Hi. Wondering if you kind people can offer some advice please:
We have a 1939 house with a 120 foot garden, mostly grass, lots of plants and some apple, pear and acer trees. It's relatively flat and just a few inches under the soil is clay.
During the winter months and heavy summer downpours, the soil is sodden and the rain pools. The garden becomes unusable.
There is nowhere to french drain the excess to as the woods behind the garden are at the same level and pretty much permanently wet from the stream that runs through them - it would just back up. I had an idea to break through the clay layer, with the thought of digging a few holes that would provide a drainage system, like pullng the plug in a sink. Using an extendable manual auger, we dug over 13 feet down and it was still clay.
The hole was there for a couple of years, would fill up and take an age to subside. It's now been filled in.
Before digging it, I Googled how deep the clay layer is in our area/postcode but could find no helpful info from any geoligal surveys or web sites, so digging seemed the only way.
It nags me that we could have been within an inch of getting through or it could have been another 100 feet.
I was wondering if you knew of any sites where I could find how deep the clay is in our area please? We live in Cardiff, South Wales.
Thank you.

If I was in this situation, I would forget about the clay. Any way that you choose to improve things will be very $$$$$!
Instead of digging down, why not dig up? Use containers or raised beds.
You can start out with 1 or 2 beds and always add more.

Welcome to the site!
Maybe some info as to your question in this report.

https://nora.nerc.ac.uk/id/epr...

I think you may just have to work with the clay. I have a spot out front that floods when it rains so I planted stuff that can take being consistently moist/wet and flooding.

anyaisle said:
We have a 1939 house with a 120 foot garden just a few inches under the soil is clay.
During the winter months and heavy summer downpours, the soil is sodden and the rain pools. The garden becomes unusable.
I had an idea to break through the clay layer, with the thought of digging a few holes that would provide a drainage system, like pullng the plug in a sink. Using an extendable manual auger, we dug over 13 feet down and it was still clay.

While your idea is a good one in an area of recent construction, a garden that's had no heavy equipment since '39... probably as good as it's gonna get.

I was once asked about a turfed area that filled with water after a rain... as they had just built the house and used heavy equipment to grade the property, I suggested a bulb auger to create drains through the hard pan... it worked. I still think they shoulda gone with wetland plants...

As far as using the garden?
Do you mean planting stuff? or going out walking the paths, lighting a bonfire kind of use?

I'd probably lay some landscape timbers on top of the ground and add some kind of rock, brick, whatever is available for free or cheap... on top of the soil between the timber / logs / whatever is free or cheap.

Dig a pond and use the removed soil to build up the rest of the yard?

Thank you for your replies and suggestions. I haven't worked out how or if I can reply to each individually, so hope this covers them all.

Catpaworchids: Although I understand your suggestion to use containers or raised beds - to raise the level and enable it to hold more water rather than flood on the surface, we already have many plants, beds and trees, as well as 7 foot beech hedges all around the perimeter. We're not getting any younger so are not looking for more maintenance. An alternative – raising the level of the grass – would involve costly topsoil and re-turfing/seeding.

Crawgarden: Thank you, and for sight of that report. I would not have found it myself. It's a 60+ pages geochemical report of the soil composition of the Cardiff area. Although soil samples were taken at many sites around Cardiff, they were too shallow for my needs, only of the surface soil (up to 0.2m deep ) and profile soil (up to 0.5m deep), there is no data relating to how deep the clay layer is. It's an interesting read though.

Hamwild: I understand your thinking but we would prefer to keep the grassed areas we have, without adding more plants and maintenance.
Stone: Ours is more claypan than hardpan and as I said, after only a few inches of topsoil. 13 + feet down, it's still clay. When it's dry enough, we spend a lot of time maintaining the garden but would like to be able to use the grassed areas more, for leisure.

Porkpal: All the neighbours in our row suffer from the same issue. Our next door neighbours have a pond. To be honest I think it adds to the water retention problem as its plastic lining completely prevents any water draining in that area and the pond overflows occasionally. Plus, as our soil is only a few inches deep, digging a pond would create a mountain of unwanted clay.

Thanks again for your suggestions and help

I have memories of this kind of ground from OH, where they scrape off the topsoil from the old farmer's field before they install the "subdivision" of cookie-cutter houses and the ground is then solid clay. Is your clay gray? Mine was.

You can fix it by repeatedly adding organic matter, over time. I can't speak about the turf because I don't like it, but as far as the non-mowed areas, I've seen what repeatedly covering those areas with a LOT of leaves can do. Other organic matter is great, but usually not as abundant in sudden windfalls. Happy to elaborate if the idea appeals.

Hi @purpleinopp. The clay is more red than brown, certainly not gray... or grey as we Brits would say :-). The trees and beech hedges leave a good covering of leaves during the autumn and we have tried leaving them, rather than gather them up which is my natural inclinination. What we haven't tried is turning them into the soial and clay, what would be a huge task for us with the resulting need to resurface the grass finish. I'm guessing climate change has worsened the situation - we've suffered from some serious rainfall this last 12 months or more. .

@anyaisle ,
Welcome to NGA!

If there is stream at the same level and all your neighbors have the same issue, it sounds to me as if the problem is the height of the water table.

In that case, I doubt there is any place for the water to go no matter how far you drill. The clay is saturated all the way down the core that you dug, correct? At some point there may be rock underlaying it. Even if the rock is permeable, as some limestones are, I would expect that it is also saturated.

If you could dig a deep canal from your location to the outlet of the stream that might help but I don't suppose that is possible.

There appears to be a government initiative to deal with water issues in the Cardiff area. Maybe you can consult with people involved with this effort for help.

https://www.sudswales.com/type...

Best wishes!

We would love to have some of your raindrops here. Wish these things could be more even.

anyaisle said:Ours is more claypan than hardpan and as I said, after only a few inches of topsoil. 13 + feet down, it's still clay. When it's dry enough, we spend a lot of time maintaining the garden but would like to be able to use the grassed areas more, for leisure.

This was actually my point...
There isn't a hard pan to break up...
You're not going to drain the clay faster than God designed in your garden.
I'm sorry I can't trade gardens with you...
When I got this place, I begged the real estate agents to show me some clay, and they just weren't ever going to.

Someone that was willing to shell out for this turf area to be useable in the winter should maybe consider the blocks they use in grassy driveways...

https://www.gardenista.com/pos...

You can't get rid of the clay, and there are no quick fixes. You might be able to regrade to move the flooding to a different area that might be more convenient. And you can, over time, improve the drainage capacity of the soil and add more loam by planting deep-rooted clay-tolerant plants. In the US, I would be recommending tough native prarie grasses and flowers, or trees and native shrubs in wooded areas. I'm sure you have equivalent native plants in the UK. As they grow, their roots create microchannels and add biomass that help water penetrate the earth instead of staying on the surface. Many prarie plants have root systems 3-7meters deep. I'm comparison, turf grasses have only a few centimeters of roots. Plants lose and replace about a third of their roots every year. Over time, this makes the soil more like a sponge and less like a rock.