Highveld Water Supply

Another important date was 9 June 1975, when a high level delegation from SASOL (De Witt and Coetzee), accompanied by their consultant (Heyns and van Niekerk) came to see me in my office. They wanted to know from which dam they could start their pipeline to supply the proposed new SASOL II plant on the Eastern Highveld of the then Transvaal. I replied that things were not so simple: that we had various other customers in the area such as the existing and proposed new coal-fired Escom power stations, coal mines, municipalities and other industries. The delegation was clearly not at all pleased with my reply and went higher-up, to no avail. This was the start of a major planning study which lead to the construction of the Grootdraai dam in the Vaal River near Standerton. Although there was no capacity in the river to meet their demand, it was considered that, because of the urgency of SASOL, water could be “borrowed” from the Vaal as backed up by the Tugela, while further resources to supply the area could be implemented. Little more than four years were available for planning, designing, constructing and commissioning of the major water supply project that would be needed. Any delay would cost SASOL millions in interest every month. A pumping station and canal would take the Grootdraai water to the continental watershed between the Vaal- and Olifants basins and from there to the plant and also into the Trichardsfontein balancing dam feeding a tributary of the Olifants to the Matla and Duvha power stations.  A further power station, called Ilanga was also already on the drawing board.

At this stage a broader picture of the water supply position on the Highveld is necessary. At the time when Escom was planning the Komati power station, it was found that the relatively large amount of water needed could not be met from local resources such as the Olifants River. The two under-used and water-rich rivers of the Eastern Transvaal, the Komati and the Usutu were identified as possible sources and the Nooitgedacht Dam on the Upper Komati was completed in 1962. The next power station to be erected in the area was Camden, supplied with water from the Jericho Dam in the Usutu basin, completed in 1968. In the early seventies another three power stations were erected on the Highveld viz. Arnot, Hendrina and Kriel. The Vygeboom Dam on the Komati River was completed by the Department in 1971 to supply the two former stations. But there was a shortfall for Kriel.  The next step was the construction of the Westoe dam on the Usutu, which was completed in 1972 and was raised a few years later. A further dam on the Ngwempisi branch of the Usutu, called Morgenstond was completed in 1978. A pipeline connection between Camden and Kriel allowed the latter power station to be supplied with Usutu water. The next step was to supply water to the Matla and Duvha power stations. From the Usutu Government Water Scheme, there was still some water available to feed the initial needs of Matla. At the same time there was still some water available from the Komati to meet the initial needs of Duvha. At first it was considered to meet the remaining requirements of Matla and Duvha by further dams in the Usutu and the Komati respectively. Storage would be provided on the Olifants River, to be filled by the extra capacity of the supply pipelines during off-peak times. The proposed dam could then also hold a strategic reserve. This proposal bore the name of Komati-Usutu link system. 

After this historic digression, it is now back to Grootdraai. The water “borrowed” from the Vaal is to be replaced by transfers from the Usutu and therefore the project was called the first phase of the Usutu-Vaal project, but is, in fact, a Vaal-Olifants link. The replacement water comes from the Assegaai branch of the Usutu at the Heyeshope site via the Usutu-Vaal inter basin transfer. Originally, DWA investigated a site in a gorge a few kilometres downstream of Heyeshope. When I drew a long section of the river bed, I found that this site needed an unnecessary high dam to command the basin, and as a result located Heyeshope as a far more economic site, notwithstanding the required length of the dam. Because of the flexibility of supply from different sources to the various power stations the supply network was now called the Komati-Usutu link system. In writing this text, my memory was assisted by a paper I submitted to the United Nations Water Conference in Mar del Plata, Argentina in March 1977. (At the last moment the SA delegation was barred from the Conference!) The paper was called: “Inter basin water transfers in South Africa”.

Another water supply project to an Escom power station that I was involved with was the Zaaihoek Dam on the Slang River, a tributary of the Buffalo River, in turn a tributary to the Tugela. It supplies water to the Majuba power station and can also supplement the resources of the Vaal River, because the scheme is an inter-basin transfer.