A Radioactive Transportation Puzzle

[VERNIG.PETER@FORUM.VA.GOV]

Group,
I live about five miles South of Rocky Flats Environmental Center or
whatever they call themselves now.  As I was waiting for a light on 
the road that goes North past the flats, a semi drove by.  The trailer was
what I would call a rock or dirt haulter.  Cross section a rounded 
rectangle.  Usually open on top but they can [and usually should] have a
canvas tarp top pulled over the load to keep things from bouncing out
and dinging windshields.  I'm sure you've all seen this type of trailer,
though my description isn't to good.  They are used to haul dirt, rock
sand, agregate, rubble, etc.  Now the puzzle.  It had a small white
with black lettering sign that said "For Radioactive Materials Use Only".
 
Anybody got any clues?  I'm just curious.  As far as I know Rocky Flats'
Pu contaminated materials is all in drums and I don't know of anything
going on out there that would use a truck like that.  Ft. Saint Vrain is
done decommissioning, I think and I can't see why a truck from there would
be on that road.  
 
Oh BTW the trailer was apparently empty.
 
Peter G. Vernig, VA Medical Center, Denver
 
Please reply to vernig.peter@forum.va.gov