Terry Pinnell wrote:

If the channel empties easily, then it may indeed be the channel (or its
bases - they are usually bedded onto a coarse concrete mix) that is
blocking the exit of water from the bedding layer of the blocks.

That sounds like an accurate diagnosis to me, thank you. It poses the
issue of what to do about it, of course! I was thinking of simply
lifting the damp bricks and hammering a long screwdriver or something
down to make holes in the membrane and also open up the hard-core a
bit. But we have a lot of clay here, so I'm not sure how effective
that would be. Hence the idea of trying to get the excess into the
shallow drain by drilling holes in the side. Although if there's a lot
of surrounding cement that might be difficult. And anyway the water is
presumably lying well below the level of such holes, which at most
would be about 3-5 cm below the top surface.

How about lifting one or two of the soaked blocks, and then excavating
the sand under it down to the Type 1 base. Then have a look and see if
water pools there (stick a board over it to stop rain falling directly
into the hole!)

If water is pooling in the space were the sand is, then you can see at
what level you would need to arrange a drain.

BTW, here's another photo (cropped from an original), apparently
showing the membrane between the sand and the hard-core.

http://i154.photobucket.com/albums/s...ksMembrane.jpg

Ah, yup, that looks like a sheet of visqueen DPM or something similar.
Completely the wrong thing to use. I would guess that your bedding layer
is totally full of water at the bottom of the slope.

You may find that puncturing the sheet allows enough to flow out of the
sodden area, but then again it might not. No harm in trying though.


(I also note that the edging course of charcoal blocks have not beed
bedded onto a concrete haunch and are just sat on sand. That means there
is no proper restraint at the edge and the whole edge could fall away.
Again have a look at the pavingexpert site for details of how the edge
should be done)


--
Cheers,

John.

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