Pro Plumbers

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?
When a person has a blockage in their sewage system they often try to fix it themselves by adding an acid or a base such as Drano in an attempt to dissolve or dislodge the problem. These chemicals can get into the plumbers eyes [14]when the sewage is splashed during the repair. The plumbers skin during the repair does come into contact with the sewage water.[15] The owner of the toilet might not report to the plumber they have already tried Drano a highly caustic base .