Do those big blocks have to be there? Anyway, I'd probably put those blocks behind and above, rather than directly above them, then run two I-Beams horizontally underneath (going from left to right, not front to back), with some vertical support columns bolted to the floor and beams and ceiling. And possibly put a walkway up there next to the tanks, since it seems that maintenance would have to go up there regularly (though if there are only flying ponies working there, I suppose walkways aren't needed...just platforms.
Good job so far. Storage tanks usually have meters and such on them, and valves along the pipes to help control, direct, and/or isolate the flow of whatever is inside the pipes. If anything, I suggest valves on the elbow right before it drains into those vats, valves on the pipes right before it enters the top of each tank, and large valves right after each vat on the large pipes. And then a capacity meter per tank, and probably a pressure meter on the face of the tank or in the pipes that feed into the tank. If that's too much for you, well...this is an industrial facility, where components are basically the same throughout
So it's really just where you make one valve and copy and paste it everywhere, re-sizing when needed. If a pipe line connects to another pipe line (where it could branch off in more than one direction), there would usually be a valve right after each branch so that the direction of flow can be controlled, as well.
