I'm think now the smell was coming from a leak from the sewer connection when they hooked it up. Probably in the soil that is in pile now.
The Abs elbow 90 degrees then a female connector to the 4' sewer pipe with the rubber gasket. The female being smaller perhaps slipped off by the soil sinking, maybe a car or truck drove over the lawn.
Haven't notice the smell for a while. I think it's gone.
The open septic has no smell so i guess no problem. How could there be after 10 or 20 years?
I suppose there will be lots of soil left over from this excavation so just as well to put in the old tank now.
Last edited by Jungle; 07-01-2014 at 12:43 PM.