83
Filters.
This practice, although considerable use has frequently been made of it when flood water was available, is purely an emergency measure and can only be used for a few months each year. It should therefore be dispensed with and the maximum requirements provided in a more uniform manner.
40. The last "Line of Communication" is that carrying a supply from the Shing Mun Valley situated on the Mainland. In this case the water, being already filtered, is supplied directly to a service reservoir in the Botanical Gardens. It is conveyed to this point by means of 24" dia. land mains on the Mainland and in the City, these being connected by the 12′′ and 18" dia. Cross Harbour Pipe Lines.
Condition of "Lines of Communications"
Eastern.
41. The Tytam Tunnel is in good condition and its future life is practically indefinite.
42. The Bowen Road Conduit was constructed about 50 years ago and is a good example of the construction of its time but it has already given good service and nears the end of its economic life. In view of these reasons and its great importance to the City supply the present condition of the Conduit gives rise to
some concern.
43. The raw water main from the West end of this Conduit to Elliot Filters is in good condition but delivery through it is restricted by the 12" dia. section which comprises nearly half its length.
Western.
44. These lines of communication are in good condition and are of sufficient capacity to convey the limited resources.
Mainland.
45. The two Cross Harbour Pipe Lines form the only vulnerable section of this line of communication. Recent examinations of these pipelines reveal that the 12′′ main laid in 1929-30 has now nearly reached the limit of its useful life. Corrosion has so affected the metal that in the event of a fracture of the pipeline it is doubtful if reinstatement could be effected. This pipe however has given excellent service and at a time of more or less emergency was originally estimated to have a life of not more than ten years. The replacing of this main may therefore have to be undertaken at any time now. Examination of the 18" main shows that corrosion of the metal is also taking place so that this main is also in need of early attention.
Future changes in delivery of bulk supplies.
Island.
46. Future increase in consumption will arise from two main causes namely (a) general increase per capita due to improvement in the standard of hygiene and (b) the development of further building areas.
47. The former will result in an increase in the bulk supplies to the present distributional areas.
48. In the case of (b) it is anticipated that expansion will take place chiefly in the Eastern District particularly in the vicinity of North Point whose only source of water supply is from the Tytam Valley.
49. As the Eastern resources are now fully developed the area which they can supply will diminish in extent and will also tend to move in an Easterly direction. Similarly the area supplied from the Western resources will tend to move in a Westerly direction. Bulk supplies of increasing amount will therefore be required in the Central area of the City and these will have to be provided from the Mainland.