drainage issue

ohlordy

Hi

I have a small garden, mostly in lawn, in a new housing development. It is surrounded on 3 sides by concrete pillar with wooden insert fences, with the base of these being concrete to a depth of up to 3ft.
When I moved in 3 years ago, the original lawn as as seeded by the developer was prone to water logging (very squelch underfoot)and puddles of standing water would appear after anything but the lightest rain. Some of these puddles were in places where I had caused soil compaction while putting in a hard core base for a shed as soon as I moved in.
The following summer I dug out the whole lawn, rotovated to a depth of maybe 18 inches, put in french drains to take water bottom corner of garden, and laid a new roll out lawn.
The drains work, the lawn at house end is now never waterlogged. The same cannot be said for the far end. The last 3 days have been characterised by heavy showers (I'm in dublin) and the bottom half of the garden is very waterlogged and squelch.
Obviously the water that falls cannot escape the garden, the concrete fence base is a barrier, the compacted earth under the shed is a barrier, and there is clearly a barrier below the 18 inch depth to which the whole lot was rotovated.
I have dug a hole in the corner where water is supposed to drain towards, and about 2 foot down I come to a fairly impenetrable (with the hand tools available to me, and the access in a narrow hole) layer of what seems to be compressed hardcore. This is likely foundation for the fence base I assume.
My aim, and I admit to only a cursory knowledge of what I'm doing, is to try break through the barrier that I believe is preventing the water soaking further down into the earth. I had hoped that I might be able to dig one hole deep enough at that spot in the garden, that would enable the water that arrives there via drainage to then seep further downwards. I clearly cannot achieve that in the spot I have chosen. Before I dig multiple holes elsewhere I need to know if doing so would work at all?
Evidently the ground a few feet below the lawn was compacted by heavy machinery during the time it was a building site. Would I need to break through this compaction in numerous places to fix my drainage, or would one place suffice? Would I be better off hiring someone to dig or drill much deeper than I am likely to manage on my own? I'd really like to avoid having to dig up the whole lawn again!

iamtony

Fill the hole you dug with water to see if you actually have a problem. Id say your way over thinking this. There is a rule of thumb for how long it should take to drain. Maybe an hour or something look it up.
My grass is pretty waterlogged dispite having generally good drainage.

looksee

You have directed water from the rest of the garden into a contained sump - assuming what you are saying about the fencing having 3ft of concrete and hard core under it is accurate, it seems unlikely.

Are there other gardens on the other two sides of the fence? If there are then you will have to dispose of the water yourself and this could involve digging a decent sized soakaway, just a narrow hole isn't going to do anything.

If the fence foundation is not a solid barrier you could be collecting water from neighbouring gardens, that might be worth investigating.

ohlordy

looksee wrote: »

You have directed water from the rest of the garden into a contained sump - assuming what you are saying about the fencing having 3ft of concrete and hard core under it is accurate, it seems unlikely.

Are there other gardens on the other two sides of the fence? If there are then you will have to dispose of the water yourself and this could involve digging a decent sized soakaway, just a narrow hole isn't going to do anything.

If the fence foundation is not a solid barrier you could be collecting water from neighbouring gardens, that might be worth investigating.

Thanks for reply

The garden behind is lower than mine, I used a plumb line to measure and it is 3 ft lower, so where on my side of the garden the uppermost concrete panel below the wood is less than a foot above lawn level, there is another concrete panel or two below it again so as to hold my garden from falling into that garden. If I haven't described fence well, it is like in first picture on this webpage https://www.abwood.ie/product-category/fence-panels

I assume the hardcore that I have reached is only located immediately beside the fence, but I'm trying to ascertain the best option other than digging multiple holes as a ground investigation survey!

The corner of the garden I have located my sump in thus has this concrete barrier to one side, and the compacted ground beneath shed base on other. 1 tonne of hardcore was placed on top of the topsoil and compressed with a vibrating plate, I assume that this has caused the ground under the shed to now be fairly slow to allow water through. And the garden to side of shed is also lower than mine, though not as low as garden behind.

I'm of the opinion that a decent sized soakaway will work, ascertaining if others with more experience of this sort of thing agree is my aim here!

ohlordy

iamtony wrote: »

Fill the hole you dug with water to see if you actually have a problem. Id say your way over thinking this. There is a rule of thumb for how long it should take to drain. Maybe an hour or something look it up.
My grass is pretty waterlogged dispite having generally good drainage.

I've never previously lived in a house with a garden with this issue, puddles during torrential downpours yes but not months of waterlogged lawn. And the fact that one half of the garden is perfectly firm no matter the rain convinced me that it can all be like that, just have to find the right solution

ohlordy

ohlordy wrote: »

I've never previously lived in a house with a garden with this issue, puddles during torrential downpours yes but not months of waterlogged lawn. And the fact that one half of the garden is perfectly firm no matter the rain convinced me that it can all be like that, just have to find the right solution

Following consultation I seem to be about to hand a guy a shade under 3k to remove a foot of topsoil, provide a layer of stones and a soakaway, replace with better quality topsoil and reseed lawn. For approx 100sqm of garden this doesn't seem a bad price to me.
Anyone think I'm wrong?
Thanks

Seve OB

How did you get on?

ohlordy

Won't really know for sure until mid winter, summer with low rainfall had never been problem