Penetrating containment wall of a hydrocarbon tank?

11Echo,
In my opinion and experience both the earthen dike and a concrete "wall' dike can be penetrated with one or more pipes for tank filling or pump suction.

The way we did it in my time was to encase the product pipe inside a larger sleeve pipe. For the purposes of this description lets say we have an 8" product pipe and a 12" sleeve pipe. The double pipe set-up penetrated the dike wall or berm of the containment area. The outer sleeve pipe was long enough to extend and clear the containment wall or slope of the berm. The end of the 12" sleeve pipe at the outside of the containment had a standard 12" slip-on flange welded to the 12" sleeve pipe. The product pipe had a 12" x 8" reducing slip-on flange welded to it. Depending on the angle of repose of the berm material the product pipe had one or more guide lugs welded to the outside of the pipe to center the inner pipe in the sleeve. The product pipe is slid through the sleeve during construction and is field welded to the balance of the dike area piping. The end of the sleeve pipe on the end inside of the containment area is open.
The double pipe sleeve is normally installed with a slight down slope toward the inside of the dike area so any leaks inside the sleeve will drain out into the containment area.
For concrete wall installations a round collar made from a piece of flat steel plate should be welded to the sleeve pipe to anchor it to the center of the wall.

I hope this is all clear.

I do not understand "So a rubber seal may or may not work."
The end closer we used was a steel flange w/gasket.
As for the 8" wall I would look at pouring a short section with added thickness at the point of penetration. This should be tied into the existing wall and act as an anchor block.
Think about it. It would be better than complicating the pump suction line profile.