Minimum Geomembrane Thickness

 

There are many ongoing discussions of the durability of the various geomembranes available on the market today. Much of this discussion of durability has centered around the thickness of the polymer materials. In September of 1990, Fred P. Rohe participated in a four-day meeting at the U.S. Environmental Protection Agency's Center Hill Research Laboratory regarding the drafting of the EPA's Technical Guidance Document on "The Fabrication of Field Seams for Flexible Membrane Liners". Prior to this meeting, the U.S. Army Corps of Engineers had requested the EPA review the Corps' specification for geomembranes and geotextiles. Many of the EPA's comments centered around thickness and seam testing. The following is a direct quote from the EPA's review of the Corps of Engineers Specifications:

"Thickness of materials should be a function of design which implies site-specific information and considerations. Although other thicknesses, 30 and 60, are allowed (Page V), this approach, we believe, ties the hands of the designer and will force the use of generic designs and could lead to increases in overall project costs. We also strongly believe and as part of our recommendation to consultants that a minimum thickness of material type should be specified then let the consultants "design" the system. Our recommendations based on seamability, punctureability and installability are as follows:
 

	Minimum Thickness (mil)
PVC	20-30 (30 is very tough)
CPE	30
CSPE-R	36
Polyethylene*	60

 

 

 

 

 

*Polyethylene is set as a 60 mil minimum primarily from a seamibility standpoint. It has not been clearly demonstrated to us that PE products less than 60 mil can be consistently seamed in the field. There is also concern that this is at the lower limit for creating conditions that encourage stress cracking. While stress cracking is still under review we are starting to see improvements in seaming techniques. It is interesting to note that the West Germans are now requiring PE thickness greater than 100 mil."
 

The preceding is typed exactly as presented to the Corps by the EPA. As you can see from this discussion, the EPA is very concerned that generic designs using only material thickness criteria can be not only costly but detrimental in many situations. The design engineer must have the flexibility of using the most effective material to provide secure containment. The requirement of a minimum 60 mil thickness without regard to material does not encourage continuing design improvement. The EPA is concerned about the seaming of PE (HDPE, VLDPE, LLDPE) below 60 mil thickness. This is not the case with PVC, CPE, or CSPE-R. Designs using 20 or 30 mil PVC, for example, can provide very effective, secure, and affordable solutions to containment problems.

If you have any questions relative to this information, please feel free to contact:
 

    Mr. Bob Landreth, Chief Engineer
    Landfill Technology Section
    Municipal Solid Waste and Residuals Management Branch
    Waste Minimization, Destruction and Disposal Research Division

 Mr. Dave Carson, Environmental Engineer
    Municipal Solid Waste and Residuals Management Branch
    Waste Minimization, Destruction and Disposal Research Division

---

   

    These gentlemen can be contacted at the 
    U.S. Environmental Protection Agency in Cincinnati, Ohio.

 

 

For more information call 800-OK-LINER today!