Heavy clay drainage help

@Scrungee From what I know in the trench went membrane, gravel, plastic pipe, gravel on top, the the membrane wrapped round, then just backfilled with what had come out the trenches. Is that what you mean?

Do you have a reccomendation on what I can ask the landscaper to do to make it better please? Thank you, it's much appreciated

 

The top soil needs to be improved. Around here the local gravel quarries give away unscreened sand and top soil - may be worth you looking. Get yourself (or hire) a cheap cement mixer, lift your clay soil carefully and mix it in with the top soil and sand. Aim to raise the whole area at least 10cm if you can.

 

I think you need to challenge them as to why their £1,000 'solution' has made no difference

 

Personally, I'd start by phoning thecontractor that did the work. I'd make it a polite and friendly chat. Ie not initially a complaint. I'd simply start by reminding him who you are and what work he did, and politely tell him unfortunately what he did has made no difference at all. Tell him, in polite conversational tones, that the garden is still waterlogged. Then listen to his response and take it from there.

It is my experience that it is rarely necessary to complain. Most people are keen to resolve problems with their work, and the more civil the customer is, the more inclined people are to help. Especially if their reputation is on the line.

I wouldn't ask him to sort the soil out. That's beyond the scope of the original job, so it would be reasonable for him to charge for it. I think I'd ask if he used gravel to surround the pipe.

Fixing the soil yourself is simple, but you will get some muscles there's a lot of digging.

I think the area of garden I did with mushroom compost was about 15metres by 15 metres. I used 60 sacks, which if I remember right cost me about £120. That was enough in my case but some patches in my case weren't too bad. Remember that mushroom compost is not as heavy as top soil, so while 2 tonnes is not that much top soil, it's a huge amount of mushroom compost. If you dig too much in, you'll create a new problem. The ground will be too soft all the time, and any lawn you put over it will just end up lumpy as some patches sink faster than others. If you enrich it, you should be aiming for soil that is very dark in colour, and is crumbly but not sticky when moist. About 50/50 by volume of clay and mushroom compost should be about right.

 

They will be working but slowly, but with clay it take longer for the water to get to the drains, the water as to find it's way through the clay, but also the top surface have been dug and leveled and worked so that makes things worst etc so it will take time for the water to drain through and every time it rains it tops the water level back up, think of the soil as a sponge, a week or two of no rain and you should see a differant, and then in the spring start on the sorting out the surface, as above with digging in compost/topsoil/girt/sand etc

 

Thank you so much for all the help, you're all lovely I'm going to phone tomorrow and nicely ask if he would mind coming and having a look when he has a spare moment because it doesn't seem to be working and the standing water is just getting worse, and like you say @clueless1 hopefully he will offer some sort of solution himself.

I'm so relieved to hear that fixing the soil is possible and relatively simple. Realistically would you think it will be possible to get decent drainage and a lawn by summer?

 

That depends on several factors. First of all, I think there's little anyone can do until it dries a bit. Fingers crossed for some dry weather.

It also depends on what, if anything, the drains man does. You can't really start anything until you know if he is going to dig it all up again.

And finally it depends how quickly you can work.

The time to sow grass seed is around April. You would need all the prep work done by then, and even then, you wouldn't have a well established lawn by summer.

Sorry, I think realistically, there is not much chance of a decent lawnby summer. Potentially you could buy some time by using turf,but I personally wouldn't. It's much more expensive and doesn't really save much time, as you still have to do the prep work, and thenyou have to look after it more while it settles in.

However, I guess the goal is to get it at least so the kids can play out. If it was mine, I'd do all the prep, then cover the lot with a couple of tonnes of sand. Then at least you have a useable space. Then I'd go for the autumn seed sowing, to have a lawn by next summer. Not ideal, but taking the time now will pay off. A rush job now will just create more work.

 

Ahhh so disappointing but it's ok, I had figured as much. I already have grass seed ready and waiting, so I definitely didn't want to pay for turf (I also really wanted to satisfaction of growing it myself if I'm honest.)

You are spot on that I'm desperate to have a usable space, but I do want it done right. Annoying as it is to still be at step 1 I will be far more upset to rush forward and still have bad drainage that kills my lawn, or plants, and limits our ability to use the garden after rain etc. it's most important to me that's it's done properly with a solid foundation to build from, if that makes sense.

sorry if this is a stupid question, but what does adding a couple of tons of sand do, is it to prevent weed growth?

Prep wise does this sound about right -

1) address the land drains - depends on what the contractor suggests but I'm thinking check they aren't blocked and potentially get them backfilled with gravel rather than just clay subsoil.
2) when the ground is drier rotovate the top foot or so of clay so it's a decent consistency and there are no huge lumps, removing rubble etc as I go
3) add a very generous amount of mushroom compost and throughly dig in
4) repeat, adding more mushroom compost until the soil is the right consistency (being sure to not add too much)
5) rake level and add a couple of tons of sand to the top (am I best buying horticultural grit or just regular sharp sand?)
6) wait until autumn and sow the grass seed

And honestly, thank you so much @clueless1 for being so kind and taking the time to give me such detailed advice, it's really wonderful of you.

 

I'm not sure I'd bother rotavating. I'd just dig the mushroom compost in, level off, add sand, level again.

The sand will improve drainage, and help you to get a level surface (sand is easy to get even than compost). But also, it will simply hide the mud. It means it will be like walking on a beach as opposed to a muddy field.

As for the type of sand, just ask your local builders merchant to mix you some sand and grit. Cheaper than anything with 'horticultural' in the name, and does the same job. Just don't use building sand, as its harder to get nice and smooth I find, although the grass doesn't seem to care.

Contrary to popular belief, grass seed will germinate and grow in sand, and in any case were only talking half inch deep so the roots will find the soil under the sand. But it means you can use it before the grass is sown. It'll be your ownprivate temporary beach, until you can get the seeds down in autumn.

 

Mix all three together if you are going to seed it. Sand dries out too quick and dry seedlings die.

 

Well I phoned and the voicemail says he's on holiday for a week, just my luck! So far the standing water has gone nowhere but Sod's law I bet it will have completely dried out by the time I get holds him so I've no physical evidence of the problem!

Thank you for the great advice @shiney he seemed like such a nice man so I'm hoping it's an easy situation.

As an aside - from a drainage perspective would it be a good idea to do something like in this photo, raising the garden/lawn level slightly?

 

Take a photo of it with tomorrows newspaper in the shot. The Bowie headlines will be proof enough.

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To be fair the drainage underneath sounds adequate but the water just cannot get through what was placed over it.