Land Drain System Maintenance

Maintaining Land Drains

The reason that most Land Drains stop working effectively is that over a period of years they become clogged up with sediment and silt. Sometimes an intrusive and thirsty tree root can also cause damage, although this is less of an issue with modern PVC pipework. Due to the nature of their construction, Land Drains cannot be effectively cleared with modern water jetting methods, so best the type of cure is prevention. If your land drain has become ineffective, the best solution for the long term is to replace it with new pipe work and granular material and whilst you are doing this, build in some preventative measures.

First, check the Outflow

Although most land drains fail because of silted up old clay pipework, It could be that the land drain system is still working perfectly but that only the outflow has become blocked, causing the pipework and the trench to backfill with water. If the drain flows into a water course, make sure that the outlet is free from debris or blockages and that the side wall of the ditch has not collapsed on to the pipe. If the land drain flows into a soakaway, check that this is still functioning correctly. If the outlet is free running, the likely cause of the problem is blocked pipes as described above. Replace them with modern PVC Land Drain and build in the following features to ensure a long-lasting installation.

Wrap the Installation in Geotextile Membrane

This product has excellent soil separation and filtration qualities. The ideal scenario is to line the side of the trench with membrane, and when the pipe and granular backfill material has been laid, fold it over the top of the backfill to completely cover it before the final layer of topsoil is replaced. Always use non-woven geotextile as this is better at keeping out those fine soil particles that can cause blockages in the pipe over the years.

Install a Catchpit

A catchpit is essentially a silt trap that can be installed in the drainage line. It usually consists of a brick-built chamber on a concrete base, with a screwed down manhole cover on the top. Water flows into the chamber from an inlet pipe built into the side wall, and flows out again once the level reaches the outlet pipe (which is built into the opposite wall at a slightly lower level than the inlet to prevent any backflow). Any silt and sediment settles out into the bottom of the pit, which can be pumped out or cleared on a regular basis. Sometimes the outlet pipe is protected by a baffle to filter out and prevent any large debris from entering the outlet.

Maintaining Land Drain in Sports Fields

Heavy use and constant rolling of the surface of sports pitches can compact the top layer of soil after many years use. This in turn creates a barrier that prevents the rainwater from filtering through into the land drain system. Specialist sports-field maintenance contractors are able to inject a new gravel layer into the soil using purpose built machinery to resolve this issue. There are also machines that can trench and install land drain in a continuous action, enabling large areas of land drain to be regenerated in a very short period of time.

Brown Patches on the Lawn in Summer?

Whilst this is aesthetically undesirable, it is actually proof that the land drain system is working. The brown patches will generally follow the direction of the land drain installation, and are caused by the water being removed from the soil too quickly and before the grass can satisfy its drinking requirements. It is generally only an issue in a prolonged dry spell.

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