The capacity of the Sha Tin treat- ment works will be increased to 240 million gallons a day and additional water mains will be laid from the treat- ment works to Kowloon by way of a second tunnel through Lion Rock, where additional service reservoirs will be built. It is probable that the oppor- tunity will be taken to make Lion Rock tunnel into a second road tunnel.
The present distribution system in Kowloon will be augmented and new pumping stations will be built for the transfer of water to Hong Kong island. As with Plover Cove, the scheme will be monitored from a central control room in the Sha Tin treatment works.
Improved access
A side benefit of the High Island water scheme is that the paved roads which must be constructed for the project will eventually open up to the population for recreational purposes the whole of the eastern section of the colony one of its most beautiful
areas.
―
The decision to proceed with the scheme will directly affect the homes of about 400 people connected with five small villages located in the area to be inundated when the reservoir is completed. Government is arranging special compensation for them, includ- ing new housing.
Some agricultural land will be lost by the building of roads, tunnels and pumping stations, but special care will be taken to ensure that the trapping of water by tunnels, catchwaters and pumping stations will not deprive farmers of irrigation and domestic water. Improved irrigation systems are to be constructed for farmers in the areas affected.
20mgd desalting plant
The High Island water scheme is scheduled to come on tap in late 1976 and will be the last water project able to make use of the colony's natural re- sources. But the rise in demand may call for an added source of water be- fore that date. And so, by 1974 Gov- ernment plans to have in operation a large scale desalting plant of 20 million gallons a day capacity.
The plant will be built on the coast near Tai Lam Chung reservoir, off Castle Peak Road, and 17 miles from Kowloon. Plant and civil works will cost HK$190 million, of which civil
Far East BUILDER, June 1971 Page 47
HIGH ISLAND WATER SCHEME PRINCIPAL STATISTICS
Main dams
Max, construction ht.
Av. level of foundation
-20 ft. P.D.
West
Crest length
2,500
East
1,500 ft.
Crest level
210
210 ft. P.D.
294
340 ft.
Max. Ht. above sea bed
227
248 ft.
Max. depth of marine deposits dredged
63
105 ft.
Av.
ditto
37
50 ft.
Av. level of marine deposits
-3
-40
-70 ft. P.D.
5,000,000
3,500,000 cu. yd.
Quantity of rock-fill (main dams)
8,000,000
4,500,000 cu. yd.
Quantity of rock-fill (coffer dams)
1,000,000
2,200,000 cu. yd.
1
2
3
(ft.)
550
125
63
(ft. P.D.)
210
210
210
60
20
15
(cu. yd.)
97,000
4000
1000
Quantity of dredging
Col dams
Crest length
Crest level
Max. construction height (ft.) Quantity of fill
Reservoir
Gross capacity Useful capacity Area at T.W.L. Max. length Spill way level
62,500 m.g.
60,000 m.g.
1,700 acres
31⁄2 miles
196 ft. P.D.
TUNNELS AND SHAFTS
Main tunnel
Dia. (ft.)
Length (ft.)
High Island Reservoir to Lower Shing Mun
Reservoir
10-13
74,000
Branch tunnels (6 No.)
10
26,000
Pipeline between Portals R & T (Pak Tam Chung)
9
1,250
Shafts (12 No.)
7-10
250 (av.)
U-Group tunnels
Main tunnel Branch tunnel Shafts (2 No.)
Z-Group tunnels
Main tunnel
Intakes & catchwaters
Intakes to tunnels
Main tunnel & branches U-group Z.
Catchwaters delivering to tunnel intakes Total length of catchwaters
Pumping stations
Main pumping station at Pak Tam Chung
Lowland pumping stations
Tai Shui Hang Kei Ling Ha Hoi Ha
Ho Chung
81⁄2-11
21,500
8
2,000
8
40 (av. depth)
8
3,500
12 No.
5 No.
1 No.
13 No.
26,000 ft.
Design capacity 120 m.g.d.
Pumpsets
4 x 30 m.g.d.
Pond capacity
Design capacity
2.9 m.g.
0.3
"
"
"
3.5
5
0.4
Pumpsets
5 mgd 10
2 x 21⁄2 mgd
4 x 21⁄2
2 x 21⁄2
2 x 11⁄4
"
"
21⁄2"
37