Cheap Salt Trumps Environment
by Lloyd Alter, Toronto on 03. 2.08
Tara Wilson Toronto Star
Road salt "burns trees, chokes vegetation, and contaminates soil. It depletes water of oxygen, and is toxic to many fish. Salts also accelerate the corrosion of automobiles, roads, bridges and sidewalks." Yet Toronto dumps 135,000 tonnes of it on the roads each winter. Why? It's cheap. There are alternatives, some made from sugar beets or corn, that are used in New Jersey, Colorado and Ohio, but they can cost up to ten times as much.
All that salt is getting into our creeks and streams, but the City refuses to release data on it, telling the Star that it is still in "raw" form. Environmentalists are appalled. "It's this odd situation where people are expecting to be able to drive 110 km/h [65 mph] on all-season radials, which are not suitable for the road conditions, because they assume enough salt has been laid down to make them safe," says Kevin Mercer, the founder of Toronto-based watershed group Riversides who has studied road salt use in Ontario. "There's a tendency to use salt exclusively. It's ridiculous and it's going to have to change." ::The Star
Ever since high school history classes I've wondered about this: historic invasive armies would salt the fields of the people they were invading so no crops would grow. How long before we've loaded enough salt into our own soil before we see the same effect?
Somehow throwing food onto our streets doesn't sound like a great alternative. Not only do we still have the pesticides and fertilizers but it helps drive food prices up more.
Other alternatives would be sand, gravel or ground up glass which can be swept up and used again.
In theory, couldn't solar hot water heaters be used to keep roads free of ice? i.e, hot water heating pipes ran under the road surface.
This would be impractical for roads, I suppose, but may work for heavily used bridges and overpasses.
the local country doesn't use salt, but it rarely freezes for more than a day or so here. They use sand, and in a few instances, a non-salt chemical deicer (no idea what it is though)
First, Iceland uses geothermal heat to keep the roads clear of ice ... but they are in a unique situation, as far as geothermal heat is concerned.
But, my biggest question is why doesn't Toronto use sand? It has to be as cheap as salt ... or at least close to it.
Salt disolves over time, which is one of the reasons it is popular. Sand doesn't. In Minnesota we use a mix of salt and sand.
Salt disolved in to the water from the melted ice and snow and is basically sprayed everywhere as cars drive through it. A lot of it ends up on cars and it later washed off.
Sand isn't as good as salt for road ice. It also does not disolve and ends up slowly turning shoulders, curves, and ramps in to slick spots almost as bad as the ice itself. For citites to use sand, they need to go back at the end of winter with street sweepers and collect it back up. If they don't it ends up become both a road hazard as well as clogging storm drains (sediment).
There are bio-firendly chemicals that have been tried by to MNDOT, but they do not work as well and cost 5-10 times more per ton. One thing the tried a few years back was a chemicl made from pig droppings, it worked but the smell was terrible ad it made people sick.
One thing about salt that is a minor bonus, the nearby soil to the road it incapable of supporting plant life which reduces the amount of spray used in weed control.
-Lego
the problem with using sand is that it results in massive sedimentation, with the potential of clogging sewers, whereas salt dissolves.
besides, a large portion of the "salt" used nowadays is not table salt - sodium chloride - but calcium chloride, which has lesser adverse effects on vegetation.
the problem with using sand is that it results in massive sedimentation, with the potential of clogging sewers, whereas salt dissolves.
besides, a large portion of the "salt" used nowadays is not table salt - sodium chloride - but calcium chloride, which has lesser adverse effects on vegetation.