I may have misheard but I'm pretty sure they said that the cemetary dated the plant and that none of the graves were from people that worked at the plant.
The "Ghost Hunters" revealed this at the end after their extensive research via an easy Google search. One of them looked at Don and was like "Oh, hey, yeah, uh so that factory exploded like, uh, well after those people died. OMG, DID YOU HEAR THAT!?" Then he pointed his flashlight at an area where the camera wasn't looking. When the camera turned... nothing was there.
Also, I'm pretty sure that the plant that exploded was once adjacent/connected to the cartridge factory that still stands well behind the park and down the river. Although, there were once other munition plants on land that now occupies KI. I don't think any of those ever exploded though.
One last thing: Don never said that the little girl in the blue dress was connected to the plant explosion, yet the Ghost Hunters seemed like they kept assuming that.
And just for the record - this was a good thing for the park. The B-Roll footage was beautiful, it got the park national attention on a wildly popular show and was fun to watch.
The show is still stupid though.
Yes very good B-roll , and FREE ad time.