Kent Barnard is a road-salt aficionado. He is also a public relations expert for the Minnesota Department of Transportation, tirelessly striving to let you know that much is being done to keep your automobile out of the ditch this and every season. If breaking news about all kinds of alternative de-icers and road sensors kept him busy last winter, there’s something about MnDOTs errands that transcends all seasons. “We’re always ready,” Barnard. “If it snows in July, we could get out there.”
Widely reported to be yellow, the darling of new de-icers this year was a corn based product from Minnesota Corn Processors subsidiary Glacial Technologies. This space-age compound can push melting points down to 40-below zero Fahrenheit. This winter, it was tested on the Lafayette bridge in St. Paul and two other undisclosed metro locations.
Still, the largest story by weight is salt. Because salt has, over the years, saved so much of the time that might have been spent prayerfully greeting loss of traction, riding in tow trucks, and sipping burnt coffee in body-shop waiting rooms, it deserves consideration in proportion to the hundreds of thousands of tons MnDOT keeps on hand.
Each year an average of 200,000 tons of rock salt are
applied to Minnesota roads. That amounts to about 102 pounds annually for each vehicle registered in the state. This is certainly a large amount, but as a percentage of body mass, it compares favorably to the 10 pounds of salt the vehicle’s driver can expect to consume over the same period. So called “nutritional salt,” though, is less likely to contain sodium Ferro cyanide. (Barnard says this anti-clumping agent is not nearly as nasty as it sounds).
Still, however you cut it, 200,000 tons is a lot of anything, and while this writer has no idea how many times it would circle the earth if each grain was laid end to end, it’s quite true that if the annual dose were dissolved into Lake Superior, it would become more saline than the Atlantic Ocean in less than two years.
While no one at MnDOT has proposed the salinization of Lake Superior, road salt does go somewhere after it’s done its work on the pavement. George Hudak, Assistant Professor of Geology at the University of Wisconsin-Oshkosh, has discovered chlorine levels in fresh surface water that can’t be explained any other way. The environmental implications are not necessarily clear, but, Hudak speculates, “It’s not so good for your steel canoe.”
Most commercial rock salt began as efflorescent deposits from evaporated prehistoric oceans. In order to form the massive domes of halite from which it is mined in Michigan, Kansas, and Louisiana, Hudak says these evaporates must spend millions of years compressed under millions of tons of rock. Being of lower density, it gradually pushes up through faults toward the earth’s surface, where Cargill and Morton lie in wait for the harvest.
Salt had been established for millennia as a fundamental element of political and military force. The Roman empire, known for its roads if not for the salting of them, nonetheless coined the word “salarium” (salary) from the occasional use of salt as payment to soldiers. Hundreds of years later, Marco Polo reported watching Roman authorities mint salt-cake coins bearing the emperor’s seal. The power and influence of Danish kings was once estimated by the amount of salt each guest could expect at a feast.
By these standards, King Jesse Ventura is a mighty lord indeed, with his sovereign rule over 292,000 tons this year alone. But before he is duly venerated, forget not the kingdom that lies to the east. Wisconsin reportedly treats its roads with as much as 700,000 tons in a single year, says Kent Barnard.
Barnard and Hudak speculate that the “lake effect” accounts for Wisconsin’s larger share of the salt pie. Yet it may be worth noting that Wisconsin’s inhabitants, according to the Beer Institute, consumed an estimated 1,165,251 more barrels of beer than Minnesotans in the year 2000. Even when adjusted for population that’s more than a third of a barrel more per person. Which raises the possibility that Wisconsin roads merely seem more slippery.
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