Groundwater brings hope for SA’s driest regions
The groundwater development team, consisting of AGES Eastern Cape (Pty.) Ltd., under the engineering project management of Uhambiso Consult (Pty.), has had an amazing experience with a borehole that was recently drilled as part of the Chris Hani District Municipality’s Cluster 2 regional water supply scheme in the Queenstown area.
The borehole was developed with a large diameter, to a depth of 120 m, and could not be drilled any deeper due to the high flow rate and enormous water pressure, which could not be discharged by the air compressor and drilling rig of the appointed contractor, Steyn’s Drilling.
This groundwater development work was based on a 2004 study funded by the Water Research Commission (WRC) and further supported by the Department of Water Affairs. The focus of the study was on the hydrogeology of fractured-rock aquifers in Qoqodala area within the Great Kei River Catchment in the Eastern Cape. This has provided a good reference to the groundwater development team to achieve a high yield within the premises of Luqolo Secondary School.
A large part of the population in Qoqodala area depends on numerous springs and seeps coming from the mountains and yet boreholes are very few. At an estimated maximum yield of close to 80 ℓ/s (almost 300 000 ℓ/hour!) “We believe this is one of the highest yielding boreholes ever drilled in Karoo lithologies in the Eastern Cape Province!” says Jan Myburgh, a Senior Hydrogeologist from AGES (Pty) Ltd.
The borehole intersected major fractures in a complexly-deformed dolerite sheet, which is associated with the so-called ‘dolerite ring structures’ that typify the hydrogeology of the Queenstown area and other parts of the province.
The borehole was recently tested by AB-Pumps with a large diameter pump which requires a lot of infrastructure, planning and organizing. Even installing the biggest testing pump available in the province, the maximum yield that could be pumped was 55 ℓ/s. This resulted in a drawdown of only 26 m, indicating that the borehole’s maximum yield could easily be close to 80 ℓ/s!
Wandile Nomquphu, WRC Research Manager who worked for the Department of Water Affairs at the time of testing the borehole, says “with its good water quality and high sustainable yield – this borehole is one of the cornerstones of the regional water supply scheme which, together with several other high-yielding boreholes in the scheme, will serve water to almost 60 000 people”.
To ensure social acceptance of the water source at Chris Hani District Municipality, a groundwater-community compatibility study was done with associated awareness creation programmes to ensure that the people take ownership of the resource.
WRC Report No: 1238/1/04
Contact: Wandile Nomquphu
WRC Research Manager: Water Resource Management
Tel: 012 330 9069