The Brew Cabin

Posted: **Sat Sep 04, 2004 1:08 pm**

My problem is this

I've laid a lovely snaking path down my garden almost in the form of an S.It is 720mm wide depth is a 60 mm paver and around 100mm of sand and crusher layer.The sides of the path are set in concrete the centre is laid on sand.(none of this could have been done without this website:-))

My garden is lower than the left hand side garden but higher than the right.Consequently water drains left to right.I have a high proportion of clay in the garden.

Now with the heavy rainfall we have had it has highlighted a minor flaw in my scheme!!!

Water draining form the left to right is blocked by the lower curve of my S shaped path and water congregates there it can take 12-24 hours to drain away.

This is going to be a shrubbed area so I can dig up and well mulch down that area but I wonder if this will work.

My amateur brain suggests that if I dig fairly deep to the right of the path and then maybe 18 inches below the left of the path could I sort of tunnel under the path ( I really want to avoid digging up the path etc) and lay a pipe so it slopes left to right.I know I should have laid drainage before laying the path Hindsight is a wonderful thing!!

If I pack the entrance and exit with aggregate and perforate the pipe will this give a route for any water that will tend to head for that area to escape.Is it worth it?

I've been around the hire shops this morning to see if there was some corkscrew sort of device that would allow me to make a circular tunnel under the path but no joy.

I supppose I could live with it and my heart isn't into digging up the path but it may have to be done.

Any help or suggestionjs would be appreciated.

thanks

Posted: **Sun Sep 05, 2004 3:26 pm**

First of all, I should point out that 100mm of sand (laying course) is excessive. The laying course material should never be more than 50mm in depth, when compacted.

Anyway, back to your drainage problem. Tunnelling beneath a path that's only 700mm or so wide sounds like a lot of hard work. It could be done - you could drive, say, a 40mm overflow pipe through the subgrade by using a wooden mallet or a maul, but for me, it would be much easier to take up a handful of blocks, drop the pipe in place, and then reinstate as required.

For such a small problem, rather than use 60mm or 80mm perforated pipe, I'd use a length of 40mm overflow pipe, and wrap the ends in a permeable membrane. There's less risk of problems in the longer term with a rigid (non-perforated) pipe, and as you're only spanning a metre of so, this would be the best option.

When it comes to the planter beds, make sure there's plenty of sand and or grit around the ends of the pipe, so that ater can get in and out with ease, and make sure the soil within the beds is sandy and well drained, and you should be fine.

Posted: **Mon Sep 06, 2004 9:55 am**

Tony McC wrote:First of all, I should point out that 100mm of sand (laying course) is excessive. The laying course material should never be more than 50mm in depth, when compacted.

Anyway, back to your drainage problem. Tunnelling beneath a path that's only 700mm or so wide sounds like a lot of hard work. It could be done - you could drive, say, a 40mm overflow pipe through the subgrade by using a wooden mallet or a maul, but for me, it would be much easier to take up a handful of blocks, drop the pipe in place, and then reinstate as required.

For such a small problem, rather than use 60mm or 80mm perforated pipe, I'd use a length of 40mm overflow pipe, and wrap the ends in a permeable membrane. There's less risk of problems in the longer term with a rigid (non-perforated) pipe, and as you're only spanning a metre of so, this would be the best option.

When it comes to the planter beds, make sure there's plenty of sand and or grit around the ends of the pipe, so that ater can get in and out with ease, and make sure the soil within the beds is sandy and well drained, and you should be fine.

Thanks for your reply Tony

You said
First of all, I should point out that 100mm of sand (laying course) is excessive. The laying course material should never be more than 50mm in depth, when compacted.[/quote]

I guess I didn't phrase my description it is a total of 100mm crusher and sand ie 50mm each layer.

So it looks like the best bet is to dig the path up.

My concern is that the sides are pavars set on there sides set in concrete.So I am going to have to break that mortar haunching in order to get the pipe through and this is not a precise science I guess.

I can see it cracking and weakening furthur down the line.

Then there is the problem of getting the pavars back to level.

Or am I worrying excessively?

I suppose I just don't like messing with my nice new path

Once again thanks for your reply

Posted: **Mon Sep 06, 2004 9:05 pm**

Reinstating is really very simple. Once the pipe is in place, you cover it with sand as a cushion, then build up your sub-base again, walloping it down with the head of a hammer or whatever you have to ensure it's firm and going nowhere.

The bit that seems to flummox people is the sand bedding - at what level should it be levelled off to accept the re-laid blocks?

Well: if you put in the sand, compact it down, then level it off with a float or a trowel so that, when a block is laid on the bed, it's roughly 7-9mm higher than the undisturbed blocks around, that should be about right. You need that bit of 'give' to allow the blocks to be compacted to refusal at the right level.

But don't worry - the beauty of block paving (and all other elemental pavings) is that, if you balls it up the first time, you can lift and start again without losing anything more than a bit of time.

The Brew Cabin

Can this be done? is it worth it?