Garden flooding

juliechandlerhome · September 2020

My garden has been paved over by the previous owner but the rainwater just stands on it.
I've removed quite a few of the flags, dug down and laid a membrane and slate but that hasn't worked. Someone came out and said all of the slabs needed to be lifted and sloped then a French drain installed. As I've already spent £350 on trying to rectify this (a gardener did this for me )I can't afford to spend lots more money on this. Any ideas? Ive tried to upload a photo but can't.

amancalledgeorge · September 2020

Ah people and their stupid ideas about low maintenance gardens...cover a whole garden in slabs must have compacted the ground so badly it will need quite a bit of work to let the water back in properly. It sounds to me your aesthetic alterations really don't address the compaction of the ground or how water moves about. Try to make the image smaller than 6MB and it will post. I would have run away from a slabbed garden like a shot. Unfortunately earthworks of any sort are either expensive or back breaking.

juliechandlerhome · September 2020

Thanks for your reply. Yeah the guy that took up the slabs said over the years the weight of them had really compacted the soil. He was actually jumping on the shovel to try and dig up some of the soil.
I thought a paved garden was low maintenance....how wrong was I. (Still can't upload photo).

Ferdinand2000 · September 2020

This is tricky, I'm afraid - and needs quite a lot of site specific knowledge to make a useful comment. And really it needs background thought to be fairly sure that your intervention will work.

Before putting a drain in, you need to know that there is somewhere where the water will successfully drain away to. If the ground at the other end of the drain is as full of water as your ground, then it will all stay in the drain and all you have is a gravel-filled covered ditch with some water in it.

In these circs it may be that this would act as underground storage for a certain amount of water whilst it slowly percolates into the soil. This would then be functioning as a "soakaway", which is a buffer underground where extra water can go whilst the ground drainage catches up with the amount of surface water.

But if your natural level of water in the soil - the water table - is high it may be that there is nowhere for the water to go, which brings us back to the start.

If you dig something like that and the water table is high, it may be that water will come the other way into your drain or soakaway, which is then termed a "sump".

You need to understand how water moves in your area, how high your water table is (it moves with seasons), and how good your soil is at percolating water away (it is sometimes the case that the top layer is slow and the next layer is better - so a deepish soakaway can help in that situation). It may be that your paving substrate is functioning as a poor draining layer

. Or not

.

You can find some of that out by looking at the lie of the land, and digging big empty holes (to find out how fast water comes in), or filling the hole with water (to find out how fast it drains away). There are calculations relating size of soakaway to area drained, max rainfall etc.

A "big hole" is anything from 2 x 2 x 2 ft to 4 x 4 x 4 ft or more. The main thing, as I learnt once, is not to step in one half full of water by mistake in the dark when going out on the posh. They all laughed like a drain (sorry).

Ideally you can make a drain or a soakaway, but you can also do things like create bog gardens and raise other bits of your plot to mitigate.

Doing your own drainage is a good way to get muscles and sleep.

If you post up more detail, we'll do the best we can.

Ferdinand

juliechandlerhome · September 2020

Thanks for your reply. Apparently before these houses were built the land was just clay boggy type soil (if the makes sense). Two of my neighbours have gravelled their whole garden and don't have an issue. One has grass and apparently this gets waterlogged too.
What other information would help? Would digging down further help and filling with more gravel?
I must admit I'm out of my depth with all of this.

Ferdinand2000 · September 2020

juliechandlerhome said:
I must admit I'm out of my depth with all of this.

But your sense of humour - unintended or otherwise - is still intact

.

juliechandlerhome · September 2020

Thankfully it's not that deep.....yet.
My emojis as well as uploading a picture doesn't appear to be working either. It's just not my day sadly.

Fairygirl · September 2020

If the photos are too big they won't load @juliechandlerhome . It's best to resize them to below 1MB, despite the site saying otherwise

I think you may be better creating raised beds if the problem is going to be too much for you to tackle easily. It doesn't sound that it's going to be straightforward, or cheap.

Liriodendron · September 2020

Raised beds could well end up cheaper than extensive drainage works. Daughter in Galway has given up with her back garden - new build, clay soil compacted by construction vehicles, bottom of a slope - and is installing raised beds, eventually all round the edge (as she gets spare money to do it). They got some great vegetables this year from the first 2 beds.

Fairygirl · September 2020

I would agree @Liriodendron. It doesn't have to be hideously expensive either. Mine certainly weren't, and they aren't difficult to do yourself if you have basic skills.

Even if you need 'a man in' it would still be cheaper. It does sound like there's a high water table in the area though, so it would involve a lot of expensive groundworks.

Garden flooding

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