CO129-588-16 Water Supply- report on the Tai Lam Chung Valley Scheme 3-1-1941 - 3-1-1941 — Page 16

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of the access road to the Jubilee Reservoir (see map).

The road which would be followed is narrow and tortuous in

places and at some points rises to such an elevation that

tunnels it a lower level would be necessary,

Pipes in Roadway.

54. It would not be possible to lay the pipes below

the existing roadway without interfering with the traffic to

a serious extent, and therefore it is assumed that the roadway

would be widened, which is desirable in any event, the pipes

being laid below the widened portion.

55. Owing to the steep mountain slopes a considerable

amount of excavation would be necessary even to lay a single

line of pipes, which would be greatly increased if the road

had to be again widened to take a second pipe line.

It is

therefore recommended that pipes be laid in the first

instance of such diameter as to be capable of discharging

40 million gallons per diem, i.e. the whele yield of the

reservoir when the catchwaters have been constructed plus 33%

to meet periods of increased demand.

Tunnel Portions.

56.

Comparative estimates show that there would be but

little difference in the cost per foot run whether the aqueduct

took the form of a pressure tunnel or a pipeline laid in the

widened portion of the road.

57.

It was therefore decided that it would be advantageous

to shorten the line by means of the tunnels shown on the map,

which would also avoid those portions of the road which lay at

too high an elevation to allow of the water being discharged by

gravity to the filters.

58.

The total length of the aqueduct between the outlet

of the tunnel and the filters would be about 64 miles, the pipe

being laid in the widened portion of the road for about 4.3 miles.