Fluoridation
10.28. Fluoridation continued in all urban areas as well as at Tsuen Wan. Sampling of the water within the distribution system indicated some fluctuation of the fluoride content which was traced to coagulation of the dosing chemical. Coagulation resulted from the humid conditions prevailing and dehumidifiers were ordered for installation at selected stations. The presence of sea water introduced by tankers from the Pearl River also inhibited the effectiveness of the fluoride slightly but the effect was not of sufficient magnitude to warrant any special action.
Salt-Water Flushing Supplies
10.29. Extensions to the distribution systems were carried out at Chai Wan, North Point, Kwun Tong, Wong Tai Sin, Hung Hom, Sham Shui Po, Cheung Sha Wan, To Kwa Wan and the city of Victoria. Work also commenced on the laying of distribution mains at Chung Hom Kok. Additional pumps were installed in the Kai Tak and Tsuen Wan pumping stations to meet increased demands.
Water Emergency
10.30. As previously mentioned, the tanker operation was the principal factor which enabled a piped supply to consumers to be maintained and this was fortunately facilitated by the existence of the main supply tunnel from the Tai Lam Chung reservoir at low level near the shoreline and of pumps and filters of adequate capacity at Tsuen Wan.
10.31. Arrangements were made to use existing berths at the Hong Kong Oil and Caltex Companies' piers at Tsuen Wan and approximately 6,300 ft. of 21"-30" pipelines were laid in approximately 14 days to deliver the water to the pumping station.
10.32. The second berthing point was at the Hong Kong Brewery at Sham Tseng where the Port Works Office constructed dolphins and a further system of large diameter mains was laid to deliver water into the tunnel. A stock of precast piles was available and a design adopted to enable them to be used which permitted the dolphins to be provided in time to prevent undue delay in the build-up of the tanker fleet.
10.33. While the salinity of the water from the Pearl River remained below 600 p.p.m., it could be delivered direct to the filters but evidence was available that it would rise to unacceptable limits from December onwards due to the reduced flow of fresh water in the river. It was therefore necessary to blend the water with water from the Tai Lam
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