Geocomposite drain flow capacity: ISO VS. ASTM

From the GMA Techline

RE: Geocomposite drain flow capacity: ISO VS. ASTM
We are evaluating geocomposite drain products for underdrainage beneath geomembrane-lined ponds. This is an international project—we are considering non-North American products for which the hydraulic properties are based on EN ISO 12958 rather than on ASTM D4716.

Would you kindly comment on how the ISO results should be interpreted for comparison with the ASTM results, and how (or if) the ISO results should be applied in the GRI-GC8 process? I imagine there are at least a few pitfalls for us to stumble into!

(Rick | Illinois)

Reply: Surprisingly, the ISO method is less prescriptive than the comparable ASTM method. Therefore, if one is following ASTM—e.g., 300mm square specimen—it will work for ISO as well. This applies for foam surfaces, heads, gradients, etc. Furthermore, if the ISO method is crafted as the ASTM’s more prescriptive method, then GRI GC8 should function accordingly.

Neat question that made us look at the ISO method again.

Bob Koerner | GMA Techline