If nothing inside the home was altered you should not be getting a smell. Personally I'm confused as to why the repair person would have left the original line there and ran another one through a new hole. I would have pulled the old line up, ran the new line (in PVC) and used the same hole in the septic tank instead of creating a new one. Did he seal up the hole in the tank from the old line?
We contacted Best Plumbing Service of Cincinnati to have the sump pump and the outlet pipes checked as our basement flooded recently and we were not sure whether the sump pump malfunctioned or the outlet pipe was blocked. Both plumbers did a fantastic job looking over the system, diagnosing, and fixing the problem. They were extremely honest, courteous , and professional. We are very pleased with their outstanding service and would very highly recommend Best Plumbing Service of Cincinnati. M Effat