Many are under the impression that tapping into an aquifer will present an unlimited and steady supply of water. It may seem that way at first. However, without borehole testing being carried out during the drilling process, you could end up with a borehole that runs dry or yields minimal amounts of water. At Aqua Borehole Solutions, we ensure that your borehole remains sustainable by conducting yield tests, thereby guaranteeing that it will produce water for many years.
What is a Yield Test?
As much as one relies on groundwater, it is important to note that this is a source that can run dry should more water be used than the aquifer can produce. Just as one relies on rainwater to top up water storage tanks, a similar principle extends to accessing borehole water. Yield tests are conducted to see that the balance between the maximum amount of water that can be pumped from the borehole and the amount of water that can be replenished by the surrounding groundwater source is maintained.
For a borehole to produce a sustainable yield, two important rules have to be followed:
- The total amount of water taken from the borehole should always be less than that of the natural water source.
- When pumping borehole water, the level must never reach the position of the main water strike.
Guiding You through Borehole Testing
The main objective of a yield test is to establish the potential of your borehole and estimate the sustainable yield as well as the hydraulic performance for a constant water supply. Preparing you for what you can expect from borehole testing, Aqua Borehole Solutions provides a step-by-step introductory guide:
- Step-Drawdown Test
This test takes up to six hours and is done to determine the effectiveness and performance of the pumping borehole system under controlled discharge conditions. During this test, the discharge rate is assessed from low constant rates and through various intervals, to a higher constant rate. The yield must be measured at least three times to ensure that the flow is constant. It is advisable to monitor the recovery level of the groundwater after the first flow test.
- Constant Rate Test
During this test, the borehole is pumped at a constant rate over a period of time, usually between eight and 48 hours or longer, if necessary. The data obtained from this test provides us with useful input regarding the sustainability of the yield of the borehole and the potential of the groundwater supply. If at any point during the test the water level is drawn down to the pump inlet, the pump is stopped, and the recovery of the water level is monitored.
- Recovery Test
As soon as the pump has been turned off, we start measuring the water levels. This test is useful in assessing the pumping effect and possible dewatering of the aquifer due to the limited amount of water produced by it. Recovery is measured until the water levels have recovered to less than 5% of the total drawdown during the constant rate test and when at least three identical results, taken in succession, are identified.
These yield tests assist Aqua Borehole Solutions in determining the correct size of the pump to be used and ensuring that the borehole is not over-pumped. During these tests, the quality of the water drawn will be tested to determine its suitability for the intended use.
Your Turnkey Solution
From borehole testing and drilling right through to installing a filtration system enabling you to access borehole water for your home or business, Aqua Borehole Solutions has been instrumental in the successful installation of numerous boreholes. Servicing over 500 domestic, commercial and corporate clients throughout Gauteng with turnkey solutions is a reflection of our excellent customer service and expertly skilled technical teams. Contact us and one of our technicians will design your borehole system according to your specific requirements.
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