1930s Drains, water, stink under floor

[DitchManPete]

Hi All,

Looking for some advice, I was looking to extend my drainage for a new conservatory however after breaking through a concrete floor and digging down I’ve noticed a foul smell. Having dug further there’s a lot of water around the foul drainage soil pipe (see photo). It doesn’t drain away or get any higher. There’s no obvious gulley though and having felt around the pipe there is just soil and stones down there and the water does smell fetid. All the earth nearby is sodden and having lifted some concrete slabs (that were under the concrete floor) they’re wet underneath. Is this normal for a build of this age (1932)? Trying to understand if this is just the system design of the age, a high water table or whether there is a big issue with my drainage. I’ve also dug a pilot hole which slowly fills with water although not to the same level as around the soil pipe. I be dug down to the foundations but have not been able to find a drainage pipes but I don’t want to dig any further below the foundations as the soil down there is so wet I’m worried about subsidence and taking away what little support there is there. There is a ceramic gulley for the bath/basin adjacent to the soil pipe which I plan to dig out tomorrow to find some connecting pipes and gauge the depth of the system and see if I can find any cracks. However, I would welcome any advice on this issue and whether I need to be doing further work or backing away from this.

Thanks

Pete

 

[JohnD]

Your photos are typical.

Yes, it is normal. I expect you've got the usual cracked and broken clay pipes in the ground which have been leaking for 81 years. There will usually be a break where the iron pipe enters the socket in the clay pipe (unsuccessful attempts to repair it with mortar have usually been made) and at the elbow (rest bend) where the vertical clay pipe turns horizontal in the ground. If you have a gulley it will also be broken.

They need to be dug up and replaced. It is not a complicated job. A spade and a strong back are the best tools. Look at the mortar between the bricks below the ground, it will have been eroded if lime. Hose out the mud from the joints and repack with a stiff mortar mix when clean and reasonably dry.

Previous attempts to hide the leak by concreting over have not repaired the breaks, and have made your job harder.

The escape of water will have softened the ground and washed away the soil, typically leaving a muddy cavity. Look for red worms which feast on organic matter.

If there is any subsidence affecting the wall, you can claim on your household insurance, though it will not cover repairs of the leaks.

 

[DitchManPete]

Thanks for the response JohnD, appreciate your time. There’s no sign of subsidence yet, although I worry that if I continue excavating I may cause this. Are there any measures I can put in place to minimise this risk whilst I repair the pipes?

 

[JohnD]

If you're digging out soft mud, I don't think you will make it any worse.

When excavating beside a wall with shallow foundations, it's common to excavate in bays, say, a metre wide, and to concrete each bay before excavating the next.

If the ground below the wall has been washed away, I think you will need to consult your insurers about subsidence.

 

[DitchManPete]

I think the ground looks more solid than anticipated, it’s water logged but still there. Think it’s quite a heavy clay soil as it definitely retains a lot of water. JohnD was right about the collar on the clay pipe, it’s broken but I’m not seeing a lot of water coming out when I flush the loo. The amount of water coming out of the pipe (a trickle) just doesn’t seem to account for the amount of water in the bottom of the ditch but maybe I’m wrong?

 

[Lower]

It’s probably been a trickle every time the toilet has been flushed for 30 years. 30 years worth of trickles add up.

 

[JohnD]

More may come out when you pull the bath plug.

The broken rest bend is deeper down.

 

[Ian H]

Look for red worms which feast on organic matter.

I saw these and thought of you x x x