Bathtub/Shower upgrade

Hello All... first post here, looks like a ton of info available!
Here's my situation... The photo below shows the back side of our tiled tub/shower that was built directly on the slab. I don't think that this was original to the house as the previous owners did a major remodel in the early '70's. I am demoing all of it to replace with a drop-in tub. I will also rebuild the wall to take care of rotted lumber. I'm trying to determine what I need to look for to tie into the cast iron drain pipe. It looks like concrete was poured around the brass drain pipe from the shower/tub. I can knock that out, but don't want to damage something in order to tie into the cast iron. Also, on the left you can see the cleanout and was told that the vent stack would be going up from there.
The one area I'm most confused about is how is DWV pipe done in a slab? Are all traps, tees, etc. in the soil below the slab, or are the done above ground and the slab poured around it all?
Last question... according to Calif. code, can any of this be done with PVC?
Thanks!
-Bill

looks lke tons of fun

you are going to have a great imte with that....

it appears that water has been seeping into the sand under your slab for years and years....


what you got to do is try to clean out that mess without messing up the copper
the cast iron too.....

in the slab you are probably going to find some cast traps
of some sort for that old shower ...


the lord only knows what is under that concrete , with a revent and another
cast line going into the floor.....


you are goin g tohave to clean that whole mess out if you plan on putting in something radically different than what you presently have and youwill most like ly hav eto tangle with that cast somewhere down the road useing a cast cutter to make modifications....

I dont know the codes in claifornia but I would assuem
that they are ok with sch 40 pvc in the slab....



have fun

PVC and ABS are both approved for DWV in residential. Depending on where you are, one or the other will be prevalent. Here in San Diego, it's all ABS. You don't find PVC drainage fittings readily available.