You are thinking of the wrong target. If the bunker is 150' underground, the entrance(s) are still on the surface. HUMINT is required to find them. The SBDs can close them. MOABs can keep them closed but are unlikely to be used in a builtup area. Once they are closed in the initial attack, imagery can indicate the efforts to open them and re-attack via cruise missile or TACAir keeps them closed. AFAIK there is no PROVEN way to get to a well-built facility that deep from the air. But you don't really need to either.
Understand.