Before it makes it to the main building, however, the rock must be mined by about 20 people on each of the two shifts. No bats make their homes in the tunnels. For that matter, nothing lives where the workers are. Before their descent, each visitor received a belt equipped with a battery-powered light and a respirator, which could be used in case of an emergency. The respirators provide about one hour of air, something the tourist didn't need to use.
Fresh air is pumped through the veins of the underground maze.
Safety is the main emphasis at the plant that is one of the most efficient in the U.S. Gypsum's corporation, Smith said. Workers wear all the needed equipment and know where the emergency escape is located. Routes are marked by fluorescent red paint. Pegs on a board keeps track of people underground. Visitors, too, have a special marking on the magnetic board.