Ingula pumped-storage scheme project, South Africa

20th February 2015

  

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Name and Location
Ingula pumped-storage scheme project, on the border between the Free State and KwaZulu-Natal provinces, South Africa.

Client
Eskom.

Project Description
The Ingula pumped-storage scheme, located within the Little Drakensberg mountain range, 23 km north-east of Van Reenen’s Pass, will comprise an upper dam (Bedford) and a lower dam (Braamhoek). The upper reservoir site is located in the Free State and the lower reservoir site in KwaZulu-Natal. The escarpment forms the border between the two provinces.

The distance between the upper and lower reservoirs will be 4.6 km, with an elevation difference of about 470 m.

The reservoirs will be connected through underground waterways and the underground powerhouse complex, which will house four 325 MW pump turbines with a total capacity of 1 300 MW, a machine hall, a transformer hall and associated tunnels, shafts and caverns.

The twin headrace waterways, consisting of concrete and steel-lined headrace tunnels, pressure tunnels and shafts, will link the upper reservoir with the pump turbines. The draft tubes, concrete-lined surge shafts and a single concrete-lined tailrace tunnel will connect the pump turbines to the lower reservoir.

The upper reservoir is a concrete-faced rock-fill embankment dam, 41 m high, with a total capacity of 22.4-million cubic metres and an active water storage volume of 19.2-million cubic metres. The 39-m-high lower dam comprises roller-compacted concrete, with a total capacity of 26.3-million cubic metres and an active storage volume of 21.9-million cubic metres.

The scheme will be operated on a weekly cycle and will have an overall cycle efficiency of 78%.

Value
R25.9-billion. As at January 31, 2015, R23.9-billion had been spent.

Duration
The units will come on line starting from the first half of 2016.

Latest Developments
Eskom reported in January this year that the first 333 MW Ingula pumped- storage unit would only be synchronised in the first half of 2016, following major disruptions to construction following an accident in October 2013, which resulted in the death of six workers and the injury of several others.

Meanwhile, Ingula’s powerhouse complex has finally been completed, albeit later than expected. The powerhouse complex has been successfully handed over to the electrical and mechanical teams.  They have started with the creation of the heart beat and the driving force of the pumped storage scheme. 

The powerhouse complex consists of three major components, the machine hall, transformer hall and the main drainage gallery. All of these components were excavated using the drill and blast method, whereby huge drill rigs are used to drill horizontal holes into the rock face, into which explosives are inserted and detonated. Thereafter, dump trucks and front-end-loaders are used to remove the rock boulders and fragments for disposal.

The side walls and roof from the blast is then supported with steel rock-bolts, steel cable-anchors, and sprayed concrete.  This process is then repeated, at the next intact rock face. In each subsequent drill and blast operation, the blast hole is extended, to form the required shapes of the machine hall, transformer hall caverns and main drainage gallery.

The machine hall, located 350 m underground, forms the ‘heart’ of the pumped storage scheme, and will house the reversible Francis turbine and generator sets, the main inlet valves and other electrical and mechanical plant. The machine hall measures 183 m long, 26 m wide and 49 m high, together with access and ventilation tunnels. It consists of three distinct floor levels, the operating floor, generator floor, and turbine floor levels. The total gross volume of the excavation is 230 000 m3. About 49 000 m3 of concrete and 3 000 t of steel was used to construct the machine hall.

The transformer hall is also located about 350 m underground and parallel to the machine hall.  It houses the electrical plant, consisting of the four oil-insulated generator transformers, contained in separate fire-protected enclosures at operating floor level; a single static frequency converter pumping mode starter system; the battery room and cable termination stations for the 1 000-m-long 400 kV cables. The transformer hall measures 175 m long, 15.7 m to 18.95 m wide and 19.2 m high. It consists of four floor levels, pipe and drainage gallery level, operating floor level, mezzanine floor level and battery floor level. The total gross volume of the transformer hall excavation is 78 000 m3. About 18 000 m3 of concrete and 1 500 t of steel was used to build the transformer hall.

The main drainage gallery runs parallel to the machine hall and is the lowest point of the entire scheme. It houses the drainage and dewatering system, which disposes of seepage and leakage water from the pump turbines; dewaters the pump turbines, penstocks and draft tube extension tunnels; and allows emergency pumping during powerhouse flooding. In addition, the oil interception system is also housed in the main drainage gallery, which removes oil from the seepage, leakage and fire-fighting, excluding generator transformer fire-fighting, water that has reached the station gutters in the drainage gallery, before it reaches the main station sump, to minimise oil discharge from the station.

Ingula’s two emergency diesel generators have been hot commissioned. During commissioning the two diesel generators were synchronised to the 22 kV Eskom distribution network to perform load testing. 

In the event of a grid black-out, where no normal power supply is available, Ingula’s emergency diesel generators will provide essential power to enable the station to perform a ‘black start’ operation.

All the components of the emergency generators were manufactured in France and assembled in South Africa by Diesel Electric Services. An estimated 20 employment opportunities were created during the manufacturing and commissioning phases.

“By hot commissioning the emergency diesel generators, we have just crossed the starting line. We are well on our way to the finish line whilst prioritising on safety, quality standards, maximizing time, sustaining mutually beneficial stakeholder relations, enhancing our reputation as a responsible corporate citizen especially within our labour sending communities, proactively engaging with our host communities in both Free State and KwaZulu-Natal and containing our cost implications on-site,” says Ingula executive project manager Avin Maharaj.

Key Contracts and Suppliers
The Braamhoek Consultants Joint Venture (BCJV), consisting of Gibb, Knight Piésold and SSI (civil, mechanical and electrical engineering, detailed design, tender documentation, design monitoring and construction supervision); Murray & Roberts (exploratory tunnel); Grinaker-LTA (access roads); CMI JV, comprising CMC di Ravenna, PG Mavundla and Salini Impregilo (underground civil works); Royal HaskoningDHV (design and construction of upper and lower dams, access roads, visitors centre, administration building and main underground works); Afriscan (water supply, sewage treatment, small access roads and building temporary Eskom offices); B&E Quanza Group (aggregate quarry); Acer [Africa] (environmental consultants); Braamhoek Dam JV (BDJV), comprising Concor Roads & Earthworks, Wilson Bayly Holmes-Ovcon, Edwin Construction and Silver Rock (dam contract); Voith Siemens Hydro Power Generation (main generating plant); Deutsche Bank (R1-billion loan); Voith (mechanical auxiliary plant, turbines and generators); ABB (electrical balance of plant); NCC Environmental Services (independent environmental control officer services); Konecranes (heavy-duty cranes); Letacla (fibre-optic communications); Siemens (generator transformers); Roshcon (line integration – main contractor); Optipower and Babcock Ntuthuko (line integration – subcontractors) and CBI and Prysmian (supply and installation of 400 kV cables).

On Budget and on Time?
The first 333 MW unit was initially expected to be commissioned by January 2013; however, it will now be commissioned during the first quarter of 2015.

Contact Details for Project Information
Eskom media desk, tel +27 11 800 3304/3309/3343/3378, fax +27 11 800 3805 or email mediadesk@eskom.co.za.
Eskom senior project manager Avin Maharaj, email Avin.Maharaj@eskom.co.za; or communications Mlungisi Shongwe email mlungisi.shongwe@eskom.co.za.
Ingula Visitors Centre, tel +27 36 342 3122 or email fifi.meyer@eskom.co.za.
ABB, tel +41 43 317 6480 or fax +41 43 317 6482.
Gibb, tel +27 11 519 4600 or fax +27 11 807 5670.
BDJV (Concor Roads & Earthworks), tel +27 11 495 2222.
CMI Mavundla JV, tel +27 36 638 6000.
Royal HaskoningDHV, Jacques du Plessis, tel +27 11 798 6000 or email Jacques.duplessis@rhdhv.com.
Impregilo, tel +39 02 4442 2115.
Voith Siemens Hydro Power Generation, tel +49 7321 370 or fax +49 7321 37 6180.
NCC, tel +27 21 702 2884, fax +27 86 555 0693 or email info@ncc-group.co.za.
Konecranes, tel +27 11 864 2800.
Roshcon, tel +27 11 629 8000, fax +27 11 629 1089 or email Rosh.Int.Comm@eskom.co.za.
Optipower, tel +27 21 845 6745, fax +27 21 845 5264 or email info@optipower.co.za.
Babcock Ntuthuko, tel +27 11 739 8287.
CBI, tel +27 11 928 2000, fax +27 11 392 2354 or email cbi@cbi-electric.com.
Prysmian, tel +39 02 6449 1 or email media.relations@prysmiangroup.com.

Edited by Creamer Media Reporter

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