Foul drains through concrete footing?

[BenGillyHills]

I’m self-building an annex and looking for some advice from those in the know…

 

I had originally intended to exit foul drainage pipes through a section where the foundations are stepped down (and therefore plenty of room with three courses of trench blocks to go through) but hadn’t considered that this section is a long way away from the bathroom.

 

Can I do as the diagram shows and channel through the already-cast concrete footing as well go through the trench block course as shown? I would install a lintel above.

 

Once drains are installed and BC are happy, would I then concrete-in the exit opening?

 

what is best practice for finishing a lintel opening like this? 
 

Any advice appreciated. Ben 

 

[dpmiller]

what do the building regs for your region say?

[BenGillyHills]

My BC officer is off for a week. He had mentioned that two courses of trench blocks were required to exit a 4 inch pipe which I planned for at the other end of the building. Bit to avoid a long run with bends running under the slab, this plan is trying to make the best of a last-minute change to exit the pipe nearer the bathroom. Otherwise I would have just stepped the trenches down in the section to allow for two courses of trench blocks. I’m trying to come up with a solid plan to present to him when he’s back. The pipe will be fully under the concrete slab so I’m hoping he will not have a problem with it. The reason for the post is to get advice on whether it looks like best practice in this situation or if there’s anything I’m missing.

[marmic]

I don't know the answer but I would personally ask SE who designed the foundation - if they say yes (covered by their PI) and provide written confirmation BCO will I believe have to accept.