In front of the building stretching about 50 feet was a tunnel, now flooded. Rumor has it that there is an even larger tunnel encircling the perimeter of the facility. I checked google maps at the time and could see evidence for this. I believe the entrance is located in a cooling tower near the baseball diamonds but that facility has more intense locks.

The replica horn I found in front of the "Global Compliance Test Facility" right across from the wave facility. It's not too large (probably the size of a person), but it's very very heavy.