Management of Sand Dredging, Fill Resources and Disposal of Mud-Excavated Materials
(without Attachments A&B)
(ACE Paper 35/2000)
This paper aims at briefing Members on the work of the Marine Fill Committee and the latest information on sand dredging and mud disposal activities in Hong Kong.
The Marine Fill Committee (MFC) is responsible for identifying and managing the supply and demand of marine fill resources for development projects, and for the provision and management of disposal capacity for dredged mud. Since 1991, about 220 million cubic metres (Mm3) of marine sand have been extracted from the seabed of Hong Kong for formation of new land, and about 190Mm3 of uncontaminated mud and 22Mm3 of contaminated mud have been disposed of in designated disposal areas. The MFC also maintains a comprehensive database on fill requirements, mud disposal and surplus excavated materials from major projects.
We use empty marine borrow pits for its disposal, thereby solving a disposal problem while at the same time restoring the hydrodynamic regime and the natural seabed which can then be recolonised. Dredged contaminated mud is disposed of at the special contaminated mud disposal pits at East Sha Chau. Locations of sand resources, mud disposal areas and major reclamation areas are shown on the plan at Attachment A.
During the last decade, the former Fill Management Committee (FMC) identified and managed many marine borrow areas and mud disposal sites. The last two years has been a period of relative inactivity but now major dredging works have commenced for the Penny's Bay Reclamation and Container Terminal 9 projects. The following sections aim at giving Members an update on the two projects.
Penny's Bay Reclamation Project Stage 1
Penny's Bay Reclamation Stage 1 requires about 66Mm3 of sand fill which will come from Hong Kong waters and from Mainland waters. The northern part of the East Lamma Channel Marine Borrow Area (ELCMBA) is allocated to the project for sand extraction. Comprehensive environmental assessment and public consultation were conducted before the ELCMBA was authorized by the Executive Council in 1993.
The Penny's Bay project requires disposal of about 0.06Mm3 of contaminated mud and about 48Mm3 of uncontaminated mud. All the contaminated mud will be disposed of at the disposal facilities at East Sha Chau. The uncontaminated mud will be disposed of in Hong Kong waters at the disposal areas east of Tung Lung Chau, east of Ninepins, north of Lantau, south of Cheung Chau and also in Mainland waters. Attachment B gives an indication of the sand supply and mud disposal for the project.
Mud dredging at Penny's Bay and disposal at the above disposal areas commenced in June 2000. Overburden removal and sand dredging at ELCMBA are scheduled to commence in September and October 2000 respectively and are expected to be completed by around March 2001.
A comprehensive environmental monitoring and audit (EM&A) programme is in place for the dredging works and currently no adverse impacts have been identified.
Container Terminal 9
The Container Terminal 9 (CT9) project requires about 34Mm3 of sand fill which will come from the south of Tsing Yi (STY) and west of Sulphur Channel (WSC) marine borrow areas and possibly areas in Mainland waters. Details are shown in Attachment B.
About 4Mm3 of contaminated mud from the terminal area and about 2.6Mm3 from navigation channels will require disposal. The contaminated mud is being disposed of at East Sha Chau and at a designated area south of Erzhou (Dangan Island) in Mainland waters. The project will also generate about 30Mm3 of uncontaminated mud for disposal. MFC has allocated capacity at the disposal areas south of Tsing Yi, east of Ninepins and south of Cheung Chau. The initial disposal at south of Tsing Yi, as shown in Attachment B, will be into the old sand borrow pit left after formation of Container Terminal 8. Later disposal here will be into empty CT9 sand borrow pits and possibility in South Cheung Chau.
Dredging of contaminated mud commenced in mid July 2000 and disposal was initially at East Sha Chau and since 1 August 2000, disposal has been in Mainland waters. Uncontaminated mud dredging and disposal at the south of Tsing Yi will commence soon, and sand dredging at the STY marine borrow area is anticipated to commence in October 2000.
A comprehensive EM&A programme is in place for the dredging works and currently no adverse impacts have been identified.
Further Reports to the Advisory Council on the Environment
We will report further to the Advisory Council on the Environment on sand dredging and mud disposal activities.
Marine Fill Committee Secretariat
Geotechnical Engineering Office
Civil Engineering Department