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50. The Mainland already makes a considerable contribution to the City's water needs and in view of this being the only source from which increasing require- ments can be obtained, the importance of the security of the Cross Harbour Pipelines, already great, will gradually become more and more vital.
Proposed Alterations, Improvements and Extensions to Lines of Communication,
Island.
51. In view of the above and the present condition of these pipelines the follow- ing proposals are made :-
(a) The present 18" main should be provided, as early as possible, with a more
permanent protective coating to arrest corrosion.
(b) As the 12" main may fail at any time and as supplies of a greater amount than the capacity of the present 18" main are now required, a new 18′′ main should be laid as early as possible.
(e) In view of their vulnerability, the pipelines should be protected by a covering or other expedient to guard against any reasonable possibility of damage or dislocation by shipping.
52. In order to provide more flexibility in emergency, to relieve the Eastern resources and to make fuller use of the present supplies available from the Main- land, the water from the latter will need to be delivered to a higher level than at present, i.e. to Albany. This will necessitate (d) the extension to Albany Service Reservoir of the main now supplying the Gardens Service Reservoir, (e) the installa- tion of pumps at a suitable point to ensure delivery to Albany in sufficient quantity through this main (d) and (f) the replacement of the 12" dia. section of the Albany Elliot main by one of 18′′ dia.
53. It will be observed from the plan that the "Line of communication" from the Eastern source enables water to be delivered to any part of the City. The im- portance of this, in the absence of the supply from the Mainland through break- down or other cause, is therefore obvious. Water, though of limited amount, could be supplied to all districts.
54. It is therefore proposed that (g) the Bowen Road Conduit be reconstructed. Pumps would be installed at Eastern with the second set of new filters proposed in para. 71 (b) and these would pump water from these filters back to the Conduit and thence to Bowen Road Service Reservoir.
55. The reconstruction of this conduit would enable Bowen Road to be used for motor traffic.
56. Similarly in the absence of supply from the Eastern resources a limited amount of water could be provided to all districts from the Mainland by means of the pumps proposed in para. 52 and designed for the dual purpose. These would be designed to deliver water through the reconstructed Bowen Road Conduit in an easterly direction as far as the Eastern Filters and in a westerly direction to Elliot by means of Albany-Elliot Main.
57. The interconnection at Albany of the Eastern and Mainland lines of communication would obviate the total absence of supply in emergency in all districts.
58. A breakdown in the "Line of Communication" of the Western resources would not seriously affect the general supply in the City as these resources are of small amount compared with those of the Eastern and Mainland.
LINES OF COMMUNICATION
Mainland.
59. Owing to the distribution areas in Kowloon being at such low levels com- pared with those of the City it has been found more practical to locate the filtration plants nearer to the sources of supply, the service reservoirs for distribution purposes being placed on points in Kowloon sufficiently high to ensure a good supply 10 the consumers. The lines of communication are therefore extended to the service reservoirs situated in the distribution areas.
60. The raw water supplied from the catchment areas of the Kowloon Waterworks is filtered by slow sand beds at a site adjacent to the last of a chain of three impounding reservoirs. The line of communcation" of these resources consists of an 18" dia. pipe line to Kowloon Tong Service reservoir and a 15" dia. pipe line to Pipers Hill Service reservoir.
61. Being in good condition and of sufficient capacity to deal with the re- sources of the Kowloon Waterworks no extension or improvement of the above mains is required.
62. The Kowloon Waterworks resources are augmented by those of the Shing Mun Valley whose "line of communication' consists of two sections. The upper section, which delivers raw water to the filters situated in the lower Shek Lai Pui Valley, consists of conduits and tunnels adequate in construction and capacity whilst the lower section, which supplies filtered water for both Kowloon and the City, is a 24" diameter pipe line. A second 24" dia. main is now being laid and these combined are estimated to be of sufficient capacity to provide for the requirements of Kowloon and the City for several years.
63. The existing "line of communication" from the Shing Mun Valley source, being of recent construction and designed for the existing and projected works is in no need of improvement.
Proposed Extensions.
64. New trunk mains of 21" and 18" dia. are proposed to supply water from the 24′′ dia. mains in Nathan Road to the proposed new service reservoirs at Kowloon Chai and Kowloon City (para. 90).
FILTERS
Island.
Existing Capacity.
65. The present normal capacity of the Island slow sand filters is 6.10 M.G./D. and that of the Rapid Gravity filters is 7.0 M.G./D. making a total of 13.10 M.G./D. Details of these, together with those of the Mainland, are shown in Appendix IV. Owing to an overlap however the whole of the filters cannot be used at the same time, the effective capacity being reduced to 12.05 M.G./D.
66. The very high consumption last summer necessitated the filters being run at rates far in excess of good engineering practice in order to provide the peak load of 16.35 M.G./D. actually passed through the filters. It is not possible to increase the filtration rate further nor can a greater amount of raw water be supplied to these filters. The maximum capacity of the Tytam tunnel being 10.0 M.G./D. this figure is the peak load which can be drawn from the Eastern Source of supply. The water is filtered at present at Eastern, Bowen Road, Albany and Elliot Filters, the working capacities of which are 2.20, 3.00, 1.73 and 1.7 M.G./D. respectively, a total of 8.63 M.G.D. The amount of Tytam water filtered at Elliot is limited to the capacity of the Albany-Elliot main.
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