RE:Some engineering sketch about a baseThis is what I would do.
Buy 2 to 4 new towers. Build a new base close to the original base. Erect a new tower on the new base. Transfer the head assembly to the new tower. Take down the old tower and re-erect it on a new base at another windmill. Repeat 100 times. They should be able to re-use the old towers.
I'm trying to imagine what could have gone wrong with the foundations. The news report mentions crack propagation. One source of this could be expanding aggregate. I wonder if they used a similar aggregate as was used in the Mactaquac Dam?