Dam safety and rehabilitation at 1,050-MW Kariba hydroelectric project require about US$300 million

After being constructed on the Zambezi River between 1956 and 1959 by the then-Federation of Northern and Southern Rhodesia and Nyasaland (Zambia, Zimbabwe and Malawi), the dam impounding water for the 1,050-MW Kariba project requires an estimated US$300 million for rehabilitation to continue safe operation, according to the Zambezi River Authority (ZRA).

In April 2014, ZRA reported structural issues first discovered at Kariba Dam in 2010 could lead to a disastrous dam failure if repairs were not effected.

ZRA operates the dam for its owners, the governments of Zambia and Zimbabwe, for water resource benefits, including the 750-MW Kariba South Bank hydroelectric project in Zimbabwe, which is being expanded to 1,050 MW; 720-MW Kariba North Bank in Zambia, expanded from 600 MW; and the 360-MW Kariba North Bank Extension project completed in 2014.

Concerns about Kariba dam’s safety arose from an alkali-aggregate reaction in the dam wall, which could induce swelling within the concrete mass.

Of great concern, according to engineers and inspectors from Zambia and Zimbabwe, was the erosion of the plunge pool below the sluice gates, which is eroding towards the dam wall’s foundations.

HydroWorld.com reported in October 2014 that the EU Development Fund extended its deadline for applications for pre-qualification to perform dam safety work to reshape the plunge pool of Kariba Dam to November 2014.

No announcement of a contract award has been made.

The Times of Zambia in December 2014 reported, “Over the next six years the European Union (EU) intends to mobilise 240 million Euros (US$270 million) for the sole development of the energy infrastructure, including the extension of the electricity grid to bring electricity to more and more people in the country,” said Ambassador Gilles Hervio, head of the EU delegation to Zambia.

The African Development Bank gave a US$108 million grant to Zimbabwe in December 2014 for repairs at the site, according to Patrick Chinamasa, Justice Minster of Zimbabwe.

ZRA plans to refurbish and upgrade the spillway system and reshape the plunge pool under separate contracts.

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Gregory B. Poindexter formerly was an associate editor for HydroWorld.com.

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