Connect kitchen drain to 2nd floor main drain

[Reach4]

Soft copper? I would still need to protect the copper via conduit or other method? That is better then running straight PEX in the trench? Right now everything after my water softener is all PEX I would be converting to copper.

What benefit is there to bury soft copper in the trench vs PEX?

This is the better copper -- type K: https://www.grainger.com/product/MUELLER-INDUSTRIES-60-ft-Soft-Coil-Copper-Tubing-4LW30

I don't know how best to sleeve it. That polyethylene sleeve looks useful. Is that for letting you pour concrete directly around the copper?

Nor do I know how to best sleeve/protect PEX. I am thinking you would run a concrete penetration for PEX through schedule 40 solid (pressure rated) PVC-- at least I think that is what is normally done for a foundation penetration. Seems reasonable for a floor too.