Causes of clogged drain pipes
A drain system that is not functioning as it should will not be able to carry off as much groundwater and rainwater. Plots fitted with drains can then experience critical air/water ratio problems, which in extreme cases can lead to the formation of pools of water. The land will then be difficult to work, if not impossible to work. This risk is particularly acute in the spring, in the event of heavy rain during the growing season and in the autumn after harvest. The result is usually a loss of yield.
How well a drain system works and how long it lasts depend on clogging processes in and immediately surrounding the drain pipes. There are various factors that can lead to clogging in the drain pipe or clogging of the outer sheath.
Particularly in the initial years following installation of a drain system, soil particles are likely to enter the pipe. This is particular true in loose sandy soils. In that case, the entire drain system needs to be flushed through. Ideally, this should happen within two years of installation.
The intrusion of clay and sand particles into drain pipes is a continuous process. These particles then settle on the base of the drain pipe, ultimately limiting the flow of water or blocking it altogether. In sandy soils, this intrusion occurs more quickly than in clay. These contaminants can be easily flushed away with regular cleaning of the drain system.
A common problem that can cause clogging of drain pipes is iron oxidation. This is a process in which iron deposits form on the drain pipe, the sheath material or the filter cloth. Annual flushing is recommended. Contamination by iron-rich water is easy to spot. Iron deposits on the end pipe and/or brown water emerging from the drains indicate a (highly) ferrous soil type.
Another cause of clogging is a filter cloth clogged with silt, which can be caused by algae growth, for example. To restore a drain system with this problem to functionality, the contamination in the filter cloth must be driven out.
Clogging in drain systems can also be caused by penetration of tree and plant roots. The roots themselves are not the only problem; dirt and silt also tend to build up on them. In addition, clogging can also be the result of partial collapse of the drain pipes. This occurs if the soil is wet during harvest. Heavily laden (tipping) trailers and tractors then leave deep tracks, especially in headland areas.
Cleaning and preventive cleaning of drain systems help to prevent the majority of problems caused by clogging. On clay soils, it is sufficient to do this every five to six years. On sandy soils, two to three years is recommended. This ensures that drain pipes are and remain in perfect condition and continue to function as they should.