Corbeled foundations and drainage depth

[bsr]

Hi

This is my 1930s bungalow. Drainage was combined but is now separate to the sewer.

As you can see, I have a clay double gully I need to move 50cm due to building work. I've measured the bottom of the gully as 40cm (16") internally. I think that's called the invert? I've checked with my hand and the U bend is towards the excavation.

I assumed the drainage would go around the corner of the building. As you can see there is a rainwater pipe further along which I assumed drained into the same underground Pipe. However I've excavated to 70cm and I believe into virgin soil but can't see any pipe yet.

In the way down you can also see that I've hit a lot of brick.

Questions if I may:
1. Could those be corbelled foundations? Or is it just the usual rubbish for infill?

2. Do you think the drainage is deeper or runs another way eg under foundations? The bend definitely curves towards my excavation. What was the done thing in the 1930s?

3. Could it run to a soakaway? Was that a thing 100 years ago?

Thoughts / suggestions welcomed.

Thanks

 

[^woody^]

A stepped foundation actually looks like laid bricks. You need to expose more of that.

I don't think drainage will run under a foundation.

 

[bsr]

OK thanks. Then which way do you suggest I dig? Down, or around the gully? I don't think I can do deeper without making a hole big enough to crouch in. I'm already lying on my stomach to get the soil out of the bottom of the hole.

I should add that the house is on a slope and this is the corner where the ground level is lowest so I would expect the drainage to be at its shallowest.

Should I try and break out the concrete around the gully?

 

[cdbe]

Rather than a sharp 90 degree bend around the corner I've seen some come out at 45 degrees with a larger radius round.

 

[bsr]

Ah that's useful thank you, then I shall dig around the gully and if necessary try and remove some of the benching. I don't know if my SDS will be up to the task!

Is it possible that the P trap drops straight into a soakaway under or adjacent to the corner of the house? I was wondering if those broken bricks might be a long-blocked up soakaway. I know nowadays the soakaway needs to be 5m from the house but this is 1930s...

 

[noseall]

a larger radius round

Slo2

• noseall
• 18 Sep 2017

 

[bsr]

A bit more digging and it turns out the red line is what is actually does! No idea where that goes because it's into next doors' garden and there are no manholes / inspection covers within 10m of that route!

I put a hose down for 20 minutes and it didn't fill, so perhaps best to let sleeping dogs lie! It's been ok for the past 90 years so I think I should just fit the new gully and not worry about where it goes. Does that sound about right?

 

[noseall]

No idea where that goes

There is often an absence of rhyme and reason to drains layout. We have been surprised many times.