Worked NG 35 years it is safe if not tampered with. Sounds like System was tampered with maybe to circumvent a terminated line! Depending on the age of the line electrolysis could be a factor in an underground line!
Or when I was a kid a family went out of town over Christmas holiday and left a burner on not ignited and it blew an apartment building up and killed 7. But that was 50 years ago.
Thanx.
we see these stories now and then, unfortunately.
I just wonder why a neighbor would make a call or knock on a door, if they continuously smelled gas. I guess I’m old school.