I bought this "HUD" house 3 years ago, where someone has poured concrete into the hole in the basement where there was a toilet bowl at one time. I would like to re-establish that basement toilet, but I'm afraid that if I start breaking up the concrete that someone poured in that hole, to seal it off, concrete will fall down into the sewage line.

Would the best way to address this be to cut out that section of the sewage line so I would not have to break up the concrete poured in the hole, and remove the concrete and sewage line without breaking anything up?

Is there a backflow preventer that is an intergral part of the sewage line? If not, why not?