Scratches on HDPE liners

From the GMA Techline

RE: Scratches on HDPE liners
A question from Australia

Do you have any research or, in the absence of research, an opinion on judging the acceptability, or not, of a scratch on a 2.0mm HDPE liner in a dam?

Thanks in advance for your response.

Reply: Now this is a very different question. Scratches in HDPE geomembranes are certainly not desirable and depending on the depth (not size) could become stress risers. If the resin is poor in its stress crack resistance it could be of concern. As you know, our GRI-GM13 calls for a 300-hour minimum SP-NCTL value. I think that for minor scratches this is reasonable.

Of course, how deep of a scratch is acceptable is another matter. I don’t know but can add a perspective. When doing extrusion fillet welding we have to purposely grind the sheet. Depths of up to 5–10% are referenced in the U.S. EPA Technical Guidance Document (that Dave Daniel and I wrote).

The grinding should be covered by extrudate but sometimes it is not. I am sure this occasionally occurs and I have not heard of such problems in many years. As a result, I think that a 10% depth for nonintentional scratches should be acceptable, but recognize that this is strictly an opinion.

Best regards.

Bob Koerner | GMA Techline