Each month Tim Stark introduces a new technical topic for discussion and possible action. This month’s topic is: “Terminology and Applications for Used Geomembrane Polymers”. This topic generated significant discussion with the main “take-aways” listed below:

Terminology for Thermo-Plastics and not Thermo-Set Plastics:
‍- Thermo-Set Plastics can’t be reworked or recycled due to reinforcement so repurpose them
- Reworked = material from like product internal to the manufacturing process but not after field/external usage; could be wrong formulation or scarp material so a “prime product”
- Reground = edge trimmings, startup scraps that from manufacturing process and has not left the factory
- Recycled = material from like product after field/external usage, melted and reformed thermos-plastics but properties degrade with every re-use
- Repurposed = after field application – same product cleaned and using it in a different application, e.g., billboard film being used as a wood pile cover
- Reprocessed = after field application - cleaned, reground, and remanufactured for less critical application - landfill geomembrane reprocessed for a less critical application, e.g., use in an agricultural application, e.g., wee control film
- Post-Consumer Products – plastic bottles are usually polyester (PET) and are not typically used for engineered geomembranes, but could be used for other geosynthetics
- IGS website has information on sustainability: https://www.geosyntheticssociety.org/sustainability/; https://www.geosyntheticssociety.org/wp-content/uploads/2022/10/Fontana-Bologna-2022.pdf
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Applications
‍- Short-term applications due to changes in applications
- Not permanent applications
- Applications driving amount of reworked material
- Agricultural applications
- Old billboards used for tarps
- Non-critical applications
- If the reprocessed material meets GM-17 for LLDPE, it may be suitable
- Water v. potable water – not viable for potable water unless it meets NSF specifications
- PFAS applications=? Probably not viable and must prove chemical resistance with new formulation
- Use forcore of multi-layer materials

 Amount of Rework Material
‍- Usually 5 to 10% for new geomembranes
- Can be as high as 50% for repurposed applications, i.e., less critical applications