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Conducting Of Pumping Test
This test to be carried out to measure the safe yield from the well. Based on the flushing yield a suitable pump is installed up to the bottom of the well and take the static water level readings. Normally the pump is selected 1.5 to 2 times of the capacity of the flushing yield.
After pump is installed the geologist will take the readings of the pump installation depth, static water level and checking the pump outlets to make sure no re circulation of water happens during the test. Normally this outlet will be putting in to a closest drain or if there is no drain the outlet will take minimum 50 meters away from the test well. Once everything is ready the geologist will record the static water levels of the surrounding wells and check those wells in regular intervals to find the influence of pumping.
This process will continue for 24, 48 or 72 hours in different stages of pumping. During the first four hours of the test the pump will take out the quantity of water confirmed during the flushing, simultaneously monitoring and recording the static water level (SWL) as well the draw down levels (DDL) on every half an hour intervals. If the water levels are keeps dropping after 4 hours the pumping will be continued for another 4 hours with same capacity and recording the drop downs as earlier. Once the water level is stable the rapid low down test begins by increasing the quantity of pumping by 5% at every half an hour intervals until the water level drops up to the pump. Afterwards the above process is repeated vice versa same and the SWL and DDL's are recorded in the same time intervals to find out the recovery of the water levels in the well. There after the geologist will analyse the data and decide the safe yield of water to be pumped out according to the information’s of recovery speed and drop down timing. There after the pump will operate till complete 24, 48 or 72 hours and monitor the drop down of the static water levels. All records will be submitted to the geologist for his recommendations. Finally hydro-geologist prepares a report with his recommendations of safe yield, hours of pumping and pump installation depth.