PUBLIC UTILITIES AND PUBLIC WORKS
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to provide salt water for flushing at resettlement estates and other private properties in the vicinity of the estates. The work entails the building of eight service reservoirs, two dams and seven pumping stations, and the laying of approximately 9,000 feet of 15-inch diameter pipe and 55,000 feet of 18-inch diameter pipe. After the schemes have been completed, it will be possible to supply about 20,000,000 gallons of salt water a day for flushing and air-conditioning. Fire hydrants are being installed on the salt water mains and, in this way, much needed fire fighting facilities will also be provided. For the same purposes consideration is also being given to the possibility of extending the existing salt water mains in the Central District of Victoria.
Work was continued during the year on the Tai Lam Chung Scheme. Contracts were let for the construction of three more service reservoirs and for about seven miles of catchwater chan- nels. About 10,000 feet of 30-inch diameter trunk main was laid. More contracts would have been let for catchwater channels, but there was strong objection from villagers in the Yuen Long area, who feared that the catchwaters would intercept their irrigation water. Work was delayed until the villagers could be convinced that the catchwaters would be beneficial to them and their farms, and that the Government would do everything possible to safe- guard the water needed for irrigation purposes.
A new dam is to be constructed to flood the Shek Pik Valley on the south coast of Lantau at an estimated cost of $220,000,000. It will hold 5,350,000,000 gallons of water and will be the biggest, as well as the most costly, so far constructed in the Colony. Preliminary investigations started as long ago as November 1954. A preliminary report indicated that the nature of the sub-soil near the valley mouth where the dam would have to be built was such as to make construction of a conventional-type dam either extremely costly or perhaps even impossible. The report went on to recommend that experiments should be carried out on the stabilization of porous strata by injecting into them a mixture of clay, cement and a varying quantity of other chemicals to make the porous materials impermeable to water. A team of engineers arrived in 1957 to conduct the experiments, which proved entirely successful, and a report was received in June 1958 that the building of a dam was a practical proposition. A contract was