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Dealing with garden drainage--clay soil.

DesthemoanerDesthemoaner FlintshirePosts: 182

I've noticed a problem with garden drainage during the winter, with various pools of standing water forming during heavy rain and thawing snow. During my internet forays I've come across the option of using rainwater crates instead of simply digging a hole, lining it and filling it with stones to form a soakaway. Has anyone else used rainwater crates, and if so, how effective are they?



  • DesthemoanerDesthemoaner FlintshirePosts: 182

    I've done some research since posting the above, and its clear that particularly with heavy clay soil, I need to dig a trial pit to make sure the ground is porous enough and the water table low enough to make a soakaway practical. I'll be doing that and if I get a positive result, pressing on with purchasing the rainwater crate.  Another factor with this is that any soakaway needs to be at least 5m away from the foundations of nearby buildings.

  • I am struggling with sitting water and clay soil although it is well within 5m of the foundations of a house so was watching your thread with interest. Alas it seems this will not be an option for me.

  • I would proceed with caution. I moved to a garden on very deep layer of very  heavy clay soil. I discovered this only after almost drowning a fruit tree planted in our first year here. I dug a number of smallish soakaways but found that the ground flooded so much that they merely formed reservoirs of groundwater that eventually backed up and flooded the areas cultivated nearby! My situation was such that I coulld not drain the garden towards land drains or drain away to surrounding areas so have settled on raised beds as my only solution. I do incorporate as much plant material and sharp sand as is practicable but without the raised beds found this was not sufficient to grow fruit and vegetables successfully.

  • DesthemoanerDesthemoaner FlintshirePosts: 182

    What I neglected to mention, and failed to consider when checking my water table level is that we're on a hillside, which would seem to dictate that any standing water will eventually run away. However, I've dug my trial pit, though only to the depth of the crate which I intend to purchase--just over 450mm--and this morning its as dry as the proverbial bone.

    If this works, I may buy a larger crate and some perforated pipes to connect to it, then position it under our patio. The patio is raised to a higher level than the rest of the garden, and it became very squidgy underfoot during heavy winter rains and thawing snow; so it seems to make sense to direct any water sitting under the patio away more quickly than Nature is currently taking it. However...Frensclan, thanks for the warning. I'm starting small with the teeniest soakaway kit that this particular manufacturer supplies. Only if it's successful and solves more problems than it creates will I consider the larger option. In any case, the effort taken to dig a pit about six times the size of the one I dug yesterday isn't something I'd look forward to!

  • I live on the top  of a hill of clay, and the problem with  standing water is bad here. When we moved here we hired a borer and drilled down holes 20ft deep all over the back garden and filled them with stones. Sadly we never came to the bottom of the clay and were just lifting out slices of stuff perfect for making pottery! An old gent who had lived in the village all his life told us that the whole hill was a lump of London Clay and we would never get to the bottom of it. How right he was as 45 years on and we still get flooded every winter. The only help we found was to plant a twisted willow tree at the worst part. This must suck up gallons, as overnight that side of the garden becomes flood free after rain. We even dug a large pond which kept it's level all through the summers despite not having a liner at all . We had a frame over it when our kids were small but filled that in when the grandchildren started arriving.

    Hope your clay is not as deep as ours. Good Luck!

  • Hope this is not a repeat as lost my first attempt!!

    Your tale sounds very familiar. I tried sumps and land drains but when it rains ; and believe me it really rains up here in Cumbria, they just backed up and drowned my fruit trees. ( have moved them and some have recovered thankfully) So as I said above I have resorted to raised beds for veg and for the rest relied on trial and error. I find hawthorn is a pretty good tree and is rowan, blackcurrant bushes don't mind having soggy feet and  much else I have planted as a bog garden.

    The thing I most notice however is that in the 4yrs I have gardened here I have spotted not a worm!!! and I have dug all of the garden more than once. Last year I bought a job lot to release in my raised beds to help with incorporation of compost and mulch ; and have I seen any of them since? not a one. I am assuming this is a result of the great depth of clay and the height of the water table.

  • You need to look at the depth of the clay, foundations and drains when you start draining land.
  • DesthemoanerDesthemoaner FlintshirePosts: 182


    It seems that dealing with a waterlogged clay garden is not going to be the straightforward issue that I thought it might be! One side of my garden, the bit with the clay bank mentioned in another thread is pretty steep, and drains very quickly into a gully which has been cut alongside the concrete pathway around the house. However, the path at the top  of the slope beneath the clay bank was very muddy this winter. I intend to lay flagstones to try to make it passable all year round, but reading some of these comments I'm wondering whether the flags will sink at the first sign of rain!

    Thank you once more for your comments. I'll report back once I know whether my rainwater crate is having the desired effect.

  • Flags will sink into the clay if there isn't a foundation.

    It would better to work with the clay rather than against it.
  • DesthemoanerDesthemoaner FlintshirePosts: 182

    Yes, I'm beginning to understand what you mean by that last comment. Clay soil is a new phenomenon for me, apart from the clay garden we had when were were kids, and which provided an inexhaustible and free supply of alternative Plasticine.

    I sank a rainwater crate in one particularly waterlogged spot yesterday: it took a fair amount of effort, at 60 years of age, to excavate a hole to fit the crate into the ground and then shift the spoil to another part of the garden. There was a heavy hailstorm here in Flintshire last night, and I woke up to find the usual pool of water sitting right on top of the place where I had put the crate. Maybe it'll drain away later, or maybe I need a Plan C.

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