We have a 20’x40’ custom-version of the Shipping Container model on our 200ac Family Farm. Dad & I built/installed it 12ft underground.
http://www.atlassurvivalshelters.com/aboutus/nbc/
This is the best-built unit on the market and can be customized very easily, to whatever config a person wants to do with it.
Wow, I’d LOVE to see that! I bet y’all are prepared. I salute you. Not even up to your level yet.
A couple questions I have after looking at that site- how do you plan to get rid of the waste water and sewage? Is there a pump out feature? How safe is the air filtration? Can it operate during flooding or a range fire (for example)?