Construction World Septemer 2017

COVER STORY

Plain Sailing with Franki … The Yacht Club, a testament to FRANKI’S FORESHORE EXPERIENCE

The Yacht Club, a multi-use development including commercial and residential space, is destined to become one of Cape Town’s most sought after destinations and is yet another prestigious AMDEC/Franki Africa partnership. The site is situated on the Malmesbury group deposition of the Cape Peninsula, Cape Supergroup in the Foreshore area of the harbour reclamation development of the 1920s and 1940s. The shale bedrock is overlain by very stiff residual material followed by marine deposits and fill comprising old harbour facilities, general tipped rubble and dredged sands. The ground water table was intersected at an average depth of 0,86 m with the bedrock falling from around -0,84 m in the west to -2,9 m in the east (elevation levels in ASML). AMDEC Property Development’s (AMDEC) The Yacht Club development is a picturesque, nautically in- spired design, located on the Cape Town Foreshore in the Roggebaai Canal Tourism Precinct near to the Cape Town International Convention Centre (CTICC) and directly south of the new multi million Rand cruise liner terminal.

Special attention was required to an existing sub-surface canal running south to north which intersects the eastern portion of the site with both the lateral support and piled foundation design modified to accommodate and maintain the integrity of this structure. “It is evident that from a geotechnical perspective the Cape Town Foreshore is not the easiest area in which to operate. The varying ground conditions with old rock-filled docks and piers and the high-water table as described above present a significant challenge,” says Franki’s Rod Schultz. “But our previous experience on the neighbouring Harbour Bridge and Canal Quays projects gave us a thorough understanding of the prevailing ground conditions in the area and enabled us to quickly offer our client the most cost- effective solution,” he says. Schultz says that it took some years of on-and-off development proposals by all, before AMDEC succeeded in producing a workable solution by securing the land and obtaining the necessary partner- ships to go ahead. Due to the past successful working partnerships between Franki and AMDEC, Franki was the preferred contractor for this challenging geotechnical work. “We know Franki’s exceptional capabilities in the Foreshore area, which requires a special understanding of its complex geological conditions. We had no hesitation in awarding Franki this contract and their performance certainly lived up to expectations,” says AMDEC’s Project Manager Arnon van As. Franki’s scope of works included the design and installation of the lateral support and

foundation piling to this multi-storeyed, double- basement project, the excavation and disposal of some 65 000 m 3 of bulk earthworks, 508 lm of lateral support and 271 no. foundation piles. The soldier piles for the lateral support were a combination of 400 mmØ Continuous Flight Auger (CFA) piles and 325 mmØ Rotapiles tied back with a single row of anchors and gunite arches. The anchors had to be carefully positioned and inclined sufficiently to not intersect with the canal, which runs very close to the site. CFA piling is a fast and economical system with no vibration and limited noise levels associated with it. “This was particularly advantageous on a site which is close to live canals and railway lines, contains a labyrinth of existing services and has neighbours who are particularly sensitive to noise,” says Schultz. The main feature of the Rotapile system is its ability to penetrate boulders and rock formations. Socketing into hard rock

Piling and bulk earthworks operations at peak with upwards of five piling rigs, two excavators and more than 200 tipper truck loads per day.

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CONSTRUCTION WORLD SEPTEMBER 2017