readiescards

Clay sub soil drainage suggestions please

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This is a photo of my 'front lawn' as you can see it has a lot of standing water and if you look in the background you can see standing water in the fields too.

When I walk on my lawn my wellies sink a good 4-5" inch into the top soil as it is sodden and little more than a brown sloopy soup with a crust on top.

The sub soil is clay that, I reckon, has been badly compressed by the build process.

 

The site has a distinct slope so I think some sub-surface drainage would help prevent this issue in the future.  However the only solution I know is to scrape off the top soil and run a mole plough through the sub soil to break it up and open up some drainage channels.  This would be quite tricky as it would need a big tractor to pull the mole plough and that would be tricky within the confines of the site.

 

Would like some advice on other drainage ideas, I'm reluctant to just accept that 3 months of the year the lawn will be underwater...

 

IMG_20180310_072437.jpg

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Posted (edited)

Following....I have a similar situation with clay.

Edited by lizzie

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10 minutes ago, readiescards said:

 This would be quite tricky as it would need a big tractor to pull the mole plough and that would be tricky within the confines of the site.

 

I have seen winch drawn mole ploughs used.

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21 minutes ago, lizzie said:

Following....I have a similar situation with clay.

 

Share your slop pics please!

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15 minutes ago, PeterStarck said:

I have seen winch drawn mole ploughs used.

 

Thinking about it so have I, using two massive stationary steam engines...not sure I have the room

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I have done a series of trenches before laid in a herringbone pattern 

the trenches have a perforated land drain pipe in them

the trenches are filled with gravel 

you can cover the top of the trenches with a geotextile material if you want to keep the top soil from migrating down into the gravel. 

 

This is all works better if you have a natural fall in the ground the way you want the water to go. 

 

Would only require a mini mini digger for a day or two. 

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5 minutes ago, Russell griffiths said:

I have done a series of trenches before laid in a herringbone pattern 

the trenches have a perforated land drain pipe in them

the trenches are filled with gravel 

you can cover the top of the trenches with a geotextile material if you want to keep the top soil from migrating down into the gravel. 

 

This is all works better if you have a natural fall in the ground the way you want the water to go. 

 

Would only require a mini mini digger for a day or two. 

 

Doh should have thought of that, brilliant thanks

 

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14 minutes ago, readiescards said:

Share your slop pics please!

I cant get at the garden pics at mo, we are planning to get topsoil down shortly but as we found unconnected drainage pipes (from the en suite!) we are digging trenches again and that is delaying garden levels.

 

This is a pic of the access road (after many 100’s of  tons of stone down) the clay in the garden is worse as it has no stone in it. The other picture is the field in front of us and you can see it is waterlogged.

 

 

6DCB4D19-CBBB-4CA8-ADF0-C4F6E33545E9.thumb.jpeg.45690669f3c4784ab26f13120c0e6011.jpeg

 

 

867A7096-5E89-4561-99DC-6EE7C2BF3E29.jpeg

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as i understand it - if you are going to go for land drain/gravel you are better off not using a geotextile membrane in clay soils as the clay will in time block water travelling through the membrane. geotextile membrane works much better in sandy conditions where it won't clog up the membrane in the long term

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7 minutes ago, jfb said:

as i understand it - if you are going to go for land drain/gravel you are better off not using a geotextile membrane in clay soils as the clay will in time block water travelling through the membrane. geotextile membrane works much better in sandy conditions where it won't clog up the membrane in the long term

 I’ve always done clay soil, geo textile over the top of the gravel to prevent topsoil from migrating into the gravel

other soils, geo textile around pipe and gravel to keep trench free draining. 

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I think the issue here is not so much the soil type, but the water table is very high, much like we have here at times. I bet of you dug a hole just now it would fill with water almost up to ground level.

 

If you do create a drainage channel system it needs somewhere to drain to. Perhaps an open trench / ditch along the front of the plot?  (we have a burn through our garden so have somewhere for water to drain to)

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When you lay your main sewer connection to the road it's usually bedded in gravel. I'm sure it's against the rule but it would be tempting to lay some perforated pipe in the trench along side the sewer and turn the whole thing into a giant soakaway.

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1 hour ago, Temp said:

When you lay your main sewer connection to the road it's usually bedded in gravel. I'm sure it's against the rule but it would be tempting to lay some perforated pipe in the trench along side the sewer and turn the whole thing into a giant soakaway.

 

 

I did pretty much exactly this around the edge of our plot (also mainly clay).  I had to dig a utilities trench around two sides of the plot, to relocate the power and phone cables in ducts, but had these filled with type 3, with a thin layer of topsoil to hide it, so turning them into big French drains at the lowest point of the plot.  Works a treat and stops a big puddle that used to form  on the lane right by the point where our drive now joins it.  I'm sure it also helps our storm surge attenuation tank drain away, too, as there is only a relatively short distance between the permeable soil in one corner of that and the hidden French drain.

 

The only slight snag is that several locals have commented on how much drier the lane now is after heavy rain.....................

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43 minutes ago, JSHarris said:

The only slight snag

Why is that a snag - do the locals like paddling9_9

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Spent the morning cutting some channels in the top soil slop to help water drain away (plot on a slope so works well). 

As you can see where my welly has been the top soil is turning into solid mud.

I'm fairly sure it is not a water table issue as the plot is higher than the surrounding land.

 

If I can get the top soil drained and dry with some sub soil drainage, will a run over with a rotavator revive it?

IMG_20180310_105621.jpg

IMG_20180310_105915.jpg

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32 minutes ago, MikeSharp01 said:

Why is that a snag - do the locals like paddling9_9

 

No, it's just a bit of a giveaway that I've put a drain in that drains the lane to the stream alongside, albeit via a French drain.  That's something the EA specifically prohibit, and put a condition on our PP to prevent rain water etc running to the stream...................

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15 minutes ago, readiescards said:

Spent the morning cutting some channels in the top soil slop to help water drain away (plot on a slope so works well). 

As you can see where my welly has been the top soil is turning into solid mud.

I'm fairly sure it is not a water table issue as the plot is higher than the surrounding land.

 

If I can get the top soil drained and dry with some sub soil drainage, will a run over with a rotavator revive it?

IMG_20180310_105621.jpg

IMG_20180310_105915.jpg

 

 

That's just the clay working as an effective aquatard or water barrier.  It's very good at sealing, which is why the canal network is lined with puddled clay to keep the water in the canals, rather than let it soak away into the surrounding soil.

 

If your services trench is downhill from the plot then it would make an excellent soakaway, as long as  you can get the surface water to run into it.  We have several runs of perforated land drain, surrounded by, and covered by, permeable stone (type 3) that are very effective at draining pretty much all of our garden, and the area under the house.

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@readiescards, how much time do you have? 

 

We are on Glacial Till overlaid by Made Ground. We like you are also on slope.

31 minutes ago, readiescards said:

[...]

I'm fairly sure it is not a water table issue as the plot is higher than the surrounding land.

[...]

 

The first thing I did with the digger I bought was to dig a deep hole (as deep as the arm would reach), mark and cover the hole with railway sleepers. And left it for a year. Each month, I'd take a photo of the water level in the bottom.  

As @ProDave suggests above, that job established the winter and summer water table.  (For that year only: but it gave an indication of an average level at that location) We did the same at another location and the level was a little bit different, but not much.

 

That exercise provides us with fairly hard evidence of where to put in land drains: and where to duct the water. On the basis of those results we have a plan for  a 'wet area' for our GCNs. When that overflows, it'll trickle off into the surrounding fields.

 

 

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Posted (edited)

One of the benefits of living in the Dartmoor NP is the geology. Upper Devonian, slates and volcanics. About 250mm of top soil then what the locals call shillet, Its been raining for weeks, roads flooded but just no standing water on site.

What Russell has suggested is a good solution, my folks had problems with clay, dug trenches, gravel, perforated pipe and always water draining out.

 

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IMG_9967.jpg

Edited by JamesP
spellin
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5 hours ago, Russell griffiths said:

I have done a series of trenches before laid in a herringbone pattern 

the trenches have a perforated land drain pipe in them

the trenches are filled with gravel 

you can cover the top of the trenches with a geotextile material if you want to keep the top soil from migrating down into the gravel. 

 

This is all works better if you have a natural fall in the ground the way you want the water to go. 

 

Would only require a mini mini digger for a day or two. 

 

That is the classic field drain pattern used by farmers.

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Posted (edited)
On 3/10/2018 at 08:04, readiescards said:

 

Would like some advice on other drainage ideas, I'm reluctant to just accept that 3 months of the year the lawn will be underwater...

 

 

Looking at the distant hill topology we might end up as neighbours if the plot purchase goes through. My current garden in the flattest region of the Fens (next stop Holland) floods each winter after heavy rain and even under water it still looks green. That green stuff is quite resilient, do as the locals do and keep off it for 3 months unless you intend to host a Christmas croquet championship. :D

Edited by epsilonGreedy
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Subsoiling and moling  may be a solution for you here. If its easy access for a machine, get a contractor in.

 

For those that don't know what that lot means, have a read of this... Field Drainage

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