Oil Tank with Cracked Ring Wall Foundation

[Connor Lewis]

I'm hoping you storage tank wizards can point me in the right direction.

Got a gun barrel tank here, built back in '91, holds a whopping 1600 cubic meters of liquid, measures a 43 feet in diameter, and no earthquake in the region. Sounds impressive, right? Well, except for one thing - the cracks in the concrete ringwall foundation. I've attached a picture of the crack for reference.

What are the possible causes of these cracks?
What are the recommended repair options for this situation or it should be replaced?

 

[JStephen]

That's a new one for me.
Those are some funky anchor bolt chairs.
Were the anchor bolts post-installed? How deep do they go in?
What was the sequence of the cracking relative to foundation construction and to anchor bolt installation?
Any chance of a cold joint there when the ringwall was poured? Or has it been repaired by topping off at some point?
You can have some soil/concrete reaction problems, but I would expect that to be down in the soil, not at the top.
Does the tank temperature vary much? Any freeze/thaw cycles?