A new method for determining the appropriate analytical interval based on recovery test results in pumping tests

Abstract

In the pumping test, one of the in-situ permeability tests determines transmissivity and storage coefficient. A staged pumping test is conducted, followed by a constant flow pumping test and a recovery test. In the recovery test, the Japanese Geotechnical Society (JGS) standard specifies that the test should be terminated when the water level in the pumping well or each observation well recovers to the equilibrium level, which is one of the reasons why the test takes a long time. In addition, it has been pointed out that the conventional method of calculating transmissivity without considering actual conditions such as well-bore-storage and steady state conditions results in discrepancies with the calculation results when actual conditions are considered. Therefore, in this study, we proposed a quantitative extraction method of test time that can appropriately calculate the transmissivity before recovery to the equilibrium water level while considering the actual conditions from the recovery test.