The Dikgatlhong dam, in Botswana, is expected to be complete in 2012 after four years of construction, reports consulting engineers Jeffares & Green.
The dam, which will have a capacity of about 400-million cubic metres, is valued at $300-million.
The new dam and the associated infrastructure will provide about 3000 ℓ/s of raw water delivery to the existing national north–south carrier pipeline, which transports water from the Letsibogo dam, near Selebi Phikwe, to Botswana’s capital, Gaborone.
Water from the dam will be transported to Gaborone, the Palapye coalfields and the proposed 3 600-MW power station at Mamabula, about 130 km north of Gaborone. The power will also be fed into State-owned power utility Eskom’s grid, which means that the Dikgatlhong dam is also significant to South Africa.
The project, located in north-eastern Botswana, will capture flows from two major rivers, and is situated about 2 km below the confluence of the Tati and the Shashe rivers. The earth-filled dam is 4,5 km × 41 m with an off-channel spillway, in the event that it fills to capacity.
The construction of a major structure across a large river that is prone to flooding each year can result in significant challenges that must be planned for and overcome. The company makes provision for yearly floods during the construction period over three rainfall seasons to ensure that the embankment is built to its final height. Construction of the critical-path river section embankment must rise by 25 m before the coming wet season when the river’s flow must be diverted through a channel located on the left flank, the company states