A contract for major tunnelling works on the Ingula pumped storage scheme in South Africa has been won by a joint venture led by Italian firms Impregilo and CMC
Tunnelling works include the underground powerhouse, a 2km headrace tunnel to the upper reservoir and a 2km long tailrace tunnel to the lower reservoir. In addition, the underground package includes shafts, surge tanks and penstocks.
The construction contract was worth approximately Euro600M (US$795M), said Impregilo. As part of the contract, the JV – in which the contractor has a 40% share – will also undertake dam construction for the upper and lower reservoirs.
South African utility Eskom Holdings is developing the pumped storage project in the border area between KwaZulu-Natal and the Free State, about 350km south east of Johannesburg. The client has scheduled the plant to come into service in 2013.
The project was formerly named Braamhoek but was rebranded two years ago. That year, contractor Murray and Roberts completed a 1.2km long exploratory tunnel. Excavation started in 2005.
Geology in the project area was found to be more complex than expected in a Karoo Supergroup sedimentary sequence, and mudrocks were frequently intersected in boreholes, though the rockmass is expected to be relatively unjointed.
An South African-Italian JV, CMC Mavundia, built the access tunnel, which includes parts of the machine and transformer caverns. A feasibility study for the project was recommended just over a decade ago and completed in 2003. Design is by the Braamhoek Consultants JV, led by Knight Piesold and Stewart Scott.
