Soil pipe through trench. How is it done?

[flanagaj]

If you have your soil pipes running internally and are using trench fill footings, then I suspect that there is a high probability that it will have to run right through the trench (see image) whilst I understand the image, I am finding it difficult to understand how you go about creating the void in the concrete.  You obviously can't use a prefabricated hollow rectangle made of shuttering ply, as you won't be able to get it out once the concrete has set.  I suppose you could use a solid piece of polystyrene which could be chiselled out after the concrete has set.

 

I suspect I've got this completely wrong, so please explain if you have had to do just this.  

 

Ps - I assume the soil pipe is not in place when you do the pour?

 

[nod]

The middle one with the lintel You really don’t need much fall to get you out of the house 

[nod]

4 minutes ago, nod said:

The middle one with the lintel You really don’t need much fall to get you out of the house 

[ProDave]

Why is your proposed soil pipe so low in the ground it is going through the concrete? or are you doing full trench fill, if so why?

 

Generally a soil pipe wants to leave the building as high as possible (minimum allowed height below ground) leaving you maximum scope for fall on the drain to it's destination.  In every case I have seen this puts the soil pipe through the blockwork, not the concrete in the trench, and it is simply bridged with a lintel.

[flanagaj]

11 hours ago, ProDave said:

Why is your proposed soil pipe so low in the ground it is going through the concrete? or are you doing full trench fill, if so why?

 

Generally a soil pipe wants to leave the building as high as possible (minimum allowed height below ground) leaving you maximum scope for fall on the drain to it's destination.  In every case I have seen this puts the soil pipe through the blockwork, not the concrete in the trench, and it is simply bridged with a lintel.

Because the location of the sewage treatment plant is quite low relative to FFL as a result of the site sloping off after the house footprint.  As a result it might require the initial depth to be deeper than normal, so as to be able to get the correct invert levels.

[Temp]

I thought the pipe is in place when you pour. You just wrap the pipe with something  compliant and support it at the right height and angle and pour concrete.

[JohnMo]

13 minutes ago, flanagaj said:

Because the location of the sewage treatment plant is quite low relative to FFL as a result of the site sloping off after the house footprint.  As a result it might require the initial depth to be deeper than normal, so as to be able to get the correct invert levels.

 

You take it through the house as shown by the photo by @nod. And your middle drawing (lintel).

 

You then take it into an inspection, use the chamfer to get the drop you need. We have several chambers and drop about 2 to 3m.