Landfill cover

Question 1

How would you design a cover construction for a municipal landfill?
Describe the different layers and their function.

Answer 1

• -0,3 m. Vegetation layer. Plants, water magazine, erosion protection.
• > 1.5m Protection layer. water magazine, protection against
  desiccation, freezing, root penetration, erosion of the layers below
• Geomembrane. layer separation
• -0.4m drainage layer. collection and discharge of percolation water, prevent water standing on liner.
• Geomembrane. layer separation
• > 1m Barrier layer. minimize gas and water transport
• Geomembrane
• > 0.5 m gas drainage/foundation layer. surface adjustment, load distribution, gas transport

Question 2

Why do you need a highly permeable drainage layer?

Answer 2

• To create a capillary break so that the liner will not dry and crack
• Remove/minimize the water table (head) on top of the liner in order to support the
  function of the liner
• Avoid over-saturation of the protection layer above including e.g. a risk for slope slide.
• Decrease the motivation for plant root intrusion.