Soil stack vent... to nowhere

[RushupEdge]

Hi,

I have a victorian property that I purchased earlier this year. We're just in the process of digging a French drain around the property and as we removed the top layer of patio slabs next to the soil stack vent, I noticed that the pipe in the ground was not connected to the pipe running up the wall. I Picked up a 110mm coupler to join the pipe, but before doing this planned to dig a bit further.

After digging a bit further today the concrete that was around the pipe in the ground has fallen off, revealing that the pipe 'in the ground' isn't actually in the ground. Theres a gap between it and another section of pipe, and that pipe just seems to be full of mud/debris.

Here are a few images:

I'm guessing this isn't right... does anyone have any advice? How worried should I be?

In terms of next steps, is this something the water company should look at, or would I need to contact a plumber?

 

[JohnD]

I find your photos difficult to interpret, but it looks to me like you have the very common "clay pipe in ground is broken".

These often crack, due to movement or settlemet or (in pre-1945 houses) bomb damage. once water starts to escape, it washes away the surrounding ground, leaving a cavity. The remaining clay pipe (or gulley, very often) sinks into the cavity, allowing still more water to escape, and cracks will open into breaks.

You have to dig out whatever's in the ground and replace with new. I expect there will be a bend that is broken, might be a few feet down, and it will connect to the socket in a pipe. The socket and pipe may also be broken and need replacing.

If you are fit and handy you can do it yourself, it is not at all complicated. But please post photos of what you find as you dig.

Look at all the other drains and gullies going into the ground as they are probably all the same. The one you have found so far might be the easiest.

There are quite a number of similar threads on here.

The water company will not do it as it is a single-house drain.

You might find a local plumber who can use a spade.

 

[RushupEdge]

Thanks - I’ll take another look at it tomorrow and do a bit more investigating (and get some better photos)

It’s right next to the foundations/footings of the house which are quite shallow (they begin roughly 25cm below the DPC) so not too sure if the pipe could be that deep? But will have a bit of a dig and see.

 

[RushupEdge]

So bit more digging complete, and it looks like whoever laid the patio had previously shattered the clay pipe and then tried to repair it with cement.

Here's a few better images:

There's quite a bit of rubble and debris inside the clay pipe, but other than the top cracked bit, the bend and rest of the pipe doesn't look in too bad condition.

Am I right in thinking I just need to cut the pipe (I have an angle grinder and stone cutting blade), clear out the rubble, insert a plastic connector (like this?) and then connect this to a new section of pipe which connects to the existing run?

 

[JohnD]

Ah, it looks like if was broken at the bend. Follow the pipe along and see how long the broken section is. If short you could just renew it.

 

[Nige F]

It's just a vent pipe - no wc connection - it must go to a manhole. If you can't see the manhole you could cut the pipe after the bend and put rods down it to measure where the m/h is

 

[RushupEdge]

It's just a vent pipe - no wc connection - it must go to a manhole. If you can't see the manhole you could cut the pipe after the bend and put rods down it to measure where the m/h is

I know exactly where the manhole is, so I think I know roughly where it's going... there's just a foot of patio above it, haha!

I've cut the PVC pipe about a meter up and removed this to have a better look. In the process the rest of the surrounding clay pipe has seemingly fallen of, held just in place by a cement 'cap' that someone had placed over the top of it.

the pipe the clay connects to looks to be in pretty decent condition (its bigger than 110mm though) - I was hoping I might just be able to angle grind a straight edge across the top of the joint pipe, insert a new plastic pipe with seal and then re-join to the stack from there. Would this work? Or do I need to replace the whole bend? It's looking like this bend is resting right on the beginnings of the foundations/footings, so I'd rather not be digging too much there.

Also, can I just flush out the mud in the pipe by running a hose down it? Will this cause any issues?

Here are some new pics:

Inside the pipe:

 

[Nige F]

110mm though) - I was hoping I might just be able to angle grind a straight edge across the top of the joint pipe, insert a new plastic pipe with seal and then re-join to the stack from there. Would this work? Or do I need to replace the whole bend? It's looking like this bend is resting right on the beginnings of the foundations/footings, so I'd rather not be digging too much there.

Also, can I just flush out the mud in the pipe by running a hose down it? Will this cause any issues?

Here are some new pics:

Inside the pipe:

Your idea with cutting and adapter is fine .But don't flush the mud into the hidden drain - It will lay as silt . pull out as much as you can and make the connection. There will be enough room for the vent to work

 

[Hugh Jaleak]

I'd sort it out properly, then if you were to run an Aco Drain around the property and connect to this pipe (using a trap of course to prevent any drain odours escaping), no-one would be any the wiser...

 

[RushupEdge]

Your idea with cutting and adapter is fine .But don't flush the mud into the hidden drain - It will lay as silt . pull out as much as you can and make the connection. There will be enough room for the vent to work

Thanks for the advice. I pulled as much out as possible, then used a 110mm adapter & wedged this into the clay pipe after angle grinding it. There was a small gap on one edge, so I've used a silicon adhesive to seal this up, then applied a liberal amount around the pipe. It's not the neatest job you'll ever see, but hopefully it is all good. Just waiting for it to cure. Do you think this will be ok on it's own, or should I put a coat of mortar around the join?

Here's an image (I've since used adhesive around the back of the pipe too):

 

[Nige F]

That's fine no need for mortar which won't stick to the plastic anyway