123
Source No. 3.-The streams above Cheung Sha Wan, now being intercepted for a temporary supply, can be picked up and connected to the main, but there is no possibility of constructing a reservoir to impound water. The supply in winter would probably be about 50,000 gallons a day, and in summer 200.000 to 300,000 gallons, making a valuable addition to the supply in a dry year.
Source No. 4.A considerable stream flows down the valley to the north-east of Kowloon Bay, but here again there is unfortunately no site for a reservoir. The stream, however, might be intercepted in a similar manner to that proposed for the streams behind Cheung Sha Wan.
Source No. 5.-Immediately below the Sai-kung road near the point where it crosses the water- parting between the valleys draining to east and west is a small reservoir site with a catchment area of 100 to 200 acres. This may be reckoned to yield a supply of about 200,000 gallons a day.
Summarizing these, the total supply available from all sources is as follows:-
No. 1,
1 (extension to east),
2,
91
""
2 (extension to west),
"
3,
5,
Gallons per day.
590,000
200,000
.390,000
.100,000
100,000
.150,000
..200,000
Total,.......................1,730,000
PROPOSED WORKS.
To meet present requirements, Source No. 1 should be utilized and a storage reservoir constructed there, all cultivation being stopped within the drainage area. As already shown this will yield a supply of 590,000 gallons a day. The reservoir should be connected by a cast iron main to Filter Beds to be constructed at a suitable elevation on the ridge above Cheung Sha Wan and from there a cast iron main laid in the new Táipó Road would convey the water to a Service Reservoir to be con- structed on the hill to the north of the village of Kowloon Tong. This service reservoir would be connected to the existing distributing system which should be extended to Kowloon City on the east and to Tai-Kok-Tsui and Sham-Shui-Po on the west. At Kowloon City a small service reservoir would be required to maintain the supply in case of a breakdown on the 2 miles of main between there and Hung Hom, where a service reservoir already exists.
The present collecting area and pumping machinery should be dispensed with, and the buildings. used as a workshop, space for which is now much needed. Probably one half of the syphon pipes (7′′ and 6") might be taken up and used again. Full advantage would be taken of the existing distribution system and service reservoirs, the only works to be dispensed with being those in the collecting area and the pumping machinery. The economy to be effected in annual expenditure by saving the cost of pumping will fully justify this, even if the machinery cannot be used for other purposes.
As the demand for water increases, collecting area No. (1) should be extended by catchwaters to the east, and collecting areas Nos. (2) and (3) on drawing No. I should be utilized. The total estimated supply available when these additions have been made will be 1,380,000 gallons a day. Before this consumption is reached, however, it will probably be advisable to seek for a new source of supply on the hills to the north-east of collecting area No. (1), crossing if necessary to the eastern slopes of Tai Mo Shan. The supply obtainable from sources Nos. (4) and (5) on drawing No. I is so limited that, if it appears at all probable that the consumption of Kowloon will eventually exceed these, it would be better policy to at once adopt a larger scheme, reserving these small areas for any industrial enter- prises that may be started in Kowloon Bay.
PARTICULARS OF WORKS PROPOSED TO BE CARRIED OUT TO MEET PRESENT REQUIREMENTS.
Storage Reservoir.-As good building stone does not appear to be abundant on the site of Reser- voir No. 1, it is proposed to construct an earthen dam with central puddle wall on the lines of that at Pokfulam, a work which has proved very satisfactory and required little or no repairs. An earthen dam would probably be completed more quickly than one of masonry, and, the natural drainage area being small, there need be no fear of injury from rainstorms during construction.
The dam will be 65 feet in height from top water level to the present stream bed. Its top will be 10 feet above overflow level and 10 feet wide, the inside slope will be 3 to 1, protected by stone pitching, and outside slope 2 to 1, turfed. The puddle wall will be carried down in a trench to a solid foundation, and up to 3 feet above overflow level,
The overflow will be constructed of masonry and situated at the northern end of the dam. It will be so designed that, with a depth of three feet overflow it will discharge a rainfall of four inches an hour on the natural drainage area (152 acres) and 1 inch an hour on the area (400 acres)