Geomembranes for pipes?

From the GMA Techline

I have been asked to wrap a proposed 30-in. circular/cylindrical sanitary sewer pipe (HDPE) with a geomembrane as a dual containment layer. Could I get some pointers as to what kind of geomembrane(material, thickness, etc.) can be used to achieve this task? Any other information, such as pros and cons, would be helpful too.

(Mano | Texas)

Reply: Interesting question and let me try to answer since I only have experience with wrapping concrete pipes. In doing so, the secondary wrap is usually separated from the host pipe by a biplanar geonet. In this mode the geonet is functioning as a leak detection layer.

In general, the secondary wrap is field placed, requiring it to be flexible (more so than HDPE). As a result, LLDPE or fPP are usually the resin types used. They don’t have the durability of HDPE but they are more flexible and easier to seam in the field.

However, if the secondary wrap is to be placed directly on the host pipe, then I don’t really understand why. It seems more logical to use greater SDR wall thickness and be done with it. Don’t hesitate to call if you want to discuss further.

Bob Koerner | GMA Techline