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Posted: Fri Mar 14, 2003 6:05 pm
by 70-1093879257
I have a problem typical to most new gardens - the lawn has been laid on 1" of topsoil, on top of a mix of clay subsoil and builder's rubble to a depth of at least 50 cm, and all thoroughly compacted. The 'lawn' is waterlogged, and largely mud, with grass hanging on in places. The ideal solution seems to be to skim off the top soil, and then remove all the subsoil & rubbish, decompact any lower layers, replace it with nice soil & returf. Not practical, however, as I couldn't even get to the bottom of the rubble layer, and it is a large area with no access to speak of. Is there any point in laying land drains (assuming we could get them in the rubble) or will the clay just hang on to the water, so only the strip directly above the drains would improve? Is there any other solution to the problem? It is not practical to remove all the lawn, and pave - too big and not appropriate. My only other idea was to turn it into a woodland - but it is too near the house, and the soil is horrible. Any ideas on how to improve things, with or without proper drainage, would be greatly appreciated.
Thanks
PS I would like to string up all builders who try to get away with this.

Posted: Mon Mar 17, 2003 9:38 pm
by 84-1093879891
Hi Fran,

sorry for the delayed response, but, as you might have seen elsewhere in The Brew Cabin, I've been away for a few days.

How old is your property? It's not uncommon for very new properties, ie, those under 2 years old, to have iffy drainage in their gardens due to all the disruption to the natural groundwater regime incurred during the building process. It always takes a season or more for the ground to adjust to the new situation, and you can end up putting in land drains that, in a couple of years time, will be parching the ground, not just draining it, so I usually advise that you wait at least one full season, ie, a full summer and winter, before deciding whether land drainage is the right option.

There's all sorts of reasons why rubble ends up buried beneath the gardens of newly-built homes, but it's becoming less common as the builders learn that quality sells, and that proper waste management is an essential requirement of running a good site. It's unlikely that rubble underlies all of your plot, but then, I could be wronmg, and, if it does, then you've been bloody unlucky.

Have you come up with a garden plan, or are you relying on 'mostly lawn'? Determining just which areas will be paved, where the shed will go, where you want flower beds or a pond etc, will all help determine which is the best method to drain your plot. It may be that additional drainage installed to drain a patio will help drain the adjacent lawn at the same time, and eliminate the need for a separate land drain system.

Land drainage work on all types of soils, as long as there is an outfall - it's a consequence of the law of gravity that ensures water will always run downhill, so, land drains may be the answer, but you've other questions to address first. :)