I had a septic tank cave in at my house in Baton Rouge. I won't drive over it with anything. Admittedly, that one in Baton Rouge was metal. Most are concrete.
I know where mine is here, from drought periods browning the grass. I don't drive over it. Prefer not to even walk over it, but I have to mow the grass. Do it walking behind my Lawnboy, nude: less weight.
Ralph