Now that the upstairs bathroom mess is contained it's time to start a new mess in the basement. Jackhammered a channel in the basement floor so the plumbers can replace the cast iron sewer lines with PVC, add a back flow valve, add a vent stack for the basement bathroom/washer/utility sink, and a washer box.
This wasn't nearly as bad as I expected. Took morning to jackhammer and afternoon to haul out concrete chunks in pails.
Utility sink now emptys into a vented drain (before it flowed uphill into the main cleanout) and the washer will also have its own vented drain. Everything passed city inspection.