Quality & Testing
A geomembrane fails at its weakest square metre, not at its average. Everything below exists so that the weakest square metre is still inside specification.
Certification
Quality management system
Environmental management system
Occupational health & safety
EN 13361 · 13491 · 13492 · 13493 · 13249–13257
Laboratory methods aligned; accreditation in progress
Geosynthetic Institute geomembrane specification
Manufacturing quality control
Frequencies are published rather than described. A property tested once a shipment is a property nobody verified.
| Property | Test method | MQC frequency |
|---|---|---|
| Thickness / asperity height | ASTM D5199, D5994, D7466 | Every roll |
| Density | ASTM D1505 / D792 | Every 90 tonnes |
| Tensile properties | ASTM D6693 Type IV | Every 9 tonnes |
| Carbon black content | ASTM D4218 | Every 9 tonnes |
| Carbon black dispersion | ASTM D5596 | Every 20 tonnes |
| Tear and puncture | ASTM D1004, D4833 | Every 20 tonnes |
| Std-OIT / HP-OIT | ASTM D8117, D5885 | Every 90 tonnes |
| Stress crack resistance (SP-NCTL) | ASTM D5397 App. | Every 200 tonnes |
| Oven and UV ageing | ASTM D5721, D7238 | Per formulation |
Field seaming and CQA
A liner is manufactured in a factory and assembled in a field. The seam is where it is decided.
Trial weld
Before each shift, after any four-hour break and on every change of welder, machine or ambient condition. Five specimens in peel and five in shear, all passing before production welding resumes.
Dual-track fusion seam
Air pressure test of the full seam length to ASTM D5820: pressurise the test channel, hold, and accept only if the pressure drop stays inside the limit and the far end vents.
Extrusion fillet seam
Vacuum box test to ASTM D5641 over the full length, plus spark testing where a conductive-back geomembrane has been specified.
Destructive testing
One coupon per 150 m of seam, tested in peel and shear to ASTM D6392. Failures are bracketed and the bounded length recapped.
Electrical leak location
Water puddle or dipole survey to ASTM D7002 / D7007 after cover placement, so installation damage is found before the facility is commissioned.