Alan Binns, director of TerraConsult and co-author of the newly published (2011) LFE4, Environment Agency guidance on Earthworks in Landfill Engineering (Reference 1). The following technical note is the opinion of the author and not necessarily that of the Agency.
Geosynthetics are used in combination with clay to form a composite liner or capping in the vast majority of modern landfills. A simple design is shown in Figures 1 and 2. In the liner shown in Figure 1 there are four interfaces on which sliding may occur:
- Waste or cover soil/drainage layer;
- Drainage layer/protection geotextile;
- Protection geotextile/flexible membrane liner;
- Flexible membrane liner/ engineered clay liner.
It is possible for some liners to have more than four interfaces, six is not uncommon.