Depth of perforated pipe for land drainage - Land drainage

Coisativo · Post: # 115552Post **Coisativo** Wed Apr 11, 2018 1:25 pm

Hi,

I have a very heavy clay soil in my back garden and am planning to install a land drainage system with perforated pipes similar to what was done in the section of Land Drainage Installation. The garden is 25meters long and I am going to be doing most to the work myself to lay a 100mm perforated pipe with membrane + gravel.

I would like to ask if I need to dig 90cm trench or if I could dig 50 or 60cm instead as this would save me a lot of time and effort.

Many thanks.

Post: # 115557Post **seanandruby** Thu Apr 12, 2018 6:24 am

Take some time to read the main index
start here

Coisativo · Post: # 115558Post **Coisativo** Thu Apr 12, 2018 9:46 pm

seanandruby wrote:Take some time to read the main index
start here

Hi Sean,

Thanks for the reply, but it was rather vague. I have read quite a bit of the website. Most of it really. Although very informative, I still failed to find the instructions/explanation why the trench for land drainage has to be 900cm deep for laying a perforated drainage pipe of 100mm diameter.

Would 600mm deep x 250mm wide trench work? 10cm bedding to lay the 100mm fully perforated and corrugated pipe + gravel or pea shingles all around the 100 pipe up to 100mm from ground level so I can fold over the geotextile membrane and finish with topsoil for the turf. All with a 1/100 gradient slope in the ground to allow water flow.

A simple answer/instructions would be most welcome.

Many thanks.

digerjones · Post: # 115559Post **digerjones** Thu Apr 12, 2018 10:13 pm

I would think that would be fine. Are you putting in any lateral. The deeper you go the bigger area will drain

Coisativo · Post: # 115560Post **Coisativo** Fri Apr 13, 2018 12:02 am

digerjones wrote:I would think that would be fine. Are you putting in any lateral. The deeper you go the bigger area will drain

Thanks for the speedy reply!
The garden is long but just about 5m wide so the plan is to lay the land drainage in the middle of the garden to start with. If water still accumulates in some areas I can then add lateral branches later hopefully. I am also worried do overdo it and the grass above the drain dry out and die. Clay is very heavy here and more than 3 meters deeper. I know because i tried to reach the next layer and gave up after 3 meters of tough digging with a digging screw. Never again!