garden drainage 2015

[Stephen]

Hello,

I am reposting this with a different subject because my original post was hidden amongst a thread from 2004. I worry if I couldn't see it, perhaps no-one else could either (assuming you sort posts by date like I do). Thanks to Malcolm who did spot and reply to my other post.

My garden consists of a patio then a lawn, which is about 2' higher than the patio. At the other end of the lawn is a block paved driveway, on which we park the car; unfortunately the driveway slopes towards the garden. In the heavy rain we have had lately, the lawn has become very boggy and we have to walk from the car to the house through it.

A job that needs doing is to lay a path, so we would avoid walking on the boggy lawn.

I am also thinking of laying a strip of channel drain, something like this:

across the bottom of the driveway. This would stop water rolling down the drive and onto the garden and I hope it would make a big difference.

The question is: how to connect the channel to the drains? If the drain needs to be 1'under the patio, do I dig a channel 3' deep along the lawn and lay 110mm pipe into this (at a suitable gradient)?

That seems like a lot of digging! Could I dig a shallower trench down the lawn, perhaps 1' deep, and then have a drop at the patio end? I wonder if I might need a rodding point at the drop?

can I refill the trench with the soil I have removed, or would I be best to use sand around the pipe?

I suppose whilst I have the trench I could include some empty 40mm pipe to use in the future for wiring or water etc.

My neighbour says that the previous owner buried some perforated drain pipe somewhere within the lawn but it doesn't go anywhere.

I presume it was something like this:

Would it be worth while to use some of that as well?

Thanks, Stephen.

[newshound]

Depending on the area of your driveway, you probably don't need 110 mm to clear rainwater. I actually drain rainwater from ~ 50 sq metres of patio through 40 mm waste pipe. Land drain is good stuff but it needs to go either into a proper drain or a soakaway.

[Michael Chare]

Another way to make it easier to walk on the grass is to use something like this:

There are many similar products, and I am thinking of buying one of them to make it easier to park a car on an area of grass.

[Dave Liquorice]

Stopping the water from the drive getting onto the garden/lawn ought to make a bit of dfference but the lawn will still have had the inch of rain or WHY on it.

Could you continue the run channel drain down the side of the lawn/newpath to a gully that connects into the drain(*). Easy to clear of leaves/blockage, just lift the cover and give it a brush.

(*) Always assuming you are permitted to put surface water into the foul drain.

[harry]

Drains are the size they are to accommodate silt. leaves and cloudburst situations. So 110 mm is normal.

You shouldn't connect surface water drains to foul drains. You should find somewhere to dump the water. Not onto a neighbours land, this is illegal

There needs to be something to intercept silt & leaves. There's usually some sort of gadget available with the drain. Either a sump or catchment box.

You should use pea gravel around drains as it doesn't settle.

That too should be surrounded with pea gravel ideally wrapped in filtration cloth.

Up to you. A lot depends on the nature of the ground and the layout (ie how easy it is to conduct the water to a discharge point. The other option is to construct a soakaway. The size of this depends on the nature of the subsoil.

This problem is becoming worse as houses are built in places not very suitable more and more these days.

You might also consider a "French drain" ie a trench with a perforated pipe in the bottom, filled to the top with gravel.

[Tim Watts]

The usual is to back fill with 10mm shingle - it allows the pipe to move, or rather, the pipe to stay put while the ground around moves.

[Stephen]

Thanks,. I thought I would just do the bit across the driveway first and see what difference that makes, and then add land drain later if necessary.

[Stephen]

Yes, I was wondering how much is from the water from the driveway and how much is from water on the lawn itself. I guess the only way to find out is to put the drain across the drive and see what happens.

What does WHY stand for? I couldn't work that one out.

I was thinking of going to the same drain as the down pipes from the gutter. I suppose running the channel down the lawn might save all that digging but OTOH there would be the expense of extra channel and it might look a bit odd.

Thanks, Stephen.

[Stephen]

What depth of shingle should there be below, to the sides and above the pipe?

Thanks, Stephen.

[Tim Watts]

Few inches generally, or more.

You line the bottom of the trench with 2-3" and lay the pipe in. Usually the trench is a bit wider than the pipe. Now you fill with shingle until the pipe has about 2" of cover.

I forgot to mention, the other thing is does is to stop large sharp stones getting wedged up against the pipe which may damage it later under pressure from above.

[Stephen]

Thank you. Just getting an estimate of how many bags I would need delivered when the time comes!

[Stephen]

Even better!

[Johnny B Good]

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What Have You

[Phil Addison]

Before you go any furthe do have a look at Tony McCormack's Paving Expert site. It tells all you all there is to know about drainage and path laying and a hell of a lot more.

- they really are, and written in clear language.