The Brew Cabin

Posted: **Fri Jul 06, 2012 12:53 pm**

I'm running a landrain (80mm perforated pipe) in behind reataining walls that have stepped foundations to form 3 terraces.

So my question is, where the landrain needs to fall vertically at each step in the foundation do I just run the perforated pipe vertically, or follow the slope?.
At certain junctions there is also a large drop of ~1m again do I just run the perforated pipe vertically, or should I install standard unperforated 100mm drainage vertically at this point and join the perforated into it top and bottom, giving me the option of a gully at the top here as well?

Thanks for your advice.

thought and image might help..

Posted: **Fri Jul 06, 2012 4:32 pm**

you cant bend it to tight 90 as it kinks, so if you can let it follow the contors and surround it with clean stone

Posted: **Fri Jul 06, 2012 4:53 pm**

water will follow the path of least resistance so its best to follow the slope with the perforated land drain, I personally would use a 100mm perforated land drain wrapped with a geotextile membrane and surrounded with 20mm clean stone

Posted: **Fri Jul 06, 2012 6:53 pm**

Thanks for the replies... got 25m or so of 80mm left over from another job, but I was going to do the geotextile wrap around washed gravel thanks for making sure though.

What does anyone think about those vertical plastic weepers (with the egg box type pattern on them) that fit snug to the wall?
Overkill?

Posted: **Sat Jul 07, 2012 7:36 am**

overkill yes

what you have suggested there looks spot on
a lot of folk wouldnt bother
looks like me and you both failed technical drawing at school :;):
good stuff
LLL

Posted: **Sat Jul 07, 2012 7:38 am**

overkill

The Brew Cabin

Retaining wall land drain + terraced.