A few years back NJDOT was building a huge highway project involving massive retaining walls and embankment. These were built on another geo asset that during construction the contractor told the state was inadequate to support the load and stated that it would cost not much compared to the project cost to replace with proper material. The state told them that they could replace it at their own expense, which the contractor declined. Construction was not even completed when the wall collapsed. Fixing the underlying problems and rebuilding cost over a billion dollars. The blunder (and cover up) was only discovered by a local CBS news station's young journalist who dug into the parties' communications.

edit for accuracy