Sessional_Paper_1935 — Page 154

149

HONG KONG.

REPORT ON THE CONSTRUCTION OF THE FIRST SECTION OF THE

SHING MUN VALLEY WATERWORKS SCHEME,

BY W. WOODWARD, B.Sc. (ENG.), A.M.INST.C.E.. CHARTERED CIVIL ENGINEER.

ORIGIN OF SCHEME.

Investigations of the Shing Mun Valley as a source of water supply were com- menced in 1921, and a short Report outlining the original proposals was made in 1922 by Mr. R. M. Henderson, M.Inst.C.E., M.I.Mech. E., M.Inst. W.E., Exe- cutive Engineer in Charge of Waterworks. This was followed by further Reports from Mr. Henderson in 1922, 1923 and 1924, the last of which was embodied in Sessional Paper No. 4/1929 and received the approval of the Secretary of State for the Colonies in May, 1924, when authority was given to proceed with the construction of the First Section of the Scheme.

GENERAL DESCRIPTION OF FIRST SECTION OF THE SCHEME,

The first section of the scheme was designed to deal with the collection, filtration and carriage to Kowloon and Hong Kong of an intermittent gravitational supply of water from the Shing Mun Valley, the amount varying, according to the season of the year, from about 2 to 10 million gallons a day.

The raw stream water is intercepted by means of an intake dam across the river, whence it flows by gravity through the Temporary and North Conduits, the North Tunnel, South Conduit and South Tunnel, and discharge into the Reception Reservoir.

The Reception Reservoir has a very important own function on this section of the scheme. In addition to collecting water from its catchment area, its capacity enables it to be used to regulate the varying discharge of the Shing Mun River. Raw water is normally drawn off from this Reservoir to the Rapid Gravity Filtration plant situated immediately below, whence, after filtration, it passes into the Shek Lai Pui Service Reservoir adjoining the filters. Any raw water surplus to require- ments and the capacity of these filters is automatically diverted to the new Bye- wash Reservoir situated in the adjacent Lai Chi Kok valley.

The Byewash Reservoir, which was subsequently included in this section of the scheme, is thus also of great value, as, in addition to increasing the storage of raw water, it is so situated as to be able to collect not only the waters of its own catchment area but the flood waters of both the Kowloon Waterworks Catch- ment areas and the Reception Reservoir, waters which would otherwise run to waste.

The Shek Lai Pui Service Reservoir forms the main storage of filtered water from the scheme. The water is drawn off by means of a 24′′ Trunk main from this reservoir to Kowloon Point, whence it is carried to Hong Kong by the first Cross Harbour Pipe from which it is passed into a 24′′ Trunk main in Hong Kong. which discharges into the Service Reservoir in the Botanical Gardens.