4 inch PVC to 5 inch clay drain problem
 

Hi

I had some new pipework laid that involved a new 4 inch PVC pipe being connected to an old 5 inch clay pipe. From what I can tell the builder used the correct adapter ie something like this

http://www.toolstation.com/shop/Roof...+to+PVC/p63345

However when a CCTV drainage survey was carried out you could see a large lip that was causing water to hold.


Attachment 26551


Does anybody know why this has happened despite using the right piece of kit?

Thanks very much

I'd reckon you are meant only to go 4" to 5" WITH the flow. Going the other way is going to have to cause a lip......

Can you excavate and redo it in concrete with a manhole?

Hi

I'm not sure I understand. The new drains are standard PVC 4 inch, the existing part of the drainage system is the old 5 inch clay pipe.

So at some point 4 inch needs to be joined to 5 inch doesn't it? And I'm not sure what you mean by redoing it in concrete.

Thanks

Any reason the CCTV operator couldn't be arsed to set the date?

As an ex Dyno-rod engineer that don't look right..

If he had of used the connector you have linked then the centres of the pipes would be aligned...

I'd not be happy with that to be honest..

Alan...

Neither the top or bottom line up...

Is any of the old clay pipe dropped in the drain. Had a few similar jobs in the past where the old cast stacks are smashed out and bits falling down. Could of used a drain connector going onto the clay.

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Did you see the connection once it was made? or the fitting used, When the drain was done?
Did you supply the fitting or did your builder?

I think they have used a LEVEL INVERT REDUCER (upside down)
I could be wrong, I agree with gueniss about it being incorrect...

As alcazar says the 4 to 5 inch reduction or flow could be the wrong way, i.e. Our homes have 4inch (mostly) and the further away from the property the bigger the pipe gets until its at the sewage plant...

Hope you get sorted fella..

Who have thought that 5 inches makes such a big difference compared to 4?

Here is a pic of the drain being laid. The problem joint is the one by the guys foot.

I'd appreciate your input.

Thanks

Attachment 26550

That old clay pipe would be 150mm ID, don't know when originally laid, but guessing could be Hepsleeve pipe. I'm not familiar with that type of connector but if it's holding water in that area then there must be a backfall maybe caused by settlement of the pipes at connector. I agree that the pipes seem to be misaligned somehow when looking at the CCTV.

In your photo of the pipes being laid, there appears to be no bedding under the pipes which should be pea gravel or similar (unless doing a concrete bed and surround for shallow pipes - not really applicable here I would have thought), this may have exacerbated the problem.

HTH

Is the image from the bottom of the connection in the pic you have shown?

looks like its at a funny angle where it joins.

How long are those hose clips going to last buried in wet soil?

a long time (decades), will be industrial stainless.

Stainless actually needs an abundance of oxygen to retain its resistance to corrosion. I would have thought being buried in wet soil could be the worst place for it (stagnant conditions where bacteria use up the local oxygen), but as you say maybe it does last decades.

We uses rather larger version and have done for donkeys years. If there was an issue would cause leakage and ofwat would get involved ;)

can you lift the man hole to get a better fall, the pipe work looks ok, to me.

Maybe both one of the pipes are not pushed home

You need to pack the 4" pipe up so if you did have any lip for any reason it would be at the top - looking at the photo the smaller pipe is set lower so the lip would appear on the bottom - get the builder back to do it properly.

Should have used 125mm plastic pipe with 125mm branch- then reduced to 100mm to new manhole. That way no lip either end to the clay pipe

as mentioned earlier it needs filling around with pea shingle before back fill.

I reckon it was installed ok ish but over time the new installation section has sunk relative to the clay pipe and caused a lip.

dig it up and do it properly and don't do it when its as muddy as the pic

the man hole should have gone where the branch is with the clay running into the man hole. close to the fence so could have been built from engineering brick

Agreed

IMO that job could have been done entirely with Hepsleve clay pipes so no need for adapters except maybe at the manhole/inspection chamber