Bunch of questions re land drainage in clay

[Alan Ambrose]

Hi,

 

I want to put in land drainage in to make the back of my plot less wet in the winter. This area has fruit trees in atm and will eventually become garden. This is in clay and to feed into a 300mm culvert that's already there ...

 

+ what depth would you put the drains in?

+ what diameter?

+ how far apart?

+ would you have a silt trap?

 

Would you use fabric or sand somehow for filtering around the pipe (as well as 20mm stone)? Would you expect this to get clogged over time?

 

Any other tips?