Kariba rescue package

US$294m package announced to rescue Kariba dam from possible collapse

Engineering News and Mining Weekly - Oscar Nkala - Creamer Media Correspondent

6 March 2015

The World Bank, the European Union (EU), the African Development Bank (AfDB) and the government of Sweden have agreed to provide Zimbabwe and Zambia with US$294- million for the repair of structural deformations on the Kariba dam wall and avert the possible collapse of the giant hydropower station, which supplies power to both countries.

The planned repairs follow a series of expert assessments of the structural integrity of the 55-year-old wall found that the entire structure is at risk of collapse because of uncontrolled outflows of water from the spillways, which have eroded part of the dam wall.

Urgent work will include a remodelling of the dam’s plunge pool to minimise the scouring of the foundation and repairs to all six spillway gates. The expert reports also warned that continuous swelling of the concrete wall, owing to slow chemical reactions over the years, is constricting the passage of water through the spillways, which could lead to an excessive build-up of pressure as the huge water body builds up on the weak wall and precipitate its collapse.

Last month, the four international financing partners and the Finance Ministers of Zambia and Zimbabwe met in Harare to sign a deal that paves the way for the start of the decade-long wall rehabilitation and repair work during the first half of 2016.

EU ambassador to Zimbabwe Phillipe van Damme said the bloc decided to provide the fund because of the potentially grave humanitarian and economic costs the region could face should the Kariba dam wall collapse.

“It was considered an emergency and the EU decided to mobilise funds as it was important to start the rehabilitation as soon as possible.”

The EU will provide US$100-million, while the World Bank and the AfDB will provide US$75- million each. The remainder will come from the Swedish government, which has pledged a grant of US$25-million.

Zambian Finance Minister Alexander Chikwanda said the Kariba dam wall should never collapse as this would cause a catastrophic humanitarian disaster on communities and economic infrastructure downstream.

He said any post collapse reconstruction of the dam – which is 128 m high and 617 m long and holds up to 181-million cubic metres of water – would cost each of the countries more than US$5-billion, which neither can afford.

Zimbabwe Energy and Power Development Ministry permanent secretary Partson Mbiriri said: “The rehabilitation will start in the first half of next year. Because of our particular situation, some of the money will be directed to Zambia, which will on-lend it to the Zambezi River Authority (ZRA).

“Both countries realise that failure to invest in the timely rehabilitation of the dam will result in the gradual degradation of key dam safety features.”

ZRA chairperson Charity Mwansa said the reshaping of the plunge pool would take three years, while the rehabilitation of the spillway gates was scheduled to take six years, with minimal disruptions to normal operations.

Edited by: Martin Zhuwakinyu, Creamer Media Senior Deputy Editor

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To read the risk research report, “Impact of the Failure of the Kariba Dam”, by The Institute of Risk Management South Africa, completed June 2015, click on the link below:

http://www.aon.co.za/Assets/docs/general/Kariba_Report.pdf

The report [12.5MB] was sponsored by Aon South Africa.

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