I need to know how deep on average a residential sewer pipe is, because I believe that mine is ceramic and I don't want to further any damage in attempt to repair. :eek:

Check with local plumbing office, some municipalities require the location and depth of sewer laterals be recorded with their office. The depth will depend on the structure, basement, no basement, and the depth of the city sewer line.

It all depends on local codes and how deep the frost line goes. In Wisconsin the sewers exit the basements at 10 to 12 feet below the ground. In Florlda our homes are on slabs and we do not freeze. Our sewers run 3 to 4 feet under ground. Take Harolds advice and call your building department.
Regards, Tom