From the GMA Techline
Subject: Geomembrane installations What are the pros and cons of letting a contractor proceed with the installation of a liner when the moisture content is lower than desired? (Marvin, New York)
Reply: I have to make some assumptions before I answer your question. I assume that you mean installation of a geomembrane liner on a wet soil subgrade. If that is not the situation, my answer will make no sense.
Assuming this to be the case, let me mention that moisture in the seam area to be bonded is the most important detriment to the making of quality seams. The area to be bonded must be completely dry! Even further, soft soil (now its moisture and soil particles) oozing up into the area to be bonded will be a seam killer. Beyond this emphatic statement, a wet and soft subgrade will make the installer’s progress more difficult for wedge welding (if that is what is being performed), but it is not impossible. If it’s solvent seaming, the downward pressure of handheld rollers will be difficult. Lastly, extrusion fillet welding should be OK.
Finally, a slightly uneven subgrade is possible for the geomembrane to accommodate so I wouldn’t be overly concerned in this regard. Hope this helps.