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Advisory Council on the Environment

Status Report on Sand Dredging and Mud Disposal in Hong Kong

(ACE Paper 4/2002)
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 September 2001 and February 2002. The last six-monthly status report was issued to Members in August 2001 (ACE Paper 34/2001).

Overview of Marine Sand Resources, Mud Disposal Areas and Major Reclamation Areas

2. The locations of sand resources, mud disposal areas and major reclamation areas in Hong Kong are shown in the drawing MFC-001C (Attachment A). Sand dredging at the authorized part of the East Lamma Channel Marine Borrow Area (ELCMBA), which commenced in December 2000, was completed in early November 2001. Sand dredging is currently active at two marine borrow areas - West Po Toi is supplying sand fill for the Penny's Bay Reclamation Stage 1 Contract while South Tsing Yi is supplying sand fill for the Container Terminal 9 Project. Uncontaminated mud disposal at South Cheung Chau, East Ninepins, north of the Brothers and south of Tsing Yi continues. Contaminated mud disposal continues at East Sha Chau.

Marine Borrow Areas

3. Sand dredging at the ELCMBA was completed in early November 2001. The results of environmental monitoring indicated that the impact of sand dredging on the water quality was localised and transient. The impact on the hard and soft corals and the seabed organisms was insignificant. With the implementation of the comprehensive environmental monitoring and audit (EM&A) programme and appropriate mitigation measures, the dredging works did not cause unacceptable impact on the environment.

4. The West Po Toi Marine Borrow Area has been supplying sand fill for the Penny's Bay Recalamation Stage 1 Contract since May 2001. The EM&A programme, which includes water quality monitoring at sensitive receivers, twice-weekly dive surveys at impact coral sites and monthly full ecological survey at all impact and control sites, indicated that the dredging works have not caused any unacceptable impact on the environment. Sand dredging at this borrow area is expected to continue in the next few months.

5. 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 any unacceptable impact on the nearby sensitive receivers.

Disposal of Uncontaminated Mud

6. The open sea floor mud disposal grounds at South Cheung Chau and East Ninepins are being used for disposal of uncontaminated mud for various projects of Hong Kong. The disposal of uncontaminated mud at East Tung Lung Chau has been suspended since April 2001. This may resume in the coming dry season in October 2002. The exhausted sandpits at south of Tsing Yi and north of the Brothers are being used for disposal of dredged uncontaminated mud from the Container Terminal 9 Project and the deepening of East Sha Chau Mud Pit IVc Project respectively.

7. The result of water quality monitoring for the uncontaminated mud disposal has so far indicated no unacceptable impact on the environment. The monitoring works will continue, and mitigation measures will be implemented where necessary, in order to ensure that the impact on the environment is kept within an acceptable limit.

8. The environmental assessment to study the impacts of year round disposal of uncontaminated mud (Category L1) in the exhausted sandpits at the north of the Brothers is progressing. The environmental assessment study will also investigate the effect of the disposal of Category M2 sediment that passed the biological screening test on the marine environment. An EM&A Manual and an Operation Plan will be developed. It is anticipated that the environmental assessment report would be completed by April 2002 and be submitted to the EIA-Subcommittee for discussion in mid- 2002.

Disposal of Contaminated Mud

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

10. With the current rate of disposal, it is anticipated that capacity at East Sha Chau will be exhausted by 2007. Following the recommendations of the Strategic Assessment and Site Selection for Contaminated Mud Disposal Study and the advice given by the ACE on 21 July 2001, action has been initiated to employ consultants to conduct a site search study. The study, which will include an environmental assessment, aims to identify the best site and option for a new facility for the disposal of contaminated mud within the Airport East and East Sha Chau areas. A plan of the study area is attached (Attachment B). This is a designated project under the Environmental Impact Assessment Ordinance (EIAO). The EIA Study Brief for the project was issued on 29 January 2002 (EIA Study Brief No. ESB-095/2001). Further details of the Study Brief can be found at the EIAO Register of EPD's web site at http://www.info.gov.hk/epd/eia/register.

Attachment

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

Attachment B: Drawing No. MFC/018 - Study Area for New Contaminated Mud Marine Disposal Facility

Secertary, Marine Fill Committee
Geotechnical Engineering Office
Civil Engineering Department
February 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