Manhole cover vent stack replacement - help!

[mjm6]

I don't know the technical terms, but there's a problem with the inspection chamber on my property through which all the sewage from my house and my neighbour's upstream flows, before it goes into the public system.

Just beyond the final U-bend is a 2-ft high cast-iron vent stack with a square-ish thing on top (AAV?). It's 100 years old and is breaking up. I want to replace it but don't know:-

- how to get it out without letting a lot of soil fall into the hole and risk blocking the sewer;

- whether you can get replacements and, if you can, what to ask for;

- whether sizes have changed since metrication and I'm stuffed;

- how to fit a replacement;

- what problems to expect.

Can anyone advise, please? Is it simple, or should I call a builder?

 

[kevplumb]

cut the top off and get an external air admittance valve

 

[Nige F]

Buy a new mica flap for it that`s all there was in it what a waste of space those things are . just stuff a big rag in it - it serves no useful purpose now - and Kev`s outside AAV`s are expensive : PS the final U bend is an interceptor trap - another pointless 19th Century relic - bit like trade unions

 

[Hugh Jaleak]

Buy some concrete mix in a polythene bag. Cut pipe off below surface, mix concrete. Stuff the (empty) bag into pipe, make good with the concrete.

 

[Nige F]

Bump- well said Hugh