PVC plastic pipe was used with rebar inside 600×600 mm holes, although the approximate depth isn’t shown I would say to get someone to work it out for you on the weight your putting on top as well as the strength of the ground your sitting upon to reduce risk of movement.
Setting a string out across the top of the PVC also allows leveling off before pouring to make sure the containers going to sit properly. In these they were then poured with concrete on site in place 8 holes and pipes taking 2 days to complete.
Another good idea they came up with though will working on this is that if the ground is level and you wanted to make all the posts in one go (Which also means you can do this and transport them to where you need if restricted on materials for concrete).
- You take one piece of PVC piping and cut to length
- Then cut it in half
- Rivot a piano hinge down the one side
- Add 2 luggage clamps to hold it together
Hey presto you now have a jig for making the posts saving money on PVC pipe and not only that if its tall enough you can use it for what they are now which is concrete fence posts.