment of coral health, AFCD would employ an independent coral specialist to audit the dive survey results.

28. On the installation of automatic device, the proponent said that such automatic device might be able to monitor the turbidity level but not the more important suspended solid level. Moreover, such a device would not be able to survive the strong water current in the area.

29. On the trigger of cessation of dredging, as laid down in the event and action plan in the EM&A, the proponent said that according to the revised EM&A Manual dated 9 July, dredging would cease if there were greater than 25 % change in the cover of live coral or number of live coral colonies.

30 On resumption of dredging, the proponent clarified that the Administration had accepted the recommendation of the Independent Environmental Checker that dredging could resume with the control provided by the EM&A Manual and its event and action plan. Dredging could resume as soon as possible and perhaps even on 10 July subject to the availability of suitable dredgers. The proponent agreed to provide to the Subcommittee regular and frequently updates on dredging and the EM&A initially on a one or two weekly basis.

EIA Subcommittee Secretariat
July 2001




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