STP163

    Measurement of Permeabilities in Ground-Water Investigations

    Published: Jan 1955


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    Abstract

    Certain physical conditions must be considered in the measurement of permeabilities of soils and sediments. Among these are sediment structure (particularly whether the sample is disturbed or undisturbed), the occlusion of air, and, finally, the effects of colloidal material. To meet some of these conditions, a special sampling procedure has been developed for obtaining undisturbed samples suitable for permeability measurement. The particular sampling device is of the piston type and contains an inner barrel, in which an undisturbed soil sample is taken. This inner barrel, with its undisturbed sample, is removable and serves as the permeameter tube in subsequent permeability measurements. The techniques for permeability measurement are described. It is emphasized that the test liquid must be one that is in equilibrium with the soil sample, so far as colloidal chemical properties are concerned. For example, in the determination of ground-water permeabilities, actual ground water, which is assumed to be in equilibrium with the sediments of the aquifer, must be used. If fluids such as distilled water or ordinary laboratory tap water are used, then severe washing of colloidal material may occur, owing to a change in the exchangeable ions, with a consequent erroneous measurement of the permeability. Finally, the alterations in permeability due to trapped air and other gaseous material are discussed. They result in a decreased value of permeability.


    Author Information:

    Smith, W. O.
    Physicist and Hydraulic Engineer, U. S. Geological Survey, Washington, D. C.,

    Stallman, R. W.
    Physicist and Hydraulic Engineer, U. S. Geological Survey, Washington, D. C.,


    Paper ID: STP46168S

    Committee/Subcommittee: D18.03

    DOI: 10.1520/STP46168S


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