After the borehole is developed, a temporary pump is installed to conduct a pump test. This test measures the borehole’s yield (or flow rate) and drawdown, which helps determine the optimal pumping rate for sustainable water extraction.
Skylake Boreholes has all the equipment required for borehole capacity tests. We have a 10 kVA single phase diesel generator which is used with submersible pumps up to 10Hp (7.5kW). If bigger yields are encountered, we will have to use a three-phase diesel generator and submersible pumps, since these pumps require three phase electricity. The tests will be carried out for a minimum of four (4) hours and we will provide written reports and data on drawdown.
We will start with a Step-draw down test (Multiple Discharge Rate Test). This test is the first test that is done during a pumping test. It serves to evaluate well/borehole performance, i.e., how much water can be pumped from the borehole, in order to check the hydraulic efficiency of the borehole and to determine the discharge rate needed for the constant discharge test. During each step, the discharge is kept constant and the discharge rates of each subsequent step is higher than the preceding step. The discharge of the last has to be higher than the expected borehole yield.
The pumping/discharge rates can be determined as follows:
A Constant Discharge Test will then be used to determine how much water the aquifer can yield on a long-term basis. The two aquifer parameters, transmissivity and storage capacity, are also determined from the test data. A constant discharge test will be carried out soon after the Step-draw down test to provide drawdown measurements for the borehole.
A recovery test will be done after the completion of the constant discharge test, upon switching off the pump, the water level recovery is measured. The results gained from the recovery test will be used to determine how rapidly the water level recovers.
Borehole pumping tests results from all above procedures are essential for understanding aquifer characteristics and ensuring sustainable water management. By providing valuable data on well performance and aquifer behaviour, helps in informing decision-making on pump sizing.
