RE my comment above: I have not looked at the proposed site map or at the map where the toxic plume had been identified years ago. It was not that easy to get a clear answer about where the plume had ended up then or if the gov thought it was still spreading. So when I said _it is not clear_ above, it was not totally clear to me from the RG article. I have not done any original research recently. I assume that some testing could be done before proceeding with the project. 
Perhaps hemp could be used for soil remediation. It is being used in other areas.