Near Experimental HallDig This!
In mid-November, workers began excavating the underground facility by digging a pit layer by layer.
A drilling rig gouges out rows of 40-foot-deep angled holes into the walls
of each layer.
Steel anchoring rods are cemented into these holes to support the structure. Shot-cretea sprayable concreteis then applied over a welded-wire mesh to form a solid wall.
Excavators then dig the next layer and the process begins again. When complete, the open pit will be four stories deep.
SLAC Today, December 1, 2006
Images courtesy of Bob Law.