Rehabilitation of Kariba Dam at an advanced stage

-Completion of the work, minimize the risks of unregulated releases of water which could flood the downstream communities, resulting in damage to property and loss of lives, the Authority said.

John Cassim

Harare, Zimbabwe (CZ) – Works on the US$294.2 million – Kariba Dam Rehabilitation Project (KDRP) are progressing well with works being 67% complete, Zambezi River Authority has revealed.

The rehabilitation project, which comprises three components: the Reshaping of the Plunge Pool, the Refurbishment of the Spillway Upstream Control Facility, and Institutional Strengthening, is projected to be completed by the first quarter of 2025.

Through funding in the form of grants and loans availed to Zambia and Zimbabwe by the African Development Bank (AfDB), the European Union, the Government of Sweden, and the World Bank, the KDRP seeks to address dam safety concerns and restore the structural integrity of Kariba Dam.

-Plunge Pool Reshaping works

Razel Bec (a French company), commenced work on the plunge pool in May 2017 and targets to complete it in the second quarter of 2024.

Works on this component are now 78% complete and involve Pumping out of the water, with the resulting lowering of the pool level, paving the way for the excavation works using controlled blasting of the exposed rock.

In total, 680 million litres of water have been pumped out of the Plunge Pool, leaving the current water level in the pool at 320m Above Sea Level (ASL).

To date, approximately 137 000 cubic meters of rock have been excavated, out of a total of 300,000 cubic meters.

“The objective of the excavation is to widen the Plunge Pool in keeping with the technical design with a focus on the bulk excavation of the rock mass around the Plunge Pool, haulage and disposal of the excavated rock at the designated dumpsite, fault treatment or repair works.
Since construction, the Kariba Dam has served Zambia and Zimbabwe for over 60 years. The Zambezi River Authority is the implementing agent for all the three project components,” Engineer Munyaradzi Munodawafa, Zambezi River Authority Chief Executive Officer said.

-Spillway Refurbishment works

The Spillway Refurbishment works contract commenced in November 2019 and is being implemented by the Zambezi River Authority as the employer and a Consortium of GE Hydro France with Freyssinet International as the Contractor.

The project is 57% complete to date although its target date for completion, is the first quarter of 2025.

This project involves the replacement of defective guide rails on the upstream spillway control facility to improve the operations of the six sluice gates.

The Contractor is focusing on the Hydro-demolition of the secondary concrete around the old Built-in-Parts (BIPs) upstream of the Sluices, fresh concreting of BIPs in Sluices number 2 and 6, repair of surface cracks on the downstream end of sluice Number 3, and finalisation of the manufacture of the Emergency Gate (in China) and the Gantry Crane (in South Africa).

-Institutional Support

“The Authority engaged the services of Gruner Stucky Limited (a Swiss company) as the Technical Services and Supervision Consultant for the KDRP.
Due to the unprecedented nature of the works’ components of the KDRP, the Authority is further supported by a seven (7) member Dam Safety Panel of Experts (DSPoE) which undertake bi-annual site visits and provide guidance, recommendations, and opinions to help resolve project execution challenges,” Engineer Munodawafa added.

According to Munodawafa, the overarching objective of the KDRP is to ensure the continued structural integrity of the Kariba Dam wall.

He said, “Completion of the KDRP works will benefit the communities in both Zambia and Zimbabwe through safer and reliable management of flood releases to avoid overtopping the Dam Wall.
This will also minimize the risks of unregulated releases of water which could flood the downstream communities, resulting in damage to property and considerable loss of lives, under worst case scenarios.”

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