Construction World December 2016

Special Mention

THE INGULA PUMPED STORAGE SCHEME

It is located about 23 km north-east of van Reenen, within the Little Drakensberg mountain range. The upper reservoir site is located in the Free State province and the lower reservoir in KwaZulu-Natal. The distance between the upper and lower reservoirs is in the order of 6,5 km and the elevation difference is approximately 480 m. The scheme consists of the following basic components: • An upper reservoir (Bedford Dam), • A lower reservoir (Bramhoek Dam), • An underground powerhouse complex and associated waterways that link the two reservoirs, • Four pump-turbines coupled directly with motor-generators, • Surface switching station, • Ancillary works that include building works, roads, transmission lines and temporary and permanent infrastructure. The rated generating capacity is 1 332 MW and the energy storage capacity 21 000 MWh (15,8 generating hours). In addition to the normal generation capacity a minimum emergency full load generation reserve of four hours is maintained throughout the normal weekly operating cycle. The design of the scheme is undeniably complex and sophisticated requiring design inputs from true international experts, each interfacing with each other to yield precise results. During off-peak periods the reversible pump-turbines use electricity from the national grid to pump water from the lower to the upper reservoir. During periods of emergency peak demands, reservoir. During off-peak power periods the pump- turbines then pump the water back up to the upper reservoir where it is to be ready for the next peak power occurrence. The multi-billion Rand Ingula project is a peaking hydro power station. The scheme allows for water to be released from the upper reservoir and delivered to the pump-turbines to produce power, before being captured in the lower

water is allowed to flow back into the lower reservoir through the pump-turbines to generate electricity. From initial site investigations it was realised that the geology at Ingula is more complex than might have been expected. State of the art numerical analyses were therefore carried out to design rock excavation support for the large underground caverns in which the main transformers and pump-turbines and motor- generators are housed. With the project located in the Little Drakensberg escarpment that is recognised for its scenic beauty, the aesthetic value of the engineering design formed the basis for its ultimate environmental approval. In particular the upper reservoir is located in a natural wetland. The layout of the project and the design of engineering elements were treated with great sensitivity towards the environment. Eskom developed and implemented an Environmental Management System (EMS), which has been ISO 14001 certified since 2011. The project has stimulated local economic development during construction with over 5 000 persons employed at the peak of construction, in addition to other direct beneficiaries in the education, health and social investments by Eskom and its contractors.

Project information • Company entering: Braamhoek Pumped Storage Scheme JV • Client: Eskom • Start date: 2005 • End date: 2017 • Consulting engineer: Braamhoek Consultants Joint Venture (comprising Gibb, Royal HaskoningDHV, Knight Piésold) • Contractors: • Murray & Roberts – exploratory tunnel • Grinaker-LTA – access roads • CMI JV, comprising CMC di Ravenna, PG Mavundla and Impregilo – underground civil works • Afriscan – water supply, sewage treatment, small access roads and building of temporary Eskom offices • B&E Quanza Group – aggregate quarry • Braamhoek Dams JV, comprising Concor Roads & Earthworks, Wilson Bayly Holmes-Ovcon (WBHO), Edwin

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Construction and Silver Rock – upper and lower dam contracts

• Voith Siemens Hydro Power

Generation – electromechanical equipment contract • ABB – electrical balance of plant (eBoP) solution. • Project value: R30-billion

2 16 BEST PR O JECTS

DECEMBER • 2016