Dikgatlhong Dam

Construction of the Dikgatlhong dam, which is located a few kilometres below the confluence of the Shashe and Tati Rivers in north-eastern Botswana, started in March 2008 and was completed early 2012. The dam is located 65 km north-east of the town of Selebi Phikwe. The project was precipitated by rapid water demand growth in the 1980s which prompted the Botswana government to undertake studies to meet the projected growth.

The 4,6 km long by 41 m high zoned earthfill embankment dam will have a full supply storage capacity of 400 million m³ and will easily surpass the capacity of the next largest dam in Botswana, Gaborone Dam, which has a maximum capacity of 141 million m³. Total earthworks volumes are of the order of 3,87 million m³, comprising 550 000 m³ of clay core sourced from borrow pits and 2,46 million m³ of embankment shell sourced from the excavation of the spillway channels. The main spillway is a 200 m long mass concrete ogee structure with energy dissipaters and is situated on the upper left flank about 2 km to the north of the river. There is also a 900 m long auxiliary spillway to accommodate extreme flood conditions and increase the combined spillway capacity to over 11,000m3/sec. Other structures include a 7 m diameter by 48 m high concrete intake tower with five gate openings which feed a 260 m long by 3 m diameter steel outlet conduit passing beneath the dam embankment before bifurcating to a pump station and a river outlet. The intake tower is connected to the top of the dam embankment by means of a 61 m long steel bridge.

The contract for the Botswana Department of Water Affairs is being undertaken by Sinohydro Corporation from China at a cost of R1,5 billion, under the administration and supervision of Bergstan Gauff Jeffares & Green Joint Venture. The design review, tender documentation and overall technical advisory aspects are managed from J&G’s Hilton office in KZN. The environmental issues are being monitored by an independent environmental consultant, and G4 consulting engineers are handling the electrical aspects.

Other associated contracts making up the project included the upgrading of 44 km of road between the villages of Mmadinare and Robelela (the nearest settlement to the dam), housing and power supply, all of which have been completed. Contracts worth approximately another R1,1 billion for the construction of a pump station and 75 km long by 1,2 m diameter pipeline have recently been let. The pipeline will convey raw water from Dikgathlong dam to the existing north-south carrier pipeline that conveys water from Letsibogo Dam to Gaborone, and which is also due for upgrading in the near future.