In situ assessment of ground permeability for soakwell and drainage design.
The falling head permeability test is a common field method used to assess the in situ permeability of site soils. The test is most commonly adopted in granular soils, such as sands, that have relatively high permeability. The permeability property of the soil is required to facilitate the selection, design and specification of optimised soakwell and drainage systems.
CMW conduct this test in boreholes drilled on site as part of the geotechnical site investigation. As the test is conducted in situ the site conditions are assessed with minimal disturbance compared to laboratory testing on disturbed samples.
The test procedure utilises a standpipe to enable recording of the fall in water level within pre-drilled boreholes over specific time intervals. Interpretation of the results of this test provide an indication of the permeability of the tested soil, which directly influences the type, size and configuration of the optimum soakwell/drainage system to be adopted.