I just spoke with a brother who volunteers on security on the site, he told me there is lots of earth moving going on but its top secret.
He said they think there is something big being built underground at the site, and thats why most volunteers had to leave, there is only 30 or so left, the security volunteers are not allowed near the main project they have to stay in the forest areas.
Most volunteers had to leave as they are not ready to proceed with any significant building works. The design team are working on changing plans so they don't build what they no longer need. As pointed out in another post removing the contaminated soil involves earthworks. Even if they are building something in the ground I wouldn't get too excited. It will not be a secret underground bunker.
I've not had the first hand conversation re what security volunteers can/can't do but the fuel, oil, battery fluids and other chemical contamination is not something you want to come into contact with. The control mentality is so strong inside the org that they everything has to have rules and a hierarchy associated with it.