Clay gully and hopper repair

[Thierry]

Hi,

I'm in a victorian house (1890) in London, this is at the back, in the side return (1m wide by 8m long), fully concreted over.
The main rainwater downpipe that collect all rain from all roofs at the back falls with a bend into a clay gully. That gully is recessed quite a bit below the cemented ground level, the cement was shaped to form a hollow. In addition, the kitchen soil pipe (sink, washing machine, dishwasher, boiler) also empties in there.

We now have damp on the inside wall, and noticed lots of cracks around the gully which seems to have sunk a bit. The 2 pipes splash a lot the surrounding area. I have broken all the cement, which was hollow, fully of voids, etc... I've cleared all the sludge from the gully. It feels smooth without any cracks. This is now what I've got (i've removed the rainwater downpipe for the picture):

How to make this good?

I thought to raise the level of the square gully using a riser:
https://www.drainagesuperstore.co.uk/product/square-hopper-riser-110mm.html

How to you attach that to the clay (glue, silicon, resin) ?
Other problem is the clay top level is not horizontal, it seems to be at an angle, I don't know how to adjust that. Maybe I'll have to cut the bottom of the riser to adjust for the level?

To reduce the number of pipes getting into the hopper, I thought of merging the kitchen pipe into the rainwater downpipe. I think this is not allowed in new builds, but this is a combined system, and 30cm below it would get merged anyway, so I'm assuming it's ok to do.
Maybe using one of these:
https://www.drainagesuperstore.co.u...0mm-single-socket-triple-boss-pipe-black.html
https://www.drainagesuperstore.co.u...es/110mm-single-socket-access-pipe-black.html

Is this ok?

Do I need one of these?
http://www.wickes.co.uk/Wickes-Terracota-Drain-Inlet-Hopper/p/435196

If I need this, I have no idea how to make the round section at the bottom fit the square clay hole I've got.

I though maybe the downpipe could "end" directly inside this (without being sealed/glued). This means I wouldn't have to end the downpipe with a bend and make it splash all over the grate? In other words, do downpipes always have to end with a "Bottom Offset Socket Bend" ?
https://www.drainagesuperstore.co.u...e-solvent-weld-socket-bottom-offset-bend.html

Finally, I thought of filling all the gaps with gravel and finish it off with a thin layer of cement on top. Do I need any additives in the cement like PVA to make it extra waterproof?

Should I just pay someone?!!?

Thanks for any pointers!
T

 

[Thierry]

Oh, another view of the repair I'm thinking of...

Current:

Proposed:

 

[oldbutnotdead]

Problem you might have is if the gulley has sunk it may be because the pipe it connects to has failed. Looks like a tricky one to dig around- might want to invest in a CCTV survey of the run before you bury the problem.

 

[Nige F]

Don't pay anyone yet - not in London ! Find where the gulley goes to ie. manhole nearby and put some pics up here - then we'll advise some more

 

[Thierry]

Water from the gully goes into the manhole nearby (2.5m roughly), along the side return:

And running water from the kitchen sink, it shows which outlet it goes to. It's a deep one (7 or 8 bricks deep)!

(the big, newer plasticky job is the new bathroom soil pipe installed a few years ago by our builder when we moved the bathroom from the back of the kitchen to the middle room on the first floor)

Hope this help, thanks for the input.
T

 

[Mw Roofline]

The proposed idea is better, crack the concrete to get you access to the clay pipe grind off the square top and put a rubber clay to plastic band seal on then simply connect the plastic rodding point to it, put your waste in the side and connect the down pipe into the top of it using a universal rainwater adaptor.

 

[Nige F]

I agree with Mw - the pictures are very useful to judge that is the way forward

 

[Thierry]

Mw, Nige, thanks a lot. I did a drawing of what I believe you mean, Proposal 2:

Rainwater to soil pipe adapter:

http://www.wickes.co.uk/Wickes-110mm-Black-Drain-Adaptor-to-68mm-Downpipe/p/432009

Soil pipe junction/access:

http://www.screwfix.com/p/single-socket-access-pipe-sp581/82593

Soil to clay, with jubilee clips:

http://www.professionalbuildingsupp...lings-93/drainage-flexible-coupling-1709.aspx

My only problem is the suggestion of grinding off the square top of the clay hopper/gully. From what I've read, clay is easy to crack. But assuming I hire the appropriate tool to avoid cracking, I still have one potential issue: do I have enough "round space" for tightening the jubilee clip on the outside of the clay pipe? The square shape goes quite low down, and then there is that "spigot" joining the 2 sides of the bend, and that might be getting in the way:

So based on your suggestion and after further internet searching, I came up with a slightly amended version, where I don't have to grind off the clay at all, the adaptor has "wings" that push inside the clay pipe to ensure the seal, proposal 3:

There doesn't seem to be that many around, here are 4 links (3 on ebay?!):
http://www.professionalbuildingsupp...-joins-pvc-pipe-to-cast-iron-or-clay-691.aspx
http://www.ebay.co.uk/itm/Drain-Ada...-Iron-Converter-Plumbing-Adaptor/261300420865
http://www.ebay.co.uk/itm/110mm-Soi...or-Black-Push-fit-uPVC-Soil-Pipe/110807223362
http://www.ebay.co.uk/itm/PLUMBING-...AST-IRON-BLACK-COLOUR-CONVERTER-/370580075050

Has anyone used these before?

If I go for either of these solutions, how to I get the surface water to drain somewhere? the side return is fully concreted over, some rainwater will go towards the neighbour side, but I wouldn't want water to pool along the house.

Thanks,
T

 

[Nige F]

looking @ how well that gulley has uncovered I would carry on exposing the pipe and probably make a connection to a round part of the drain that will be revealed by some more digging.Then you could fit a new plastic gulley to the clay drain. I thought the whole lot might have been encased with concrete. Carry on and break out a little more path.That doesn't look too thick either. Expose the pipe and post pics. again.Looks like it's going well for you.

 

[Thierry]

Hi again...

I wasn't really convinced in digging it all out, I don't want to break the concrete anymore that I should... But...
One last thing has convinced me: the water level in the drain. Since that somehow the thing has sunk unevenly, or was never installed properly, it relied on the cement hole and pointing around it to contain the water. When the washing machine drains, the level of the water raises quite a bit before it has a chance of evacuating, and even overflows. The left is what I've got, the right is what I imagine it should be:

So ok, I will break the concrete to uncover the clay pipe and make a join with a 110mm plastic pipe. Annoying thing is removing the 200L water butt above that, it is full to the rim after all the rain in the last 2 days, and pond is already full. Damn!

From what I've read it's very difficult to cut clay without breaking it. Any recommendations? A tool to hire?

Thanks,
T

 

[JohnD]

you say you are in London. It is very common (actually usual) for clay gullies like that to break at the bend, when the house settles into the clay. Even more so as there will have been bombing up to 1945.

I would greatly prefer to dig the whole thing up.

Does the nearby ground seem damp, and have you ever seen a red worm?

 

[Thierry]

Ground seems fairly dry, definitely not damp or wet, not ever found worms (there are 1000s in garden proper).
I will dig up anyway

 

[Nige F]

Hi again...

I wasn't really convinced in digging it all out, I don't want to break the concrete anymore that I should... But...
One last thing has convinced me: the water level in the drain. Since that somehow the thing has sunk unevenly, or was never installed properly, it relied on the cement hole and pointing around it to contain the water. When the washing machine drains, the level of the water raises quite a bit before it has a chance of evacuating, and even overflows. The left is what I've got, the right is what I imagine it should be:
View attachment 82750

So ok, I will break the concrete to uncover the clay pipe and make a join with a 110mm plastic pipe. Annoying thing is removing the 200L water butt above that, it is full to the rim after all the rain in the last 2 days, and pond is already full. Damn!

From what I've read it's very difficult to cut clay without breaking it. Any recommendations? A tool to hire?

Thanks,
T

You have the right idea ! An angle grinder with a diamond disc is a good way to cut the pipe - remember you can cut random shapes out and remove bits, you don't need to go straight across like cutting a swiss roll. You'll find a socket and cement seal as you suspected - maybe broken or just cemented in crooked. Post some more pics as you progress

 

[Thierry]

OK! a few red worms, and the soil is definitely damp. The collar between the clay pipe and the U bend is broken:

The builder who did the extension (left of red line) literally buried the clay pipe in the foundations. I'm having a hard time creating some space around the pipe. There is roughly 30cm between the pipe and the floor level (between blue lines).

I'll keep digging to create a nice space around the pipe for the new connector, get an angle grinder and cut the pipe flat-ish.

Is 30cm enough to fit a connector and bottle gully on top of this? How do you deal with the angle?

Thanks again,
T

 

[Thierry]

Sorry, was a bit quick posting questions... Bottle gullies are generally about 30cm tall, but it will sit near the clay pipe, not on top, so I don't have a height issue. The angle might be an issue, but I've noticed adjustable bend (single socket) that I could use if the standard 15-20-30deg don't work. Is this about right?