New sewer chamber on 6" sewer

[BobTheBear]

Hi everyone,

First post, just discovered this forum and it looks very informative, so helping someone may be able to offer me some advise please

I'm building an extension, have all the permissions required and I have to relocate the sewer chamber to a new position which will be outside of the extension. The sewer is 6" and clay pipe and I need to connect a new 4" pipe to it for the sewerage from my house and next door. I will be putting in a new chamber to connect mine and next doors, which will lead to this 6" sewer.

Digging down to the sewer and exposing it isnt an issue, but how do I make the connection into the sewer? I could cut off the top of the sewer, so that forms the 'trough' in the bottom of the sewer chamber, just need to know how to connect in the new pipe???

Options
1. Cut the whole 6" pipe out and replace with a 6" to 4" ready made '6" trough' with 4" curved connection.
If this is possible (is it?), how do I make the connections, perhaps with a couple of those rubber connectors and jubilee clips??
Would my plastic 4" inlet pipe then just connect to the 4" curve???
2. Cut the top off of the sewer and then a piece from the side and 'somehow' make a connection which doesnt leak. I'm gussing a curved piece of 4" pipe could be purchased and concreted in place, into the piece I'd cut out of the side of the 6" sewer???
3. Anything better???

Whatever I do it seems that I will have to cut into the sewer and this could bet messy!!!

Thanks for any thoughts you may have on this.

Bob

 

[noseall]

You can buy pre-formed plastic chambers with a 6" through channel and 4" (110mm) inlets.

These can be 'grafted' in quite simply.

At no time should you be choking a 6" run down to 4".

If you do a search you will find plenty of info'. Try typing grafting.

 

[BobTheBear]

Thanks for your reply, really appreciated

I've been told to build a concrete/brick chamber by the water company, so the pre formed plastic chamber isnt going to work here.

I havent mentioned 'choking' the 6" sewer down to 4" anywhere, have I??? I just need to join a 4" pipe into the 6" sewer

 

[noseall]

I havent mentioned 'choking' the 6" sewer down to 4" anywhere, have I??? I just need to join a 4" pipe into the 6" sewer

...er no.

OK. Expose a lot of the pipe i.e. dig a big hole aboot 1.2m square.

Dig around the pipe exposing the full depth of the pipe.

Buy a 6" - 4" channel junction, cut away the existing pipe enough to allow the channel junction to fit.

Fill the trough level with the channel, with fatty concrete (add extra sharp sand and cement) and bed in the channel junction, butt your 4" inlet pipe up to the channel then let the concrete set.


Lay about 4 courses of 225mm brickwork, then do your benching. Use a 18" x 24" frame and lid as a template for the brickwork.

Et voila!

 

[BobTheBear]

Thanks Noseall

Is that what the piece of pipe is called - a channel junstion?

and this is fitted by cutting a piece of the original 6" pipe out and removing it, replacing it with the channel junction???

Thank you

 

[noseall]

Is that what the piece of pipe is called - a channel junstion?

and this is fitted by cutting a piece of the original 6" pipe out and removing it, replacing it with the channel junction???

Correct on both counts.

If the concrete is particularly sloppy, then the channel junction may 'float' a bit until the concrete has stiffened. This means that you may not get the ideal position straight away. Don't worry just have a cup of tea and a kit cat by which time the concrete may be more obedient.

You can dig a lesser sized hole if you intend using manhole sections otherwise it is is going to be a big shovelling effort if you intend going with 225mm (9") brickwork.

If you look at a manhole section drawing you would see probably 100mm of concrete below the pipe so you do need to dig a bit out once you have cut the pipe. The entire concrete base is then thick enough to support the walls of the chamber too.

 

[BobTheBear]

Thank you for all your help, really appreciated

 

[BobTheBear]

Finally dug out the new sewer chamber and pipe runs all looking good.

My existing sewer chamber (the one I have to move) is built from a single thickness of brick, have regulations changed do I now need to build the new chamber with 9" walls? The chamber will only be a couple of feet deep, so very little weight/pressure.

Can I also build the chamber using concrete blocks, or do I have to use foundation bricks?

Would I need to put short lintels over the sewer? If so do I just pug up to the sewer with morter and cut pieces of brick?

 

[noseall]

Use pre-formed sections.

No need for lintels unless you are re-sizing, lid wise.

 

[BobTheBear]

OK thanks, but I guess I could use foundation bricks if I needed to?

A builder friend (who I finslly got hold of this evening), said that 4" walls are fine for a chamber in a footpath.