Drainage Sump - positioning

50Twuncle

We are currently having our front garden paved over and due to the (approx) 5 degree slope of the garden - towards the house - have requested a drainage sump (filled with broken tiles etc) - to give somewhere for rain water to go - what I was wondering was where this sump should go ?
Obviously - a grid will need to be fitted at the lowest point - but that will be tight up against the house wall - and I do not want the sump in the same place - (up against the foundations)
The area that is being paved is about 4 metres by 3 metres

Also - the ground is clay - so how deep and what size should this sump be ?
Any advice welcome....

muckybutt

A soakaway is normally dug under the front lawn away from the house, the drain would be within a couple of feet from the house due to the slope, then connected to the soakaway with a drainage pipe.

anotherbaldrick

IT won't work if your soil is clay. In winter it will not drain and the surface water will lake up against the wall of the house. The only way if you do not have an outfall (ditch, stream , S.W. drain) to connect to is to use a permeable paving which can spread the perculation into the ground over the paved area. If you concentrate it into one end or corner you will need gumboots.

keystone

You have applied for your planning permission of course?

Cheers

50Twuncle

keystone wrote: »

You have applied for your planning permission of course?

Cheers

No - don't need it! !

rxbren

planning permisssion would be needed if impermeable paving and not using a soakaway anything under 5m2 doesnt need planning
you can go as big as you like with permeable paving
soakaway suitabillity all depends on the ground so trial hole neede and needs to be at least 5 meters from any buildings
also broken tiles not suitable for filling soakaway

50Twuncle

rxbren wrote: »

planning permisssion would be needed if impermeable paving and not using a soakaway anything under 5m2 doesnt need planning
you can go as big as you like with permeable paving
soakaway suitabillity all depends on the ground so trial hole neede and needs to be at least 5 meters from any buildings
also broken tiles not suitable for filling soakaway

From what I understand - You can go as big as you like if using a soakaway or permeable paving - but permeable paving is not all that it is cracked up to be - the holes quickly become blocked causing all sorts of potential flooding problems ??
So what should I expect the hole to be filled with - if not broken roof tiles ?

anotherbaldrick

No soakaway will work in clay no matter how big you make it. Try it for yourself, dig a small hole 9" deep and pour a bucket full of water in it.
Clay is used to waterproof the bottom and sides of lakes reservoirs and ponds , is more waterproof than concrete.
There are other ways of achieving permeable paving than using porous blocks, one good way is to leave 2" gaps between the pavings , bed the pavings on sharp sand and fill the wide gaps with pea shingle.

50Twuncle

anotherbaldrick wrote: »

No soakaway will work in clay no matter how big you make it. Try it for yourself, dig a small hole 9" deep and pour a bucket full of water in it.
Clay is used to waterproof the bottom and sides of lakes reservoirs and ponds , is more waterproof than concrete.
There are other ways of achieving permeable paving than using porous blocks, one good way is to leave 2" gaps between the pavings , bed the pavings on sharp sand and fill the wide gaps with pea shingle.

But the paving will not be stable on a slope without cement and proper basework. ... Will they ?

anotherbaldrick

A slope of 1:20 (5 deg) is nothing to worry about, that is only 100 mm across the width of your patio. If you make the bed 50 mm of sharp sand, tamped and levelled you could put a dab of mortar under the corners to stop any rocking that would be stable. Question though, is this ornamental or for parking a car on ?

50Twuncle

anotherbaldrick wrote: »

A slope of 1:20 (5 deg) is nothing to worry about, that is only 100 mm across the width of your patio. If you make the bed 50 mm of sharp sand, tamped and levelled you could put a dab of mortar under the corners to stop any rocking that would be stable. Question though, is this ornamental or for parking a car on ?

I guess that it is ornamental
and it is more like 20cm drop between the highest and lowest points - so perhaps 10 degrees - over the 3metres width ?