What's the story on the sonotube wrapped in the sheet poly (in the foreground; far right); is there some reason for that?
Well, up here the frost usually sets from 2 to 4 feet into the ground every winter.
If you put a bare sonotube into the ground, the water in the top few inches/foot or so freeze first... And that includes and penetrates into the nice, wet, waterlogged sonotube and the cement column inside it.
When the NEXT foot or 3 freeze, they expand 10% or so as they do it, underneath the already frozen top layer (and the rather firmly locked into that first layer support colum), lifting it up. Maybe only a fraction of an inch to an inch. And in the Spring, the column never quite settles back... And every year after, same thing happens. As the upshot of all this frost heaveing/less than 100% settle, your nice, properly leveled support columns slowly get spat out of the ground. Due to natural variations in soil and water content, they NEVER get raised and lowered equally. So your structure gets all kinds of misalignment and wracks, and continually LEVITATES. When a cargo container with 70,000 lb. of contents gets wracked, the doors stop working. So you go out to pull a fireworks show for New Year's Eve, open the doors- And need a locomotive jack, shims and much profanity to close them again.
There are TWO layers of 4 mil polly wrapped around that sonotube. The polly is quite smooth and slippery, as well as breaking the ice layer, which does not extend through it and into the cardboard/cement. So the 2 layers will slip past eachother as the soil heaves, leaveing the column pretty much where we put it, resting on the subsoil. If we measured correctly and had the container set higher than the frost heave pushes any of the other soil under it, after all the frost melts in the spring and things settle down, the whole outfit is (usually) still properly aligned and leveled as we intended.
The things I have learned while all I really wanted was to blow S#$% up...