New underground drain run - bends

[pilsbury]

Replacing some old and laying some new stretches of underground foul drainage. In one place, I have to remove an inspection chamber as this is where foundations for the extension are going. The inspection chamber is obviously a point of change in direction, I'm guessing about 95-100degrees (slightly over right angle). I intend to replace this inspection chamber with rodding eyes slightly further up the end of the straight runs.

Whats the best way of linking up my over right angled run? a 45 and an adjustable bed set to about 50?

Ideally no bends at all, but whats the max for a 110mm drain on a run?

 

[Agile]

I think that a layout plan would be the best solution to get the most useful advice from this forum.

Technically you need Building Regulation approval for changes to foul drainage.

Depending on who is to deal with the inspection of the extension you may need to consider that point.


I have a 45 degree slow bend in my kitchen.

 

[pilsbury]

Building regs will be involved at the appropriate points. Just asking as I read a previous post about someone commenting on a 30degree bend in a pipe. The plans added show existing in red and new in green. Clearly basic as just show the 90 degree direction change rather than the consideration for 2 45 degrees.

 

[Agile]

Are you sure the inspection chamber cannot stay ? It looks a distance from the founds.

If it was mine then I would build a new chamber a short distance further away from the founds and have the smallest slow bend of just a few degrees just to the left of the chamber.

Something pleasing being able to watch effluent in a chamber!


You seem to have two new 90 degree tee connections under the floor. Are these permitted without a chamber?

 

[pilsbury]

The drawing was done by me - schematic rather than actual. I would not want 90 degree bends under the floor - a recepie for getting blocked - hence me trying to ascertain whether 45 degrees are acceptable.

Again, with the inspection chamber, my diagram is misleading. The chamber falls about 9" into my foundations. A new chamber far enough out would miss the intersection, hence rodding eyes.

 

[Agile]

A new chamber where I described would not need any rodding access at all!

 

[Hugh Jaleak]

If the BCO allows that I would be very surprised! You're planning on removing the existing chamber, (does that currently only take foul waste from your property, or do others drain through it?), and putting 2 blind connections onto the existing run.

It may be possible to move the current chamber position, by kicking it out slightly with a 45deg bend on the inlet, and another on the outlet so it clears the proposed founds, but still allows full access to the drain.

Internally, the new drain in the kitchen, I'd run it at a 45deg angle to join onto existing drain, with an access plug on the internal end. The WC would be better run at an angle to bring it outside the property and connect to the existing drain outside the building with a chamber.

 

[pilsbury]

Hugh - The chamber only takes waste from my property - currently a single run from the bathroom (toilet, sink, bath, shower). Can you elaborate a bit on how I "kick out" the new proposed chamber with a 45? In my head, that means turning the existing straight run inlet away from the foundations which is against the flow.

Fully agree with the proposed internal works with kitchen and WC.

 

[Agile]

I think that Hugh means to move it further from the house and putting a 45 degree bend at the inlet and at the outlet.

But I think my suggestion is better. That is to allow the 90 degree change of direction to occur inside the chamber and then have a very small bend to allow it to realign with the pipe towards the left.

That will mean the only additional bend will be very shallow and close to the chamber.

Hugh, like me, does not think that any BCO will agree to your two proposed "tee" junctions under the floor with no access!

Tony

 

[Hugh Jaleak]

Thanks Tony, yes, that was my idea, not ideal but looking for ways round the situation. One of the golden rules of drainage, is all sections must be accessible for rodding/jetting in the event of a blockage.

How deep is that existing run at the rear? If less than 600mm deep, a smaller diameter plastic chamber could be used, which helps save space, and could get you in tighter to the curtilage of the property.