Test pumping is a common and important process that is carried out in any new or existing boreholes/wells.

Test pumping is the field activity that is performed on a borehole where it is pumped at a constant rate or variable rate and the drawdown measured in one or more observation wells. The main aim of pumping tests is to obtain hydraulic properties of aquifers, identify aquifer boundaries, as well as evaluate the well performance.

This article sheds light on the entire concept of test pumping, why it is important, and how it is carried out. Dive in.

What is test pumping?

Test pumping can be defined as the activity of pumping of a well from its measured static water level at known yield, and recording the rate at which the level of water in the well changes. At a particular point where the dynamic water level is attained, the rate of inflow is equal to the rate of pumping. At the end of the test, some water sample is collected and analyzed. All this is done to enable hydro geologists to get the accurate pumping rate, drawdown for a given discharge rate, and the installation depth. This way, they are able to estimate specific aquifer hydraulic properties such as storage coefficient, coefficient of permeability, and transmissivity.

What are the different types of pumping tests?

There are different pumping tests that can be carried out in a well/borehole. The common ones we perform at Bluewaters LTD are:

Constant rate tests

This test is carried out by maintaining a constant head (the pumping at the control well is maintained at a constant rate). It is the most common pumping test method that is used to obtain the different aquifer properties.

Step-drawdown tests

This test is performed through a sequence of constant-rate steps at the control well. This way, you are able to determine the well performance characteristics like well efficiency and well loss

Recovery tests

This test makes use of the water-level measurements (drawdown) after the pumping is done. Although it is often interpreted separately, it still forms a major part of the pumping test.

What is required in designing a pumping test?

There are several factors that go into designing a pumping test. It is not just done haphazardly and at any time of the year. A lot of planning
and reconnaissance work is required for best results. The factors worth consideration include the time of year, the off-site groundwater users
that may have a direct influence on the water levels, strategy for disposing pumped water,location of both new and existing wells, pumping duration, and the depth setting and pump type in t he control well. Other factors include:

• How the pumping test will affect nearby water users
• Field equipment required,
• Possibility of salt water intrusion if in coastal areas, and
• Potential aquifer boundaries such as faults and streams.

How to dispose the pumped water?

As mentioned above, one important factor to consider is the strategy on how to dispose the pumped water. This is very important when carrying out a pumping test where water is extracted from the aquifer. Care should be carried by first ensuring that the water is disposed in complete compliance with the regional applicable laws and regulations. There are other considerations that you need to keep in mind for disposal of pumped water.

For one, it is important that that direct discharge onto the ground be avoided as it is likely to recharge the aquifer below. It is possible to discharge the water to a nearby surface water feature as long as the water body in question is hydraulically disconnected from the aquifer. And finally, adverse biological, thermal, or water-quality erosion impacts should be avoided when discharging the pumped water.

FAQs

What tools/ equipment are required to carry out a pumping test?

There are specific tools that you need to perform a pumping test in any well. The main ones
include a submersible pump, power inverter, generator, and extension cords, flow measurement
devices, discharge pipe, reducers/enlargers, and connections, tape measure, Ph and conductivity
meters, and data collection forms.

What is the duration of a typical pumping test?

The test duration is determined by a number of conditions such as whether the objectives of the test have been met and the hydrogeological conditions of the test site. Usually, longer tests are necessary to accurately estimate the specific yield or observe boundary effects.

What are the cons of pumping tests?

One main disadvantage of pumping tests is that it is not always possible to identify the recharge boundaries or the interconnected between a surface water body or other aquifers unless they are in close proximity to the well being pumped. Moreover, many of the existing wells may not be suitable for pumping tests.

Conclusion

Borehole water is known to be free, but you still need to factor in the budget required for annual maintenance and testing schedule. Pumping tests are very important to ensure that you utilize your borehole to its full capacity, and the right equipment are specified for your borehole. Ultimately, pump testing ensures that the selected pump will perform at designated flow, amperage, pressure, and horsepower.

At BlueWater Ltd, we ensure affordability without compromising quality in our borehole test pumping services. Through our streamlined processes and efficient methodologies, we deliver precise and reliable test pumping results at competitive rates, making high-quality assessments accessible to all.