144
PUBLIC WORKS AND UTILITIES
which would be involved if a replacement airport was built at Chek Lap Kok Island, near Lantau Island.
Drainage and Anti-pollution Projects
Flood protection to urban and rural areas is afforded by stormwater drainage culverts and nullahs. Sewage from developed areas is, in general, collected by separate sewage systems and subjected to various modes of treatment depending on the quality of effluent acceptable in the waters where it is discharged. During the year a number of related projects were undertaken.
Construction of major stormwater culverts and intercepting sewers at Aldrich Bay reclamation at Shau Kei Wan and of sewage pumping stations at Hung Hom and Tsuen Wan started in 1979. River training works at Tung Chung on Lantau Island were completed.
New sewage treatment works at Repulse Bay, Aberdeen, Ap Lei Chau and Tai Po were completed. Construction of sewage treatment works at Tuen Mun and the detailed design of additional sewage treatment facilities at Yuen Long and Tai Po were in progress. Con- sulting engineers continued with the design of the first stage of sewage treatment and disposal works for north-west Kowloon. Construction work for the first stage of the permanent sewage treatment plant to serve Sha Tin New Town progressed satisfactorily. Submarine outfall construction for sewage effluent from Chai Wan, Repulse Bay, Ap Lei Chau, Kwai Chung and Tuen Mun was completed.
The long-term monitoring of the quality of Hong Kong waters to establish pollution levels and trends and to provide data for the timely implementation of sewage treatment facilities continued. A data report summarising all monitoring results to mid-1978 was completed. A technical report discussing the monitoring results was prepared.
About 1,130,000 tonnes of solid waste was treated at the five controlled tipping sites at Sai Tso Wan, Ma Yau Tong, Gin Drinker's Bay, Siu Lang Shui and Shuen Wan. This is an increase of 10 per cent over the previous year's figure. Construction of a replacement tip at Junk Bay was in progress.
A refuse incinerator at Kwai Chung became fully operational in 1979. The plant has a capacity of 900 tonnes a day. Construction of a pilot refuse baling plant at Sai Tso Wan was completed and commissioning started. This is the first refuse baling plant in Hong Kong and it has a capacity of 600 tonnes a day.
The construction of Hong Kong's first full-scale refuse composting plant at Chai Wan was completed. The plant will deal with 240 tonnes of refuse a day and will be capable of a future upgrading to 480 tonnes a day. During the year, consideration was being given to the possibility of building a composting plant at Sha Tin.
Port Works
On Hong Kong Island, construction works for a total of 1,840 metres of seawall were completed in Western District, at Po Chong Wan and Shek Pai Wan in Aberdeen, and at Aldrich Bay. The construction of a second passenger ferry pier at North Point was com- pleted. Work continued on 900 metres of seawall foundation in Western District. Two contracts were let for the construction of a total of 1,450 metres of seawall in Western District and at Quarry Bay.
In Kowloon, a new ferry pier at Hung Hom was completed and put into service. The construction of a section of seawall for Cheung Sha Wan reclamation and Sham Shui Po