The Civil Engineering Contractor January 2018 | Page 19

ON SITE
“This first phase was crucial, as these
walls supported those buildings and
any mistake in calculation would have
been disastrous,” Alves says.
In the first phase of the process,
Franki supported the walls with
249 no. four-strand anchors and,
simultaneously, 82 no. soldier piles
were installed on the northern and
eastern faces, which included Maud
Street and Rivonia Road respectively.
This intricate operation took from
1 December 2014 to the middle of
April 2015 and, shortly before the
end of this phase, permission was
granted to proceed with phase 2,
which was to demolish the existing
four-basement parking garage,
excavate according to the new
plans and then laterally support the
remainder of the site.
The three main disciplines –
geotechnical, earthworks and
demolition – worked concurrently
on a confined site, which presented
enormous challenges, overcome
fortunately, by close collaboration and
excellent cooperation between the
various contractors.
Alves comments, “From the client,
Eris Properties, through to the project
managers SIP, AECOM quantity
surveyors, Aurecon engineers,
Boogertman and Partners architects
through to the contracting team of
Franki, earthworks specialists Zero
Azania, Phoenecian Demolition,
Pro-Frag Drilling and Blasting and
Diamond Cutting and Coring
Company, there was cooperation and
understanding that made the success
of this job possible.”
A task that was both i mportant and
intricate, happening out of sight, was
the separation of the basement from
the existing structures of the Balalaika
and Protea Hotels. Alves explains,
“This was achieved through precision
cutting and sawing by the Diamond
Cutting and Coring team under the
supervision of Aurecon who ensured
that the cuts were made in exactly
the correct positions. There was
absolutely no extraneous damage in
this critical operation.”
Also happening around the site
were relatively minor civils jobs that
involved the surrounding buildings.
Although they were minor, they were
nevertheless critical in that they made
it possible for neighbouring businesses
to continue their day-to-day activities
uninterrupted. These included: the
regrading of the Holiday Inn Hotel
entrance; the creation of emergency
walkways for safe passage to and from
all the surrounding hotels; erection
of all the hoarding around the site
and making safe the common areas
with the surrounding buildings; and
the relocation of storm water and
sewerage pipes.
In addition to all the ancillary civils
work, Franki had to control the noise
“With a project like this you allow
for a substantial contingency. We
managed it with our contingency.”
James Reid, AECOM.
level and the dust on site. “This was
exacerbated by very hard granitic rock
that we encountered which required
drilling and blasting. One can imagine
just how controlled this operation
had to be to do it not only safely, but
also as quietly as possible and with as
little dust as possible. Once again, the
teamwork was exemplary,” Alves says.
Additional considerations
Time is always the task-master on jobs
of this magnitude and this project was
no different.
The location of the site necessitated
that the work day be strictly limited
to between 07:00 and 18:00, while
the ‘unbelievable’ volume of ground
water present on the site, created
time pressure resulting in the constant
collapsing of the soldier-piled side
walls, necessitating temporary
casing of all the piles. In addition,
underground there was a ‘maze’ of
services which had to be avoided or
moved about. This was compounded
by the fact that there was almost
no information about the services,
which slowed processes down
significantly. In fact, an anchor did
strike an underground sewerage pipe
in a position that made it very difficult
to repair.
Also, a challenge as far as time
was concerned, was the 3 000m³
of contaminated soil, detected by
a strong petrol odour. “We believe
this may have been caused by an
old petrol station on the site which
had leaked petrol over many years,”
Alves says. “We got Envirowaste to
isolate the contaminated area and of
course it had to be excavated with
great care. This unforeseen challenge
took its toll on time and delayed
the programme somewhat along the
Maude Street face.”
As luck would have it, the
contaminated area was located exactly
where the first handover section was.
The building contractor was scheduled
to take over the Phase 1 of the site at
the end of October 2015. However,
the full extent of the contaminated
area could not be determined at the
time. In addition, the contaminated
soil was up against the lateral support
face, limiting the progress of this
critical-path operation. Nevertheless,
with some creative lateral thinking
Franki made up the lost time and
the building contractor was able to
establish by the required date and
the lateral support of the demolished
basement went ahead as planned.
Alves emphasises this was technically
the most challenging project he has
ever been involved in. “This was truly
an incredible, unforgettable contract,
which, more than anything, displayed
the power of teamwork,” he attests.
Construction status
Reid assures that the project is ‘pretty
much on time with the construction’,
while procurement, on the other
hand, ‘has been a massive challenge,
from a QS perspective’. He points out
the complexity of having to coordinate
140 procurement packages. “For us,
that has been a big challenge, getting
all of the procurement out and getting
all the info from the architects.”
CEC January 2018 - 17