How to drain a soaking lawn?

Chappy · Post by **Chappy** » Tue May 20, 2014 8:52 pm

I have been asked to sort out the drainage on a lawn. The soil is heavy clay, and water just sits on the surface with no where to go. Its unusable right through the winter and then in dry spells it dries up and the grass dies off. Its hopeless.
Short of digging the whole lawn up and relaying a new one on a sharp sand bed, what are my options here?
I thought about digging a series of sump holes in a one meter grid across the whole lawn, about 18 inches deep and 6 inch wide with my post hole digger or an auger. I could line the holes with landscape fabric and then fill with gravel to within about 4 inches from the surface, and turf over them.
The idea being to form a series of mini soak-aways to drain the surface and give the grass roots some chance.
The garden is surrounded on all sides by neighbours so theres no chance of piping the water off site.
I thought about hiring a petrol lawn aerator/spiker, but would that go deep enough to make a difference?

Someone-Else · Post by **Someone-Else** » Tue May 20, 2014 8:56 pm

Only a thought, but if the soil is all heavy clay, and you make some holes, where will the water go?

Would it not be a better idea to remove all the clay to around 30cm, put pipework down to a sump, and back fill with soil and then lay lawn on top. Install a sump pump with float switch in the sump.

Chappy · Post by **Chappy** » Tue May 20, 2014 9:17 pm

Massively expensive - its about 10 meters by 8 so removing a foot off that would be truckloads. I'm just reading one of Alan Titchmarshs books and he reckons that surface soil compaction on hard-used family lawns is a big factor, and that aerating it would break the impermeable surface layer and the water could drain given a head start, even in clay soil.
I have to brush some grit sand into the spiked holes to prevent them closing up.
Sounds like a plan - anyone tried this?

mikew1972 · Post by **mikew1972** » Wed May 21, 2014 7:40 am

You want a lawn corer. A spiker pushes a spike about 5mm diameter into the lawn making a hole but compacting the soil around the hole as it pushes the soil aside to make the hole. A corer pushes a tube about 10mm diameter into the soil and removes a plug of soil. The grit sand is then brushed into these holes.
Only problem with both as you say is the depth of the holes made. Are they deep enough? If they are deeper than the depth of compacted surface soil / clay you have yes, if not no.

dewaltdisney · Post by **dewaltdisney** » Wed May 21, 2014 7:56 am

On football pitches they run over with a verti-draining machine. It is a tractor drawn special powered roller that has 6 to 7 inch long tines that cut slits. There is an optimum time that this work can be done which is usually early spring or autumn when the ground conditions are right. Compaction and mulching grass clippings all add to drainage issues.

Now I accept that you cannot use a machine in this instance but you do need to spike quite deeply, at least a fork depth I would say to have any chance of improvement. It might also be too dry now.

DWD

Chappy · Post by **Chappy** » Wed May 21, 2014 6:24 pm

So is there any mileage in my original idea then to put 18" deep sump holes and fill with gravel? I could do it quite quickly with a 4 inch hand auger, without compacting the soil even more with the spiking action which has been mentioned. If the lawn dries out in summer, would it be a good idea to then fill all the cracks with grit?

Someone-Else · Post by **Someone-Else** » Wed May 21, 2014 8:07 pm

I would say no, because a hole here and one there is of little use if the water is some where else.
Obviously you will try and make the holes in the worst places, (from a collection point of view) But I would say your 2nd best option is what mikew1972 said.

Leif · Post by **Leif** » Fri May 23, 2014 9:29 am

Chappy wrote:Massively expensive - its about 10 meters by 8 so removing a foot off that would be truckloads. I'm just reading one of Alan Titchmarshs books and he reckons that surface soil compaction on hard-used family lawns is a big factor, and that aerating it would break the impermeable surface layer and the water could drain given a head start, even in clay soil.
I have to brush some grit sand into the spiked holes to prevent them closing up.
Sounds like a plan - anyone tried this?

My lawn is about 300 square metres. I had poor drainage in some areas. The lawn was mainly moss and weeds on heavy compacted clay. I killed the lawn, spread 1" of sharp sand, then rotavated it in, killed the weeds that grew, and reseeded. Thus far drainage is much improved. I do not know if the sand was needed, or it was just compaction. Anyway, after rotavating I had huge numbers of worm hills, whereas before the soil was almost devoid of worms. And I now have a pretty good lawn, albeit with weeds, but what the hell. The digging would take you 1 day max using a good sized rotavator, spreading the sand takes a few hours. So a fair bit of work.

PMF landscapes · Post by **PMF landscapes** » Sat May 24, 2014 8:23 am

Simple plan would be to install some land drains. Dig out lines across the lawn every 2 meter or so connecting the trenches at the ends. Once thats done lay the land drains surrounded in pea gravel/pipe bedding which is then wrapped in terram. The terram will stop any loose soil particles blocking up the land drain. The land drai should then be directed to a sump hole

How to drain a soaking lawn?

How to drain a soaking lawn?

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