S Trap into concrete floor
My daughter has just bought an old Baltimore home cira 1950, it has a toilet, shower and sink in the basement. The sink needs replaced and it drains down into the concrete floor. She also wants to hook up her washer to this drain. The LG washer has a 1 1/2" tailpipe approx. 6" long that would go into the tailpipe drain from the sink. The washer has a 7/8" hose attached to the center of this tailpipe. I've never seen one hooked up like this as I have a set tub that the hose dumps into on my washer. Anyway, my question is do I need to have a AAV installed and where would I put it using an S trap. Because the piping is in the floor I don't know what or where the vents would be in this house. Any tips on this would be helpful and appreciated. Any alternatives to this hookup also would be appreciated.