Ventilation of the lawn helps with drainage

drainage

Problem case waterlogging

Gardening without drainage is often not possible, especially in river valleys with heavy soils. "Heavy soil" is a very loamy or clayey soil that is very compact and difficult for water and plant roots to penetrate. The reason for this is the particularly fine-grain structure, which leads to an enormous density of the soil. If pressure is then also exerted, for example from construction machinery, the soil layers are compressed into solid lumps. Soil cultivation on such soils is particularly difficult because the earth is very firm and sticky. Heavy equipment is often required to penetrate deeper layers. Water is stored for a long time in heavy soils and can only run off slowly or not at all due to the lack of coarse grain. So-called waterlogging occurs again and again with puddles of water on the surface that only slowly seep into the ground. When the soil is saturated with water, lime is washed out and the pH value continues to drop - the soil acidifies.

The lawn can literally drown in the autumn reservoirs, and apart from a few pond and marsh plants, very few other gardeners like to have wet feet. Although smaller areas with heavy soils can be improved in the long term by regular digging and incorporation of sand and compost, compaction in the subsoil, the real cause of waterlogging, cannot be brought under control. So if the lawn in your garden is under water after every downpour, often only drainage will help.

Drain small areas selectively

Smaller wet areas of the ground can be aerated using an aeration fork. This special tool is stabbed at least ten centimeters into the ground at the water-retaining points. The resulting holes are then filled with sand (grain size zero to two millimeters) for better drainage. If only individual small puddles form in the lawn or bed after the rain, these can also be drained selectively. To do this, drill into the wetted areas with an earth auger - depending on the depth of the compacted layer, at least 50 centimeters deep hole. This is then lined with fleece and filled up to around 15 centimeters below the surface with fine gravel or coarse construction sand. Then you apply the topsoil and, if necessary, the sward again. Thanks to the gravel, the water can now run off better and the fleece prevents soil that has been washed in from blocking the "drainage" again.

Legal regulations on drainage

Drainage is the targeted collection and drainage of excess rainwater from the ground. However, according to the Water Resources Act (WHG, part of German water law), rainwater is considered wastewater. The removal of rainwater therefore belongs to the field of wastewater disposal. For the infiltration of rainwater on the property, in many, but not in all cases, a permit under water law from the district administration is required. It is therefore important to familiarize yourself with the water laws of the relevant federal state or municipality and to take a look at the so-called "technical rules" for infiltration. In order to protect the groundwater, certain filter systems may also be required when rainwater seeps away. With the natural seepage through an upper soil layer of 30 centimeters, a natural cleaning of the rainwater takes place. However, if this is not possible due to the nature of the soil, the water that is drained off via roofs, streets, gutters and sealed surfaces must be filtered before it seeps away - but not the rainwater that falls directly onto the lawn without detours.

If, on the other hand, you want to channel the rainwater into the sewer system, higher wastewater fees are due in any case. You also need a permit from the municipality to connect the garden drainage to the rainwater drainage system on the property. In addition, the use of the sewer system for private rainwater disposal is completely prohibited in most municipalities - and rightly so: On the one hand, the rainwater is not so heavily contaminated that it would have to be passed through the sewage treatment plant, on the other hand the additional and mostly spontaneously rising water is a burden Amounts of water unnecessarily drain the sewage system. In any case, it is essential that you inquire with your municipality about how to deal with the amount of water before installing drainage on your property.

Preparations for drainage

For professional drainage you not only need several meters or rolls of drainage pipe, but also weather-resistant filter fleece, a lot of grit or seepage gravel, spades and shovels with the associated powerful helpers and possibly a septic tank. Simple drainage pipes are slotted plastic pipes that are hand-wrapped with a non-woven fabric or covered with a non-woven hose in order to avoid contamination of the pipelines. If you like it more convenient, you can use so-called full filter tubes. These pipes are coated with a layer of coconut fiber that keeps soil and debris out of the pipes. Carefully plan and measure the course of the drainage pipes to determine your material requirements.

Laying drainage in the garden is not an easy matter, especially with heavy soils. Depending on the size of the garden, it is advisable to rent a mini excavator to dig out the pipe channels and fill in the gravel or gravel. Very important: Draw the position of the drainage pipes and the infiltration or drainage facility to scale in the floor plan of your property before you start with the system. In most cases, the best solution is a sufficiently dimensioned drainage shaft through which the water is drained into deeper soil layers. You can also first channel the water into an underground cistern, from which you can then take irrigation water for the garden. It is provided with an overflow through which excess water can then flow into the drainage shaft. Important: plan the cistern and drainage shaft at the lowest point of your property so that you can take advantage of the natural gradient.

Lay the drainage pipes correctly

There are small slots or holes in the drainage pipes through which the water enters the pipes. If the pipes were simply buried, these slots would fill up with earth and mud in a very short time and the drainage would no longer work. You should therefore lay the drainage pipes in a so-called gravel pack that is 15 to 30 centimeters high and wide and at least 50 centimeters deep. If not only the lawn, but also a vegetable patch or even an orchard is to be drained, the pipes must be 80 or 150 centimeters deeper. To prevent the drainage pipes from clogging, the gravel packings are covered with fleece. You simply lay out the trenches with it and then apply the gravel. A total gradient of two to three percent is necessary so that the water can run off properly. You can do this by excavating and later filling the canals with gravel. Regularly check that the slope is adhered to, as this is the only way for the drainage to work later. The distance between the pipes should be two to three meters, depending on the size of the terrain. At the end of the area to be drained, the drainage pipes are connected to a collecting line. It consists of a larger, closed pipe and directs the water into the cistern or drainage shaft.

Our tip: Photograph and mark the route of your drainage pipes and also make a note of the depth before closing the channels again. In this way you avoid unpleasant surprises in later construction and digging activities.

Create drainage shafts, drainage trenches and drainage troughs

Drainage systems serve to drain the rainwater collected in the laid drainage pipes into the deeper soil layers, where it can then flow away more easily. Since the infiltration process takes time, it is important that the storage capacity of the infiltration device is sufficient. If you wanted to lay drainage, you should have it calculated by a civil engineering engineer so that the drainage shaft or drainage basin does not overflow. For a simple drainage shaft, a hole at least one meter in diameter is dug into the permeable soil layers at the end of the slope, which should reach at least one meter deeper than the drainage pipes. Correspondingly large manhole rings made of concrete are then inserted into them in order to stabilize the side walls. After connecting the collecting pipe, the shaft is filled with gravel or coarse chippings. Seepage shafts of various sizes are also available from specialist retailers made of plastic.

So-called seepage tunnels or trenches work in a similar way, only that a trench is dug here instead of a shaft. Line the trench with fleece and fill it with gravel as well. The rainwater is collected from the drainage pipes via the connected supply pipe and drained into the trench. A drainage ditch must also be wide enough and reach far enough into the permeable soil layers to be able to absorb the amount of water that occurs. The gravel packing of the drainage ditch is completely encased in fleece. Then apply 20 to 30 centimeters of topsoil on top so that the drainage ditch is not visible from the outside.

A drainage basin takes up a relatively large area and is basically nothing more than a small rainwater retention basin. The trough must be so deep that there is enough storage space below the collecting line of the drainage system - therefore it is particularly suitable on sloping properties. As a rule, septic tanks do not need fleece or gravel packing, as the seepage area is comparatively large - only in the case of very impermeable subsoil you should drill several holes down into the permeable soil layer and then fill it with gravel. Drainage basins can be incorporated into the garden design - for example, by designing them as wet biotopes with suitable plant species.

Drainage shafts, trenches and troughs should be built at a sufficient distance from the basement of the residential building so that no moisture gets into the walls. Important: When planning and purchasing, always emphasize that it is a rainwater infiltration system and not a drain for dirty waste water such as detergent or toilet water! In principle, different requirements and material requirements apply for this.

Tips and hints

Effective drainage is not an easy matter, especially on larger plots, and it is advisable to seek professional help. Experts from the region also know about the legal requirements. If you want to lend a hand yourself, you can use ready-made infiltration systems from specialist dealers. Here pipe connections, filters and any drainage points are already attached or pre-assembled. A detailed drainage plan helps in any case with the implementation of your own garden drainage. However, it is essential to find out beforehand the necessary size of your septic tank and the waste water regulations.