One of Johannesburg’s iconic landmarks, the Sentech broadcasting tower near Auckland Park, is literally falling apart. Bits of concrete are flaking off the 237m-tall structure.
The tower is in a state of disrepair thanks in large part — it’s suspected — to acid rain that has rusted steel reinforcements in the tower. However, Sentech has assured residents in the area that the problems don’t pose a danger to them. There is no risk of the tower collapsing.
The structure, which was erected in 1961 at a cost of just R300 000, will soon receive a major maintenance upgrade to fix the problems. Demolishing the structure is not an option: a new one would cost about R300m to erect.
Sentech’s acting GM for operations and maintenance, Zane Mannell, says the company has commissioned international construction and engineering Arup, which originally built the tower, to determine what needs to be done to restore it to full health.
Arup, which also designed the Sydney Opera House in Australia and the Centre Pompidou in Paris, France, is expected to file its report to Sentech in the next week. After that, the state-owned broadcasting signal distributor will put the repair job out to tender.
Mannell says the work needs to be carried out urgently.
Arup has been asked to provide Sentech with details of the extent of the “spalling” problem, where bits of concrete are flaking off the structure.
“On one side there’s a lot of spalling because of moisture and acidity of air which has rusted some of the metal, pushing the outer layer of concrete away,” Mannell says. “We want to ensure there is nothing structurally wrong, and then fix it.”
Arup has also been tasked with investigating a kink two-thirds of the way up the tower — the structure was built with the kink, then reinforced to counter the problem. Sentech wants to ensure the kink isn’t damaging the structure.
Lastly, Arup is expected to report back on the condition of the concrete “shells” that surround the top of the tower, where some delamination has taken place, leaving holes that mar its surface.
Mannell says Sentech also wants to fix holes that were created when Sentech erected neon lighting under the bell of the tower – the lighting was removed after complaints from the local residents’ association.
Fixing the tower, which is designed to withstand winds of up to 200km/h, will cost millions of rand, Mannell says. The full extent of the costs will only become known once Arup has filed its report and tender applications have been received.
The tower, which provides television and radio broadcasts to most of the greater Johannesburg region, is an integral part of Sentech’s broadcasting infrastructure in Gauteng. It provides signals to 7m people in the region. — Duncan McLeod, TechCentral