Connecting pvc pipe to clay socket pipe at manhole

[infoseeker5]

I am planning to replace my existing clay pipe house drainage pipework with PVC. Having searched this excellent website and previous forum posts I could not see answers to my specific problem. Hence this post seeking advice on two issues:
1) Where is the ownership demarcation line at manhole on public sewer running across my garden
2) how do I connect the new replacement PVC pipe to existing clay branch pipe at the manhole if water authority won’t replace it with PVC

My house, drainage and sewer were all built mid 1950’s. Pipes are socket and spigot glazed clay. They connect to the main sewer via a clay branch pipe passing through 9� thick brick wall of manhole chamber, connecting directly to the channel junction of the 6� combined storm and foul public sewer.

This public sewer runs across the back gardens of adjacent houses, i.e. in private land rather than public highway. I know the water authority owns the main sewer and manhole, but where exactly does the pipework become mine. Is it outside the manhole at inlet to the branch pipe before it passes into the manhole chamber wall? If water authorities own this branch pipe do they ever replace (at houseowners request) the existing clay pipe with PVC at their cost (am I living in dreamland)?

My problem is how to reconnect new PVC to existing clay branch pipe because where it emerges directly outside the manhole wall, the concrete base is approx. level with centreline/waistline of branch pipe. So the bottom half of the pipe and socket are both inaccessible for direct connection of 110mm PVC using external adaptor couplings.

As mechanical attempts to remove concrete risk damaging pipe do you know whether using strong brick acid to soften and remove concrete from around underside of clay pipe to create space for the adaptor coupling is feasible? What other possible options are there?

I presume the ultimate solution is removal of existing clay branch pipe and replacement with a new PVC branch pipe.
I’m in the Severn Trent Water area, do they ever undertake such work? I would be grateful for comments and advice from any experienced helpers out there.

Thanks in anticipation.

[seanandruby]

read this.
Have you had lid off and checked depth. Some drainage pipes and manholes are very deep ( just put one in 8 metres deep ). It is a costly exercise putting in new, or replacing drainage. Why woukd you want to replace it all? Have you thought about getting it relined? No acid won't help and sounds dangerous. We usually break the concrete from around a pipe by starting at furthest point from pipe and nibbling gently towards the pipe. Old clay is very fragile so need to go slow. Trenches, manholes etc: even for experienced guys like me are dangerous places to be, can be confined space regs'. It would all be at your expense i would of thought. Any photo's?

[infoseeker5]

Sean,

Thanks for posting your comments on my message, regarding the points you raise I can advise as follows.
1) I have looked inside manhole and measured depth (1.8 metres ground level to branch pipe invert)
2) I want to replace all my old clay pipe runs as they are in poor condition (all the sockets are cracked with fragments broken off and some root ingress) and some leakage into soil is evident during my trial hole excavations.
3) Only the final branch clay pipe entering through the manhole is in decent condition (I dug down to look at it but have since backfilled, sorry didn't take a photo)
4) I would feel much happier with new 110 dia plastic than lining repairs to existing clay.
5) I had already read the very FAQ note on drain ownership but it didn't seem to address my situation, i.e. the common sewer running across my garden was originally private but was adopted by Severn Trent in 2011.

I need to know where the actual boundary ownership line falls - is it inside the chamber at the point of contact with main sewer channel, or outside the chamber where the branch pipe socket is?

Do you have any further advice for me?

[seanandruby]

You need ask Severn Trent for advice on ownership and bounderies.

[jwill]

You will be responsible for section after branch as guessed. Can't see STW replacing the branch why don't you just change everything apart from last few hundred mm before branch and put flex coupler on?