Zambezi authority seeks gate, spillway investigations at Kariba Dam hydro complex

The Zambezi River Authority (ZRA) invites applications for pre-qualification to inspect and investigate an emergency gate and spillway of the Kariba Dam hydropower complex on the border of Zimbabwe and Zambia. Responses are due September 21.

Zambezi River Authority operates the 128-meter-tall double-curvature arch dam for its owners, the governments of Zambia and Zimbabwe. The hydro complex includes the 750-MW Kariba South Bank 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 in Zambia.

ZRA said in January that total rehabilitation of the dam for safe operation will require US$300 million. Concerns arose from an alkali-aggregate reaction in the dam wall, which could induce swelling within the concrete mass. In addition, the plunge pool below the sluice gates is eroding toward the dam’s foundation. The amount of water in Lake Kariba is reported at its lowest in 20 years, spurring a power shortage in the region.

ZRA seeks applications for pre-qualification for Kariba Dam Emergency Gate and New Gantry Underwater Visual Inspections and Special Investigations. Work is to include underwater inspections of upstream concrete faces of the spillway using a remotely operated vehicle, drilling of concrete cores on the upstream and upper part of the spillway, laboratory tests of the concrete cores, opening of inspection windows in the upstream grooves of Sluice No. 2, filling of the drill holes and inspection windows, measuring of controlling dimensions and geometries of several concrete faces in the spillway system, bathymetric surveys of potential sites for a slipway, and reports.

Pre-qualification documents in English may be obtained by e-mail request to They also may be obtained from the ZRA Internet site, ZRA plans to seek bids at the end of September.

Applications for pre-qualification are due September 21 in pdf form by e-mail to Zambezi River Authority at,,

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