As the state Department of Transportation, municipal public works departments and squads of private companies battle the relentless snowstorms of the last few weeks, there is an ongoing secondary storm over what they use to clear their roads.
For several years now, truckers in particular have complained here and in other snow-belt states that the extremely effective salt compounds in wide use the last decade or so for snow and ice removal are corroding vehicles faster than the older methods of sand, or sand and salt.
Not everyone agrees.
In fact no one agrees on much except that there is corrosion – on infrastructure like bridges and roads as well as on vehicles.
Whether it’s worse is debatable. Among those who think it is, there’s plenty of disagreement over what the cause is. As for what to do about corrosion, there are countless opinions with very little science yet to back up most of them. And that’s not to mention the mostly unknown environmental impacts of all of the above.
The whole stormy mess prompted legislation in Connecticut last year to study the problem. The Connecticut Academy of Science and Engineering (CASE) is on the case, pun intended. But the results are not expected until mid-spring, long past any possible impact on this season’s snow removal efforts.
The Other White Stuff on the Roads
What we’re talking about here are salts: sodium chloride, magnesium chloride and calcium chloride. They corrode metal. No dispute.
They also do a great job clearing snow and ice.
“There’s a reason every single winter-weather state is using salt,” said Kevin Nursick, spokesman for the Connecticut DOT, which switched from sand to salt combinations to treat its roads around 2007, among the last of the snow-belt states to do so. “There are zero cost-effective options for any DOT other than salt and the additional chlorides.”
They work by lowering the freezing point of water – sodium chloride to about 20 degrees Fahrenheit and the others down to single digits. Depending on the type of storm, the DOT may use a salt brine that’s 75 percent water and 25 percent sodium chloride to pre-treat certain surfaces, like bridge decks and inclines, that have more problems with freezing.
Once snow is plowed after a storm, the DOT will use rock salt for melting, or combine it with a 30 percent concentration of liquid magnesium chloride. For every lane mile of road, the DOT generally applies 250 to 300 pounds of salt and one gallon of the magnesium chloride.
It’s the magnesium the trucking community points to as the corrosion culprit.
“We don’t deny the fact that magnesium chloride does a very good job of keeping the snow and ice down on the highways,” said Mike Riley, president of the Motor Transport Association of Connecticut, a trucking advocacy group. “But there is an unintended consequence that is a big issue for the people that I represent.”
Riley and others in the trucking industry point to corrosion around brakes, electrical components and the frames of vehicles. But with magnesium chloride concentrations that low, many doubt it’s the culprit in Connecticut.
In Maine, the DOT protocol for snow removal uses roughly the same ingredients, though in different concentrations and configurations. The University of Maine has also studied road snow and ice removal, much as CASE is now.
“When people say it’s those liquids you’re putting down, I just laugh,” said Brian Burne, the highway maintenance engineer for the Maine DOT, who conveyed his experiences to the study committee at CASE. “I don’t deny that they’re seeing it. But I think we need to step back and take a hard look at their trucks, how they’re made.”
He’s not the only one who thinks so.
Some say trucks are not as well made as they used to be. Some point to too many seams, especially between dissimilar metals, that act as entry points for salt. Many point to a specific change in the anti-corrosive coatings used in cars as well as trucks.
Hexavalent chromium was commonly used as a coating for brake lines, electric systems and other vehicle components. If it sounds a little familiar, it should. It was made infamous by Erin Brokovich, who helped expose it as a carcinogen. Her effort was later immortalized in the movie named after her in which Julia Roberts starred.
Vehicle manufacturers stopped using hexavalent chromium about the same time the use of road salts ramped up, leading some to believe there may have been an unfortunate confluence resulting in greater corrosion.
“It’s definitely possible,” said Chelsea Monty, a professor of chemical engineering at the University of Akron, a leader in corrosion engineering and home to the National Center for Education and Research on Corrosion and Materials Performance. Monty also provided information to the CASE study.
Monty and her colleagues at Akron have been studying road salt and corrosion. She said what happens is the tough, hard rock salt will hit the vehicle as well as road and bridge surfaces and begin to put little holes in vehicle coatings and concrete, just the way sand used to. That lets the salts seep in, eventually corroding vehicle components. On infrastructure, once the seepage gets down to the steel reinforcing rods, the whole structure is in jeopardy.
Truck-maker Freightliner said it had eliminated hexavalent chromium from its vehicles. The replacements, it said, are now as good or better. Trailer-maker Great Dane said it too had replaced the small amount of hexavalent chromium it used.
“We have seen more corrosion and evidence of the increased use of aggressive corrosion-causing road chemicals on roads in the past 15 years,” said Charles Fetz, Great Dane’s vice president of design and development, in an email response. “Our perception is that road chemical issues have gotten worse in the past six to eight years.”
Monty said one of the biggest problems with salt is that it sticks to surfaces. “So even if you wash it off,” she said. “Some stays.”
But washing is still considered key to preventing salt corrosion. It’s what the Connecticut DOT recommends to truckers. The questions are how and with what?
Anti-Corrosives, Neutralizers and other Solutions – the Wet Kind
One thing is for sure – you shouldn’t power-wash vehicles. That just pushes the salt deeper into crevices.
Many snow removal operators use salt-neutralizing chemicals or organic compounds when they wash vehicles. But with proprietary formulations, it’s a little hard to know what’s in them. Even so, Monty and her team found many of them ineffective.
“We found neutralizers used at concentrations manufacturers recommend you wash at are not high enough concentrations,” she said. “They can do more harm than good.”
If salt is not washed off entirely and an anti-corrosion coating is then sprayed on, it seals the salt in, making the corrosion worse, not better.
Another common attempt to lessen corrosion is made by adding anti-corrosive substances to the salt mixtures. Some of them are chemicals – but favorites include sugar-based products, including beet juice, corn syrup and molasses.
“We don’t really know if they prevent corrosion,” Monty said. “What works in one state in one kind of weather condition on one kind of truck may be different in another state — even district to district we see differences.”
In New Canaan, highway superintendent Mose Saccary said about five years ago he switched from using sand on his 250 lane miles to a pre-mixed salt, magnesium chloride and food-grade molasses compound. He also uses salt neutralizers on the DPW’s trucks.
“I’m not seeing any heightened corrosion on the vehicles,” he said. “But I don’t think the product prevents rusting.”
He thinks the sugar helps melt the salt and its stickiness keeps the salt in place on the road instead of letting it bounce around. That way, Saccary said, he uses less salt.
In Washington State, Jay Wells is the DOT’s statewide superintendent for maintenance operations. He’s also a board member of Pacific Northwest Snowfighters, an organization that partners with a 30-state research group called Clear Roads (Connecticut is a new member at $25,000/year) to come up with the best methods for snow and ice removal.
Wells uses, and swears by, the sugar-based anti-corrosives.
“They’re a waste stream product that, after everybody’s got the good stuff out, they’ve got this yucky stuff left over, and they re-ferment it and process it, and they found out that it takes the corrosiveness out of the chloride,” he said, admitting he doesn’t know why. “But we do know that they work.”
Connecticut remains unconvinced after experimenting with beet molasses for a couple of years. “We saw no benefits to our equipment,” said DOT spokesman Nursick. ”And we saw a lot of clogged injectors because of the goopiness of the stuff.”
One of the biggest unknowns about everything – the salt, the anti-corrosion materials, salt neutralizers and even the spray-on coatings – is what happens once it lands on the ground. Early indications are none of it is particularly good for the environment.
The Connecticut DOT – and others – like to point out that one big advantage salt has over sand is that it doesn’t clog drains, catch basins and water bodies, that then need to be cleaned out. Nor does it leave dusty residue that needs to be removed from roadsides.
“Generally these products that we are using now are superior for the environment,” Nursick said. “Are they good for the environment? Probably not. Are they better for the environment than the sand-salt mixture that we were using? Yes.”
But the DOT, which is responsible for 10,000 lane miles – handles far less than half of the state’s roadways. The rest are handled by municipalities that use a hodge-podge of snow removal protocols – including sand. And then there are untold numbers of private snow-removal contractors handling things like parking lots. It’s anybody’s guess what they’re using for deicing, whether they’re using it properly and whether they’re handling other aspects of the operation according to state regulations, like how salt is stored so it doesn’t leach into waterways.
Another question is how to handle and dispose of water used to wash down trucks. The Department of Energy and Environmental Protection has rules for that, designed to keep salts and the anti-corrosion and salt-neutralizing solvents from winding up in the ground or water.
It’s probably safe to say the DOT is properly capturing salt and solvent-laden water cleaned from its salt spreaders. And most major trucking firms have washing facilities that do the same. But Oswald Inglese, director of DEEP’s water permitting and enforcement division admitted DEEP has no way of knowing how many such facilities there are, that there is a likelihood others may not follow the rules as well, and that there is an even bigger likelihood that municipalities and private contractors are using snow clearing and anti-corrosion products DEEP doesn’t know about.
“Absolutely,” he said. “Maybe we should have a little bit more transparency with how much they’re using and how they’re applying it.”
The small amount of research that does exist is sounding some alarms. Steven Brady, as a graduate student in evolutionary ecology at Yale University a few years ago (he’s now doing post-doctorate research at Dartmouth College), looked at two species of amphibians in roadside water bodies in northeast Connecticut to see how they might be handling what was in the runoff.
The first thing he found in the water was a lot of salt.
“I was absolutely shocked by it,” he said. “In that region I expected very low concentrations of salt.”
He found the spotted salamanders he was studying had adapted somewhat to the salt, but the wood frog had not. In both cases survival rates were lower.
“It buys us some time from a conservation perspective,” he said. “But it doesn’t give us the go-ahead to continue business as usual.”
More worrisome he said, is that we know there’s a limit to the amount of salt they can withstand. “But we don’t know what that limit is.”
It also made Brady wonder how well the two species would handle another environmental change on top of the salt, or multiple changes such as those from other snow removal products like chemicals, soaps and even the sugar-based products – natural though they might be.
The sugar products “might be better for corrosion; they’re not necessarily better for streams,” said Margaret Miner of Rivers Alliance, one of the only environmental groups paying attention to issues related to snow removal. “The nutrients are just like pouring fertilizer in.”
That’s because as the sugars decompose and are consumed by bugs and bacteria, they gobble up oxygen, depleting it for everything else and causing problems like algae blooms.
“It can do harm for years or decades before people figure it out,” Miner said. But, she quickly added: “We don’t want to be in a position that people should have terrible car accidents to save our streams.”
What to Legislate?
Two years ago, the Motor Transport Association’s Riley was pushing to get rid of magnesium chloride altogether.
“Yeah, well, we had a bill in to do that because it’s more dramatic,” he admitted. “And before we knew much about it.”
The problem now, he says, is that DOT says wash it off, and DEEP says not to wash it off without proper disposal of the waste water.
“The Department of Motor Vehicles sees the defects and gives us tickets for those defects. And then when we go to get the expensive repairs done, the parts and labor are all sales taxable,” Riley said.
He’d like to see legislation allowing DEEP to back off enforcement of rules for washing the undersides of trucks. He’d like the DMV to point out corrosion violations, but not ticket truckers if they are road-salt related. Truckers would still have to get them repaired, but Riley would like to see the sales tax for that waived.
Monty at the University of Akron said the future she sees is customized processes for states and even smaller areas while establishing methods to monitor for corrosion in vehicles, roads and bridges. Everyone is going to have to give a little, she said.
“I’m not suggesting that they stop using it,” Riley said. “I mean I’m no fan of it, and no trucking company is going to tell you it’s great stuff, but it does work well on the highway.”
“It’s a double-headed dragon,” he said.