Project: Northern Areas Sewer Phase II
Location: 5.2 km of major collecting sewer pipeline running from Vanguard Drive, along Jan Smuts Drive in Pinelands to the
Langa Pumpstation at the N2.
Scope: The Contract entails the second phase of the replacement of the original NAS (constructed in 1951) using
concrete pipes with a sacrificial layer, including construction of the associated manholes.
The selection of the NAS to be replaced starts just west of Vanguard Drive and follows the Elsieskraal River Canal
up to Stella Road where it turns south traversing through the Thornton residential area up to Viking Road,it then
turns in a westerly direction along Viking Road up to Jan Smuts Drive, and then turns in a southern direction
along Jan Smuts Drive up to the Langa Pumpstation just north of the N2 National Road.
The total length of the NAS Phase 2 is approximately 5.2km and the sewer diameter and associated pipeline lengths
are as follows:
The depth of installation of the NAS Phase 2 typically varies between 4m and 7m. In terms of bedding preparation,
trench excavation will be to a depth of up to 8m. In terms of deep trench excavations in specific areas of
limited working space, shoring will be required to provide safe working conditions on site. It should be noted that a
high water table will be encountered on site.
In addition to the construction of the new outfall sewer, manholes will be constructed at approximately 90m intervals,
and also at changes to the vertical and horizontal alignment of the sewer, to allow for access for operation and
The manholes typically comprise of an in-situ cast concrete chamber (with benching) constructed to be below
ground level, and provided with an access chimney constructed using precast concrete manhole rings.
Furthermore, the existing 525mm diameter Kensington Sewer which currently discharges into the existing NAS at the
Langa Pump Station, will be re-routed for approximately 60m using a 600mm diameter concrete pipeline to discharge
directly into the wet well of the Langa Pump Station.
This rerouting will also include the construction of an in-situ cast concrete screening chamber.
Considering that large volumes of soil and construction materials may have to be transported to and from site, provision
is made in the Contract for reinstating some internal roads in the Thornton residential area that may be
damaged due to construction traffic.
Construction of the sewer at major road and railway crossings shall be carried out by means of pipe jacking. The
total number of pipe jacks envisaged on the Contract are nine varying in diameters from 810mm to 1675mm, and
the length varying from approximately 22m to 84m.
Northern Area Sewer
Project Value: R 146 million
Duration: 18 months
Extent of Participation: A total of 9 pipe jacks and a 1.7km section of Cured In Place (CIPP) is subcontracted, the balance of work by CSV.
Recent Articles relating to NAS Project (please click on the links below to read the articles):