The claim: facility has renovated, occupied WWII detention compounds and "mock city" that closely resembles Anytown, USA.
What it really is: First, the claim that the sites were World War Two detention compounds (or POW camps) is false. There never were any POW camps there.
As for the claim that the facilities have been renovated, well, both bases are 70 years old, so it isn't surprising that the buildings there are occasional renovated and update from time to time.
There is also no evidence to suggest that the bases have mock cities located on them, and even if they did it still wouldn't mean the place is a FEMA camp, just that it's a place to train in urban combat.