The Preekstoel Water Treatment Works relies on both surface and groundwater to supply Hermanus with vital water resources. In this update, we cover the performance of the Gateway and Hemel and Aarde wellfields, based on recent monitoring by Umvoto, and provide key insights from the latest Hermanus Monitoring Committee meeting.
Attended by Tobie Louw PrEng, HRA’s Infrastructure Services Portfolio lead
The Preekstoel Water Treatment Works (WTW) receives about 78% of its annual raw water from the De Bos Dam, while the remaining 22% is supplied from groundwater. This groundwater is drawn from two wellfields: the Gateway Wellfield, which contributes about 10% of the total volume, and the Hemel and Aarde Wellfield, which contributes 12%. Each wellfield includes several production and monitoring boreholes, and regular monitoring is essential to ensure sustainable delivery.
Umvoto, an earth-science consultancy, was responsible for the establishment of these wellfields and continues to perform ongoing monitoring duties of the boreholes. On a quarterly basis, Umvoto provides feedback to the Hermanus Monitoring Committee (HMC), a selected committee, on the monitoring and performance of the wellfields.
I began attending these meetings as a representative of the Hermanus Ratepayers Association, with the aim of sharing high-level feedback on the management of this critical water source.
Gateway Wellfield:
The Gateway Wellfield consists of four production boreholes, with an approximate total annual yield of 403,000 cubic meters. In addition, there are around 10 monitoring boreholes serving the Gateway Wellfield, located both near and far from the field. Groundwater levels within the vicinity of the wellfield are stable, showing no significant impact on other groundwater users in the area.
An overview of the Gateway Wellfield’s hydrochemistry, including metals and microbiology, did not reveal any concerning results from monitoring during this three-month period.
Hemel and Aarde Wellfield:
This is a collective name for two wellfields: the Camphill and Volmoed wellfields. Together, they include six production boreholes, with an approximate total annual yield of 508,000 cubic meters. There are also seven monitoring boreholes serving the Hemel and Aarde Wellfield. There were no issues of concern regarding flow rates and groundwater levels in the six production boreholes across this wellfield.
Additionally, the hydrochemistry results for these wellfields did not reveal any concerns.
The meeting was well attended by representatives of Overstrand Municipality’s infrastructure directorate, the Overberg Geoscientists group, and several representatives from prominent Hemel en Aarde farms. Peter van Niekerk of the Onrus Estuary Forum chaired the HMC.
I found the feedback to be well-prepared and professionally presented by Umvoto. The monitoring of our wellfields is clearly in capable hands.
