CQA Solutions’ Glen Toepfer has made a name in the field through elevating construction quality assurance not just on site but in conference discussions and in publications. On Uncontained, a column and video-driven content site produced as an offshoot of his main CQA Solutions company website, he takes up a wide range of issues, such as extrusion separation of welded geomembranes.
Of extrusion separation, which he files under one of his pet peeves in the field, Toepfer says, “It’s something that can be avoided in most instances and it’s also something that leads to a lot of arguments.”


Toepfer demonstrates how weak points might develop in a geosynthetic containment system during extrusion welding due to a cool point on the tack as the extrusion bead passes or when a wrinkle or improperly prepared substrate is welded over.
“[In some cases] the top sheet has separated from the bottom sheet and is still being held together by a portion of the extrusion,” Toepfer says. “It’s going to be a weak point in the system.”
The extrusion holding it all together is thin and may easily puncture, even if a coupon might technically pass a test.
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The risk of migrating liquids is greatly increased if these weak points are not identified and repaired. It’s a concern for geomembrane installations in all containment sectors (mining, waste management, wastewater, oil and gas, etc.).
In the video above, Toepfer discusses how heat tacking issues will crop up from time to time, but most other situations (e.g., welding over a wrinkle) can be avoided. He also discusses proper repair for when these weak points are discovered.
See more videos and read columns at www.uncontained.co.
Learn more about CQA Solutions’ work at www.cqasolutions.co.
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