Here are two pictures.
First is the street where the city sewer line runs. My house is about 15' behind the fence.
This is inside my fence.
You can see the elevation change and the trees. If I do need a new connection, I'm pretty worried about avoiding serious damage to the tree roots.
The main stack in my basement is roughly 25' from the corner of the house that is shown in the second photo.
I wonder if the new line - again, if one is needed - can come from the house toward the street, turn 90 deg, run in my side yard parallel to the street, then turn and come down the stairs down in the first photo. This would avoid as many trees as possible. My gas line runs there, though.
Edit: maybe directional drilling would solve the tree issue. Certainly seems better than trenching.