How? In our case the thing got a fair amount of press. It’s also close enough so we saw construction happening. But the trick is they lied about what it was/is. During construction they called it a testing facility for optical sights. But as the details trickled out, as with the big generators, and the deep water wells, they gradually hedged what it was for. Then they admitted they never tested anything.
All of these projects start out as lies. One has to watch for construction projects and look at the details to see what makes sense. Note that they are NEVER part of a regular military facility. Wouldn’t want to be a natural target, doncha know? It helps to be knowledgeable about construction, hardware, supply systems, etc. to be able to spot stuff that doesn’t ring true. It also helps to watch the money: If a County is putting up a new building, for example, how much Federal money, if any, is involved?