SVP out and back into building envelope - is this possible?

[Moonshine]

I am looking at simplify my drainage layout

 

The WIP drainage plan is below left, with the blue line indicating the section to the right. I am seeing if i can loose the inspection chamber and pipe run in the red bubble in the plan.

 

In the section, i have indicated the brown to show the path of the SVP to the inspection chamber in the garage, with where the washing machine will connect via a trap.

 

To do this i will have to run the SVP below the block and beam, and back into the building envelope at the top of the retaining wall. From there the SVP will drop down in a boxed in section in the entrance hall below the slab to the inspection chamber.

 

My concern is the two penetrations in the warm building envelope, and wonder if anyone can comment if this is actually possible or advisable.

 

[Mr Punter]

It is quite difficult to see because of the split levels, but I would not want to bring the pipe back into the building if avoidable.

[Nickfromwales]

If there is free-draining material behind the retaining wall then I see no issues whatsoever. The penetrations will need ‘grouting’ to make them watertight but as long as that is executed meticulously you should have no problems with that proposed run IMO. 

[Moonshine]

2 hours ago, Mr Punter said:

but I would not want to bring the pipe back into the building if avoidable.

 

1 hour ago, Nickfromwales said:

If there is free-draining material behind the retaining wall then I see no issues whatsoever. The penetrations will need ‘grouting’ to make them watertight but as long as that is executed meticulously you should have no problems with that proposed run IMO. 

 

Two contrasting answers! ?

 

Below is hopefully a bit clearer with the blue line the line of the horizontal SVP (with suitable fall)

 

There will be free draining material below the pipe and Type A waterproofing, with a perforated drain at the bottom.

 

If the levels and falls work it may not actually be a fully penetration of the retaining wall, but the pipe located in a notch on the top of the wall.

 

As well as the waterproofing the insulation will have to be fitted well around the pipe, and the plan is for the pipe in the vertical in the boxed in section is enclosed in mineral wool for thermal insulation.