Often we encounter unique, proprietary, or mixed chemicals that need to be contained with geomembranes. With only a few hundred chemical tests available for reference and many thousands of chemicals in use there will inevitably be chemicals for which we will not have geomembrane compatibility test data. This tech note outlines a method of field testing geomembranes for chemical suitability.
Layfield has developed a test container that can be shipped to our clients pre-loaded with geomembrane samples. The client pours their liquid chemical into the container and exposes the geomembrane samples for seven to 30 days (depending on application). After chemical exposure the chemical is drained and the container and geomembrane samples are cleaned. The cleaned container is returned to Layfield for evaluation and testing. Layfield will then report on the compatibility of the geomembrane specimens tested.
The advantage of this test procedure over current methods is that this method does not require shipment of hazardous chemicals. It also has the advantage of letting the owner of the chemical perform the immersion test. Often the owner of the chemical has the facility to handle the chemical in question on their site. Issues of chemical safety and disposal are less of an issue in the chemical owner's facility. This reduces the cost of chemical testing dramatically in that extra costs for shipping, special handling, and disposal of chemicals are avoided (or reduced).
1. Layfield will prepare a test container with pre-cut geomembrane samples. The container is a double-walled stainless steel bucket with stainless steel racks for the samples. The samples will be chosen based on current best estimates of chemical compatibility. Each geomembrane will be represented by three specimens in the container. Samples will be suspended from the sample racks as appropriate (in some tests not all racks will be filled).
2. Samples will be prepared from representative geomembrane materials in strips 1/2" (13 mm) wide and about 5" (125 mm) long. Seven specimens will be prepared for each geomembrane, three will be loaded onto the test racks, and four will be retained for control testing. All test and control samples will be taken from the same location and orientation.
3. Physical properties of the specimens will be checked prior to loading them into the container. Physical properties may include; weight, thickness, dimensions, or other property depending on the test criteria. The scope of the test criteria will be determined between Layfield and the client prior to testing.
4. The test container, loaded with measured specimens, will be shipped to the client for immersion testing via a suitable carrier. The test container will be packaged to protect it during transportation.
5. Testing will normally take place at room temperature of 23C (73F). Allow the test chemical and the test container to stabilize at room temperature before beginning immersion.
6. After following all appropriate safety procedures fill the test container with 1.5 litres of the test chemical (1.6 US quarts). There is a removable ring marking the maximum liquid level which is 1" below the top of the container. The test rack is attached to the lid. Carefully place the lid on the container for the duration of the test.
7. Place the test container in a safe location for the duration of the test taking into account venting, chemical condensation, or other storage requirements for the chemical being tested.
8. The length of test is to be determined between Layfield and the client prior to testing. Secondary containment applications normally use a 7-day test period, while primary containment applications use a 30-day or longer test period. For most testing the 7-day immersion will be used.
9. After immersion the container will be drained and cleaned following the procedure in ASTM D5496. Exceptions to the procedure are that specimens will not be removed from the container. Another exception to the ASTM procedure is that the test rack and the samples should be dried before shipment.
10. Allow the test assembly to drain of liquid for a minimum of 30 minutes as a precaution to minimize exposure of workers to fluid. Dispose of the test chemical appropriately.
11. Wash the specimens with a suitable cleaning agent to remove the test chemical. Typically the container would be filled with a solution of soap and water and the test rack would be agitated in this solution. Do not immerse the lid in any liquid. The use of solvents as cleaning agents should be discussed prior to use. Do not remove the specimens from the test rack or wipe or abrade the specimens during washing. Wash the container, the test rack, the lid, and the specimens to remove all traces of the test chemical.
12. Rinse the container, test rack, and specimens in clear water as required to remove the cleaning agent. Allow the apparatus to air dry. Drying time should not exceed 24 hours.
13. Package the washed, dried apparatus in its shipping container. It is the client's responsibility to ensure that the apparatus shipped back to Layfield does not contain hazardous chemicals, liquids, or other hazards that could endanger the carrier, or Layfield staff when opening the package. If there is any doubt as to the toxicity or hazard of the package then call Layfield to discuss shipping and testing options.
14. Layfield will test the specimens after their return. Testing of the immersed geomembrane specimens will generally follow ASTM D5747 Tests to Evaluate the Chemical Resistance of Geomembranes to Liquids. Exceptions to the test method includes testing samples "as received" without conditioning.
15. Tests performed on the specimens will be discussed between Layfield and the client prior to testing. The basic tests performed will usually include visual observation, weight loss, and tensile strength changes. Other tests that may be done include dimensional changes, elongation measurements, and other physical tests as required.
16. Immersed specimen properties will be compared to retained specimen properties. A brief report will be prepared comparing the before and after properties of the materials. Interpretation of the results is the responsibility of the project engineer.
17. The Layfield Field Chemical Testing method is provided as a low cost service to our customers. By using this test method you agree that Layfield may publish the results of the testing to promote its geomembrane materials. For confidential chemical testing a consulting fee will be required, payable in advance.
The use of field testing can quickly identify geomembranes that will be suitable for specialty chemicals. It is an especially important tool in the evaluation of chemical mixtures and proprietary chemicals. If you have any questions on this procedure or to book your field chemical test please contact your Layfield representative.