A civil engineering project using Technicrete’s Armorflex concrete erosion-protection blocks to prevent storm-water flooding of an open-cast platinum mine in the Pilanesberg, near Rustenburg in North West Province, is nearing completion.
According to the engineers, the Armorflex solution is also saving millions of rand in construction costs over original estimates.Water draining from the northern slopes of the Pilanesberg hills into a stream that runs near the mine has been the prime cause of its flooding in recent years. The project involves the re-routing of the seasonally flowing stream, the excavation of a new storm-water channel away from the mine area, and lining of the channel with the Armorflex concrete blocks. About 50 000m² of the blocks are being laid along the 2.5km length of the diversion channel.
Peet van der Merwe, of Midrand-based civil engineering construction company VVB Construction, says Technicrete’s Armorflex system was selected as the best solution to the flooding problem.
“Initially, gabions were proposed, but, on looking more closely at what needed to be done to prevent future flooding we decided to take the Armorflex route. Not only is that saving the client more than R2 million in construction costs over the gabion option, we are also shaving about 50% off construction time.”
Specialist paving company, Pavebuild Civil Contractors is laying the blocks. Managing director, Dawie Ruthven, says the project should be completed in February. The final step will be to cover the concrete lining with topsoil to encourage the growth of grass through the slots in the Armorflex blocks, which are specially designed for this purpose.
“By re-routing the existing channel the mine is doing a lot more than preventing future flooding at the workings – it is making an environmentally conscious contribution to the area,” says Ruthven. “Eventually, the new channel will be transformed into an attractive grassy stream in summer.”