ARTICLES

Borehole Drilling Increasingly Important from Pretoria to the Cape

Borehole drilling is increasing, not just around Pretoria, but nationwide. Even before the recent scare which left residents of the Mother City wondering when their taps would finally run dry, it was apparent that South Africa is facing a severe water crisis. Gauteng is also no stranger to prolonged periods of drought and, apart from being the most populous of the nine provinces, it is also the site of the nation’s main industrial powerhouse. Over 600 kilometres from the ocean, there would be no temporary desalination plant to rescue residents in this province if the worst were to happen.

As things stand, borehole drilling in the Pretoria and Johannesburg areas offers the sole respite from the consequences of drought for Gautengers. We have grown used to the swimming pools and green lawns that are among the first things to grab the attention of overseas visitors when flying into O.R. Tambo International. That these are, in practice, something of an anomaly in an area which is officially designated as semi-arid is something that even few locals are aware of. Water tariffs are continuing to rise and the restrictions that are often placed on water usage, and periods with none, are more than a little disruptive.

Increased borehole drilling around Pretoria has perhaps been a response to the increasingly frequent declines in the water level at the Hartbeespoort Dam and others in the region. Despite the efforts to extend man-made catchment, the bulk of the country’s rainfall finds its way into underground aquifers. As it permeates through the soil before encountering a channel in the bedrock that allows it to form a subterranean stream, it is filtered free of most contaminants. If sufficient care is taken with its extraction, it is suitable for most purposes, requiring only minimal processing to render it potable.

Unlike a well, which is shallower and wider, a borehole requires drilling by specialists. The narrow shaft contains a metal liner which extends into the bedrock beneath. The liner serves to prevent the entry of contaminants into the flow far more effectively than the brickwork used to support the walls of a well. The narrow shaft, of course, means that the subterranean water must be pumped to the surface. The size of the pump required is determined by the depth of the shaft together with any elevated pipework above, as well as the length of any additional horizontal piping required to deliver the water to a storage tank or irrigation system, for example.

Even though underground aquifers are numerous, the routes they follow are determined by the subterranean geology. As a result, all borehole drilling, whether in Pretoria or Poffadder, should be based on the findings of a professional, hydrological survey. This will identify where it is best to drill, give the drillers some idea of how deep they must go to intercept the water table. When water is struck, measurements of capacity and refresh rate provide an estimate of the potential yield and the lifespan of the installation.

The need to relieve the mounting pressure on municipal water reserves is clear, as is the importance of underground sources and the services provided by borehole drilling experts like the Water Pump Group, located in Pretoria.