Q.can I plant rosemary and/or garden sage over septic tank
I am building a patio next to the septic tank. I can’t cover the septic tank with concrete (if something goes wrong with the septic system, I will need access). So I thought I would make an herb bed but I don’t want the roots to invade the tank.

Certified GKH Gardening Expert
The roots won't invade the tank. Herbs have pretty shallow roots. That being said, there are some other consideration to take into account. This article explains them:
https://www.gardeningknowhow.com/edible/vegetables/vgen/gardening-over-septic-tanks.htm