I noticed no one has responded. May I suggest you be a little more specific as far as the application.
For example, I'm familiar with the 3 layer Polyethylene pipe coating system; for tank apex, have used gravel or crushed stone enclosed by a HD polyethylene pipe sealed to the membrane; there is the HDPE pipe.
These are but a few examples of applications, so with more information maybe someone can offer some feedback.
Greg Lamberson, BS, MBA
Consultant - Upstream Energy
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