[ritamax]

Do you have any idea, how to improve drainage in a water-logged corner of a path and patio? There is a very slight slope there and in case of a heavy rain and deep watering from a hose the corner gets water-logged for a day or so. The soil is very claye. Should I just dig it out and put sand in, would it be enough?

[MikeHardman]

I'm not sure what the patio/path is made of, but I'll assume it is solid, perhaps steel-reinforced.

Some suggestions:

1. After the rain/hosing has stopped, brush the water away with a broom or pool/window-cleaning squeegee.

2. Cut a groove with an angle grinder. Use a board for guidance; it'll look rubbish unless it is straight and clean. The groove will need to be kept clean, of course. If you have the space to wield the angle grinder, consider putting that groove right at the edge. There it will be less obvious, and could lead the water to the soil underneath - so it might drain downwards a little (depending on your clay), as well as sideways.

3. Drill a drain hole through the path/patio near the lowest point, using a masonry tank cutter (as you'd use to put an vent tube through a kitchen/utility room wall for a tumble drier, though it could be smaller than that). ...And continue drilling downwards in the clay below (you can get extension pieces for these tank cutters). Insert a plastic pipe that you have drilled lots of small holes in, and perhaps fill it with gravel (depends on the particle size distribution of your clay). Fit a drain cap. That's a small soakaway. The first thing to do would be to find a drain cap, tube and cutter of compatible sizes.

4. Stand some pots in a line (or perhaps one long trough), with a strip of capillary matting underneath, leading to a lower point just past the path/patio. Asssuming the cap.mat remains hydrophillic, and assuming the deepest point of your puddle is only a few cm, the cap.mat should 'wick' the moisture away. Allow other drainage for the pots/trough as well.

5. Use a concrete floor grinder to wear away some of the patio/path. That wouldn't be feasible if the patio/path has a decorative top which would be worn through. In effect it would be a wider version of the groove in the 'angle grinder' suggestion.

6. Depending on access and on the scale of the patio/path, excavate a little under the high edge, and with the clay thoroughly wet (eg. in winter), put weight (eg. lots of concrete blocks) on the high side and be patient. If such patience is not available (!), and if you have access to a JCB, you can use the bucket to press down gently on the high edge (with old wooden boards between bucket and patio/path). The trick is to avoid the low side rising (cantilever effect) - so you need to press in the middle and ensure the boards spread the load well. Do not rush it else the patio/path may crack.

Let us know what you do and how well it works!

[ritamax]

Thanks a lot, Mike! I will find some english-speaking workers to do something from your list, I suppose the options drainage pipe and concrete blocks into the soil in well chosen places could do the thing. The covered patio (in Spanish called "naya") is part of the house, so it must have a solid foundation. The path is done in a very easy way with sand and stone between concrete edging, depth of the path being probably 50 cm). The soil in the corner is covered with geotextile and stone chippings, the next plants are some meters away, as plants die in this corner, indicating that the place is water-logged for longer and it is also shady (towards north with roof ending just over it, so in a rare case of heavy rain it pours probably from the roof directly here). Here is another photo, where the corner (marble chippings) is seen from further away, in this photo no water there.

[MikeHardman]

...Not solid - ah well that sounds a lot easier / more options.
For instance:
Assuming there is somewhere lower adjacent or nearby for the water to drain to, I would:
1. lift some of the gravel
2. cut a slit through the membrane (geotextile), leaving a slice in the soil below (you will need a very sharp knife/scissors, otherwise it will snag and pull if it is of the woven type)
3. peel back the membrane
4. use pegs or short rebar to mark the ends of the slice mark in the soil
5. dig a channel sloping away along the slice line to a lower area (obviously, position slice (step 2) bearing this in mind; leave the marker pegs in place else you'll lose the line)
6. lay-in a piece of guttering, its top to be a few cm below the top of the gravel at its shallowest point
7. backfill with soil tight around guttering up to the lip
8. lay the membrane back; it will lay in the gutter
9. cover-over with the original gravel; you will need some extra to make it level, use some large stones (eg.) to hold gravel in place at the 'downstream' end
10. consider the water exiting the gutter in storms - where it will go and if measures need to be taken to prevent gulleying.

[ritamax]

Thank you so much, Mike, really helpful! Your thorough instructions should be perhaps put into the section hard landscaping.
There is nowhere to lead the excess water except deeper into the soil, but actually with our low precipitation (2-3 heavy rains during the winter, often under 300mm a year), it shouldn't be a problem. The soil is very dry and compacted, one could mould pottery with it, that is why the water stays on the surface. The plants nearby are getting slowly established and the watering from the hose can be reduced. Could a drainage pipe filled with gravel be simply led from the surface into the earth?   

[MikeHardman]

Re 'Could a drainage pipe filled with gravel be simply led from the surface into the earth?'
Yes, but it is difficult to say how effective it might be. You would be creating a small soak away, and its small volume would limit its effectiveness, and it would rely on the water finding a way to dissipate into/through the soil - which obviously depends partly on the soil itself down there (who knows, maybe there is a ban of shingle?)

If the water cannot get away well enough, you stand a chance of making things worse - from the point of view of any nearby plants susceptible to waterlogging.

I wonder how the storm water drains across/from your garden. Presumably it finds a way, otherwise your original posting would be about your villa being surrounded by water at such times! If you can remember where it goes, maybe you can route your drainage the same way.

Do you have any gutters on the villa?
If so, where do the downpipes route the water to?
...and could you route the problem drainage there as well?
(I wont' suggest routing the drainage into your domestic soak-away; that would not be wise.)

Also, if the problem area is quite small, and the adjacent land does not provide a drainage route: could you re-make the area without drains, but just a few cm higher? (Depends on the height at which it would cause water to drain towards the villa; no point in moving the puddle nearer the villa.)

[ritamax]

No gutters, and no problem even with heavy rain except this one place. There was one incident with the irrigation, though. It was programmed wrongly (not by me!) and kept watering for some 6 hours a day. In a couple of days the side of the grounds towards the seaside was slightly under water, there is a cypress hedge and an edging of about 30 cm (which held the water) between our grounds and the neighbour's. On the opposite side of the garden there is a patio and a slope towards the street, the water runs away there.

[ritamax]

To inform you about the issue. We digged out a large amount of clay (a hole about 1m broad and 60cm deep) in that corner and filled it with the stone chippings. It helped a lot, even after a heavy rain fall there was no water logging anymore. The problem however is, that there is a double slope down to that corner. Guttering would not solve that.