Cast Iron piping under concrete filled with dirt
Our house resides on a ranch, a 4 inch slab of concrete. The full bathroom is located directly straight from the access area on our front lawn (sewer). We had a problem with water backing up there, so we had roto rooter snake it, which relieved the problem. But we were still experiencing bubbles coming back up through the toilet when the washer was running.
The washer and kitchen are on the opposite side of the house from the bathroom. While remodeling the kitchen/washer area, we noticed the vent pipe going out would be a good idea to put a 1/2 bath, flange right by the vent, and about 5 feet away is where we'd put the sink (hot/cold water already there, cause that's where the water heater is)
So we cut through he cememt where the vent pipe is, dug the pipe out and cut it. Unfortunately the pipe was completely packed with dirt, this is 3 inch cast iron. Even more surprising is that it has a 2 inch pipe heading directly towards the sink, away from any water flow. This pipe also was filled with dirt. Again we were fairly surprised that a pipe would be heading that way, it doesn't seem to go anywhere. So we're assuming now the kitchen connects in where the washer is, and they both flow by the master bathroom. Going round this 2 inch pipe. Which is OK except for the fact the washer/kitchen/master bath have little to no air flow going out the vent.
Our idea is to cut down the cast iron vent pipe (also goes through attic), replace that and the tee with PVC. For the tee/flange area, we then would rent a 50ft auger from HD and snake that towards where the washer/kitchen piping passes by.
This make sense? We've done plumbing before, but obviously the dirt through a wrench into what would be a straight forward toilet area. Also what the heck is the 2 inch piping going to? Since it's dormant, we were thinking of capping it.
Any ideas would help!