Draining a Lawn? Advice welcome ...

HayDay18

The issue with our lawn is that the soil on it (and all surrounding the site) is quite heavy, clay type soil. Its very squidgy/squelchy to walk on in areas during wet weather. It has poor drainage in the soil itself I think and we have rushes growing in the field and now on our lawn also. We want to tackle the lawn and improve it before we progress with any other groundswork. Our initial idea (Option 1) was to drain it in the form of some french drains / shores with 4-ins pipe across the lawn at 15ft intervals. After chatting to people, one person we know suggested scraping all the soil off the lawn and putting down a full gravel drainage layer (Option 2). He said that if we drain it using drains we could have a stripy scenario where some parts are well drained and some are not. I had never heard of this idea but it sounds very good. I chatted to the diggerman he said any type of gravel would work for this even shale.

Regardless of which method we use we will be topping it off with some good brought in top-soil. its a sloped lawn but that has never helped it be less wet.

We need to scrape some gravel off from around the site where concrete is to be laid so we can probably provide half the gravel needed for Option 2. The expense of either method is not a deal breaker, we want a nice lawn that doesn't have rushes growing on it and we didn't invest in doing it right on Day 1.

Any advice recommendations welcome, especially from anyone that has improved a heavy/wet lawn. TIA

Calahonda52

Where will water go in option 1?

Where will water in option 2 go once the gravel is water logged?

which way does it slope?

Are u generally in a hollow?

Urban or rural?

What I did for a client was have a meter deep/meter wide by 10m long trench dug at the bottom of the slope and filled it with crushed stone ,and covered with permeable geotextile membrane and then a decorative gravel to finish.

At one end of the trench a sump was fitted inside a 12" vertical land drain pipe and a submersible pump with a float switch was fitted at the bottom. if the trench filled, due to really heavy rain, the pump came on and water pumped out.

muffler

As above you need to determine where you can run the drainage to regardless of any method you employ. Apart from the natural rainfall falling directly into your garden is there surface water running off or seeping through from adjacent higher ground? If so explore the possibility of picking this up with a well constructed land drain. Following on from that you could consider rotavating and re-seeding the plot which would be a far cheaper option.

HayDay18

Not in a hollow, on a elevated rural site.

Lawn is sloped (towards west if thats what you are asking by which way it slopes?) so its not a matter of water lying on the surface due to dips or hollows. No issues with where the water goes we have existing drains both sides of the lawn and a shuck directly adjacent to pipe any drains into.

The lawn was freshly seeded 3 years ago when we moved in so without addressing either drainage or soil I don't see how rotovating and re-seeding will do anything.

"Where will water in option 2 go once the gravel is water logged?" - I'm learning here but my understanding of this suggestion is that it would help the lawn to function as if there was good soil that has naturally good drainage, that it would stop the top layer of soil from being overly soggy. As i said the lawn is already sloped so water should not be lying on the surface.

"is there surface water running off or seeping through from adjacent higher ground?" - this is a good point and possibly some yes from the upper part of the lawn which becomes the field.

Calahonda52

So is the lawn sloping away from or towards the house or left to right or what?

HayDay18

The lawn is mostly sloping towards the lane which is also sloped, part is sloping towards the house but theres a drain along that perimeter.

HayDay18

My own feeling is that the soil itself is the primary issue and that taking in good top soil will be crucial. While I'm at it though I feel I should do some form of gravel drainage. Perhaps the french drains/shores will be sufficient.

Is it ok to plonk top soil on top of the existing soil or should we scrap some of the existing stuff off? What depth of top soil is best for a good lawn?

What intervals are best for the drains and should they just go across or in a herringbone pattern as I've seen online?

monseiur

How big is the lawn? It may be more economical to remove the existing top soil & sub soil completely to a dept of say 800mm Back fill 150mm with small loose stones/clean pebble (aka drainage stone) going with the natural fall of the site. The greater the fall the better. Then lay your 80mm perforated land drainage pipe in rows 2 metres apart and continue back filling with drainage stone until pipes have a 300mm cover. Then cover the whole area with good quality woven anti weed membrane then finish off with good quality light loamy top soil and reseed.

HayDay18

Thank you monseiur but that definitely sounds like the least economical job! Would be some job though! I think we are going to do the drains every 2 metres and cover the existing soil with 6 inches of good topsoil.