Rigid land drainage pipe under gabion wall - Laying pipe to avoid collapse

[DorrisMorris]

Hello,

Bought a house 2 years ago at the bottom of a hill. In winter I took up the floorboards and water under the house was almost touching them. The patio sloped towards the house and was built half way up the airbricks meaning Surface water run off was all going through the airbricks and under internal floors. Both the neighbours have increased the height of gardens so they also drain into mine. Lots of water to have to deal with! Garden is heavy clay.

I’ve smashed out patio and dug down installing new patio sloping away from the house 9m x 5m. I have dug a 9m x 50cm trench 75cm deep which directs water from the patio and the land to a concrete lined sump pit I put in when doing the patio. I then pump out water into the storm drain (sewer pipe sits too high to cheekily tap into). I would like to fill the trench with gravel as advised on this site and have a rigid land drainage pipe which I plan to lay in the gravel.

My question is related to the Gabion retaining wall I would like to sit on top of the gravel filled trench. This will be 50cm x 50cm to retain soil and terrace the garden. I plan to cement stone steps on top of Gabion cages to act as a patio seat so it’s really important they don’t sink. I’m wondering whether it would be better not to have the rigid pipe and rely on the gravel only for drainage as I’m concerned the pipe may collapse causing wall to sink.

Has anyone else had experience of land drains running under Gabion walls? Looking for advice as to likelihood of holding up.

Thanks in advance

[Tony McC]

If you are using a *rigid" perforated pipe, either clayware or corrugated plasticware, then there is little risk of any 'collapse', regfardless of what you build over it (within reason!) as long as the pipe itself is properly constructed with adequate cover.

It's the flexible pipes, currugated or not, that are prone to collapse if overlaoded.

[DorrisMorris]

That’s great thankyou. I can carry on with confidence. These are pipes purchased 150mm

https://www.drainagepipe.co.uk/twinwall-drainage-perforated-c-261/

[Tony McC]

They're fine