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DECEMBER • 2016
Construction
WORLD
32
Specialist Contractors or Suppliers
B
The second and final phase would encompass the excavation and
lateral support to the new proposed basement layout, including
the demolition and removal of the existing four-basement parking
garage. Challenges were numerous, including but not limited to
unknown location of services, concrete obstructions covered by
soil, a diabase dyke running through the site with the unknown
position and extent, retaining neighbouring property structures and
basements and the most difficult of all, the time constraints.
Due to the nature of the complex goestrata in the location of
the site, the lateral support design had to cater for the constantly
varying soil conditions.
In addition, the neighbouring property structures comprising
the Balalaika, Protea and Holiday Inn Hotels, the Bull Run Pub and
Restaurant, Nedbank Building and the highly traffic-congested
Maude Street and Rivonia Road, all depended upon the absolute
effectiveness of the lateral support design and installation.
The proximity of the neighbouring property basements provided
a further challenge as the required anchor lengths would clash
with the existing basement positions. Accurate surveys had to
be undertaken to determine the location and depth of these and
anchor designs were adjusted accordingly.
Exceptionally long strand anchors were installed along the
Maude Street and Rivonia Road faces while exercising extreme
care not to drill into neighbouring basements.
A grout design capable of complying with strict quality
requirements, but still allowing the tight programme to be met, was
implemented and maintained throughout the project execution.
The lateral support was designed using the observational
129 RIVONIA ROAD
(VILLAGE WALK), SANDTON
In June 2014 the decision was taken by Eris
Property Group to redevelop the old Village Walk
site. The primary phase would support the existing
boundary walls with the Balalaika and Protea
Hotels, this paving the way for the second phase.
method. Numerous unforeseen challenges were encountered
during the lateral support and excavation phase and these had to
be accommodated in the specified programme time. The lateral
support was also complicated by diabase intrusions which was
encountered as water-bearing and often saturated silt and required
additional support.
Blasting of hard rock, constituting a third of the overall
basement excavation volume, was undertaken with precision and
each blast design individually prepared with its own parameters
and restrictions. Overall, in excess of 80 blasts were set off without
a single problem.
The lateral support structure installed had to provide a safe
environment during the earthworks and lateral support contract
as well as for the duration that the building contractor would take
to construct the basement structure. This period would be in the
region of 30 months.
A strict environmental plan was adhered to in order to have
as little impact on the daily activities around the site as possible.
Being a highly traffic congested area, strict traffic control
measures were implemented and maintained throughout the
construction phase. Dust control was continuously enforced with
the use of water bowsers.
The fine balance between time, cost and safety was respected
to ensure that the client benefited from the optimum solution.
Multi disciplines were running in parallel with the lateral support
activities, these including bulk earthworks, blasting, the surgery
precision saw cutting of existing beams and slabs as well as the
bulk demolition of the existing four basement structure.
All disciplines were planned to a micro level to ensure all
contractors could work simultaneously in a crowded and space
restricted environment.
The introduction of the building contractor halfway into the
lateral support contract further complicated the site logistical
challenges. Almost half of the site footprint was handed over to
the building contractor, in early November 2015 with six months
still left to run on the bulk earthworks and lateral support contract.
Working works were strictly adhered to as the three surrounding
hotels with 80% occupancy had an obligation to their guests.
Activities were carried out during working hours and Saturdays
Project information
• Company entering: Franki Africa
• Client: Eris Property Group
• Main contractor: Franki Africa
• Architect: Boogertman + Partners
• Principal agent: SIP
• Project manager: SIP
• Quantity surveyor: Aecom
• Consulting engineer: Aurecon
• Subcontractor: Zero Azani
• Subcontractor: Phoenecian Demotlition
• Contract value: R140 000 000
until 14:00 only, further restricting the overtime
facility to catch up on the lost time.
Therefore, from both a technical and
management aspect, Franki showcased the
optimum solution, bringing the ultimate goal of
a successful project to the client that entrusted
Franki Africa with this responsibility.
Winner