Zambezi river hydropower authority the Zambezi River Authority (ZRA) reports that it is progressing with work on the Kariba Dam Rehabilitation Project (KDRP), which comprises projects to reshape the plunge pool and refurbish the spillway gates.
The KDRP has been ongoing since 2017 and is expected to be completed in 2025. From inception, the project’s objective has been to ensure the enhancement of the structural integrity of the Kariba dam, thereby ensuring sustainable generation of power primarily for the benefit of Zimbabwe and Zambia’s citizens, as well as the entire Southern African Development Community region.
Work on the reshaping of the plunge pool, which includes bulk excavation of the rock in the existing pool to facilitate the stabilisation of the plunge pool and prevent further scouring or erosion along the weak fault zone towards the dam foundation, is progressing well.
This reshaping work will be achieved through construction of a temporary water-tight cofferdam to facilitate the reshaping works under dry conditions.
Despite some delays encountered during implementation, in particular unforeseen geological complexities, this project, which started in May 2017, remains on course for completion by the end of 2024, with work currently 60% complete.
The ZRA reports that its spillway refurbishment works are also progressing well.
These works are meant to replace secondary concrete and built-in-parts of upstream guide slots of the stop beams and ensure free movement of the electromechanical equipment that is used to block the flow of water from the upstream face-of-the-dam wall.
An emergency gate for closure of sluices under emergency conditions (to be used where a gate fails to close after release of excess flood water) is also being manufactured.
This project, which started in November 2019 and is being implemented by a consortium that includes GE Hydro and Freyssinet International, is targeted for completion in January 2025.
Meanwhile, the authority reports that while consistent measures have been adopted and implemented to mitigate the effects of Covid-19 on the KDRP, the project has been impeded following negative impacts to site arrangements, offshore supplies and logistics.
The impacts include loss of time as a result of returning expatriates and other local employees having to be quarantined each time they were diagnosed with the virus.
Further, the ZRA reports that it was also set back as a result of the owner and owner’s engineer failing to timely witness the factory acceptance tests (FATs) and vendor quality surveillance (VQS) for the KDRP’s equipment before such equipment could be approved and shipped to the project site.
In addition, the prevalence of the Covid-19 pandemic also led to tightening of border crossing restrictions, resulting in traffic congestion which impacted the project, thereby impeding timely delivery of project equipment.
These disruptions resulted in both time and cost overruns against the project baseline schedule and budget, respectively.
To mitigate these challenges, the ZRA reports that the project owner, through stakeholders’ support, has remained resilient in devising meaningful mitigation measures, including programme enhancement through night shifts.
The owner’s engineer representation in FATs and VQS, as well as accelerated Covid-19 vaccination and testing for the KDRP site staff, have also been instrumental in re-aligning the project to its implementation plan, notes the ZRA.