Mutipani Muyangwa via web
Test pumping activities were undertaken over the period of 11th of August and 19st of August 2014, these activities were undertaken at Tom Ryan Estates, in Lusaka Zambia. I was under the supervision of Mr Ruben Wester- Project Hydrogeologist and Mr Isaac Sinkala. The purpose of test pumping is to obtain the hydraulic conductivity of a borehole and also to determine the sustainability of the borehole. The main reasons for test pumping is to know the water level before the start of the test, how the water level changes over time once the pumping has started and how long it takes for the water level to reach its original level. The test consists of three stages the step draw down test, the constant test and the recovery test. The test are done in such a way that the water is kept running at a specified pumping rate and the water level measurements are taken using a water level meter after 30 seconds then after minutes and then after hours twenty four hours a day. Information collected indicates the time against the level of the water. However, due to the general low yield of the bore, it was discussed that the step draw down test should not be done and the test should immediately go into constant test. The main challenge faced was that the borehole was not responding too well to the test, in terms of even its recovery responses, the static water level was at 28.91 m below ground level, the draw down went up to 29.295 and the 90 per cent recovery went to 29.03 m. I personally appreciated this training because this was the first time I test pumped a low yielding hole and I got insight on how to go about it more so because the pump installed had no valve hence, we had to use a bucket calibrate it and then set the pumping rate, which we set at 0.6 litres per second. The conclusion drawn from the pumping test was that the client should continue to pump at the rate they are pumping if the borehole is to run sustainably. Under ideal conditions, the riser pump would have been connected to a manometer for discharge reading purposes, but as the yield was very low the pipe was laid straight into the orifice tank.