PUBLIC WORKS AND UTILITIES
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At Plover Cove, Hong Kong's largest impounding reservoir, there were 215 million cubic metres of water stored at the beginning of 1976, compared with 181 million cubic metres the previous year. Inflow during the summer months ensured that salinity of the impounded water remained at a low level, which at the end of the year was 76 ppm. The quality of the abstracted water remained satisfactory through- out the year.
Some 84 million cubic metres of water were piped from China to Hong Kong in the supply period from October 1, 1975 to August 10, 1976. Agreement was reached with the Bureau of Water Conservancy and Hydro-Electric Power, Kwangtung Province, to increase the annual supply from 84 million to 109 million cubic metres with effect from October 1, 1976. The supply period was reduced and it is now from October 1 to July 31.
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Demand for water increased by 12.3 per cent in 1976 compared with the previous year-primarily due to the rapid recovery of Hong Kong from the worldwide reces- sion. Average consumption throughout the year was 1.1 million cubic metres a day compared with 0.9 million cubic metres a day in 1975. A total of 405 million cubic metres of potable water was consumed, compared with 361 million cubic metres in 1975. In addition, 78 million cubic metres of salt water for flushing were supplied- 15.4 per cent more than in 1975.
Work progressed satisfactorily at High Island Reservoir in the New Territories. Leakage through the permeable zone of the east sea cofferdam was brought under control by grouting and the construction of a temporary earth bund between the cofferdam and the main dam. This earth bund enabled dewatering of the main dam foundation, so permitting foundation preparation to proceed prior to complete sealing of the leakage through the cofferdam. It is estimated that the need to carry out these additional measures will result in a delay of 14 months in completion of the reservoir works.
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Construction of the east dam core and the supporting rockfill commenced, and the west dam was built almost to its final elevation. Construction of seven of the eight lowland pumping stations was substantially completed. Most of the main tunnel system was commissioned and the yield from the associated intakes was fed into Lower Shing Mun Reservoir, making a useful extra contribution to total resources. The two additional clarifiers at Sha Tin treatment works were commissioned and uprating of the filters from 800 000 to 1.1 million cubic metres a day was almost completed. The construction of the 96 000-cubic-metre service reservoir at Lion Rock progressed satisfactorily.
Work on the 182 000 cubic metres a day desalting plant near Tuen Mun was almost completed. The first of the six units was subjected to a 180-day performance and reliability test, in accordance with the contract. But tests of the remaining five units were reduced to 30 days due to staff shortages and in the interests of economy, having regard to the favourable reservoir storage position. After completion of the tests, one unit remained in service for the remainder of the year. A total of 7.3 million cubic metres of water was produced and pumped into the supply system.