CEN TC189 has almost completed "Geosynthetic Barriers – Determination of Permeability to Liquids". It is applicable to geomembranes but not to GCLs. Water, or any other relevant liquid, is maintained at two different pressures on each side of a geomembrane sample – 150 kPa upstream and 50 kPa downstream. Flow through the geomembrane is measured by upstream and downstream volume changes. Typical volume/time curves are shown below. The method is valid for flow rates down to 10(-6) m3/m2.d. Lower values are simply reported as <10(-6) m3/m2.d. The standard has just been submitted for CEN Enquiry.
