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Advisory Council on the Environment

Status Report on Sand Dredging and Mud Disposal in Hong Kong

(ACE Paper 27/2002)
For information

Purpose

This paper aims at providing a status report to Members on sand dredging and mud disposal in Hong Kong covering the period between February 2002 and July 2002. The last six-monthly status report was issued to Members in February 2002 (ACE Paper 4/2002).

Overview of Marine Fill Sources, Mud Disposal Areas and Major Reclamation Areas

2. The locations of marine fill sources, mud disposal areas and major reclamation areas in Hong Kong are shown in the drawing MFC-001E (Attachment A). Sand dredging at the West Po Toi Marine Borrow Area for the Penny's Bay Reclamation Stage 1 Contract was completed in March 2002. Sand dredging is currently active at the South Tsing Yi Marine Borrow Area only for supplying sand fill for the Container Terminal 9 Project. Disposal of the mud suitable for open sea disposal continues at South Cheung Chau, East of Ninepin, and south of Tsing Yi. The mud requiring confined marine disposal continues to be disposed of at a confined disposal facility located at East Sha Chau.

Marine Borrow Areas

3. Sand dredging at the West Po Toi Marine Borrow Area, which commenced in May 2001, was completed in March 2002. The results of the environmental monitoring and audit (EM&A) programme, which included water quality monitoring at sensitive receivers, dive surveys at impact coral sites and ecological surveys at impact and control sites, indicated that the dredging works have not caused unacceptable impact on the environment.

4. Sand dredging at the South Tsing Yi Marine Borrow Area is progressing smoothly to provide sand fill for the Container Terminal 9 Project. The EM&A programme of the project, which covers the reclamation, comprises water quality monitoring at 34 stations. The EM&A results have so far not indicated unacceptable impact on the nearby sensitive receivers.

Mud Suitable for Open Sea Disposal

5. The open sea floor mud disposal grounds at South Cheung Chau and East of Ninepin are being used for disposal of mud suitable for open sea disposal from various projects in Hong Kong. Mud suitable for open sea disposal arising from the Container Terminal 9 continues to be disposed of at the exhausted sandpits at south of Tsing Yi. The disposal at East Tung Lung Chau's exhausted sandpit has been suspended since April 2001 but this will be resumed in the coming dry season in October 2002. The exhausted sandpit at north of the Brothers had been used to receive dredged mud suitable for open sea disposal from the deepening of East Sha Chau Mud Pit IVc Project until the end of March 2002.

6. The results of water quality monitoring at the above active disposal sites have so far indicated no unacceptable impact on the environment. The monitoring works at the above mud disposal sites will continue to ensure that the impacts on the environment will be kept within an acceptable limit.

7. The environmental assessment conducted by our consultant on the impacts of the proposed year-round open sea disposal of Category L1 sediment in the exhausted sandpits at north of the Brothers is approaching its final stage. This environmental assessment also investigates the effect of the proposed disposal of Category M2 sediment that has passed the biological screening test on the marine environment. Upon completion of the assessment, an EM&A Manual and an Operation Plan will be developed for the proposed disposal operation. We aim to submit the above documents to the EIA-Subcommittee for discussion in the later part of 2002.

Mud Suitable for Confined Marine Disposal

8. Disposal of mud suitable for confined marine disposal from various projects in Hong Kong continues at the East Sha Chau disposal facility with the Container Terminal 9 Project being the main user. With the implementation of a comprehensive EM&A programme and appropriate mitigation measures, the result of the monitoring indicated that the disposal had not caused unacceptable impact on the marine environment.

9. The Strategic Assessment and Site Selection for Contaminated Mud Disposal Study was completed and the ACE was briefed on its findings in July 2001. Following the recommendations of the above study and the advice of the ACE, a consultancy study was commenced in June 2002 to identify the best site and disposal option for a new facility within the Airport East/East Sha Chau area. More information on the progress of this consultancy study will be provided in the next update. We expect that a paper on the best site and disposal option for the new facility will be submitted to the ACE for discussion in early 2003.

Efforts to Reduce Mud Dredging

10. It is Government policy to minimize mud dredging wherever possible, in order to reduce the amount of dredged mud requiring disposal. However, it is unavoidable that some mud must be dredged for certain works including land formation, maintenance dredging for port facilities, flood protection and essential dredging for certain development projects. A Government internal circular on Management of Dredged/Excavated Sediment will be issued soon to minimise mud dredging in government projects.

Attachment

Attachment A: Drawing No. MFC-001E - Marine Fill Resources, Mud Disposal Areas and Major Reclamations

Marine Fill Committee Secretariat
Geotechnical Engineering Office
Civil Engineering Department
August 2002




1Category L: Sediment with all contaminant levels not exceeding the Lower Chemical Exceedance Level as defined under Works Bureau Technical Circular (WBTC) No. 3/2000.

2Category M: Sediment with any one or more contaminant levels exceeding the Lower Chemical Exceedance Level and none exceeding the Upper Chemical Exceedance Level as defined under the WBTC No. 3/2000.

 

 

 

 

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Friday, 28 April, 2006