That's been around for 20 years or more, apparently there's iron sulfide in the coarse aggregate that was used in the concrete, and over time the water and air has caused it to oxidize and the foundations to crumble.
The quarry operator is the one responsible for that, testing should have found the mineral before it was released from the pit.
The quarry operator is the one responsible for that, testing should have found the mineral before it was released from the pit.