I asked the plumber again today why he couldn't jet the pipe to get the grease out. He said that where the grease was located, they couldn't jet from the outside cleanout and if they jetted from under the kitchen sink, that it would pull the grease back towards the sink instead of outside. I asked him if there were any other options to get the grease out and he said you could use chemicals, but that since the pipes were ABS and under a slab that it might cause more issues. If the jetting won't work, what other options do I have? What are your thoughts on this?