Remove/move/cap cast iron cleanout and add new one above?

[Celswick]

I seem to find my way here from Google searches often, so I figured I might actually sign up and post a question.

For starters, I have no plumbing experience before my current project....

I'm doing a partial finish in my basement, which means adding walls etc. I'm doing everything with permits.

I'm redoing plumbing against an exterior wall. There is a metal vent stack coming up out of the foundation, and next to that is the drain stack, in Abs. The drain stack runs from the kitchen sink directly above., and then into a cast iron Wye in the foundation.
The 45 side previously was used to drain a mop sink that also collected from the washing machine.

I'm attaching a diagram of my current mock up for a new washing machine drain line on one side, and a sink on the other.
They connect to the drain stack with a double fixture tee just above the cast iron hub/wye.

My main issue I'm trying to figure out right now is what to do about the cleanout.
My understanding is the 45 side of the cast-iron wye should have been a cleanout and not used for the sink drain ever.
Fine.
But I'm building an interior wall in front of the stack now, which means giving access to the CO. It's at a tricky angle, and might end up behind either the sink, or dishwasher I plan to install there.

So I'm thinking I'd place an sanitary tee in the vertical stack, above the counter. That instead of a cleanout Tee because there's about 8" between the stack and the face of where the wall would be, so I figured having the directional help would be a good idea....

I believe having the cleanout above the double fixture, and above the height of the washing machine standpipe, is all well and good?
But what do I have to do about the old cleanout opening since it would be covered by a wall?
Is it OK to just cap it? I have a feeling that's a hard no....
Would I be required to bust out the concrete and remove the old cast iron wye?

I hope my terms and explanation makes sense.

 

[Sylvan]

Your Double LTTY is installed wrong (Upside down) look at your vent drawing again

 

[Sponsor]

 

[Celswick]

Your Double LTTY is installed wrong (Upside down) look at your vent drawing again

Thank you for pointing that out.
Physically I have it installed correct. I have someone helping out with the drawings because mine look crappy, which is probably why they couldn't tell from my drawing which way it was installed.

 

[Tuttles Revenge]

The big cleanout should be accesible somehow since it likely is 4" pipe in the ground. a Mainline machine would be sitting on the ground in front of that opening to work best. The rest of the 2" ABS can be serviced from cleanouts at each fixture with a small handheld machine.

The orientation of the vent fitting is a pedantic triviality. It looks more professional if its oriented "correctly" but either direction would keep proper air flowing through it. The only time it matters is if its orientation prevents condensation from draining back into the drain... speaking of.. I would plumb the bottom of that double cross back to the drain as well to prevent that cap from pooling water. Not totally necesary, but we like to prevent any standing water in the system that doesn't need to be there.