Originally Posted By teddy12b:
An additional concern I have is that if I ever experimented with this it'd be in sandy soil near a river. In that case the in the event of a flood, I'd want as much air out of the container as possible so that the air wouldn't bring it up like a bobber. Obviosly I wouldn't experiment with this kind of thing where it would intentionally flood, but it could happen in certain areas and it's something else to take into consideration.
If I'm correct the standing rule on getting below the frost line is 3' or more. I think digging 3' or more of frozen dirt out during the winter would be a major undertaking and a pain in the arse, but if that's what you have to do you could always make that happen. Might be a good time to have a camp fire on top of the area first, if possible.
I wouldn't bury in a flood plane. Flood waters are POWERFUL. It is also hard to simulate a flood, unless you bury it in a river bed during the fall, and look for it after the spring melt.
Also, if my thinking is correct, removing the air from the container will lower density, thus causing MORE of a 'floating' action. You would want to increase the density: use lead shot or such to weight it down so it won't float. Things don't float due to air, things float due to density differences in a fluid.