This year in Cleveland the snow left early. But most winters the city uses 60,000-70,000 tons of salt to make winter driving less hazardous. Maybe you've wondered where all that salt comes from. Some of it is mined from huge underground deposits on the Gulf Coast. There are also salt mines in Kansas and Utah. But most of the salt that's dumped on northern highways comes from ancient salt beds under the Great Lakes. 90.3 WCPN's Karen Schaefer reports.
Karen Schaefer- It looks like any other industrial site in a busy, Great Lakes port. Pick-up trucks cluster around warehouses, while railroad cars and semis stand ready to receive their loads. But working here is not at all like working in a factory. To get to their jobs, workers at the Cleveland Salt Mine make a daily descent nearly 2,000 feet straight down.
Deep beneath the earth lies a bed of salt 60-feet thick. It was formed 400 million years ago by the drying of an ancient sea. Limestone and shale deposits later buried the bed. Retreating glaciers left the Great Lakes on top and the salt remained a hidden asset until the 1950's. That's when miners dug a 1,750-foot shaft down into the salt from an island in the city's harbor. From here, a vast honeycomb of underground rooms stretches three and a half miles out under Lake Erie.
Shawn Wilczynski- ...You can stack the tallest building in Cleveland in here twice and still have extra room. So that kind of gives you an idea of how far you're going down beneath the surface...
KS- It's a world most people will never see. More than 400 miles of underground roads link rooms of salt where giant machines lumber in near darkness. It would be easy to get lost in this city of salt. But for mining engineer Shawn Wilczynski, heading to the salt mine is all in a day's work.
The Cleveland salt mine produces almost 2 1/2 million tons of salt a year. It's the same salt that appears on our tables. But rock salt has too many impurities to use as food. The mining cycle begins with nightly blasting to loosen new salt. Miners bore holes for explosives in the rock face or cut deeply into salt near the floor. In the morning loose salt is scooped up and dumped into machines that break it into smaller pieces. From there the salt is taken by conveyer belt to an underground mill for processing. Then it's hoisted to the surface in huge production elevators -- or skips -- that carry 20 tons of salt each trip. It's noisy, salty work lit only by headlights. But for supervisor John Good the mine holds a special fascination. He's worked here for 22 years.
John Good- Every day you come to work, you know, and you're underneath Lake Erie. Quite a bit of time, there were fishes swimming through here, you know, and now it's being mined out for rock salt for highways. And I say I work at a salt mine and I'm swamped by entertainment. Everybody wants to know what you do.
KS- Mine safety is carefully monitored at the Cleveland Salt Mine. Huge fans direct fresh air into the farthest working sections and blow exhaust gases back out. Miners use other machines to scale loose salt from roof and walls to prevent rock falls. As in any mining operation, workers brace the roof with bolts spaced a few feet apart. But Wilczynski says salt is different.
SW- Salt always has a small amount of movement to it. It's almost impossible to stop, because it's kind of an elastic type of rock. Whereas other stuff will just fail quickly because it's brittle, salt is more of a ductile thing. It will actually creep and move on you a little and it's difficult to stop.
KS- Because of salt's tendency to bend rather than break, miners leave about half the salt behind. Between the rooms, huge salt pillars support the roof of the mine. This room and pillar system of mining rock salt has its roots in prehistory. But what man takes away, natural forces replace. In 1994, part of a similar mine in upstate New York collapsed. Officials thought an earthquake had taken place. Parts of the Genessee Valley caved in and surrounding homes and farms were swallowed. The mine had to be abandoned. Government experts agree that the failure of the Retsof mine was a unique event, unlikely to be repeated elsewhere. Shawn Wilczynski says that's good, because the Great Lakes salt mining industry is growing. Wilzcynski says the Cleveland mine is growing at a rate of twenty feet a day in every working section. As old sections are mined out, they're closed off to help with ventilation. But Wilczynski says there'll probably still be miners here when his children are grandparents. In the Cleveland Salt Mine there's enough salt for hundreds of years of years to come. In Cleveland, Karen Schaefer, 90.3 WCPN, 90.3 FM.