Hello, I have found many answers over the years here, but now my search has come up a little empty, so I registered for my first post.
Finishing the basement, which was roughed in for two full baths via ejector pump. The existing plumbing on the upper two floors uses a single 2" vent line, no other vent lines anywhere on the roof, so no dedicated vent put in for the ejector pit. The pit is not convenient to any chase or void to the roof without demolition, although it is adjacent to an exterior wall. The main 4" drain running horizontally across the ceiling of the basement (and then to the septic) has, near the end, one 2" clean-out in a relatively horizontal position which I assume is the place for the pit discharge, and then a 2" vertical line which I assume is vent.
I have learned under no circumstance should the pit use an AAV, and rightfully it should have a dedicated roof vent. But, given what I have, what is the lesser of the two evils: using the 2" vent line (along with all the new basement drains) or running a 1" vent out the adjacent exterior wall (basically at street level)?