Geomembranes are found in a wide range of applications. They are used for infiltration and drainage purposes, as part of the sanitary sewerage system and for water storage. This article aims to explain geomembrane liner integrity testing, why they should be tested regularly and how these tests should be undertaken.
What are geomembranes?
Geomembranes are a type of synthetic membrane. They are used for various purposes, such as lining landfills, retaining walls and water reservoirs. Geomembranes can be made from HDPE or polyethene (PE).
Geomembrane liners are typically installed in landfills to prevent leachate from entering groundwater or contaminating surface water systems.
Why undertake geomembrane liner integrity testing?
Geomembrane liner integrity testing is vital to maintaining the liner’s integrity. Without it, you could be facing issues such as:
- Leaks in your system
- Cracks that allow water to seep through
- Damages that are too large for repair
How is geomembrane liner integrity testing undertaken?
Geomembrane liner integrity testing is undertaken by a specialist who will assess the condition. The assessment may include testing for leaks and tears in the membrane, punctures through holes or rips in the membrane, and cuts made by machinery when cutting or drilling materials into the earth.
Standard geomembrane liner integrity testing methods
Geomembrane liner integrity testing is a process that involves testing the strength of geomembranes. The different methods used to test geomembrane liners include:
- Sandblasting. This method uses sand and water to break down the surface of the membrane. It can be done manually or by machinery, but it’s not as effective because it takes more time and requires more equipment than other methods.
- Ultrasonic levitation force (ULF). This method uses ultrasonic vibrations to break down membranes into small pieces that can be removed easily by hand or vacuumed away with a hose attachment on an air compressor system (AC).
- Sea surface observation (SSO) and non-destructive testing (NDT)
SSO and NDT are used to check the integrity of a geomembrane. SSO involves visual inspection of the outer surface of the geomembrane, while NDT includes ultrasonic, magnetic particle and eddy current testing.
NDT detect surface cracks or pinholes in the geomembrane material before they grow into more significant gaps that could lead to leakage problems.
- Surface water integrity test (SWIT).
The surface water integrity test (SWIT) is a non-destructive test that uses water to detect leaks in geomembranes. This process involves using a high-pressure water jet to detect geomembrane leaks at the surface of reinforced concrete slabs and bridges. SWIT can be used on all drainage channels, including maintenance holes and culverts.
- Hydrostatic test (HT).
A hydrostatic test (HT) is a method of testing the integrity of a geomembrane liner. It involves pumping water through the geomembrane and increasing its pressure until it fails.
Two methods can perform hydrostatic testing:
- Pressurised water jetting – This hydrostatic test uses pressurised jets to inject water into the sample with high pressure, causing it to rupture when reaching its maximum allowable stress point.
- Penetration depth hoppers – A penetration depth hopper is used for more extensive samples that cannot fit inside an HT machine because they are too large or thick for easy access through pipes etc.
What to do if geomembrane failure has occurred?
If you have any concerns about the integrity of your geomembrane liner, it is vital that you notify the relevant authorities. This can include local government officials and a professional engineer.
If possible, isolate the affected area until experts can conduct their tests and complete remediation work. This will help prevent further damage to your property or equipment and ensure that there are no leaks into surrounding areas.
Geomembranes play a vital role in modern society
Geomembranes play a vital role in modern society, and liner damage can cause catastrophic damage. Therefore regular inspections must be performed to check that they are in good working order and that any faults or defects are repaired as soon as possible.
Conclusion
It is important to note that geomembrane liner integrity testing can provide crucial information. For example, if there are any leaks or faults in your pipes, then they need urgent attention before they become a bigger problem.
