re: #474 Anymouse πΉ
My wife is watching YouTube videos on home tornado shelters. They debunk every βreasonableβ suggestion (modified culvert pipe, modified septic tank, &c).
All of them fail for interior space and cost. Engineers suggest building your own.
I would think burying a section of culvert, and and sealing one end while fashioning a steel bulkhead & door on the other would work