Overuse of salt can cause damage to concrete, steel and the environment. (Photo by Lester Graham)
Each year about 118,000 people are hurt and 1,300 people are killed on
the roads during snowy and icy conditions. So, snowplows hit the
roads, scraping snow and ice off the surface… and spreading
incredible amounts of salt on highways, streets and roads to help keep
them clear. Lester Graham reports there’s some concern about the long-
term effects of all that salt:
Transcript
Each year about 118,000 people are hurt and 1,300 people are killed on
the roads during snowy and icy conditions. So, snowplows hit the
roads, scraping snow and ice off the surface… and spreading
incredible amounts of salt on highways, streets and roads to help keep
them clear. Lester Graham reports there’s some concern about the long-
term effects of all that salt:
This dump truck is getting ready for a load of salt for a coming
winter storm. Salt helps make icy roads safer. It helps prevent
people from slipping and falling on sidewalks. And… it’s pretty
cheap. But there are problems with salt. Salt pollutes and salt
corrodes.
Mark Cornwell has spent a good deal of his career trying to convince
highway crews that there are better ways to keep things safe and reduce
how much salt is dumped on roads and sidewalks:
“Salt basically damages just about everything it comes in contact
with. Salt moves through concrete and attacks structural steel,
bridges, roads, parking structures; it eats the mortar out of bricks
and foundations. It damages limestone, you know, just on and on and
on.”
So, even though salt is cheap, the damage it does costs a lot. It’s a
hidden cost that’s seldom calculated. Imagine the cost of having to
replace a bridge five years early because the structure is weakened by
salt. And then there are your direct costs: trying to keep salt
washed off your vehicle, and still seeing rust attack your car.
Cornwell says there are some cities and road commissioners working to
reduce the amount of salt spread on the roads. But in most places, the
political pressure to get the salt trucks out early, and laying it on
thick to keep drivers happy, outweighs any concerns about trying to
reduce the salt:
“I’m sure the public expects full attention to snow and ice. And they
have absolutely no understanding, however, of what it costs to provide
that.”
Nobody thought a lot about the damage salt was causing until the last
couple of decades. In a few places, the people responsible for keeping
the roads and walkways safe have been trying to reduce the amount of
salt they use and still keep public safety tops on the list of
concerns:
“So, this is our shops. The brine-maker is right here.”
Marvin Petway is showing me some of the tools in his arsenal to reduce
how much salt is used and still keep things safe. He works at the
University of Michigan, where there’s a goal to cut the amount of salt
used in winter in half. What they’ve learned is using innovative ways
of putting down salt can actually help melt snow and ice faster. One
way is to mix it with water to get the chemicals in salt working
a little more quickly:
“Why use 5 pounds of rock salt when you can use 2 gallons of liquid
salt? We’re able to get better coverage, quicker, better cost, and
we’re putting the material that is effective in reducing ice build-up
directly to the area where we don’t want ice located.”
The crews trying to reduce salt use computer assisted spreaders to
measure out only the salt needed, they mix in less corrosive chemicals
that make salt brine more effective, and even just wetting the salt in
dump trucks with chemicals all help to melt snow and ice faster and in
the end use a lot less salt.
Nothing is going to replace salt altogether, but those efforts can add
up to a lot less salt. That means less destruction of infrastructure.
But there are more reasons for reducing salt than the damage to
roadways and parking decks. Salt also damages the environment:
Mark Cornwell first noticed the effects of salt because he was a
horticulturalist. He’d work all spring, summer and fall planting
shrubs, make the grass green, tending beds of flowers. Then the winter
would come:
“Unfortunately what we were doing in six months of winter was
undoing everything we did in the other six months of the year.
If you’re going to get ahead, you’ve got to solve the problem
and in my mind, that was misuse of salt.”
Use too much salt and it kills plants. And it turns out the cost of
using all that cheap salt could be even greater than anyone guessed.
For decades, it’s been assumed that rain washed away most of the salt, but
studies in Ontario find that a lot of the salt doesn’t get washed
away.
Instead, a good deal of it is percolating down into shallow aquifers.
Researchers predict that in the future we’ll start find salt is getting
into the groundwater that supplies many of the wells where we get our
drinking water.
For the Environment Report, this is Lester Graham.
