KZN’s most successful borehole? , 2004/12/12
Parts of the Zululand District Municipality (ZDM) have been experiencing severe water shortages. This shortage has especially been felt in the town of Nongoma where the local Vuna dam has silted up and water supply has been fraught with problems. It is hoped that groundwater will help alleviate these problems. The ZDM, through ZAI Consulting Engineers, recently commissioned a borehole to supply a small community just outside Nongoma.
The borehole was sited by Terratest and targeted a small (±3m-wide) dolerite dyke and was drilled by Pollard Drilling to 100m at a diameter of 203mm. The hole kept collapsing at the contact zone and Symetrix Drilling was used to secure the borehole through this zone. The borehole intersected two fracture zones; the first a synthetic fracture probably paralleling the dyke and the second at the contact between the host shales of the Vryheid Formation (Karoo Sequence) and the dolerite dyke. The combined yield from these two aquifers resulted in a blow yield of 250m³ / hour while drilling was in progress. This dropped to 180m³ / hour once casing had been installed. It is thought that this is KZN’s highest yielding borehole.
The ZDM’s Head of Department for Technical Services, Mr Christo Nel says: “Groundwater has in the past been viewed as a temporary and unsustainable solution to water supply. This has largely been the result of the application of a non-technical approach. We decided to call on Terratest for help. This has paid off and we have now hopefully solved a major problem in Nongoma”.
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