1.1This test method covers the procedure for determining the in-plane transmissivity of geosynthetics under varying normal compressive stresses using a radial flow apparatus. The test is intended to be an index test used primarily for geotextiles, although other products composed of geotextiles and geotextile-type materials may be suitable for testing with this test method.

1.2This test method is based on the assumption that the transmissivity of the geosynthetic is independent of orientation of the flow and is therefore limited to geosynthetics that have similar transmissivity in all directions and should not be used for materials with oriented flow behavior.

1.3This test method has been developed specifically for geosynthetics that have transmissivity values on the order of or less than 2 × 10⁻⁴ m²/s. Consider using Test Method D4716 for geosynthetics with transmissivity values higher than 2 × 10⁻⁴ m²/s.

1.4The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.5This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.