(Expensive) New Turf Lawn is Constantly Waterlogged. Please Advise on Drainage Solutions?

thefeester05403 · 2 February

Hello there,

We knocked down an old house and build a new one last year. As part of this we put in a large (about 950m2) new lawn using lawn turf about last August/September.

Image: https://us.v-cdn.net/6030279/uploads/editor/w7/e0xgvnamk3d7.jpeg

Unfortunately the new lawn is not working out at all. We're located close to the sea (about 350m as the crow flies) and our site is certainly prone to being wet, if you dig down about 4-5 feet you get to very sandy soil and water and we had to put the house on piles. In saying that the house that was here before had a nice garden and the lawn looked good in winter and never became waterlogged even after heavy rain.

The problem main problem with the new lawn is it's constantly wet. To walk around on it it's nearly constantly squelshy underfoot. If we get rain for any length of time pools of water appear.

Image: https://us.v-cdn.net/6030279/uploads/editor/wi/n2bpkpecaonb.jpeg

Image: https://us.v-cdn.net/6030279/uploads/editor/9s/5a11q9id2cy8.jpeg

The areas where water is pooling have turned yellow and do not look healthy. But the main issue was the lawn was mainly for my football mad young sons and we've spent pretty much the whole time since the lawn has gone in not letting them go on it as it is too wet underfoot and we don't want them destroying it. The lawn is also (you can't see it from the pictures) incredibly wavy and uneven. It started off reasonably flat (but not great) but its become really wavy in just a few months and I'd imagine it will get worse.

I'm not happy as this lawn was incredibly expensive to put in and I don't think the guys doing it did a great job. I suspect the ground got quite compacted during the build and they did not do much to loosen it up. They basically added a bunch of screened topsoil and sand (which I see mixed opinions on whether this should be used) on top of what was there and plonked the grass on top. They are trying to argue that it's not their fault that the lawn is not doing well.

What I'm looking for is suggestions on what can be done to improve drainage and try to make the lawn more usable?

I'm guessing some sort of drain put in under the lawn leading to storm drain pipes might be the best in that the water would be drained away. Not sure if this could be done simply.

The other option might be somthing like here: https://www.youtube.com/watch?v=5R8StYZQi_8 Basically drilling a bunch of holes with an auger and filling with pebbles. Not sure if this would work and as I say it is very wet when you go down deeper so this may not work. But it would be a simpler solution.

Anyway, any advice would be much appreciated. I have had poor luck with gardeners so I don't have anyone competent to advise me on this. This site seems to be filled with knowledgeable people so I'm hoping someone can point me in the right direction and then I can find someone to do the work.

Thanks in advance!

BenCotto · 2 February

I’m afraid I have no first hand advice but if you put ‘lawn drainage’ into the search box you’ll open up lots of pertinent discussions.

Here’s one posted by @glasgowdan, a lawn expert, but as he has not been active on the forum for three years this prompt is unlikely to reach him.

https://forum.gardenersworld.com/discussion/994144/drainage-in-a-pan-flat-clay-lawn#latest

wild edges · 2 February

thefeester05403 said:

I suspect the ground got quite compacted during the build and they did not do much to loosen it up. They basically added a bunch of screened topsoil and sand (which I see mixed opinions on whether this should be used) on top of what was there and plonked the grass on top. They are trying to argue that it's not their fault that the lawn is not doing well.

This is very likely to be the problem. Contractors rarely protect landscaped areas from compaction as much as they should.

A couple of questions: Do you know the depth of new soil on top of the compacted ground? Where does the rainwater from the new house go?

thevictorian · 2 February

Has it been an exceptionally wet year where you are? It could be a high water table plus the compaction.

I was also thinking where does the water from the house go, is the soak away under the lawn?

JennyJ · 2 February

You're probably right that the building work has compacted the soil, particularly because the previous garden didn't have the same problem.

Holes filled with pebbles might work short-term but the soil will gradually filter down into the air spaces and you'll get sunken patches in the lawn over the pebble areas.

thefeester05403 · 2 February

wild edges said:

thefeester05403 said:

I suspect the ground got quite compacted during the build and they did not do much to loosen it up. They basically added a bunch of screened topsoil and sand (which I see mixed opinions on whether this should be used) on top of what was there and plonked the grass on top. They are trying to argue that it's not their fault that the lawn is not doing well.

This is very likely to be the problem. Contractors rarely protect landscaped areas from compaction as much as they should.
A couple of questions: Do you know the depth of new soil on top of the compacted ground? Where does the rainwater from the new house go?

Thanks for the reply.

I'm not really sure of the depth of soil, at a guess maybe about 10cm. Here's some pics of it going in but they had already spread soil around previously. I suspect they did nothing to break up the compacted soil underneath.

Image: https://us.v-cdn.net/6030279/uploads/editor/4e/zua7xsloj550.jpg

Image: https://us.v-cdn.net/6030279/uploads/editor/le/7zh2n8vxs5wj.jpg

Image: https://us.v-cdn.net/6030279/uploads/editor/1t/hzc9rba0gtfa.jpg

Image: https://us.v-cdn.net/6030279/uploads/editor/3i/c6ifqso3er8n.jpg

Regarding the rainwater, there is a large (circa 10,000 litres) rainwater harvesting tank close to the house and then from that a drain running to the end of the garden (behind that wooden building) where all the drains run to.

So in theory there probably is somewhere to drain the water to close to the lawn but I suspect you could not run the lawn drainage into the harvester as it would be dirty

thefeester05403 · 2 February

thevictorian said:

Has it been an exceptionally wet year where you are? It could be a high water table plus the compaction.

I was also thinking where does the water from the house go, is the soak away under the lawn?

Yes, it there has been quite a lot of rain at times, but as I say we lived in the previous house/garden here and even in very heavy rain never had the waterlogging we have now.

We were going to have to put in a very large rainwater attenuation tank as well as the rainwater harvesting as part of the planning process but our engineer said it would be pointless in that if you dig down the ground is often full of water (especially when the tide comes in at the sea close by) so it would not have worked. We got permission not to have it.

thefeester05403 · 2 February

JennyJ said:

You're probably right that the building work has compacted the soil, particularly because the previous garden didn't have the same problem.
Holes filled with pebbles might work short-term but the soil will gradually filter down into the air spaces and you'll get sunken patches in the lawn over the pebble areas.

Thanks, good to know. As I say we already have issues with the lawn becoming very wavy/uneven so don't want to make it worse. We had hopes of having a tennis court out there but it's not going to happen.

Trying to get the lawn more level/even is another project if we can ever sort out the drainage issues!

bédé · 2 February

Where are you?

Digging a few trial holes to see what is down there would be a good idea. There is probably a specialised auger that would do the job.

If a high sea level causes this sort of flooding, be prepared for worse.

Ceres · 2 February

Before assuming this is all down to compacted soil (and possibly builder's rubble), I see you have houses round about so have any of your near neighbours experienced this sort of thing in the last few months? There has been a lot of rain in some areas this year and also more storms than usual. How far above sea level are you?

thefeester05403 · 2 February

bédé said:

Where are you?

Digging a few trial holes to see what is down there would be a good idea. There is probably a specialised auger that would do the job.

If a high sea level causes this sort of flooding, be prepared for worse.

Thanks, we had holes dug with diggers for percolation tests. It gets sandy after a few feet and water did not drain away. But as I say the previous garden was fine and did not get waterlogged so I thin it should be doable. Out front which got very compacted also is the same

The house is up on piles and about 1m up in the air so we're hopefully fairly flood proof for the future!

(Expensive) New Turf Lawn is Constantly Waterlogged. Please Advise on Drainage Solutions?

Posts