Inorganic rock?I've got the main. It's 3 inch that goes into a soft corrugated section. Will uncover the mesh point and pull the corrugated section off and look both ways.
I ran into alot of in organic rock up to 120 feet from the house.
In the pipe?
Is the main clay tile? If so that corrugated section is probably a repair of a broken clay. Or someone has previously done what you are doing…
Corrugated tile can really slow down the flow of thicker “liquids”, but grey water should be fine.