Graham In a town near where I live a underground car park was built with huge slabs of foam in the base
A burst 12 inch water main has flooded the foundations turning the carpark into a car crusher as the blocks float up lifting the floor with them

I nicked the pictures from my local newspapers site and twitter
http://www.kentonline.co.uk/dartford/news/cars-crushed-as-flooded-car-103807/