<p><p><strong>References:<br></strong><em>Chu and Choa (1995)<br>Chu et al. (2004)</em></p><p><strong>Method Summary</strong></p><p>Tests on PVDs are used to obtain information on the filter quality, discharge capacity, and tensile strength. For PVDs with an apparent opening size (AOS) greater than 40 μm, ASTM D4751 can be used to determine the AOS of the PVD. The permeability of the PVD can be determined in accordance with ASTM D4491. ASTM D4632 is often specified to measure tensile strength of the PVD. Chu and Choa (1995) describe the buckled drain tester, which can be used to confirm that the drain integrity and discharge capacity are maintained in a buckled drain. The drain is placed vertically in the buckled drain tester, which is filled with clay. The drain will buckle as the surrounding clay consolidates. The discharge capacity of the buckled drain is measured. After the discharge capacity has been determined, the drain is excavated and inspected for damage.</p><p><strong>Accuracy and Precision</strong></p><p>Some methods for PVD material testing are more reliable than others. ASTM D4751, used to determine the AOS, is not always reproducible, and the results are dependent on testing conditions (i.e. inclination of PVD, temperature, and humidity). This method receives a rating of L. ASTM D4491, used to measure permeability, and is considered to be reliable and accurate. This method receives a rating of H. ASTM D4632, used to measure tensile strength, is a function of straining rate and the moisture content of the PVD. This method receives a rating of M. The buckled drain tester is considered reliable for short-term measurements, but due to project constraints, may not be feasible for predicting long-term discharge capacity of a buckled PVD.</p><p><strong>Adequacy of Coverage</strong></p><p>Tests are conducted on PVDs intended to represent the batch of PVDs to be installed in the field.</p><p><strong>Implementation Requirements </strong></p><p>Requires specialized equipment and experience.</p><p><strong>General Comments </strong></p><p>Commonly, the PVD is delivered with manufacturer certificates certifying the product meets specifications. The material testing methods mentioned are usually reserved for aggressive QC/QA programs and are not performed for most projects.</p><p>The discharge capacity of the drain is affected by the applied pressure; therefore the discharge capacity of the PVD should be tested at various pressures. The tensile strength, either straight or buckled, can be tested. A standard method for determining the discharge capacity of a PVD has yet to be established, although Chu and Choa (1995) recommend using the discussed “new drain tester.” If feasible, long-term discharge tests should be conducted, as it is known that discharge capacity can significantly decrease in as short as a month.</p></p>