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Posted: Wed Nov 11, 2009 7:41 pm
by Ramsey
Hi,
I am attempting to properly drain a circular flower bed (diameter 4.5 metres) which is situated in the middle of a gravel driveway. At the moment, the flower bed (which had been dug out to 50cm deep about a year ago) is full of water up to the top, and has been for months. The water hardly drains at all - we are situated in an area with very heavy clay soil.
My plan is to dig down a couple of metres and fill with reject stone. I will wrap the reject stone in terram, and have 50 cm of top soil on top. I also plan to dig a trench across the drive in order to drain some of the water to a low part of the garden. I will use some perforated land drain wrapped in membrane at about 50 cm depth just above the reject stone, and this will be connected to solid pipe buried in the trench and drain to the low ground.
Does this plan sound OK, or is it unlikely to work. If anyone can give me any advice or suggestions, it will be gratefully received.
Thanks,
Rams
Posted: Wed Nov 11, 2009 9:37 pm
by cookiewales
digging down will only make a swimming.pool your idea of going across the drive is the way to go - are there any road gulleys.you could link into. pictures would help you would only need a french drain around the inside of flower bed.no need to dig it all up french drain could be formed with gravel and land drain.hope this helps cheers cookie 
Posted: Thu Nov 12, 2009 1:25 pm
by Ramsey
Thanks for the advice Cookie. Above is a picture of the flower bed that more resembles a pond. I thought that by putting some reject stone at the bottom, it would allow for the soil at the top to at least drain a bit. I know that it would not function as a soakaway due to the heavy clay soil, hence the land drain and pipe to lower ground. Rams
Posted: Thu Nov 12, 2009 1:56 pm
by cookiewales
that looks like a pond as it is just check if you have a membrame stoping water draining.you could take out a line of sets put in 75 mm land drain underneath lay sets back on top then plant with plants that like wet conditions good luck rams ps win the lottery and i will come and lay setts and make feature of wet bit :p cheers cookie
Posted: Thu Nov 12, 2009 2:03 pm
by cookiewales
ps looking at the pic again you have a low spot on single row of sets gowing away from pond good spot to drain away land drain around inside of sets will take the water away thats coming of gravel
Posted: Fri Nov 13, 2009 11:56 am
by Tony McC
Digging down and creating a sort-of soakaway using 'reject stone' will do buggerall. It will just become a sump for additional water.
You need an outfall for the water. This may be a soakaway located elsewhere which could be connected by a pipe, it may be a ditch or stream, or you may have to construct a sand drain through the clay to a permeable sub-layer, something that is not always possible or practical, depending on the site. If you really have no other option, you could connect to the existing drainage system, but you would probably require PP under the Front Garden Driveway regulations.
Posted: Fri Nov 13, 2009 12:14 pm
by Ramsey
Thanks Tony.
So would it be ok just to drain it as though I were draining a lawn with perforated land drain, connected to polypipe and draining to low ground?. Laid out as below:
How deep should I aim to put the land drain? And would it be ok to have it just above thick clay? As the pictures show, there is a real problem with drainage, and the water will just sit there all year.
Thanks
Posted: Fri Nov 13, 2009 12:19 pm
by Tony McC
You wouldn't need herringbone within the circle, but, if you;re over clay, you may need herringbone at the other end, as it's to act more as a leach field than a collector.
I'd use solid pipe within the circle, with a filter inlet, and the same under the driveway. Embed in concrete if you use uPVC otherwise it *will* deform. You need to be around 450-600mm deep as a minimum, which then dictates the depth beneath the lawn, where you can/should switch from solid to perforated pipe. You need to ensure it is falling *away* from the circle area. The bigger the leach field, the more effective it will be.
Posted: Sat Dec 19, 2009 10:54 pm
by Ramsey
Thanks for all the replies.
Sorry to reignite this question, but I am planning to finally do this is a couple of weeks and wondered if I could just check what I'm planning to do is right.
So... I am planning to drain the flowerbed as shown in diagram below:
The picture shows central waterlogged flower bed with new drainage to a ditch.
As the flower bed is already dug out, it would be difficult to construct trenches to put the perforated pipe in surrounded by gravel and wrapped in geotextile. Would it be OK just to do a whole layer of gravel with the pipes in, then a covering of terram, and then topsoil on top. As below:
Thanks again for advice so far.
R
Posted: Sat Dec 19, 2009 11:13 pm
by mickg
yeah that looks fine
Posted: Sun Dec 20, 2009 12:57 am
by lutonlagerlout
looks the correct approach from here
LLL
Posted: Sun Dec 20, 2009 6:00 am
by seanandruby
If you were to dig a hole 2 metres deep you would have to allow for battering which make the hole at least 3 metres wide. a filter is the way to go.