Construction World December 2016

Project information • Company entering: Hatch • Client: Eskom • Project start date: May 2015 • Project end date: December 2016 • Main contractor: Rula/Stefanutti Stocks Consortium

MAJUBA POWER STATION SILO 20 RECOVERY PROJECT

In November 2014, an incident occurred at Majuba, during which the wall of Silo 20 fractured, leading to the collapse of the upper section of the silo. The conveyor transfer house and the coal conveyor gantry sections that were supported by Silo 20 also collapsed, resulting in damage to the head end of the overland conveyors, take up structures and the tail ends of the over-silo link conveyors. The configuration of the coal plant relies on the distribution of coal to the desired silo from the Transfer House located on top of Silo 20. Due to the structural failure of Silo 20 and the associated conveying infrastructure, no coal supply to any of the silos was possible. Hatch won a competitive tender to provide engineering services for the permanent solution, consisting of a detailed civil and structural design for the plant, as well as a basic design, for all associated interfacing plant, including Bulk Material Handling (BMH), Electrical, Control and Instrumentation (C&I) and Low Pressure Services (LPS). The scope of the permanent solution project includes Silo 20 reinstatement, strengthening of Silos 10 and 30 and all supporting systems. During the design phase, the urgent timeframe resulted in Hatch having to shave several weeks off the engineering design schedule. To date the project has been a success. Challenges going forward include conveyor construction, lifting Majuba is a six-unit, coal-fired power station that produces a total of 4 107 MW of electricity. It comprises three dry-cooled units producing 657 MW each, and three wet-cooled units producing 712 MW each. Construction started in 1983, with the first unit connected to the national grid in 1996. The last unit was connected in 2001.

of gantries and the transfer house sections to the top of Silo 20, which include lifts in excess of 40 t, and commissioning at the live power station. The project scope is large and complex, with the main focus being a very tight deadline. It is an interesting project in that the entire Silo 20 was not demolished. Rather the base and bottom half from the hopper up were incorporated into the new structure. Another engineering design challenge has been to ensure that the plant, which was built originally over 20 years ago, complies with all the latest regulations and requirements, without changing any fundamentals such as the layout. A significant challenge is that the coal feed to the fully functioning power station cannot be interrupted at all, which is why Eskom has phased the project, with a bypass conveyor as an interim solution. Silo 20 is 65 m high, which presents a challenge in terms of heavy lifts due to the windy conditions at this time of year, as well as significant safety risks to all individuals working at heights to perform these difficult installations. Another major challenge in terms of the sliding in particular is that the concrete mix has to be precise, an area where Hatch’s site engineers paid particular attention to.

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2 16 BEST PR O JECTS

DECEMBER • 2016