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THE ENVIRONMENT

Island South and Tsuen Wan-Kwai Tsing areas, and of the unsewered areas in the Tolo catchment, were initiated.

The principal sewage treatment works providing biological treatment are in Sha Tin, Tai Po, Shek Wu Hui, Sai Kung and Yuen Long, with seven smaller plants at Hei Ling Chau, Shek Pik, Tung Tau, Stanley Fort, Ah Kung Kok, Sha Tau Kok and Mui Wo. Primary treatment is employed at Cheung Chau, and screening plants are provided at other locations. In the current 10-year sewage treatment and disposal programme, priority is given to extensions of the existing works in Sha Tin, Tai Po, Shek Wu Hui and Yuen Long, to cope with increases in population growth and industrial production.

Principal achievements in the provision of municipal sewage treatment and disposal facilities during the year have been the completion of the Sham Shui Po screening plant, the Tsing Yi sewage disposal plant, the Sha Tau Kok sewage treatment works and the Sai Kung sewage treatment works. Several sewage disposal projects began, such as screening plants at Shau Kei Wan and To Kwa Wan, a scheme to provide major new sewerage infra- structure for the north-west New Territories, and a similar scheme to provide treatment and disposal facilities for Kowloon. Several other sewage disposal works are under construction in various parts of the territory. The major ones are Wan Chai (East) screening plant, North Point screening plant, and Pillar Point sewage treatment works stage II.

Plans have been finalised for the disposal at sea of sludges from sewage and water treatment works. From 1990, some of these sludges, which are currently disposed of at landfills or discharged to watercourses or coastal waters, will be dumped in the sea at a site east of Waglan Island. Construction work for the docking and loading point for the sludge-dumping vessel is expected to start in 1989.

Solid waste arisings are forecast to more than double over the next 15 years, so arrangements need to be made now to ensure that adequate facilities exist for their disposal. To this end a comprehensive Waste Disposal Plan is being drafted, setting out the proposed type, quantity and location of waste treatment and disposal facilities that will be required up to the turn of the century, together with a timetable for their construction. The proposed strategy involves a move away from incineration and small local landfills to a system of transfer stations feeding a small number of very large landfills.

Planning work was completed and detailed design began on two of the major long-term disposal facilities, the West New Territories Landfill and the North-east New Territories Landfill. Environmental Impact Assessments (EIA's) completed for both these projects have recommended, among other things, the engineered containment of highly polluting leachate (decomposed waste liquid residues). A proposal to treat leachate from the North-east New Territories Landfill at Shek Wu Hui sewage works is currently under investigation. Planning work is proceeding for the disposal of leachate from the West New Territories Landfill via the North-west New Territories effluent outfall at Urmston Road. Planning for a third landfill to serve the South-east New Territories is underway. These three landfills will provide sufficient disposal capacity for Hong Kong's needs over the next 20 years.

Encroachment of development has virtually surrounded several small closed landfills in north-east Kowloon. A study of the potential for landfill gas migration beyond site boundaries was completed at Sai Tso Wan Landfill. To mitigate the risks associated with gas movement, recommendations were made for on and off-site gas control systems. Proposals were also developed for the recovery of landfill gas as an economic energy

resource.

A contract was signed for Hong Kong's first transfer station. A facility will be constructed in east Kowloon with the capacity to handle 1 800 tonnes of (mainly domestic)

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THE ENVIRONMENT