Heavy clay drainage help

Yes that's it @JWK i did mean volume rather than mass! i need to phone the supplier back and check whether buying 7 tonnes would be 7 tonnes of volume or 7 tonnes of weight! My reasoning was that 7 tonnes of something relatively lightweight like the mushroom compost would be an insane amount and probably wouldn't even fit into the truck, so my guess is it was obviously 7 tonnes in volume.

Spot on @Scrungee thats the patio, it is just an ancient cracked poured concrete slab that needs completely redoing anyway, (it's on the list) so having extra drainage channels added to it that run straight into the sewer or similar (and using something permeable like sandstone pavers instead of poured concrete) I'm thinking would be a good solution to any resulting flooding? I do like the idea of having the entire garden level raised, a small retaining wall would be doable. the concrete fence gravel boards are a good 4-6inches above the current garden level anyway, and it's a 6 foot fence so I have some leeway. I calculated that it would need roughly 20 tonnes of topsoil just to raise 6 inches though, so no small amount!

 

@Smudgedhorizon as Scrungee said you want 8.4m3 which will probably be about 11 tonnes of mushroom compost.

 

No sadly that is the other joy my garden brings into my life - access is only through the garage, so everything has to be wheelbarrowed from the front garden/drive down the garage through regular sized doorway to reach the garden. Fun times!

I figured with whatever we end up getting it would be fastest to go to my nana's and swap the kids for their wheelbarrow so we have two wheelbarrows - I can stay at the front and shovel a barrow load while my husband wheels it and dumps it in the back, by the time he is back with an empty barrow I will have loaded a full on ready to instantly wheel back, that way someone is always wheeling and someone is always shovelling. Should be roughly twice as fast that way, but yes, lots of hard work! It would be easier to move house haha!

 

I still think multiple tonnes is far too much. The goal is not to replace topsoil with compost, which I believe would produce tragic results. You just need to add some to the clay to provide structure to the existing soil so it can breathe and drain.

@smudge, the tonne is not a measure of volume either, it's only a measure of weight. Weight and mass are the same thing on earth. Weight represents the effect of gravity on mass. If you had a 1kg bag of sugar, it has a weight of 1kg and a mass of 1kg. Put it in space in zero gravity, and it has a weight of 0kg but it's mass is still 1kg. Nothing to do with volume

Back to the original point though, if you enrich the top few inches, ie not replace but enrich by mixing incompost, then the surface will drain faster, and the worms wwill mix it further for you over time.

 

You folks are giving me quite an education. Over here it is impossible to equate volume with weight unless you know already know the weight of the specific substance. Length x width x height is all you have to know about anything, be it compost or concrete. A dump truck for instance holds about 10 cubic meters of any substance but a dump truck full of rocks weighs a tad more than a dump truck full of nice fluffy compost.

 

A ton of feathers weighs more an a ton of lead

 

The garden is giving me a ton of sh*t, I know that much!!
That was what I was getting at @chuck I was thinking 7 tonnes was the volume capacity of the vehicle and not the weight of the compost. I don't know!

My husband has seen an advert locally that says there is around 15 tonnes of "quality topsoil used for a successful vegetable allotment free for collection" - would it be a good idea to collect a few car fulls bagged up and keep to the side for after the drainage has been fixed and the clay has dried out, then mix compost with the clay we have and add more decent topsoil to raise the whole garden?or bad idea? This was the photo with the advert -



I appreciate that in time repeated application of compost etc will slowly improve the soil we already have, but I'm also desperate to have a usable space for the kids. I can keep all my plants potted indefinitely and work on the borders drainage and soil quality over as much time as necessary, but i need that non-waterlogged lawn! Not that I'm looking for a shortcut as such but anything that would help get there faster that might work, like raising the entire garden level, even if it means a lot more work short term.

 

I don't think I'd raise it much, if at all.

If you go for the topsoil, I'd use it to replace some of the existing soil rather than add to it. And I wouldn't do it a few bags at a time, but rather hire a pickup and get tonnes.

But, how do you know the topsoil on offer is any better than what you already have? Just because someone grew veg in it doesn't say much. They might have had a combination of better drainage and irrigation, to combat what might be heavy clay based topsoil like you already have. You could go and look. It should be rich, dark, crumbly and slightly gritty feel to it when you rub it between finger and thumb.

Clay is actually good as a base for soil. It just needs 'bulky organic matter' (this is what makes it dark). That's compost, leafmould etc in layman's terms.

It gets a bit scientific here I'm afraid. The only difference between clay, loam, sand and grit is the particle size. It's all rock, just ground/eroded to a different extent.

The larger the particles, the smaller the surface area, and the lower the water storing capacity.

Clay is good because it's large surface area makes it good at holding huge amounts of water. However, this very advantage is also it's disadvantage.

Water has funny properties. It is, at the molecular level, incredibly sticky (surface tension). Water in soil faces a battle between gravity that is trying to pull it down, and surface tension that makes it cling to the soil. I'm sand or grit, the particles are large and therefore the gaps between particles are large. So the weight of water between the gaps is too great for the surface tension to hold, so it drains freely. In clay the opposite happens. The gaps between particles are tiny, so there is enough surface area to create enough surface tension to hold the water in place, so it doesn't drain.

If you're still with me, you'll see why clay plus compost is brilliant. Mixing compost in effectively holds clay particles apart from each other, meaning that the gaps between clay particles are big enough to allow gravity to win the fight over surface tension, enabling it to drain, while still clinging to enough water to keep the soil eco system alive and well. Adding compost is not meant to replace or botch inferior soil. It revitalises good soil. If you mix one bucket of compost to one bucket of clay, that would really be too much compost for a lawn (too soft), but such a 50/50 mix in the top few inches wouldn't stay that way. It would just kick start the soil eco system, and then all the worms and bugs would chew it up and drag it about, further enriching the soil for you.

And once you get a lawn established, that too will contribute to the health of the soil. Grass sucks up a lot of water, and its roots dig tiny holes. Root dies off (natural part of life cycle), decomposes, leaving another drain hole. Meanwhile a new root is making a new tunnel, and so it goes on.

Top dressing with sand also helps prevent standing water in two ways. To a small extent, it's simply because sand drains well, but of course it has to drain somewhere, so the soil needs to be able to drain (see above ). Problem is, anything that hits the soil surface, be it your feet or simply rain drops, compacts the surface, forming what is termed a 'pan' (but I prefer the term 'crust'). This is usually just a few millimetres thick, but is enough to stop water draining through to the soil below. Top dressing with sand means that any weight on the lawn pushes the sharp sand particles into the crust of soil below, helping to break it up and keeping it free draining. It will still eventually crust up, but that's why we aerate the lawn every now and then too.

 

My first piece of advise, for what it's worth, is to make the area slope enough for the water to drain of naturally, either by adding or removing material. My second piece of advice is to be very leery of free topsoil, quality or not. Its free for a reason

 

As a brief update - finally got the contractor round on the 22nd January.
He tried to tell me that it was all ok, I just had to wait for it to dry out. I tried as politely as I could to say that the surface water hadn't dried in 7 weeks now, and there was never any water leaving the outflow, which wasn't what we expected from a £1,000 drainage system, and that when I'd been unable to contact him I'd had a drainage company do a site review and they had confirmed my suspicions that it isn't working. They told me it wasn't done correctly and would never work, and needed completely redoing, especially because things like the drain outflow had no trap so nothing to stop raw sewage or smells back flowing from the chamber into our garden!! so I was obviously pretty distraught.

He never once apologised and wasn't particularly nice about it. He told me to get back to him once I had a copy of the report I got. I phoned him to let him know I had the report on the 24th, and left a message asking him to contact me but never heard from him. Finally emailed him the report with a letter on the 5th Feb, and posted a hard copy to him, just explaining that as we discussed the drains were still not working and the garden was a mess and an independent expert had performed a site review and told us it wasn't right and needed redoing (and that the mess he has made of our garden will actually be MORE expensive to fix than just installing drainage was in the first place) I couldn't get in touch with him but I was hoping to hear back within the week whether he wanted to a) remove and redo the drainage system properly, b) pay for another contractor to remove and redo the drains if he had prior commitments, c) refund us, as we do not have the working drainage system we paid for.

The week is up on Friday and so far no reply, either by telephone, email, post or in person.
The garden is still a swamp!

 

What's the UK version of small claims court?


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The small claims court.

You can also do it online via the government's moneyclaim website.