1) There is some evidence of some contamination with some hazardous materials. This goes as far as evidence from medical exams and autopsies, which originate from outside the base and aren't secret. They've been presented in court.
2) Some people think that some of the work done at the site has been moved to other sites. Note that I am not saying that this happened.
3) I think it's plausible that (1) might have led to (2), if (2) happened.
There is evidence of some workers being exposed to hazardous materials via the use of open burn pits, there isn't (AFAIK) evidence of the test facility itself being contaminated or unable to be used etc..
But more to the point, you're still not providing any clarification about what you're referring to re: these claims being made...
"Some people think that some of the work done at the site has been moved to other sites."
Who? Who are these people? Do you have a link?
You've referred a few times to there being a plausible hypothesis or allegations being made but you're seemingly unwilling or unable to link to these allegations/claims, why is that?
Is it something you've read on a conspiracy website or something and now don't want to link to? Is it something you've made up yourself? If not then why not just provide some clarification. I've not asked you to provide a complete proof that this is defiantly true etc.. I'm asking you where this hypothesis/allegation has come from.