Driveway surface water - French drain under driveway

[Colin James]

I have had a very long running dispute with the joint owner of my driveway.
The matter was referred to a "Man of Skill", who has recommended taking the whole driveway up and relaying, and he has given a specification for that. He has also said there should be an arrangement for dealing with surface water. There is no specific arrangement at present, the driveway is so broken up the water is finding its own nature route.
Can a French drain or similar be put under the driveway, so that the water is dealt with entirely within the boundaries of the driveway? If not under can it run immediately alongside the driveway? (I would keep the original total width, just reduce the running area and the drain would be on the original edge). There is no other drainage in the immediate area.
I am looking to deal with a driveway area of about 140 m2 along a 19m long edge. I am west of Glasgow and it can rain here occasionally!

Regards,
Colin.

[Carberry]

Sounds like you want Permeable paving. Make sure you get someone who knows what they're doing though, most in Scotland don't lay it / don't know how to lay it because there is no requirement for it like there is in England.

[Colin James]

Yes, I have looked at this, and if the driveway was entirely mine, I would look at it closer.
But, it the driveway is jointly owned and the specification is a traditional style (225mm compacted Type 1 and 70mm tarmacadam). It has taken several years of lawyers letters to get an agreement on this , without me now trying for something not specifically mentioned in the specfication.
From the Main site, I got the impression that the French drain could be put under the driveway but maybe it wasn't the best way.

Regards,
Colin.

[EngineerUK]

Permeable paving is good for a reasonable period of time but tends to choke eventually.
I may be picking you up wrong but by surface water do you mean ponding on the tarmac/rising ground water?
if you mean ponding on the tarmac then it requires the installation of a gully or similar drainage point installed at the point of ponding or resurfacing.
If you mean ponding alongside the driveway then a french drain could be installed along the edge?

Or maybe I'm just an idiot who has picked you up wrong all together :0

[Colin James]

You are on this Website, therefore you cannot be an idiot!

The driveway is being totally replaced. The top area, approx. 120 m2 cannot drain anywhere, it is effectively enclosed. The specification calls for the surface water to be dealt with, but doesn't detail how. Because of the very poor condition of the current surface (possibly tarmac 50 years +) the water finds its own way vertically through the surface and ponds at one end and slowly sinks away. When the new surface is put in, the water will hang around as it cannot perculate through the new surface. I thought of catching it at the area where it naturally ponds and using a French Drain as a soak away to get rid of it. But I think the French drain needs a minimum length to act as a soak away. Can this "length" be under the driveway itself. From what one of the surveyors who examined the driveway said, this might have been the original construction, but I got the impression that it was nolonger considered the best practise. As the specification has been arrived at via lawyers, I want to stick to it to avoid any other problems. So is it practical to have a French drain under the driveway? If it is it would need to be at a good depth to avoid undermining the Type 1. Or is this style of construction not considered these days?

Regards,
Colin.

[EngineerUK]

Having a French drain running under tarmac will pose no real threat to the tarmac itself providing there is a capping of, as you say, 250mm of compacted type 1. However water will be hard pressed to percolate the type 1 and tarmac area in any case.
In terms of storm water the tar should be laid to falls to allow adequate run off. If there is nowhere for the water to run off to then there is a requirement for either a gully or channel drain to be installed and connected to a storm line in the area. You could also connect to a foul line providing you use a trapped manhole or channel drain.
If however there are no nearby connections then yes you could install a soakaway if the ground is reasonably permeable. If water tends to hold in the ground then you would need to increase the length of the trench. However if the ground drains reasonably well then a 1.5m³ storage soakaway would suffice.

[Colin James]

Thank you.
1.5m3 shouldn't be too much of a problem with the side length I have to use.
The area is immediately outside the front door, so I want to make sure the water clears quickly.
To get to an existing drain would require a lot of work and involve a second party, so using a soakaway at the area is preferrable.
The soil seems to be a sandy clay with large round pebbles. In the general garden area the water sinks/drains away very quickly. I will try a test pit when the old surface is lifted.

Regards,
Colin.

[local patios and driveway]

Run a tidy linear drain to collect all the water then run the water to a soakaway. Instant solution, simple to do, no making do, proper job bob

[Mikey_C]

a soakaway should really be 5m away from any building and 2.5m away from your boundary. so when you say outside the front door?

it might pay to have a good read of the suds page on this website.

[Colin James]

Thank you.
The distances from the house and boundary are not a problem. The property is a Victorian villa now split into flats.
The type of surface and dimensions are restricted by legal aggreements, not common sense. So the water has to be dealt with within the existing boundaries of the driveway. Putting a soakaway adjacent to the existing mutual driveway isn't desirable, because that belongs to one party, not mutual. Fortunately the existing driveway is quite wide, so it can afford to lose 1/2 metre off one side to act as a collector/drain.

Regards,
Colin.