Land drains

Agricultural land drains have to be installed sufficiently deep to avoid plough damage.

These can be laid in an excavated trench, or a horizontal hole is formed in the ground using a mole plough and the pipes are forced in by means of a hand or mechanical press.

Many modern land drains are created utilising rigid or flexible plastic pipes pierced with holes, laid in pea gravel.

Specialised mole ploughs are available that can form the hole, insert the perforated pipe (and gravel if required), all in one simultaneous and continuous process.

Also the static loads on any subterranean structure and retaining walls can be massively increased by the presence of water in the surrounding ground.

Ideally, land drains are laid with access points so that high pressure water jetting is possible to clear silt.

However, whatever the technology, all land drains have a finite life and eventually become ineffective due to the ingress of silt and/or the blocking of the surrounding filter media.