It is not good to have a main transformer sink and tilt. They are connected to the plant by brittle conductors, and thin, buckle-prone steel work. As the recent Japanese earthquake showed, transformers tend to blow up during earthquakes.
We finally noticed one day that this transformer had sunk 7 inches over 30 years and was still sinking and tilting. There was no easy explanation since this was on highly compacted granular material, which does not settle.
When I found out about this, I imposed myself on the project people who wanted to have nothing to do with me! In the course of my investigations, I talked to the original engineers (retired), and read all the old reports. I concluded that the basement sump pumps had tapped into an old dewatering well, and were pumping 300 L/per minute. This was more than enough to seriously settle the general geology, much like New Orleans, or Mexico City.
As usual, I found myself in severe conflict with the Powers. I recommended that they use helical piles, but they went with an outside company who did grouting at 10 times the cost of piles. As of this writing, the transformer is sinking worse than ever.