Garden Drainage Problems are Very Common

Several things can cause poor garden drainage. Often in new housing estates, compacted soil from builders’ trucks combined with the mixing of sub-soil and topsoil when all the trenches and foundations were excavated lead to a heavy, wet plot.

In cases where new estates have been built on old arable land that has been cultivated annually for centuries, a “plough plan” may have developed. This means that an impervious layer of more compacted soil lies just below the maximum ploughing depth, caused by years of polishing the sole of the plough.

Of course, human activity is not the only thing that causes garden drainage problems. Clay soils are water retentive by nature, which causes the flow of water through the soil to be very slow. The problems get worse when the contours of the land form depressions in which surface water can collect.  Low lying gardens can be affected by the natural water table of the area. In gardens which have a very shallow water table, not much can be done to avoid water logging after a heavy rain. Water can rise to the surface of the land, or actually rise above it forming a pond.

Do you Have a Drainage Problem?

During wet weather you can tell just how good or bad your natural drainage is. Patches of water on the surface are the most common signs of a drainage problem.  You can check your drainage in dry weather by digging a hole about 24” by 12” in your garden. Fill the hole half full with water, and leave it alone for 24 hours. In well-drained soil, the hole will empty. On very wet land however, the hole may actually fill!

If your topsoil is very poor, it’s probably worth stripping off the top 6 inches or so and applying a fresh layer of topsoil. When your topsoil is very water retentive, the problems may be reduced by simply double-digging and incorporating large amounts of bulky organic materials. However, where the soil is inherently heavy and waterlogged, some form of drainage will still be necessary.

Sprinkler Scape Can Help you Select the Right Drainage for your Garden

The type of drainage used depends mostly on the extent of the problem. If the water logging is not very severe, and you are only dealing with excess surface water, it may be possible to overcome the problem by shaping the garden surface so that the water will flow off into ditches.

Another method would be to create a soakaway. This requires a large hole (at least 6 feet deep by 6 feet wide) at the lowest point of the garden. The hole is filled with rubble, or rubber bricks, and then covered with soil. There is not always a need for underground pipes to direct water to a soakaway, however land with insufficient gradient to drain water into the soakaway will require the use of some sort of pipes.

Plastic land drain pipes consist of crush-resistant plastic with perforations. They are usually stiff, but still flexible so that the line of the drain doesn’t need to be straight. The pipes can be laid into a trench and surrounded by gravel. When there is a large area to drain, the most efficient way is to lay a number of pipes in a “herring-bone” pattern.

Underground pipes should always be laid above the local water table, or else they will only move the groundwater instead of actually draining the topsoil. Pipes at ground level should be sloped underground to encourage water to drain away quickly. On sloping land the main drain should run down the slope. Drained water will obviously need to go someplace, so all pipes should empty into a soakaway or ditch.

SprinklerScape can help you with all of your drainage problems. Contact us today!