Ross Shaft at one-year mark

The five-year project to replace steel supports in the 5,000-foot Ross Shaft began a year ago yesterday, and the crews are slightly ahead of schedule, according to Underground Access Director Will McElroy. In fact, crews set a one-month record in July. ?They installed seven sets of new steel, or 126 feet,? McElroy said.

The Ross Shaft, constructed in the early 1930s, is supported by steel I-beam frames, or ?sets,? every 6 feet. The new tubular steel is assembled in 18-foot sets.

New steel has been installed to just above the 800-foot level. (Crews have actually replaced nearly 880 feet of steel in the shaft. That?s because the 800 Level is deeper than 800 feet at the Ross Shaft. Levels in the Homestake mine were measured from the top of  the Golden Star Shaft, which started at a lower elevation.)

Installing steel is a multi-step process. In the photo, for example, Infrastructure Technician Talon Tucker is using a chain saw to cut or ?gad? rock from a ?rib? in the shaft. (A ?gad? is a rock chisel. ?Rib? is a mining term for a rock wall.) The new steel sets are hung from bearing beams that rest on saddles anchored in the rock. The saddles sometimes require greater clearances than provided in the original shaft, so engineers paint grids on the ribs to indicate where and how deep to gad. ?It?s a precision job,? McElroy said. ?We?re not as smooth as Mount Rushmore, but we?re getting pretty close to it.?

In addition to the special chain saws, like the one in the photo, technicians also use air-driven gadding hammers, jackleg drills and a tool called a ?micro blaster,? which removes small amounts of rock by exploding black-powder charges. ?It?s like a big firecracker,? McElroy said. Barriers prevent rock from falling down the shaft. The gadded rock is hoisted to the surface in steel-box conveyances called ?skips.?

The refurbished Ross Shaft could be used for construction of proposed new underground experiments such as the Long-Baseline Neutrino Experiment.