Land Drainage Installation Guide for Beginners

Intro to land drainage system, interceptor drains, required equipment, and steps to complete installation


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A land drainage system is a special type of method where water such as rain water or drain water gets “drained away”. It can typically be found in most households, agricultural environments, and even in specific types of constructions such as roads and highways. Installing such a system will ensure that any excess water gets disposed of rapidly, potentially keeping the water level to a minimum. In most cases, special perforated pipes are used to get rid of any water. Further applications can include the use of geotextile materials incorporated with the pipes. Installing a drainage system can be a tedious task for those who do not possess the technical knowledge. Therefore, it is advised that you leave this type of task to the professionals.

Interceptor drains

One of the most popular applications of land drainage in conjunction with land drain pipes are interceptor drains. This specific type of drain is in the form of a gravel trench that is excavated into a thick soil layer, preventing water to seep through easily. The function of an interceptor drain is to collect and remove ground water when it flows through the thick soil. These interceptor drains are commonly used for collecting water found in gardens, buildings and even pavement. Interceptor drains will need perforated land drain pipes to function properly.

First steps

Before you start digging into the ground and developing a trench, you will need certain tools such as a spade or shovel, cart (optional), measuring tape, perforated pipes (length depends on your specifications and diameter around 100mm), geotextile material (length again depends on the size of your project), and gravel (preferably crushed sandstone). Once you have these materials and equipment, you are pretty much set to perform installing any perforated land drain pipes.

Start digging

Once you are set, the first thing is to remove the topsoil and dig the trench deep enough for your land drain pipes. If you are careful enough, you should be able to dig the topsoil neatly so reapplying it later will not be too much of a hassle. Similarly, you should also try to dig the trench neatly. Try not to dig too deep as digging more than 1.2 metres will require you to support the trench. The trench you dig should not be too wide (around 250mm) as you only need a narrow area for your rocks and land drain pipes. Once you have completed the digging process, it is time to move on to the next part.

Applying the geotextile

The next step is lining up the construction grade geotextile. If you use standard quality geotextile, there is a chance that it will get torn apart once you start applying the gravel. It is better to spend a little bit more on quality products in the long run. How much geotextile you will need depends on your specifications such as the length and depth of your trench. You should look at options available in your hardware store and consult with the shop assistant before making any purchase. Moving on, when you have selected the geotextile, you can roll it out and apply it in the trench by using your spade or shovel. You will need enough width so that this geotextile will later wrap around the entire trench before reapplying your topsoil.

Applying the perforated pipe

Once the geotextile sits firmly on the bottom of the trench and before lowering any perforated land drain pipes in your trench, apply some gravel as bedding (about 100mm in depth) and spread evenly at the base for your perforated land drain pipes. Once that step is done, apply the pipes in the centre of the trench. As the pipes might coil, you might have to weigh it down with some pipe bedding. When the pipes are in place, you can start to fill the trench with the remaining pipe bedding. Repeat this process for the entire length of your land drain pipes.

Final steps

The final round to completing this project is to wrap the geotextile around the pipe bed gravel. Make sure it is totally enclosed in order to prevent any dirt from entering inside the geotextile area. When this is done, firmly reapply the topsoil that you had initially dug up. If you dug your topsoil carefully the first time, you won’t have to replace any damaged topsoil. Finally, to complete the project, you might have to wait a week to let the soil to settle in and bind.

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