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Advisory Council on the Environment

Management of Sand Dredging, Fill Resources and Disposal of Mud-Excavated Materials
(without Attachments A&B)

(ACE Paper 35/2000)
For discussion

Annex II

Purpose

Management of Inert Construction and Demolition Material

Background

Construction and demolition (C&D) material is a mixture of inert and organic material arising from site clearance, excavation, construction, refurbishment, renovation, demolition and road works. The inert portion comprising rocks, concrete, asphalt, rubbles, bricks, stones and earth is known as public fill and is suitable for reuse in reclamation and site formation works. Some of it can also be recycled for use as construction materials. The organic C&D material comprising bamboo, plastic, timber and packaging waste is known as C&D waste. It is non-recyclable and should be disposed of at landfills. Over 80% of the C&D material produced locally is inert.

  1. Between 1991 and 1999, the amount of C&D material produced annually by the local construction industry increased by more than 75% from about 7.7 million tonnes to 13.5 million tonnes. In other words, in 1999, we needed to handle an average 37,110 tonnes of C&D material daily. Among them, 29,220 tonnes (78.7%) were public fill and were reused in public filling areas (a designated part of a development project that accepts public fill for reclamation purpose). The remaining 7,890 tonnes (21.3%) were a mixture of public fill and C&D waste and were disposed of in landfills. Information on C&D material generation and their use as public fill between 1991 and 1999 is shown in Attachment C MSWORD.

Public Fill Strategy

  1. The limited capacity in the existing landfills in Hong Kong makes it necessary for us to identify measures to divert C&D material from landfills. The reuse of the inert C&D material for reclamation would also reduce the required dredged or imported sand for land formation. The current strategy adopted is as follows :
    1. Maintaining a well-managed public filling programme with sufficient public filling areas and barging point at convenient locations
       
    2. Encouraging sorting of mixed C&D material
       
    3. Encouraging reuse and recycling of C&D material
       
    4. Avoiding and minimising C&D material through better design and construction management

Public Filling Programme

  1. The Public Filling Programme monitors the demand and provision of capacity in reclamation projects to accommodate the public fill. The programme faces both long and short term problems. First, it is not always possible to match the demand for public fill with the available supply. The demand for public fill depends highly on the programme of individual reclamation projects. Where the demand exceeds the supply, project proponents would likely import or extract marine sand so as not to delay the reclamation works. This, however, is actually a waste of the scarce public filling capacity. On the other hand, when the supply exceeds the demand, it would be necessary to adopt temporary measures, such as using public fill to surcharge newly reclaimed land to accelerate the settlement. Such surcharge material would have to be removed to other reclamation projects later.
     
  2. Second, we are running short of public filling areas. At present, they are located at Tseung Kwan O Area 137, Pak Shek Kok and Tung Chung. The available public filling capacity provided by the approved reclamation projects is shown in Attachment D. We expect these project to provide sufficient public filling capacity till mid-2002. While other reclamation projects are being planned for receiving public fill, securing approval for these projects is becoming increasingly difficult because of the general sentiment against reclamation. Moreover, even if projects can proceed after public consultation and revised planning, the reclamation programme would have to be squeezed to mitigate the time lost. Project proponent would prefer the use of imported sand instead of public fill whose availability is more certain.
     
  3. Third, transportation of public fill by trucks to remote public filling areas create environmental and traffic problems. To alleviate these problems, we have been providing barging points in a number of districts. These barging points have incorporated special features to minimise environmental nuisance to nearby residents, such as fully paved compounds, water sprays for dust suppression, enclosed unloading halls to contain noise and dust, perimeter walls and planters to soften the visual impacts. There are off-street vehicle queuing areas to alleviate the burden on adjoining roads.

The Way Forward

  1. We need to make good use of the available capacity in public filling areas, lest the pressure will be shifted towards the three strategic landfills, which also have a finite capacity and life.
     
  2. In addition to the regular quarterly meetings of PFC, the Public Filling Works Progress Meetings are held to monitor the public filling activities under various contracts. The Public Filling Planning & Co-ordination Meetings are held to keep public filling as an important element in the planning of the imminent development projects.
     
  3. We are actively considering the setting up of "Fill Bank" to provide better regulation of public fill demand and supply. However, the fill bank requires a large piece of land with an area in the order of 60 hectares, and hence much would depend on the timeframe for the long-term and short-term developments of the land available.
     
  4. We are aware that, in the long term, provision of public filling capacity through reclamation for land development is unable to cope with the demand. The Government would need to look for long term outlet in order not to let the C&D material generated by the construction industry to become a burden of our community.

Public Fill Committee Secretariat
Civil Engineering Department
September 2000

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