The falling head permeability test is used to determine the permeability of fine grained soils with intermediate and low permeability such as silts and clays with permeability in range of 1x10-5 to 1x10-9. This testing method can be applied to an undisturbed sample. The falling head principle can be applied to an undisturbed sample in a sampling tube and to a sample in an oedometer consolidation cell.
This test method covers laboratory measurement of the hydraulic conductivity of laboratory-compacted materials with a rigid-wall, compaction-mold permeameter and may be used with compacted specimens that have a hydraulic conductivity less than or equal to 1 × 10−5 m/s.