Leading piling contractor, Gauteng Piling, had to resort to an age-old piling technique to cope with space restrictions and heritage preservation while providing the foundation elements for extensions to the Market Theatre complex now under way in Newtown, Johannesburg.

The Market Theatre Foundation commissioned the alteration and demolition of some of the buildings on a city block bounded by Bree Street to the north, Miriam Makeba Street on the east, and Margaret Mcingana Street on the west. The new development - east of Mary Fitzgerald Square – will provide additional facilities for the Market Theatre precinct, including a new theatre, rehearsal rooms, library, gallery space, classrooms and offices. It has been designed by KMH Architects. The construction site is located among some early Johannesburg buildings and facades, including Schlom’s Eating House, and the Graffiti Building, east of Mary Fitzgerald Square.

Schlom’s Eating House dates back to 1914 and has, according to leading heritage consultant, Herbert Prins, ‘strong social significance’. It was in this ‘eating house’ that black and white people dined together in days when restaurants were legally prevented from serving mixed races. Graffiti Building, which was at one stage a grain warehouse before its walls were over the years adorned by graffiti by some talented street artists, was built a few years after Schlom’s. Master Builders Association North member, Gauteng Piling, was sub-contracted by the main contractor, Solidaire Construction, to provide 73 auger cast piles and 14 bored piles, varying in depth from 8 to 12 metres, and 250mm to 850mm in diameter, on the development site of about 2 000 square metres  in Newtown.

Martin Eygelaar, Contracts Manager at Gauteng Piling, said because the Market Theatre Foundation especially re-arranged the large-scaled redevelopment of its property to preserve these historic buildings, particular piling precautions were essential to avoid damaging the heritage structures. “The piling required within the confines of Schlom’s Eating House, in particular, proved particularly challenging and called for a return to the historic ‘pile-driver’ method of piling. “We utilised a bored piling rig, equipped with an 800kg hammer, which was then dropped from a height within the building itself to create 14 holes, between 6m and 7m deep, and 410mm in diameter. Reinforced steel cages were then placed in the piling holes prior to these being filled with concrete. The use of the ‘old-fashioned’ compact rig was essential because a normal rig would not have fitted within the enclosed confines of the building,” Eygelaar added.

The drop hammer technique of piling is the simplest form of piling and was through the ages most frequently used for the installation of concrete piles. The traditional type of pile driver consists of a heavy weight (drop hammer) placed between guides so that it is able to freely slide up and down in a single line. The weight is then raised, now usually with diesel power (or, in days of old, with animal or human labour), and when it reaches its highest point, it is dropped to smash on to the pile to drive it into the ground. Such drop hammers – which can weigh up to 5 000kg – are fitted with a lifting eye and lugs for sliding in the guides. Today, although not commonly used, drop hammers can be operated with great accuracy – and this was essential for the Market Theatre project. 

For the rest of the auger piling holes required on site, Gauteng Piling used a Williams Digger LDH rig and a Williams Digger MF rig. With a torque of 5.5 metric tons, the Williams LDH digger has for many years been the benchmark for auger machines in the piling industry.  Williams MF rigs are exceptionally fast, mobile and reliable with some models capable of drilling to a depth of 18 metres.  Adds Eygelaar: “There were no major challenges to provide the piling in the open air outside the heritage building, although we did encounter some underground water for which we had to use the drill-and-cast method instead of auger piling to prevent collapse. Drill-and-cast operations call for a concrete truck to be on standby right next to the drill rig. When the rig has reached the required depth, the operator immediately lifts the extracted soil to the surface and concrete in then cast – within seconds – to prevent water ingress and the collapse of the piles.”

A total of about 160 cubic metres of concrete and around 3 tons of steel were used for the piling contract. Established 18 years ago, Gauteng Piling (led by MBA North immediate past president, Hennie Bester), has completed close to 1 500 major piling contracts. The company has attained 135% BBBEE recognition. Gauteng Piling has a fleet of 23 straight shafted auger-cast machines, three cranes, four bore rigs and six Grundo hammers (mainly used for residential foundations), as well as three machines for lateral support.

The company recently completed the contract for the piling for the construction of southern African’s largest single-phase retail centre, Mall of Africa, which called for over 400 piles. Other recent contracts handled by Fourways-based Gauteng Piling include the piling for the massive Value Logistics warehouse in Kempton Park, the Fire & Ice Hotel in Pretoria, The Grove Shopping Centre in Pretoria, and the Bon Accord Police Station, also in Pretoria. The company also handled the piling requirements for a new FAW auto dealership in Croydon in Ekurhuleni, to name just some of its recent work.