Kitchen sink rough-in a second opinion

I know I'm pushing the limits for a plumbing system but would like a second opinion on a remodel plumbing tie in. Do to limited existing space and that the floor is a slab on grade this should work, though what I'm concern about is the back up up pressure if all fixture are feeding at the same time into this system. If you need more information I'm grad to provide it. Thanks
I have attached a photo:

you can not wet vent a kitchen sink with a bathroom group.
also, the lav trap arm should be vented before it turns downward.

The lavatory drain cannot turn down into the branch drain like you have it. It will need it's own vent, which could turn and tie into the kitchen vent once it is higher that 42". The trap arm will need to be a little higher to get a sanitary tee in there, and hopefully that will work on your lavatory. You will probably have to rework the supplies to get the vent past the copper too.

cacher_chick said:

The lavatory drain cannot turn down into the branch drain like you have it. It will need it's own vent, which could turn and tie into the kitchen vent once it is higher that 42". The trap arm will need to be a little higher to get a sanitary tee in there, and hopefully that will work on your lavatory. You will probably have to rework the supplies to get the vent past the copper too.

Click to expand...

Thanks both of you.
There is just too much crap going on in that location. I knew that was most likely what was needed though I was hoping since I had a 2" horizontal waste line at 1/4" slope and the lavatory was wet venting under 48" to the stack and that there was the additional vent I might had the required air break but you are right if I have fixture running at the same time there is chance the system could fill to the point it would create a vacuum on the lavatory drain. OK, I will have to move things and do some tile work in the existing bathroom, which I was trying to avoid.
Thank

IT would take some drilling, but I could revise it "properly" without doing ANY tile work. Having a 2" opening for the kitchen sink just creates a 'size' problem that could cause difficulties if space becomes tight in the cabinet. You have fallen into the same "trap" that many DIYers do. The fact that a vent is withing 60" of a drain does NOT automatically make it right. It depends on HOW the piping is arranged within that 60" that determines "legality".