For planning purposes I am trying to figure out my plumbing under the slab. Can I safely assume that this is the right setup?

Question

I am trying to guess if it is possible to relocate the blue pipe to the right of the vertical one This is the basement, concrete slab. I can't quite figure out the plumbing for the main drain and I am not sure if I will break the concrete above it. It is essential for me before starting the work, to know that what I want is possible and there is enough room to install the horizontal blue pipe above the horizontal grey drain

I am tying to move the yellow pipe in the picture below in the position where the vertical red pipe is The red pipe is what I am planning to install, the yellow is what I am planning to remove

Suggestion by ecnerwal

Here are the real distances for the existing pipes in the basement 16" for the fist to the left vertical black line in the picture (the sink I am relocation and whose pipes are discussed here as a possible replacement for the lower section of the yellow pipe) 4' for the second one. I also highlighted the contour of what appears to be where the opened the floor to install these to the left you can see the clean outs of the soil stack and the dry vent (1.5") this is the yellow pipe I am trying to relocate

And here is the updated Sketchup model including Ecnerwal's changes The bath tub will rotate 90 degrees counter clock wise and will be replaced by a shower pan The sink will move to the south of the picture in the corner where the bath tub ends

Answer 1

That should work if your wishful thinking is correct, though you might find it more practical to leave the stack alone and re-route the yellow vent around to where the red pipe is, rather than tearing up the stack to put the vent connection on the opposite side. Messing with the bottom of a stack is not trivial.

IF the pipes to the sink are big enough (and probably not if they were not intended for this) you could also route an above-the-slab dry vent from the sink and the sink drain line would wet-vent the rest, but if it's not big enough that won't fly.

Unclear from your comment, but if the place you "need to move" the yellow pipe is the upper floor, you can run it (properly sloped back to the drain) "horizontal" once it is 6" above the flood level of the highest fixture in the floor it serves (the basement.) Not the highest fixture it serves, the highest fixture on the floor it serves. So you could make the move (if the upper floor is the area of concern) without getting into the concrete.