Foul Drainage

[JGB]

Hello

I have an issue that I am unsure how to solve.

 

 

I am looking to get a single storey extension added onto my property.

 

 

Please see attached floor plans, existing and proposed.

 

 

The extension would be over a public sewer (blue), therefore I need a build over agreement. I have decided to have the manhole moved to form a new y junction onto the main public sewer.

 

 

I have new foul water pipes (pink) going to the new inspection chamber from the

1 Existing SVP pipe

2 New Utility (I was told by my architect that I could not simply join it to the existing SVP for some reason, blockage)

3 New WC.

 

 

I noticed that a lot of the new pipes are going either under or over the existing public sewer pipe. Is that acceptable or even possible??

 

 

Would it be possible to simply join the utility piping to the WC piping and route the foul water out that way?

 

 

Will and inspection chamber actually be able to accommodate that many pipes at that angle?

 

 

All seems a bit confusing to me so any help would be greatly appreciated.

[Mr Punter]

The new IC will be fine in terms of inlet numbers and angles.  It is important to check invert levels but the connections from the utils and kitchen will be above the main sewer pipe and the connection from the new IC to the sewer will either be at the same level or on top if it is a saddle onto a larger pipe.

[Jml]

19 minutes ago, Mr Punter said:

The new IC will be fine in terms of inlet numbers and angles.  It is important to check invert levels but the connections from the utils and kitchen will be above the main sewer pipe and the connection from the new IC to the sewer will either be at the same level or on top if it is a saddle onto a larger pipe.

 

We will be having a similar layout. Will sewage be able to flow from new IC to mains sewage pipe, given the angle betwen entry and exit is at most 90 degrees?

[Mr Punter]

Most of the plastic 450 chambers have inlets at 90 deg to the main channel.  The outlet has to be from the main channel but you can put a 45 deg bend on it and still rod OK.  You can also put a 45 on the inlets, so lots of flexibility.

[Jml]

9 hours ago, Mr Punter said:

Most of the plastic 450 chambers have inlets at 90 deg to the main channel.  The outlet has to be from the main channel but you can put a 45 deg bend on it and still rod OK.  You can also put a 45 on the inlets, so lots of flexibility.

 

So the main channel you describe, will be a short pipe (i.e less than 450) within the chamber which runs parallel to the mains sewer, to which the inlets enter and outlet leaves?

[Russell griffiths]

a modern plastic chamber looks like this, so as @Mr Punter said pipes can enter at 90 to the main drain run, you can also add an angle joint on the entry and exit pipes to vary the inlet route. 

 

the  ic in the pic is a 320mm a 450mm looks a little different as they can have a lower exit pipe. 

Have a look for some images and it will give you a feel for the parts available. 

[Jml]

20 minutes ago, Russell griffiths said:

a modern plastic chamber looks like this, so as @Mr Punter said pipes can enter at 90 to the main drain run, you can also add an angle joint on the entry and exit pipes to vary the inlet route. 

 

the  ic in the pic is a 320mm a 450mm looks a little different as they can have a lower exit pipe. 

Have a look for some images and it will give you a feel for the parts available. 

 

I think  i nearly understand, so in @JGB example that plastic chamber could be used but sealing off unwanted inlets?

[PeterW]

Chambers such as the one linked usually come with 4 or 5 bungs fitted as it’s rare to use all of the inlets. 

 

Bear in mind it all has to be a minimum of 50mm above the main sewer level - you can’t rest pipes on each other so all of your house levels have to come in I would expect 200mm above sewer level to start with. 

 

I would also  put long slow bends on any run into the chamber so they can be rodded easily from the chamber. 

 

No  idea why your architect is saying use separate flows for the stacks either - I prefer using a combined stack as you know it’s going to be continually flushed through and less likely to get blocked by infrequent use. 

[Jml]

1 hour ago, PeterW said:

 

 

I would also  put long slow bends on any run into the chamber so they can be rodded easily from the chamber. 

 

 

Many thanks, to all on this thread, think have actually understood how to do my drains at last!

 

One last question (sorry about hijacked thread), can you rod an s shape i.e. 45 deg out of IC, then 45 deg into mains sewer?

 

[PeterW]

Decent rods will flex - I would be running straight from the IC and the only angle would be the 45 going into the main sewer run. 

[Jml]

7 minutes ago, PeterW said:

Decent rods will flex - I would be running straight from the IC and the only angle would be the 45 going into the main sewer run. 

 

Confused (again), in  @JGB example at the beginning of this thread how would that work?