With heavy snow, rain and then ice earlier this week, around western Massachusetts and throughout New England, many store shelves are empty of rock salt or de-icer. Even municipalities are running short.
In Chicopee, Massachusetts, a multi-day delay of 40 tons of salt based de-icer mucked up the street clean up.
Several city trucks were sent earlier this week to Albany, New York, to pick up tons of "common rock salt" from a state vendor, said Mike Pise, chief of staff to Chicopee Mayor John Vieau.
It's not uncommon for municipalities to turn to the state when there's a shortage of "material needs," said a spokesperson from the Massachusetts Department of Transportation.
"After this weekend’s weather event MassDOT is beginning to experience the effects of the road salt supply issues," said the spokesperson. "The scale of our statewide snow and ice program provides us with the flexibility to shift materials between depots as needed to ensure roadways remain safe. MassDOT will continue to monitor supply levels and respond to road conditions accordingly.”
Why salt?
Salt, NaCl, sodium chloride — whatever you want to call it — in the Northeast this winter has been a critical component for ice-free roads and walkways.
"When you dissolve a solute, or what we call an ionic substance, or something that dissolves easily into water, it lowers the freezing point," said Massachusetts State Geologist Brian Yellen said.
It's basic science.
"Whereas fresh water freezes at 32 degrees Fahrenheit a solution of salt and water is going to only freeze at a lower temperature," Yellen said.
When it comes to municipal needs and road networks, salt may strike that balance of effectiveness and cost to keep cars from careening off the road.
Salt and environmental concerns
With salt use, there are environmental issues Yellen said, "so we need to balance the safety of drivers with the protection of the environment."
Road crews around the U.S. use millions of tons of salt a year to treat roads, according to the Pioneer Valley Planning Commission, and New England relies heavily on salt applications during the winter.
"The use of salt on roads leads to the potential for artificially high salinity levels in local surface water and groundwater resources and can be harmful to human and environmental health,” the PVPC said in a FAQ sheet.
A de-icing salt application may be essential for winter travel and public safety, according to a New England interstate commission in addressing water quality, NEIWPCC, but it comes at a cost.
"We know we are pumping a lot more salt into our rivers, lakes, and streams than we used to, and this is having negative results on aquatic ecosystems and our drinking water," said Christina Stringer, the director of Wastewater and Onsite Programs at NEIWPCC, in a recent article.
On a smaller scale, NEIWPCC and others recommend get ahead of the ice, by removing snow and only using salt as needed, and not when temperatures are below 15° F.
Some communities are looking to eliminate or lessen the use of road salt adjacent to drinking water areas.
In the city of Westfield, salt brine is put on roads — ahead of storms. City officials recently let residents and motorists know they "can expect to see Westfield [Department of Public Works] crews pre-treating the roads with salt brine using specially modified tanker trucks or units that mount to the plow truck. Most of this equipment is capable of spreading salt brine over one, two, or three lanes of pavement."
Similarly pickle juice has been used on roads in New Jersey.
The salt we eat v. the salt we throw on the ground
The salt we sprinkle on fries has to be pure enough to eat. It might come from a salt mine or ocean water, and then be processed into something for humans to consume.
For better and for worse (health) it's the "ultimate condiment," according to NPR's The Salt.
"It's the only rock we eat," writes The Salt, "and it makes our food taste better. There are dozens of varieties, from hand-harvested Himalayan pink to plain-old kosher, to various herb-infused blends.""
But for road salt, geologist Yellen said, we don't need high levels of purity "and so we can use a variety of different geologic formations where salt was deposited in ancient oceans.
In the past, in different climates and tectonic settings where small, ephemeral seas would completely dry up, Yellen said, "similar to how at the bottom of a salty puddle you might see a little rime of ice, in the bottom of these ephemeral seas that would have dried up hundreds of millions of years ago, you could actually get a really thick accumulation of salt that ultimately becomes a geologic layer in sedimentary rocks."
Use molasses or maybe beer
Some environmentally friendly options for small icy areas, like driveways and sidewalks, are byproducts from brewing beer and molasses, suggested Yellen.
Historically for traction, municipalities used coal ash Yellen said, "although that has all sorts of environmental problems associated with it."
In the northeast, Yellen explained not so much in terms of a highway official but as a geologist — sand is typically used.
Because "we have abundant sand from the legacy of glaciers," Yellen said.
