A Thanksgiving holiday trip over the passes sparked that question when my husband and I spotted that big yellow-green harbinger of winter, a state Department of Transportation (DOT) anti-icer truck.
Jeff Adamson, DOT communications manager for the North Central region, said most of the calls he receives on this subject are from people worried about the effects on their vehicles, not the vegetation. But he has answers to questions on both.
First, the environment. Adamson said research along Blewett Pass essentially determined that regardless of how much de-icer or anti-icer is applied, by the time it reaches creeks or rivers it is not measurable. Environmental agencies encourage the use of de-icers rather than sand, Adamson noted, because if sand gets into a stream it can block the air flow through salmon egg beds and the eggs won’t hatch. For that reason, the DOT does not use sand at all in Tumwater Canyon.
Brown branches on trees near the roads are the result of “plow trucks throwing a 40-mile-per-hour curl of snow and ice,” and not anti-icer, Adamson said. “If you look at the back side of the tree, those branches are fine.”
A Forest Service scientist has suggested that chemicals made airborne by big trucks may be damaging branches on trees above the roadway but that damage is “extremely limited,” Adamson said. And with forests already hit hard by spruce budworm and in an unhealthy condition, well, it’s hard to say.
Now about your car. “After a trip over the pass, when you can, as soon as you can, wash the vehicle,” Adamson said. The chemicals, when mixed with water, are corrosive and should be removed. (Below freezing, he said, it doesn’t matter because the chemicals are inactive in frozen water.)
Anti-icers are liquid calcium chloride, magnesium chloride or inhibited salt brine, applied to a bare road before a storm to prevent a hard bond of ice from forming, to reduce the amount of snow buildup, and to speed snow and ice breakup after a storm. De-icers are liquid or solid calcium chloride, magnesium chloride, sodium chloride or inhibited salt brine, applied to remove a thin layer of snow or ice already on the road. It can also be used to prevent black ice and freezing rain from adhering to the road.
Although transportation officials do not make claims about reducing accidents, Adamson said they’ve been able to document that chains have been required less often since using anti-icers. Average winter speeds on Blewett Pass from 1990-99 were about 45 miles per hour, compared to nearly 60 miles per hour today.
Please drive safely
Ice and snow, take it slow (WSDOT)