Richmond cofferdam, we barely knew ye.
River Swale: 1. Overconfident workmen: 0.
(It was so clearly not going to hold up to any serious amount of water. And it got a serious amount of water. Note to designers of future cofferdam: make a very elongated length of dam going upstream at an acute angle so the water glances off rather than hits it obliquely. That way, your dam might hold up to a bit of water..)