Problems can occur during or after the installation of the drainage system.

Errors during installation
If the end pipe is not carefully connected to the drainpipe, leakage can occur at the joint. As a result of this, water can seep under the outlet and the soil there will be washed away. This may cause the outlet to sink and the outflow can be seriously blocked. The outlet can sink also because the outflow is not directly above the water in the ditch but on the slope. As a result, the soil will be washed away, the slope will collapse and the outlet will sink further.

It is quite common that during the winter the outlet becomes damaged by frost. This might be caused when the thaw sets in, by floating ice, or by damage to the slope caused by the ice which was frozen onto the slope, breaking and falling when the meltwater is pumped away. The outflow of water can freeze and cause the outlet to break. PVC end pipes are at a high risk while outlets made of polypropylene and polyethylene can withstand the frost.

Ditch cleaning
It is possible that the outlet may become damaged when the ditch is cleaned. A ditch mower or ditch dredger can cause severe damage. Well placed marking can prevent this from happening. Take care that the dredgings from the ditch do not obstruct the outflow. All in all, the outlet is a very weak component of the entire drainage system. They should always be checked before and after ditch cleaning.

The position of the drain

Determining the position
There are several ways to determine the position of the drain.

Clearing rod
Clearing rods are an excellent way to check the drain for any troubles which may occur because of material defects, sand, or root growth.

There are altimeters available in which a measuring head will stop at various predetermined distances and then the altitude can be determined. The measurements are registered and are shown on a diagram.
This equipment can be used:
-    to adjust drain machinery;
-    to check the drains before the handover of the installation;
-    - to check existing drain systems.
This method is labour-intensive and costly, therefore its use is limited.

A drain tracing system is available whereby a transmitter is inserted in the field drain. This can be done using a flexible rod, but the transmitter can also be placed in the tube of the clearing rod or on the nozzle of the flushing equipment. The receiver converts the transmitter’s signal to a sound or light signal. If the direction of the drain is unknown, the transmitter can be followed right from the beginning. By continuously reducing the reception area, the location of the transmitter can be determined. The transmitter is always in the centre of the circle which is shown by the receiver. With some experience, the depth of the transmitter can also be determined.

Image inspection
There are ways of checking the entire drain over a great distance by inserting a camera in the outlet or manhole. This is an excellent way to inspect the field drain. This will provide a good picture of the inside of the drain, unless this is excessively dirty. These camera systems, which are mainly used for sewer maintenance can only cover a limited distance but at least give an impression of the condition of the drain.

Vereniging Nederlandse Drainagebedrijven

Norgervaart 26
9336 TE  Huis ter Heide (Dr)