Drain it away
Is an unsightly, waterlogged lawn leaving you wringing your hands? With the right drainage system you could have the problem sorted before the rainy season
By Gina Hartoog
Does the thought of the rainy season leave you feeling less than enthusiastic? You know that very soon your lawn will be a marshland and you can only dream about a good game of cricket on a perfectly dry turf.
Nobody likes walking over a waterlogged lawn, but added to that, it isn’t a healthy situation for your lawn or plants or the foundation of your home. If you are serious about sorting out the problem, you’ll need to get to grips with garden drainage.
Signs of peeling or flaking paint on the walls of your home, dying plants in very waterlogged areas of the garden, or water pooling on the lawn or in flower beds (that takes a while to drain away, if at all) are all indications that you probably have a drainage problem.
There are two types of drainage in the garden – surface and subsurface drainage.
Properly installed surface drainage takes care of excess water on the surface of the ground. It collects this water and redirects it elsewhere. Water is collected from your roof, along guttering and downpipes and on hard surfaces like your driveway or patio.
Subsurface drainage systems are underground. They can either be installed at the time of building or when required in an existing garden. Subsurface drainage systems generally use a system of pipes to collect excess water and move it elsewhere. Pipes should wrapped in geotextiles to prevent soil from clogging the drain. Subsurface drainage systems should also be used behind retaining walls to direct water away from the structure.
French drains: Old and new
French drains were actually named after a farmer, Henry French, who penned a book on farm drainage in 1859. Although French is credited with the ‘invention’, the Romans developed the concept.
Today, French drains are not often used as a solution for drainage in suburban gardens. However, French drains are still used as an integral part of septic tank systems.
Here, partially treated effluent is removed from the septic tank and soaks away into the surrounding soil. It is further filtered through the soil layers before reaching the water table.
Common causes of poor drainage
Before attempting to find out the exact cause of your garden drainage problems, check that your gutter and downpipes are correctly fitted and properly channelling water away from your home’s foundations.
Look for areas where garden beds are against the house. Check for peeling paint. If this is noted, you will have to waterproof the area and remove any soil that is piled up against the house.
Other causes of poor garden drainage may be related to your soil composition and compaction. Soil particles vary in size. Even in a very clay soil, there are particles of silt and sand.
An incorrect gradient or slope of the land may cause water to pool in low-lying areas. A high seasonal water table in your area could also contribute to water sitting close to the surface, especially in the rainy season or you may also have underground springs in your neighbourhood.
The solution for poor garden drainage will depend on the cause. Here are several options that you can consider.
Levelling off or sloping
Over time, especially on newly built properties, the ground may settle and begin to slope towards the foundation of your house, instead of away from it. A correct slope is gradual enough to keep some water on your property, but move it quickly away from any buildings.
Soil type may also affect how well soil drains. Loamy soil drains very well, while poorly draining soil tends to have a high percentage of clay.
Solve this problem in your garden beds by adding compost and digging over the area very well. You may need to apply several applications before drainage is improved.
If your plants are struggling, the addition of compost can greatly improve the quality of your soil.
An uneven lawn, bumpy lawn with pockets and dips may cause water to pool at low levels. A simple solution would be to add more soil to the low spots and level off the ground.
This solution works very well if the problem is indeed an uneven surface, but if there is another underlying problem, it may do little more than move the waterlogged spot elsewhere.
You can use topsoil to build up the low areas or create a better slope. Foot traffic over the lawn during wet periods often reduces permeability, so rather keep off the lawn when it is very wet.
If the pooling problem in your garden is confined to a specific area, you may want to consider turning it into a feature in the garden by building a bog garden.