waterlogged garden, what now?

[rrussell]

My garden is very clay like.
in the summer we had gapping cracks and in the winter/ after heavy rain it stays wet and boggy for a long time.
it was uneven and had a slight mount in the middle.
so to even it out in the summer/ autumn I removed the grass, top soil and about 2inches of subsoil (22 tonnes in total). I then rotovated it.
I was planning on putting 22tonnes of topsoil back and grassing it nice and level, so me and me boy can have a kick of football with out him getting his ankle caught in the gaps. Needless to say I ran out of time to get some topsoil delivered before winter.

this is what the garden looks like now, would topsoil and grass prevent the flooding?
My neighbours garden to the left is about 3inches higher and my neightbour to the right about 3inches lower. There is no run off for the lawn.

advice please for this summer project

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• rrussell
• 17 Mar 2015
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• rrussell
• 17 Mar 2015
• 1

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• rrussell
• 17 Mar 2015
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[ban-all-sheds]

If you put 2" of topsoil over the clay then when it rains you'll get 2" of waterlogged topsoil sitting on top of the clay which, without a lot of effort, you'll be able to turn into 2" of wet mud.

I can't advise on how to do it, but basically if you don't create a way to drain lots of water away your garden will often look like it does now.

 

[Iangardenguy]

Hi,

The problem you have is one i see a lot on new build properties due to them leaving a lot of clay near the surface and essentially creating a false water table.

I am experimenting with ways to solve it that do not involve excavating the surface of a garden and then bringing in new topsoil.

One idea i am looking to try is to make a lot of small diameter holes that go 1-2 meters deep past the surface clay (avoiding pipes obviously) and then either fill them with gravel or put off cuts of cheap hose pipe down them and then over the hole or over the hose pipe end a piece of weed fabric so clay/silt etc cannot be washed down and create a future blockage.

After that top them up to the ground level with soil and put the bits of turf i cut out back over the holes and see if they works like mini soak always/land drainage system.

I want to be clear and say that i have no idea if it will work but the theory is sound enough.

Looking at the massive puddle in the image you linked id say its the perfect spot to poke a few holes and test the theory out.

Id create a puddle using a hose and see how long it takes to drain away.

Then poke a few deep holes in the area and use the hose to create another puddle and see if it drains faster.

If it does id go with the hose option for in the hole personally as the weed fabric will only stop clay and silt going in from the top not the sides if you use gravel.

If you try it id be really interested in knowing the results obviously.

 

[Iangardenguy]

Actually now i think about it....

The option above was for people who do not want to dig out and replace their garden and as you already have done the digging out half you POTENTIALLY (see bottom of post) have another option.

As you are going to bring in new surface material to replace what you dug out anyway id start with several tons of sharpe sand (not from a marine source obviously as salt does not go well with plant life).

Rotorvating a sharp, grit sand into the clay, will not only improve the drainage characteristics of the ground,

It will also improve the aeration of the soil, render it easier to work, and help strong root formation by your plants.

A sharp or gritty sand, NOT a building or a soft sand, which contain too many 'fines' and clay particles.

A good grit sand will contain a reasonable amount of tiny pebbles in the 3-6mm size range, along with smaller sand grains, but less than 3% clay particulates.

Step 1.

Rotorvate to at least 200mm but the deeper you can go the better (300mm or 450mm is even better and doable if you have access to a Howard gem). No need to break it up small yet so just loosen it as deep as you can.

Step 2.

Spread about 3-4 inches of sharpes sand over the surface and then rotorvate it in until it is reasonably well mixed, and there are no obvious patches of all-soil/clay or all-sand.

You can repeat it with a final mix of the top soil you were planning on using and sharpes sand and by this point you should not see clumps bigger that 40-50mm.

And remember that if you are going to seed it or turf it you need to let it settle for a bare minimum of a month, longer the deeper you went.

So why i said "potentially".


It maybe that you do the soil improvement routine, and your garden is still damp or waterlogged as your garden is in a natural hollow or low-spot.

As such you could try the option i mention in my first post or as you already have the area dug out you could install some of the cheap land drainage pipe described in the link below.

http://www.pavingexpert.com/drain03.htm

On a entirely selfish level id prefer it if you tried my idea first so i can see if it works not but that is as i said for entirely selfish reasons.

 

[rrussell]

Thanks for your input its very much appreciated.
Ive been out in the garden and dug two small holes one about 2.5ft deep and the other about 2ft, they are bare holes with no filling
its been dry for the last two days but the holes are still full of water. My thinking is if I make the holes a lot bigger the waterlevel will be a lot lower.
opinions please

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• rrussell
• 7 Apr 2015
• 1

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• rrussell
• 7 Apr 2015
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• rrussell
• 7 Apr 2015
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[Iangardenguy]

Thanks for your input its very much appreciated.
Ive been out in the garden and dug two small holes one about 2.5ft deep and the other about 2ft, they are bare holes with no filling
its been dry for the last two days but the holes are still full of water. My thinking is if I make the holes a lot bigger the waterlevel will be a lot lower.
opinions please

They need to be deeper not wider.

A trial hole needs to be at least 1.2m up to 1.8m deep.

Leave the excavated trial hole overnight, covering with a board or fencing-off to prevent accidents. 24 hours later, inspect the pit. If there is no water in the trial pit, then a soak-away is highly likely to work and work well.

If there is any water present, the level will have stabilized at water table level, and this should be measured from ground level to determine the how deep the water table is.

 

[rrussell]

Its been left for two days like this with no rainfall.
im going to drain the water and go deeper as you said.
my only concern is it will not soakaway due to the denseness of the clay, but we shall see
Thanks