Questions and answers from the GMA Techline
I have a question concerning lining systems in embankment dams and want to ask for your advice (from your experience only, no need for any calculations).
There is a wastewater reservoir built of clay, with a single HDPE geomembrane on top of the clay (i.e., a kind of composite liner, clay with geomembrane on top).
Of course, there’s a need to have a drain somewhere in the embankment, likely in its downstream toe.
Do you think that adding a drainage net underneath the geomembrane, on the slopes of the embankments, could be a better solution (for minimizing the infiltration into the embankment) than the original design (the GM placed directly on the clay, with good contact between them)?
The two alternatives for the upstream slopes of the embankments of the reservoir are:
Alternative A—HDPE liner placed directly, with good contact, on compacted clay.
Alternative B—HDPE liner placed on top of a drainage net that is placed on compacted clay.
Which option will cause a smaller amount of infiltration into the embankment?
Dori | Israel
The preferred answer is “A,” having the geomembrane directly on the compacted clay. In so doing, you have a classic composite (GM/CCL) liner. Now comes the dicey part insofar as leakage collection and removal.
It depends on the configuration of the dam. Options are beneath the CCL, in trenches along the sideslopes, etc. Hope this helps.
Bob Koerner | GMA Techline