Lessons Learned from the Application of Standard Test Methods for Field and Laboratory Hydraulic Conductivity Measurement

Standard ASTM test methods are now available for laboratory and field measurements of hydraulic conductivity of compacted clay soils which are used in liners and covers at waste facilities. They are widely used in waste facility design and construction quality assurance. Many of these methods require input of qualified professionals to select appropriate test parameters. Unless the parameters are carefully selected, conflict may arise over the suitability of test results and thus the regulatory acceptance of a liner or cover. Four case histories are presented which illustrate the use of both laboratory and field test methods and some of the variations which may result. These variations can usually be explained in terms of test parameters, but they emphasize the importance of suitable engineering judgement for careful selection of test conditions, and data reduction methods which are appropriate for to site conditions and allow for comparison of test results from various tests.