P.W.E. New Territories
Q 132
In its construction the following materials were used:—
2,435 c. yds. of fine cement concrete (4:3:1).
2,048 c. yds. of cement concrete displacer (7:1) deposited up to 610 A.O.D.
1,844 c. yds. of cement concrete displacer (8:1) deposited between 610 A.O.D. and top water level.
226 c. yds. of lime concrete filling deposited above the top water level.
The up-stream face and coping are of cement concrete blocks, of which an amount of 457 c. yds. was utilized, while for the down-stream face granite rubble to the extent of 435 c. yds. was used.
Good rock was reached below 600 O.D. with the exception of a soft pocket met with at the Southern end of the Dam as referred to in last year's Report. Both ends of the Dam were carried well into the hillface and founded on compact decomposed granite.
3. This Dam blocks a small gap about 100 yards North of the Main Dam and no special difficulties were anticipated or met with during its construction.
Its overall length is 102 feet and the maximum height 31 feet from the lowest foundation level to the level of the path, 240 c. yds. of fine cement concrete, 183 c. yds. of displacer cement concrete, and 59 c. yds. of lime concrete filling being used in its construction.
It is faced on the up-stream side with 58 c. yds. of cement concrete blocks while the down-stream side is unfaced, but concealed by a turfed embankment. It is entirely founded on compact decomposed granite and shows no sign of leakage.
4. (a). The East Catchwater diverts the yield from the 441 acres which formerly drained into the Kowloon Reservoir. It has a total length of 690 feet and is capable of dealing with a rainfall of 2 inches per hour, the gradient being 1 in 500 throughout, and the level of the overflow sill at the intake stands at 778.25 A.O.D.
(b). The West Catchwater deals with the yield from a stream, now within the catchment area of the Shing Mun Valley Reception Reservoir, with a drainage area of 214 acres.
It has a uniform gradient of 1 in 450, is 580 feet in length, and is capable of dealing with 2 inches of rain per hour. The overflow level at the intake is 713.00 A.O.D.