LAND, PUBLIC WORKS AND UTILITIES
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Environment and Food for the management of construction and demolition (C&D) materials and utilisation of land-based fill reserves. The CED provides administrative and technical support to both committees, which comprise representatives of various government bureaux and departments.
In 2001, about 66 million cubic metres of marine sand were used for reclamation projects; about 26 million cubic metres of it were imported from nearby regions in the Mainland. To reduce future use of marine fill and help preserve the limited marine fill resources in Hong Kong, more use will be made of inert C&D materials as fill for reclamation.
During the year, about 7.9 million cubic metres of C&D materials were generated by local construction activities. Of this, about 6.6 million cubic metres were re-used as fill in reclamation projects, including those at Tseung Kwan O Area 137, Pak Shek Kok, Tung Chung, Tseung Kwan O Town Centre and Tuen Mun Area 38.
The PFC continues to explore ways to minimise the generation of C&D materials and reduce the disposal of C&D materials at landfills. For example, the construction industry has been encouraged to adopt construction methods and materials that reduce the generation of C&D materials at source. Sorting facilities were established at Tseung Kwan O Area 137 and Tuen Mun Area 38 to recover suitable inert C&D materials for re-use or recycling.
The MFC maintains a Fill Management Database on fill requirements, mud disposal and surplus excavated materials from major public and private projects. Its purpose is to help the construction industry co-ordinate sources of fill materials and make the best use of surplus materials. All project data is available on the Internet. The CED manages mud disposal facilities. In 2001, about 40 million cubic metres of uncontaminated mud and six million cubic metres of contaminated mud were generated from various works projects. Uncontaminated mud was disposed of at open sea floor disposal grounds or exhausted marine sand borrow pits. Contaminated mud was placed in specially selected and closely monitored exhausted sand borrow pits, which were then capped with uncontaminated mud on completion of filling to isolate the contaminants from the environment. The use of exhausted sand borrow pits for mud disposal is preferred as it has the dual benefits of providing much needed disposal capacity and at the same time restoring the seabed to its natural profile and
state.
In connection with the management of Hong Kong's fill resources and mud disposal capacity, the CED, on behalf of the MFC, continues to undertake a series of geotechnical, environmental and ecological studies and monitoring to examine the effect of the dredging and disposal activities, and to investigate possible ways to avoid or minimise the impact on the marine environment.
Hydraulic Studies
Coastal engineering projects may affect the flow of water, sediment transport and wave activity in Victoria Harbour. To minimise any adverse effects, the CED employs sophisticated computer hydraulic models to analyse the likely effects of proposed schemes, both during and after the construction phases, to ensure that they are within acceptable limits. The models are used for reclamation layout planning, design of marine structures, waterway studies and assessment of future maintenance dredging requirements.