I had wondered if perhaps it had some relevence to the Dwyer Hill JTF2 training facility, but considering how battered the sign is, it's more likely related to Area 9 to the Southeast (see http://coord.info/GC46ERN for more info on Area 9).
Satellite imagery shows there are several buildings and at least two antennas in place.
Is Area 6 still active? I have no idea, but the "No Trespassing" signs on the gate across the road appear to be new, as they were not shown on the September 2014 streetview imagery.
The cache is listed as a micro, but it's actually larger than a micro and smaller than a small.
When placed, the cache contained a combined log roll and stash sheet.
Bring your own pen or pencil.
August 16, 2015: Since placing the cache, the Area 6 sign has either fallen down or has been removed.