It’s been an active winter in the First State, weather-wise. There was last weekend’s bomb cyclone and massive snowfall, not to mention the also-rare snow and ice storm at the end of January. Those storms prompted driving restrictions from state officials, both to keep drivers safe and to give DelDOT some time and space to clear the roads.
Clearing those roads means using salt - a lot of salt. For the late January ice storm, for example, DelDOT put some 15,743 tons of salt - in various forms - on the roads, about 700 semi trucks full of salt. And while that salt keeps the roads safe, it does come with an environmental cost.
“Salt seems like it's not such a big deal, but really it can be, especially for sensitive plants and sensitive aquatic ecosystems," says Holly Michael, University of Delaware Professor of Earth Sciences and Civil and Environmental Engineering, and director of the Delaware Environmental Institute.
She says one problem with salt is that it’s persistent. Long after the ice and snow are a thing of the past, and we’re back to wearing short sleeves and eyeing a beach trip, the winter’s salt is still going to be there, lurking unseen.
“It's not just that maybe we'll have extra salt for a couple of weeks during the winter when everything is dead," she says. "No, this actually persists during the summer and from year to year.”
She notes there is evidence that using salt on the roads is having an effect on the environment.
"There are studies that have shown all over the United States, salt levels and streams have been increasing over time, and particularly in cold places where we use a lot of road salt," Michael says.
So the salt is there, and it’s going to hang around. What does that mean for the animals and plants around us?
“The organisms like amphibians and things like that are really, really sensitive to salt levels. And so even if it's low enough that maybe we could even still drink it, it can affect the organisms,” Michael explains.
It isn't just amphibians, however. Salt can also get into our drinking water.
“Even at lower levels where you can't quite taste it yet, especially for people who can't take in a lot of salt, that can be a major health issue," Michael says.
And then, there are the effects on the fragile coastal ecosystem, already under assault by rising sea levels.
“That's a major problem all along our coastlines. But if you then add salt that we're just adding to the system in addition to sea level rise and all the other things that are happening, then it just makes the problem worse," she says.
All of this is something that DelDOT, the agency responsible for those trucks and plows that ply the state’s roads after - and sometimes during - snowstorms, is all too aware of. The environmental impacts of the salt they use mean that DelDOT has to think past the asphalt.
“We're really trying to find that happy medium where we're getting roads cleared as quickly as possible without just overusing salt that can ultimately have negative environmental impacts and impacts on our infrastructure," says C. R. McLeod, DelDOT’s Director of Community Relations.
There are ways to mitigate salt use, Michael says. One way starts on the salt truck itself.
“Just having the right technology on the salt trucks so that they're putting the right amount of salt on," she says. "Just enough to make sure the roads are safe but not so much that we're really killing the environment.”
McLeod says that’s something already in place on DelDOT trucks. Their salt spreaders can be controlled by the driver, letting them control how much salt is being dumped. McLeod says that just makes sense.
“The whole idea is we want to keep the salt on the roadway so it does its job, and it's not just bouncing off onto the shoulder, into the grass, and then ultimately into the ground," he says.
But if you really want to cut down your salt usage, McLeod says, you’ve got to use brine - those thin white lines you see down the middle of the road before the snow hits..
“It's a diluted rock salt, so it's about twenty-three percent rock salt and seventy-seven percent water," McLeod explains.
Brine, he says, has environmental and economic benefits.
“It sticks to the roadway when it's wet, so the salt isn't just bouncing off the road and then getting into the environment," he says. "It's also cost-effective as well, because it takes four times less salt.”
He adds that the brine keeps water from freezing, giving DelDOT plows more time to clear the roads.
Meanwhile, the next time snow and ice hits the First State, whether it’s this winter or next, the salt trucks - loaded with rock salt or brine - will roll, as DelDOT and environmental advocates keep a wary eye on the effects.
