Nowadays, we are witnessing a push for urbanisation due to strong industrial and civil expansion, which on the one hand increases the amount of water that needs to be disposed of and on the other hand reduces the amount of land that can be used for water absorption.

For this reason, drainage systems are increasingly being developed underground with trenches or tunnels that aim to remove excess water by dispersing it in the soil.

There are various methods to disperse water in a surface, the simplest being to build a drainage trench. This technique creates a permeable “path” that the water will follow until it slowly dissipates.

In order to construct an effective trench, an excavation must be created in the ground between 500 centimetres and a maximum of 1 metre wide; the depth depends on the running surface. Drainage trenches are in fact divided into:

  • surface: maximum depth of 5 metres;
  • deep: the trench excavation can be as deep as 25 metres.

In order for a trench to drain soil, non-woven fabric (or geotextile) must be placed around the trench to prevent soil from clogging the trench. It must then be filled with coarse-grained material (sand or gravel) so that water can pass through it. Finally, the excavation must be covered with waterproof material.

The choice of backfill material is crucial to the success of the drainage system as it is the contrast in permeability between the trench soil and the surrounding soil that determines the direction of the water and thus its dispersion.

To facilitate the inflow of water into the trench and its subsequent dispersion, cracked pipes and/or dispersing cells can be inserted into the excavation.


Discover the drainage systems                            Why you should drain land