I want to add a bathroom to a bonus room upstairs. My options for tying into the main drain in the slab are not good. Looks like the best thing is to run a drain down through the garage busting up the slab and then tunneling over to a closet that is 10ft away and then bust up the slab again. The main drain is underneath the closet. If I try to run the line through the attic I will not have enough slope on the line since it will be about a 35ft. run. Has anyone performed any tunneling like this before and can a DIY perform the task?