7.23. The more important mainlaying projects were:
(a) 1,198′ of 27" dia. and 24" dia. steel mains as outlet mains for the Tai Po Road Service Reservoir. These were laid in conjunction with the road work for the Tai Po-Castle Peak road link.
(b) 1,250′ of 24" dia. steel main in Tai Kok Tsui Road to improve supplies in the area.
(c) 805' of 24" dia. steel main in Lok Shan Road to extend the outlet from Ma Tau Wei Service Reservoir.
(d) 856' of 18" dia. cast iron main in Yen Chau Street to improve the supplies in Sham Shui Po.
(e) 1,112' of 18" dia. cast iron main in Po Kong Village Road as part of the Tsz Wan Shan Service Reservoir outlet main.
(f) 1,040′ of 12" dia. cast iron main in Ki Lung Street to improve pressures.
Service Reservoirs
7.24. All service reservoirs were cleaned and sterilized and inlet and outlet valves overhauled as required.
Catchwaters
7.25. The severe typhoon season caused numerous landslides. These principally affected the Shek Pik and Tai Lam Chung catchwaters. In the case of the former 140 ft. of catchwater lining collapsed but temporary protective measures were taken and the flow maintained after only minor interruptions. Permanent repairs were eventually effected in all cases, with the exception of a blockage on the Shek Pik catchwater where permanent repair work was still in hand at the end of the year.
Water Treatment Plants
7.26. Fluoridation was maintained at all plants serving the urban areas as well as Tsuen Wan and Yuen Long at the rate of 0.7 parts per million until the 1st November. It was then increased to 0.9 p.p.m. and maintained at this figure until the end of the year.
7.27. When cholera is present in the Colony a chlorine residual of 1 p.p.m. at consumers' taps is desirable and with normal chlorination, this is only achieved by the uneconomical addition of chloride of lime at service reservoirs. Experiments were carried out on the use of ammonium-sulphate to 'fix' the chlorine dosage in order to give the desired strength of residual chlorine and yet not to make the taste of chlorine so noticeable. The independent distribution systems at Repulse Bay, Sai Wan and Yuen Long were chlorinated in this manner for periods of approximately 2 months in each case. The results, although not conclusive appeared to be satisfactory. These experiments are to be continued.
77
7.23. The more important mainlaying projects were:
(a) 1,198′ of 27" dia. and 24" dia. steel mains as outlet mains for the Tai Po Road Service Reservoir. These were laid in conjunction with the road work for the Tai Po-Castle Peak road link.
(b) 1,250′ of 24" dia. steel main in Tai Kok Tsui Road to improve supplies
in the area.
(c) 805' of 24" dia. steel main in Lok Shan Road to extend the outlet from
Ma Tau Wei Service Reservoir.
(d) 856' of 18" dia. cast iron main in Yen Chau Street to improve the supplies
in Sham Shui Po.
(e) 1,112' of 18" dia. cast iron main in Po Kong Village Road as part of the
Tsz Wan Shan Service Reservoir outlet main.
(f) 1,040′ of 12" dia. cast iron main in Ki Lung Street to improve pressures.
Service Reservoirs
7.24. All service reservoirs were cleaned and sterilized and inlet and outlet valves overhauled as required.
Catchwaters
7.25. The severe typhoon season caused numerous landslides. These principally affected the Shek Pik and Tai Lam Chung catchwaters. In the case of the former 140 ft. of catchwater lining collapsed but temporary protective measures were taken and the flow maintained after only minor interruptions. Permanent repairs were eventually effected in all cases, with the exception of a blockage on the Shek Pik catchwater where per- manent repair work was still in hand at the end of the year.
Water Treatment Plants
7.26. Fluoridation was maintained at all plants serving the urban areas as well as Tsuen Wan and Yuen Long at the rate of 0.7 parts per million until the 1st November. It was then increased to 0.9 maintained at this figure until the end of the year.
p.p.m. and
7.27. When cholera is present in the Colony a chlorine residual of 1 p.p.m. at consumers taps is desirable and with normal chlorination, this is only achieved by the uneconomical addition of chloride of lime at service reservoirs. Experiments were carried out on the use of am- monium-sulphate to 'fix' the chlorine dosage in order to give the desired strength of residual chlorine and yet not to make the taste of chlorine so noticeable. The independent distribution systems at Repulse Bay, Sai Wan and Yuen Long were chlorinated in this manner for periods of approximately 2 months in each case. The results, although not con- clusive appeared to be satisfactory. These experiments are to be continued.
77
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