Construction World December 2015

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2 15BEST
PROJECTS
64
CONSTRUCTION WORLD DECEMBER 2015
Professional Services C
AECOM was appointed in 2009 by the
City of Cape Town (CCT) for the
professional services related to the
design of the new Northern Areas Sewer
– Phase II (NAS2), and the subsequent tender
compilation and contract administration.
The existing Northern Areas Sewer
(NAS) is a major collector sewer
currently serving an area of 4 100 ha
of the northern suburbs of Cape Town.
Project information
• Company entering: AECOM
• Project start date: 7 May 2013
• Project end date: 20 October 2015
• Client: City of Cape Town
• Main contractor: CSV Construction
• Principal agent: AECOM
• Project manager: AECOM
• Consulting engineer: AECOM
• Subcontractor: Wepex
• Project value: R160 708 688,14 (including
VAT, 10% contingencies and escalation)
Construction of the
Northern Areas Sewer
– Phase II
The NAS starts just east of Jan van Riebeeck
Drive and follows the Elsieskraal River up
to Jan Smuts Drive where it turns south
along Jan Smuts Drive up to the Langa
Pump Station. The total length of the NAS is
approximately 8,7 km.
The NAS was originally commissioned
in 1951 and is over 60 years old. Since 1994
it was reported that the NAS does not have
sufficient capacity to service the existing
catchment area. To this extent a portion
of the NAS (from the start just east of Jan
van Riebeeck Drive to a position just west
of Jakes Gerwel Drive, i.e. a total length
of approximately 3,8 km) was replaced in
2000/2001.
This project entailed the replacement of
the remaining 4,9 km portion of the original
NAS, downstream of Jakes Gerwel Drive up
to the Langa Pump Station.
AECOM conducted an updated estimate
of the expected future flows in the NAS (in
terms of the required capacity) based on a
design life of at least 50 years. The predic-
tions took into account all future develop-
ment plans in the catchment, including the
plans to develop Wingfield, Acacia Park, the
Conradie Hosipital Site and the Old Mutual
Golf Course site. In addition, densification
was taken into account based on the CCT’s
Densification Strategy.
Based on these assumptions, it was esti-
mated that the maximum flow that the NAS2
would need to accommodate during future
peak wet weather flow conditions would be
approximately 3 000 ℓ/s. This is significantly
higher than the current capacity of the
existing sewer which is in the order of 600 ℓ/s
CSV Construction was appointed for the
construction of the NAS2 in May 2013.
Highly
Commended