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Other pages related to garden drainage
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Garden drainage systems
from lawn aeration (forking over) to laying drainage pipes or gravel French drains
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Some kind of garden drainage system will be necessary if underground springs are causing waterlogging or damp spots in the garden, If surface water is flowing into your garden from higher ground or if water lies in pools after rain.
Some drainage systems will be as simple as forking over the surface of a compacted lawn to allow surface water to drain through after rain. Flowing water from a spring or rainwater flowing from higher ground will almost certainly need a garden drainage system that intercepts the water and directs it away into a drainage ditch, soakaway or more likely into the rainwater drainage system.
Drainage trenches can be built using plastic drainage pipe systems, gravel or a combination of both. Over the years I have found the gravel drainage systems (French drains) last longer and are the most effective drainage system, when they are installed correctly.
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Drainage system for surface drainage
paved driveways and patios.
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| Linear drainage system |
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Linear drainage systems are typically used to intercept rainwater and carry it away to a drainage point, They usually come as a u-shaped cross-section made from polymer concrete or plastic, with plastic or metal grating over the top. Linear drainage systems are normally fitted when the flagstones or block paving is laid. They are easy to fit into existing driveways by cutting out a gully large enough to fit the channels in.Corner units and other fittings including T-junction units are available with most makes of linear drainage systems.
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| Underground drainage systems
for large waterlogged lawns and garden borders
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Modern plastic land drain pipes (example right) are made from crush-resistant plastic with perforations, it's fairly stiff but flexible enough to be laid around slight curves. The pipes are laid into trenches dug in a "herring-bone" pattern and surrounded by gravel. On level ground, the pipes are sloped to the soakaway or drain system, on sloping land, the main drain should follow the slope. Soakaways do not work in heavy clay, so the pipes will need to be connected into the rainwater drainage system, not terminating under your neighbours fence.
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| Perforated plastic drainage pipe |
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French drain drainage system layed under the lawn or border
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The gravel drain system known as French drains is installed under the turf or garden topsoil to solve waterlogged garden drainage problems, its probably the best and longest lasting drainage system, certainly for clay gardens. The French drainage system takes about three days to install and the area will be useable within a few days.The gravel is laid into lined trenches dug in a "herring-bone" pattern.
After the French drain system has been installed the area is covered with grit sand and can be seeded or returfed. A lot more information and DIY tips can be found on my lawn and garden drainage pages.
Sump and Pump Garden Drainage Systems
Remember, wether using plastic pipes or a French drainage system to sort out a wet soggy garden, the water will need to be got rid off, providing the slopes are all flowing in the right direction this can be a soakaway, ditch or most likely the surface water drainage system. Tempting as it may be, surplus water should never be channeled to terminate in your neighbours garden. If the slopes are flowing in the wrong direction you will need to install a Sump and Pump Garden Drainage Systems that works by collecting and pumping the water to a discharge point. How to instal the sump and pump is explained on my drainage sumps and pumps page
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For small localised wet patches and soggy areas, these drainage tips may help
Puddling
When rainwater water lies on the surface of a lawn for more than a couple of hours after rain its probably caused by compacted soil or clay made worse by dips and humps in the surface. Compacted soil puddling is fairly easy to sort out by digging holes with a garden fork or even a crowbar over the whole of the affected area and filling the holes with coarse sand or gravel. If the problem is caused by clay, this wont work, check out these pages, improving clay soil and garden drainage
Soggy area or spongy lawn.
If you have a soggy area that is permanently wet it can nearly always be dried out by digging out a soak away 1m square and depending on the severity up to 1m deep or if the sogginess is spread over a wider area, dig a soak away trench through the area about 18inches wide and as deep as you can. Half fill the trench or soak away with clean rubble topped with 20 to 30ml gravel and finished with about 6inches of top soil. You will end up with quite a lot of surplus soil, if its clay you will need to get rid, if its good loamy soil use it to raise your borders.
Leveling dips that catch surface water.
If your lawn has good drainage properties but puddles on rainy days, mark out the dips with bamboo canes, wait until the lawn dries out, fork over the area and fill the dips with Grit sand. Its important not to smother the grass so leave the tips of the grass poking through the sand. This process can be repeated over the growing season, until the whole lawn is free of hollows and dips.
Raised beds for small soggy areas.
If the wet soggy area is limited to a small part of the garden, raising the area by adding topsoil can work. Raised beds are the best way and can be made from almost any material available, my raised garden bed exclaims how. If the whole garden is waterlogged, raising the level with soil does not work you would be creating a swamp.
Bog gardens for low wet areas.
Turning the unusable swamp in a low part of your garden into a colourful bog garden planted with Bog plants that actually thrive in soggy soil works, how to is explained on my bog garden page.
Using permeable paving.
Permeable paving allows water to drain through and back into the ground instead of diverting it to where it will cause a wet soggy area or as with tarmac driveways that slope away from the house, onto the road causing dangerous ice traps in winter (very unneighborly). Block pavers are a good example of permeable paving.
More About French drain drainage systems here Lawn and garden drainage
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