FR
BOWEN ROAD SERVICE RESERVOIR
ROM articles and letters ap- pearing in the local press from time to time, it can readily be appreciated that the ever increasing population of the Colony is, and indeed always has been, a source of embarrassment to the authority res- ponsible for supplying this fluctuating A population with adequate water. history of the site on which the new Bowen Road Service Reservoir is now being constructed gives an ex- cellent example of the alterations and modifications necessitated to the water supply system by the ever in- creasing water consumption of the Colony which is, to a large extent, governed by the political situation in the hinterland of China; a factor which is extremely difficult to pre- dict.
On this site was completed in 1891, as part of the Wanchai Gap pumping scheme, a series of slow sand filters, the filtrate from which was used both to provide drive water for the hy draulically operated pumps at a level of about 60 ft. below the filters, and feed water which was pumped to a level of 650 A.P.D., or 350 ft. above the pump house, to a service reser- voir adjacent to the Magazine Gap Road. The drive water was ex- hausted to a small service reservoir of 0.72 million gallons adjacent to the pump house and used to supple- ment the Wanchai Supply.
The continued growth of the po- pulation of the Colony warranted in 1925, a reclamation to the seaward of the area served by the plant, known as the "East Praya Reclama- tion" which was completed in the early thirties, and indeed would have been completed at an earlier date had Morrison Hill not proved such a hard nut to crack. To deal with this increased area, the slow sand filters were replaced about 1926 by rapid gravity filters, the former being converted into a service reservoir in order, both to maintain the required working head for the pumps, and to supplement the storage capacity of filtered water.
The combined ca- pacity of both service reservoirs was, and still is, 1.12 million gallons.
With the advent of the scheme for the centralisation of filtration of all water originating from the Tytam reservoirs by the construction of the Eastern Rapid Gravity filters, which
were put into commission in 1949, the plant of the Bowen Road rapid gravity filters was removed and re- Bowen Road site so as to permit the installed at Eastern. This freed the
construction of a service reservoir of adequate capacity to serve the Wanchai Area, and the area served by the "650 tank," the combined consumption of which is three million gallons per day. While it is con- sidered desirable to provide service reservoirs of a capacity of twice the daily consumption of the respective areas served, it has not been possible to achieve this aim in this particular case, for the reservoir at present under construction will hold five
million gallons when complete. A total excavation of 108,000 cubic yards will be required, and the walls ft. in length, will be required to of the reservoir being 183 ft. and 220
sustain a pressure resulting from the storage of water to a depth of 20 ft. The large quantity of excavation mentioned above is necessitated by the lowering of the crest of the spur of the hill on which the site is found- ed to provide an area large enough to accommodate the required size of reservoir on solid ground. A further factor which has determined the for- mation level of the reservoir is the
proposal to use the same hydraulic engines and pumps to raise water to the 650 tank as at present exist. the 650 tank as at present exist. These engines consist of one horizon- tal reciprocating engine and two tur- bines all operating pumps of the ram type. Though the former was ins- talled about 1891 and the latter two
UPPER SERVICE RESERVOIR CONVERTED FROM SLOW SAND FILTER CAPACITY 0.40 M.G
TWL 35300
S' RISING MAIN TO 650 FT
TANK TO BE RELAID
EXIST BOWEN RD. PUMP HOUSE
F. L.2 80.94
EXHAUST FROM
TURBINE
about 1926, all are in excellent con- dition and still have many years of useful life before them. All are
head of 60-80 ft., and as it is pro- designed to operate under a hydraulic posed to discharge the exhaust from these engines to the new reservoir it is necessary that the formation level of the pump house shall be between 60 and 80 ft. below Bowen Road, and yet above the top water level of the reservoir.
These considerations give us the following levels:-
Bowen Road main, hydraulic level............400-386 A.P.D. Level of suctions to pumps......
.324 A.P.D.
T.W.L. of new reservoir.....
.316 A.P.D. Invert level of new reservoir..... .....296 A.P.D. Though it is possible to supply the 650 tank from a source other than from the existing pump house, the supply to the Wanchai area must be maintained throughout the con- struction operation. This is at pre- sent provided by a 15" cast iron main which crosses the reservoir site and which must be relaid before the existing main is removed.
Owing to the present world short- age of steel, walls of gravity section. in mass concrete were first examined. Such walls however would require a thickness at the base of over 14 ft. and the considerable saving which could be effected by reinforced con- crete counterfort walls was such as to warrant the release from the prel sent stocks of the quantity of stee-
24′ MAIN FROM EASTERN PS
OLD R.G FILTER
NEW PUMP HOUSE
NEW BOWEN AD. SERVICE RESERVOIR
CAPACITY 5.00 M.G
LOWER SERVICE RESERVOIR
CAPACITY 0.72 NG
TWL./200.00
TO HOUSE SERVICE
TWL 316.00
INVERT LEVEL 296.00
359.75
TO ALBANY *
RISING MAIN TO
450 FT. TANK
FL 322.50
EXHAUST FROM TURBINE GAUGE BASIN
TO HOUSE SERVICE
EXISTING MAINS SHOWN THUS FUTURE MAINS SHOWN THUS
Diagrammatic representation of the existing and proposed layout.
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