Basement rough. Need help with pipes.

Hello,

After looking around quite a bit, I think I figured out most of this basement bathroom situation, but I'm still stumped on one part of it.. or maybe all and I'm just way off.


What I think I know..
I've got a shower pit, toilet, and sink in a line on the left.
A vent stack access above and one coming from the floor.
A cleanout on the back right.

But then there's this other tube.
- Black, about 4 inches. And there's a threaded cap down it. It's down below the floor line.

Is that just another cleanout?
If so, do I need access to both of them? (they're less than 2 feet apart.

Thanks for looking.

 

Yes, that's what it looks like. I

 

Welcome to the forums!

The cutout at the top left looks like it could be a tub drain instead of a shower drain. The way to tell for sure is whether it's 1.5" or 2" pipe. 1.5" pipe must be used with a tub. 2" is usually shower, but can be used for either.

The black cleanout may be a cleanout for a underground french drain or storm drain. Since it's a different material, it doesn't seem like it would be a sewer cleanout. I would assume it needs to be left accessible.

Does the vent from below connect to the vent to ceiling/roof? Usually that's where the sink would be connected in. It's odd that you'd have an additional sink drain that doesn't come up into the wall.


I know this doesn't answer all your questions, but hopefully it helps a bit.

-Mike