Water, Sewage & Effluent Mar Vol 30 No 2 | Page 30

current 15-month time schedule that is now
possible using this hybrid technique.
The roof was designed by Corestruc, who
will also deliver, as well as lift and place the
precast elements. At the time of writing,
Corestruc was pre-casting the elements
of the roof, while the M&D Construction
team was forging ahead on site. The
roof is supported on pre-cast stubs that
are supplied by the sub-contractor and
installed on the cast in situ columns.
As Venter points out, the contractor is
using a full-climbing system from Doka to
cast the walls. It is a “walking” system with
rails, which has been designed for high
productivity. Bear in mind that to complete
the four quadrants, formwork has to be
placed 16 times and heights will eventually
exceed 15m on the last four lifts.
As it’s located on top of a koppie, Venter
says the site will eventually encounter
severe upward winds. He says careful
planning is needed to ensure a safe
construction site.
Interestingly, the wall sits free off the
base, with the only connection point being
a section of rubber that is placed between
the foundation and the wall. He says this
was designed by Dunlop and manufactured
by Aubert Pipe Systems.
Venter says that this also resulted
in several technical challenges at the
implementation stages, considering
that each connection had to be moulded
and cured in place, as opposed to being
undertaken by conventional welding.
Venter says this process takes up to five
hours for every connection. All internal
pipework started in February.

Stepping over
M&D Construction was a partner in the
MDWK JV on the Pilanesberg North Water
Scheme (43km of 1 016mm welded steel
pipeline) before taking on this project.
When Water Sewage & Effluent
visited the project, the joint venture was
connecting the pipeline to the reservoir.
The pipeline transports water from Vaalkop
Dam, the main water source. The pipeline,
which was being commissioned at that
time, also feeds the mines financing
the project.
Venter says the reservoir is designed to
accommodate two more pump stations
to be undertaken in the second phase of
the build. It comprises an inlet control

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Water Sewage & Effluent March/April 2016

chamber with four inlet pipes leading into
the reservoir. Another interesting aspect
of the build is that the reservoir houses an
additional 5Mℓ reservoir inside, acting as a
water reserve.
M&D Construction’s factory started
operating two years ago and it is now
manufacturing the first stainless steel
pipes to come out of the factory for this
project. M&D is also using its team of
expert welders, who worked on its pipeline
contract at OR Tambo International
Airport. This has also kept the works
on track. The stainless steel pipes run
underneath the reservoir floor and have a
five month long lead-time.
Another test for the contractor is the VAG
valves in the control room that have to be
designed and manufactured for the project.
Venter says the valve has a traditional
casing, but the mechanism controlling
the butterfly is extremely spe