Rain surface water under my new back extension

[John D v2.0]

What if the clay is 4m deep

Theoretically you could dig 4m but that would be an engineering operation rather than a hole.
It would have to be a strict bco to insist on a soakaway rather than just giving you permission to send to the sewer!

 

[Nige F]

I recently had a side and back extension built and decided to pave the back garden by 50%.

so thought I'd try the forum just in case someone has experienced something similar.

Yes indeed have just solved something similar @ D i L's house . The builders of the extension ( some years ago) built over the existing connection to a rainwater sewer. Then dug a hole in solid clay. You could see the water seeping out through the ground and running down the garden. That was the lucky bit because the garden slopes down hill to a path and then a stream. The water now goes out the far side of the pit and underground in a pipe to near the path and thus the stream If yours is the same but flat you're in bother. But you might be able to find the original rainwater drain.

 

[Nige F]

What if the clay is 4m deep

Just get a Welldigger and his mate in

 

[bouhalia]

 

[Ian H]

You could always leave everything connected to the soakaway the run an outlet to a proper drain.

Did they test the ground first, like this:

 

[bouhalia]

That's a good point. No they did not test the ground at all. I dug about 30cm deep and took these samples. What do you think clay? It reminds me of plastercine at school. See sample photos and also a few more photos i have taken in the last few months of the garden.

 

[bouhalia]

 

[bouhalia]

 

[Ian H]

Yes, hard clay.

 

[bouhalia]

 

[Doggit]

Be creative; clear the weeds, enjoy the ice rink after Christmas, and then put in the land drains in the spring.

 

[bouhalia]

see

 

[John D v2.0]

My wife was looking at those photos of the mud over my shoulder, didn't realise they were mud at first
Agreed you need to get the ground drained, even just a drain at the surface would help!

 

[bouhalia]

lol. Someone mentioned french drains maybe along the perimeter of my walls? (see my back garden pics)

 

[John D v2.0]

lol. Someone mentioned french drains maybe along the perimeter of my walls? (see my back garden pics)

French drains are a good last line of defence for your house, but ideally you'd not have a flooding garden.
French drains are usually a compose when patios are sloping towards a building and the home owner doesn't want to dig the patio and relay it properly.
I think you should focus on not having a flooded garden. Must be very annoying so even land drains would be a good move.
Really depends if you want to start modifying the existing setup or just want to deal with any excess water with land drain.
Good luck, John