Civil Engineering nOVEMBER 2021 | Vol 29 No 10

steel bridge makes it impossible to drill and build a foundation right beneath the structure. The pier will sit in the centre below the current bridge, and the three piles on either side will be linked to the other three via a pile cap,” explains Erasmus. The new pier is founded on bedrock that averages a depth of 7.5 m below ground. To hold back the very loose river sand and alluvium material present in the Namib Desert, all six piles were founded by oscillating a temporary casing to rock level. Once the temporary casing was seated in the bedrock, the Stefanutti Stocks team was able to form rock sockets of up to 2.5 m in pegmatite, classified as Class R5 very hard rock. Once the sockets were cleaned, a permanent galvanised 1.6 mm liner was installed along with the reinforcing. Although the river was diverted for the duration of this project, the concrete had to be cast underwater using the tremie method due to the river flowing through the sands below. Once the concrete pile shafts were cast and formed, the tempo- rary casings were extracted to reveal the complete pile. Finally, to ensure a good quality product with no anomalies, all six piles were sonic logged. “Proper planning is an essential part of all of our contract management; however, it is of particular relevance in our cross- border projects, which are often in remote locations that can prove logistically chal- lenging in the face of incomplete upfront planning. At Stefanutti Stocks we believe that ‘proper planning prevents poor per- formance’ – and this strategy continues to result in the successful completion of many projects, both cross border and within South Africa,” says Erasmus. Stefanutti Stocks Geotechnical is currently working in four South African provinces on projects in a variety of sec- tors ranging from mining to industrial, luxury hotel and leisure develop- ments, and transport infrastructure. These include: Q Q Open hole auger piles at the new Steve Tshwete Hotel and Conference Centre in Middelburg, Mpumalanga Q Q Continuous flight auger pile instal- lation that forms part of the new in- frastructure development at iThemba labs in Cape Town, Western Cape Q Q Lateral support and temporary cast in-situ cased auger piles on the N2 in Durban, KwaZulu Natal Q Q Open hole auger pile installation at the Amandelbult Platinum Mine in Thabazimbi, Limpopo. If you’d like to discuss your project’s geo- technical and lateral support requirements, please contact Tiaan Erasmus, Stefanutti Stocks Geotechnical commercial director at tiaan.erasmus@stefstocks.com or +27 (0)11 571 4483. For more information www.stefanuttistocks.com Civil Engineering  November 2021 5 An aerial perspective of Stefanutti Stocks’ piling operations on site at the steel structure. Visible on the right of the bridge are the three temporary casings seated in the bedrock, which are mirrored on the other side of the structure