Any ideas on how this drainage works?

[SillyMan]

I am currently redoing my patio and in the process I am considering adding an extra linear drain. I will need to connect to a pipe which is coming from the another drain in the patio so I lifted a paving slab and dug a title way down to expose the pipe, but when I did that I discovered this construction.

IMG_0485-annotated

• SillyMan
• 31 Oct 2020

IMG_0492

• SillyMan
• 31 Oct 2020

Its only 2 metres from the house, not under the patio itself but under a small stub of path sticking out into the garden composed of two paving slabs. The hole next to the pipe coming from the patio was where I pulled out a few large pieces of hardcore which I assumed was the sub base for the paving slab. I have also removed a broken piece of paving slab which was acting as a cover to this junction, in the photo you can see where the bricks and the mortar were supporting this

The area between the two pipes was all mud. I cleared this out, I assume this is just where there originally was a void which has silted up. About half a metre into both pipes were blocked with mud which I have also cleared out. The pipe which I have marked as leading to a soakaway? is at least nine metres long (thats as long as my set of drain rods) and runs off at 45 degrees across to near the garden boundary. I am just puzzled by what I have uncovered, is this the corner of an old soakaway that is just all silted up? If so what is the second long pipe for? It runs away from the house into the garden. I am, guessing it goes to a soakaway. An overflow?

I am guessing that the position of the brick partly obstructing the pipe from the patio and the position of the pipes relative to each other are not that significant and are just that way because the construction was thrown together. Does that make sense or is there some point to it that I am missing. Is that piece of cast iron just some buried rubbish or does it have a role? In the second photo I removed some of the turf to expose the concrete sitting on top of it, again I am not sure if that is significant or just a bit of old path which has become buried. I don't want to dig much further to explore that way at the moment because it would involve moving a large pile of earth.

I am interested to know what is going on here, anyone got an idea?

The house was built in 1974. Soil is clay

 

[noseall]

It looks like the original inspection chamber was badly damaged after the last driveway 'improvement'.
Soakaways are pointless in clay and have a limited lifespan especially poorly built early ones.
I'd re-build using a modern IC and would likely replace the clay for plastic where it runs under the drive.

 

[SillyMan]

There is no drive. This is a path at back of the house which leads to the patio, just paving slabs. I know it is quite difficult to get a good impression of what is going on from the photos but it isn't much of a constuction, its definitely not something which has been carefully built and then damaged, it has been constructed from bits of rubble and just a couple of bricks. I lifted two Pavers and dug through some sand, very friable mortar and mud to get to where I thought the pipe was likely to be. Everything looks to be very 'thrown together and the cap was mortared on, so I presume the intent was not to allow for access.

This pic might give you a better idea of how it fits into the garden, it is taken from the opposite viewpoint so you are looking at the opening to the long pipe. I have losely filled next to the pipe from the patio back in again, temporarily, just to make it easier to get to the garden without having to leap. That why it might look a bit different from the photos taken yesterday.

IMG_0514

• SillyMan
• 1 Nov 2020

You can see the bit of broken slab that was used as the cap for the 'construction' and the two pavers I lifted piled up next to the hole.

 

[SillyMan]

I dug a little further to expose the cast iron thing. I still have no idea what it is but I am assuming it isn't functional its just some buried rubbish.

IMG_0518

• SillyMan
• 1 Nov 2020

 

[JohnD]

the square thing looks to me like a yard gully.

the concrete patches round it might be the remains of an old yard.

if it is set level, then it is unlikely to be rubbish that someone threw down.

I don't know about the iron.

If the pipe went to a soakaway, the house gutters probably used to connect to it. Where do they drain now?

 

[SillyMan]

I think the house gutters drain to the same soakaway that the long pipe leads to, that would make sense given where the pipe is pointing. When you mention about 'the square thing' I wasnt sure which bit you were referring to, do you mean where the water is on the photo in my last post? Maybe you are right, it could be a home made gully but it seems odd then to set the cap in mortar, all very bodgy.

 

[SillyMan]

A picture with the cap back in position:

IMG_0519

• SillyMan
• 1 Nov 2020

 

[Ian H]

It looks to me like someone has bodged on a makeshift junction and covered it with a slab. Now the metal has gone do you have 2 inlets and 1 outlet or is there just 1 in, 1 out?

 

[SillyMan]

The cast iron is still there, its the rusty thing, I am not sure what it is but I think it is rubbish. I have dug out a bit of mud under it to see if there is another pipe but I cant find anything so it appears to be one in and one out. I think you are right, it's very bodgy but I reckon it must've been conceived as a junction and semi accessible access point, that would explain why there is some space between the two pipes.