Stefanutti Stocks Coastal is project managing the construction of the Point Promenade for Durban Point Development Company (Pty) Ltd – a joint venture formed between the eThekwini Municipality and UEM Sunrise, a Malaysian parastatal. The geotechnical and piling contract was sub-contracted to Stefanutti Stocks Geotechnical.
The promenade is being constructed on reclaimed land on the beach-front. Its lower level will house public amenities, a water sports club and public parking. The upper level will be a continuation of the public walkway going from Moya’s Pier to the Northern Breakwater (harbour). The project commenced in the middle of January 2018 and will run over an extremely tight programme duration of eighteen months. The piling on which the structure is founded commenced in March 2018. Save & Exit
Ground conditions and water table
As the construction area is a reclaimed beach area there are a high number of weak pockets, approximately six metres deep. The shallow water table, at two-metres deep, affected approximately seventy per cent of the sewer trench and culverts, and a variety of other obstructions hindered the piling process.
The most feasible founding solution identified, to accommodate the loads of the promenade structure, was the Continuous Flight Auger (CFA) type pile. Due to the existing sandy soils, and the absence of bedrock, the piles were designed as shaft friction piles only. A total of 1 055 CFA piles (including 250 x 250mm, 426 x 450mm and 379 x 600mm piles) were installed. As well as two-hundred-and-twenty-one 130mm diameter self-drilling anchor type micro-piles. “The highly variable ground conditions (diff erent to the initial soil investigation) required additional extensive soil investigation and resulted in the piles having to be individually designed,” says Marcin Szatkowski, Stefanutti Stocks Geotechnical site agent. “As the site is located on reclaimed land, bad pockets, boulders and rubble were encountered and led to the refusal of some CFA piles – due to adverse in-situ ground condition, we introduced the self-drilling anchor type micro-piles.”