Salt is driver-friendly in winter but harms roads and the environment. For now, short-term public safety comes first.
More than 24 million tons of salt is spread on American roads each winter with the intention of making them safer.
But there's a price to be paid for that improved safety.
All that salt is taking a toll on those roads and the environment as it eats away at roads and bridges and runs off into streams, rivers and lakes.
As scientists express growing alarm at the collateral damages of de-icing, transportation officials are looking at ways to reduce or even bypass salt use. But for now, it's still the most affordable and readily available material to clear roads, transportation officials said.
“I would love to find that silver bullet, a non-salt-based product that works very well. But until we find something else, we will be as cognizant as we can about our impact to the environment as we manage the safety of the public and perform cost-efficiently,” said Jon Fleming, chief of the maintenance technology leadership division of the Pennsylvania Department of Transportation in Harrisburg.
The problems with salt: Degraded infrastructure
Salt doesn't disappear with the snow and ice. Salt that remains on roadways degrades pavement and bridges. Washington State University professor Xianming Shi estimates the country spends $5 billion a year on infrastructure damages caused by road salt.
Salt also degrades pipes that carry drinking water, causing lead contamination in places, according to research.
And salt, over time, can leach calcium from concrete in bridges, roads and sidewalks, thereby weakening them, researchers say.
Salt also eats away at cars, corroding and rusting the undercarriage and other exposed metals at an annual cost of $3 billion to car owners, according to AAA.
Environmental costs
The environmental effects of salt use include the increased salination of water and soil.
Pamela Silver, a biology professor and aquatic biologist at Penn State Behrend, monitors salt concentrations in water and snow on the Harborcreek Township campus, which is bounded by the busy Bayfront Connector. Salt used to clear the highway and the campus itself is adding to the salt content of the water, Silver said.
Salt content in the water and snow, measured by the water's ability to conduct electricity, at times has reached conductivity levels of 20,000, or 40 times higher than it should be, Silver said.
“Fresh water should be in the 500 or lower range,” she said.
Streams on campus flow into Four Mile Creek and ultimately into Lake Erie, the major source of drinking water for 272,061 Erie County residents.
“I've seen credible estimates that if we don't reduce salt use, in 50 years there won't be potable drinking water in the northeastern United States,” she said.
The salt also degrades aquatic habitats and soil's ability to sustain plant life.
Still, there's no easy alternative to salt, Silver said. Some de-icing compounds, including nitrogen-based solutions, also have negative effects on the environment.
“Salt is a hard problem to solve,” Silver said. “On both sides of the equation, you have human health and well being. In the short term, there's traffic safety, the danger of slipping and falling, and all sorts of health risks related to slipperiness.
“On the other side of the equation, in the long term, there are changes to soil, water conductivity, water becoming a very poor habitat for aquatic life and the organisms that depend on it,” she said, and drinking water already is scarce in many areas worldwide.
“As a scientist, I deplore the use of salt,” said Silver, who is Behrend's associate dean for academic affairs. “As a campus administrator, I know why they have to use it. We can't have students, faculty and staff falling on the ice.”
The benefit of salt: Affordable public safety
PennDOT is aware of the long-term effects of salt on infrastructure and the environment. But it's also responsible for keeping highways and streets safe.
“It's a very serious consideration at PennDOT, so much so that we have staff here who deal with winter full time, 24/7, 365,” PennDOT's Fleming said. “They basically work on training aspects so that everybody who plows for us, whether temporary or full time, receives some level of training to use the right material for each winter event so that we start to reduce our environmental footprint.”
The department tries to balance safety, environmental considerations and cost, Fleming said.
“We find ourselves balancing what is an acceptable, safe highway versus how making it safe impacts our environment, then how to take the tax dollars we receive and use them the most prudently,” he said.
The best material to melt snow and ice depends on road and air temperatures, how fast snow is falling and other factors.
Salt brine, a liquid salt mixture, works faster than salt and under certain conditions can be applied before a storm to prevent snow and ice buildup. A New York State Department of Transportation study in 2014 found that four times more salt is needed to remove ice after it forms.
“A secondary effect is that brine makes salt sticky,” Fleming said. “Instead of hitting the road at 45 mph and bouncing and flying everywhere, brine has the tendency to stay in place on the road surface.”
Brine, though, is not effective as long as salt.
“We looked at running 100 percent brine on roads but found the same thing that (other) studies found, that it's not the greatest option because it doesn't last long enough. Salt makes it last longer. It's the combination of both that we really like,” Fleming said.
"We're truly trying to use the least amount of salt for the safest road,“ he said.
The comparatively low cost of salt is a major factor in its use. Alternative de-icers made from beets, cheese brine and other agricultural products cost between four and 10 times as much, according to Temple University researchers.
“On top of that, it has to be shipped. And because it's heavier than water, only 4,000 or 5,000 gallons can be shipped at a time,” Fleming said. “We use over 11 million gallons of brine solution a year. If we were to purchase that amount, it's going to be far more expensive, even just to transport it.”
Most of PennDOT's county maintenance offices, including the Erie County maintenance office in Summit Township, make their own low-cost salt brine.
Down the road: No easy answers
Compounding the problems with salt is that state highway departments aren't the only ones using it. Municipalities, private contractors and individuals also spread salt to clear roads, parking lots, driveways and sidewalks.
On top of that, the public tends to focus on immediate needs for de-icing rather than the long-term consequences of salt use, Silver said.
“I don't see how to balance the equation right now unless we take responsibility and change our habits,” including providing interior walkways between buildings in future construction, salting some walkways and closing others, and even wearing appropriate footwear, Silver said.
“But you know how likely that is,” she said.
Kyle Bagenstose of USA Today Network contributed to this story.
Valerie Myers can be reached at 878-1913 or by email. Follow her on Twitter at http://www.twitter.com/ETNmyers.
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