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CONSTRUCTION WORLD
FEBRUARY
2017
28
PROJECT PROFILE
Maydon Wharf was developed for the
then expansion of the Durban harbour, in
particular to meet the needs of the growing
Witwatersrand. The berths were built of
timber, with berths 1-4 and 13 and 14 later
rebuilt using steel sheet piles in the 1950s.
Safety is of utmost importance when
dealing with timeworn structures which
have been in use since the mid-1900s.
Constant monitoring of movement of the
existing quay wall is taken very seriously
to prevent collapse or failure during
pile driving, timber pile extraction and
excavations taking place in proximity to
the old berths.
The project is overseen by Transnet
Capital Projects and RCE Consultants are
the design consultants.
Project description
As the largest and busiest shipping terminal
in Southern Africa, the aged berthing
structures require far greater capacity than
the original 20 000 DWT vessels it was
originally designed for to meet current and
future demands.
The reconstruction of Maydon Wharf
consists of demolishing the existing quay
structure, the removal of old timber piles,
installing a new steel combination wall
with concrete cope beam and back of quay
layer works. Included in the scope of works
is the deepening of the seabed by some
4 m to achieve a draft of 14,5 m CD, with
the placement of scour rock adjacent to
the quay wall, preventing washout by the
propellers of the vessels.
Torrential winds and harsh sea
conditions, are just some of the milder
challenges faced on the exciting marine
construction project. At berth 13 and 14,
extremely hard driving conditions were
encountered and the issue was further
exacerbated by the old quay wall alignment
being far worse in condition and envisaged
location, resulting in subsequently changes
in design alignment. As such, all aspects
of the project required exceptional survey
accuracy. Once completed, the six berths
will be able to handle bigger vessels with
drafts of up to 13 metres.
Construction innovation
Two integral elements of the project are
the anchor piling work and concrete cope
beam construction.
A first for South Africa, the Müller
Verpress Pile (MV-Pile or HP) has been
used extensively in Germany, Netherlands
and the United States for anchoring large
combination-wall systems (both grouted
and un-grouted) as an alternative to the
traditional dead man anchor solution and is
known to be exceptionally economical both
in terms of cost and performance. The HP
piling rig makes use of an IHC 70 hydraulic
piling hammer to drive the piles. The barge
is capable of jacking itself out of the water
which prevents it from being affected by the
waves of passing vessels, the swell in the
harbour and also prevents the piling being
affected by tidal variations. By operating
on a hydraulic platform the rig can be
positioned to the millimetre as well as track
to three positions per barge movement.
The bespoke anchor piling barge is
capable of driving the 33 metre long HP
piles, while grout is simultaneously pumped
at 1 000 kPa from a colloidal mixing plant
on land as the pile is being driven. The
grout acts as lubricant during driving and
once set it bonds to the steel pile and
the surrounding substrate increasing the
frictional resistance of the anchor, as well
as protecting it from the adverse effects
of corrosion.
A selection of HP piles are tested
under tension loading of 450 tons on each
berth. The execution of the HP piling can
be measured through the results of the
test piles which have passed the stringent
testing and specification requirements set
forth in the contract. The use of HP piles
something the Stefanutti Stocks Axsys
Joint Venture prides itself in accomplishing
successfully as a first in the country.
The design of a water tight shutter
system for the cope beam construction
was of a complex nature and as such,
required rigorous analysis. Initially, a
detailed concept of a coffer dam was
developed. The coffer dam concept was
however discarded due to handling issues
RECONSTRUCTION
and
DEEPENING
of Maydon Wharf
The Stefanutti Stocks Axsys Joint Venture (SSA JV) was awarded the
contract for the rehabilitation of berths 1-4, 13 and 14 in April 2014,
a total of six out of 15 berths at Maydon Wharf, the Port of Durban’s
largest break bulk, edible oils and dry bulk handling precinct.