SINGAPORE
TOA PAYOH SEWAGE PURIFICATION SCHEME
SINGAPORE'S Toa Payoh sewage
purifcation scheme provides for the disposal and treatment of sewage from the 6,000-acre Toa Payoh Basin.
Of this area 600 acres is taken up by the satellite town of Toa Payoh it- self which contributes three fifths of the planned population.
The scheme was drawn up as early as 1959 by the Public Works Depart- ment, but the intended creation of the Toa Payoh Town by the Housing and Development Board altered the planned course of the sewerage deve- lopment and increased the urgency of the project.
Consequently, in 1961 the Gov- ernment called in consulting engineers. J.D. & D.M. Watson, to design the pumping stations, rising mains and treatment works.
at
The overall scheme comprises: two large pumping stations, one Braddell Road and one at Bartley Road: 24 in. and 39 in. diameter ris- ing mains; 54 in., 66 in. and 72 in. diameter gravity sewers: a compre- hensive treatment works linked to the existing Kim Chuan Road treatment works; and three miles of effluent out- fall and digested sludge mains to Ser- angoon sludge disposal works.
Expansion to the Serangoon sludge disposal works to cater for the in- creased demand in the secondary treatment of sludge, though technic- ally part of the scheme, forms an- other phase of sewerage development by the Public Works Department.
38
The population and flow adopted in
PUBLIC WORKS DEPARTMENT, SINGAPORE
J.D. & D.M. WATSON
developers
consulting engineers
(a) From Toa
Payoh Town
(b) Other Areas
Population
300,000
200,000
DWF/Capita
40 galls.
60 galls.
Total D.W.F.
Max. Flow : 3XD.W.F.
-
40 x 300,000
12 m.g.d.
36 m.g.d.
60 x 200,000
36 m.g.d.
=
12 m.g.d.
Total:
500,000
24 m.g.d.
72 m.g.d.
the design of the scheme is shown above.
The initial provision was made for 50 per cent of the ultimate require- ment,
Pumping stations
Though 50 per cent of the requir- ed capacity was required initially, it was considered practical and more economical in the long run to con- struct pumping stations to the full ul- timate size. The pumping equipment and mains, however, were installed for initial requirement with space for fu- ture expansion to ultimate require-
ment.
At Braddell Road, provision for eight pumps (2 Nos. 12 in. dia, and 6 Nos. 18 in. dia.) delivering into three rising mains (one 24 in. dia. and two 39 in. dia.) was allowed. Only the
two 12 in. dia. and three. 18 in. dia. pumps were installed and the 24 in. dia. and one 39 in. dia, rising mains were laid to give a pumping capacity equipment to 36 m.g.d.
The Bartley Road pumping station linked in series by the rising mains and gravity sewer to Braddell Road pumping station would be required to handle the contributing flow from Braddell Road plus sewage from population of 21.000 from a branch sewer to serve the Bartley vicinity. The same pumping arrangement as for Braddell Road is provided at Bartley Road.
а
Braddell Road Pumping Station, at present the largest in the Republic, is provided with aerated spiral flow grit channels and comminutors, but no grit removal or comminutor facilities are provided at Bartley Road except for provision for a small installation
Far East BUILDER, July 1968.
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