Aspen puts mag chloride on ice
Aspen will go with the lesser two of three evils to keep its main streets clear of snow and ice this winter.
The City Council, presented with conflicting recommendations on which de-icing chemicals to apply to the streets, agreed Tuesday to continue its ban on the use of magnesium chloride and apply a considerably more expensive alternative.
The city quit using mag chloride in February, 1988, citing concerns about the effect of chloride in the Roaring Fork River and its tributaries and the potential health effects associated with the use of mag chloride.
A subsequent state study that involved Aspen air samples appears to link mag chloride use to an elevated risk of cancer, though the city’s environmental health director concedes the analysis was hardly conclusive.
“I, for one, looking at this study, cannot justify saving $50,000 when there is a potential health risk to our citizens, to our kids, to our guests, to anyone else,” said Mayor Rachel Richards.
The city used sand and an alternative de-icer, CMAK, all last winter with unsatisfactory results, according to Jack Reid, superintendent of streets. The snow-packed streets led to a multitude of complaints.
The city uses de-icing agents on Main Street, in the downtown core and on bus routes.
“It is the opinion of the street department that CMAK is pretty worthless,” Reid said of the agent, a liquid mixture of calcium magnesium acetate and potassium acetate that does not prevent the bonding of ice to asphalt as effectively as mag chloride does, he said.
Reid pushed for resuming the use of mag chloride, barring more convincing evidence that it is dangerous. Lee Cassin, director of environmental health, disagreed.
A study of air samples from Aspen, Denver and Pagosa Springs indicates an increased risk of cancer as the result of various heavy metals present with the use of mag chloride.
The study found arsenic, cadmium, chromium, barium and manganese in Aspen’s air when mag chloride was used, at levels considered higher than acceptable thresholds.
According to the study, the safe level is one case of cancer resulting from exposure to each metal per one million people. Aspen’s cancer risk for chromium was 36.30 cases per one million people, according to the study. For arsenic, it’s 2.45; for cadmium, it’s 3.77; for barium, it’s 2.41; and for manganese, 1.77.
“That means a child growing up in Aspen and exposed to those metals would have an increased risk of cancer,” Cassin said. “I think the bottom line in the study is we should be very concerned.”
However, she added, the number of samples considered in the study was so small no firm conclusions can be drawn from it. The results are inconclusive at best, she said, and at worst they indicate mag chloride puts carcinogens in the air.
Reid said he believes the results are inconclusive. Exposed mine tailings all over town could put heavy metals in the air whenever the wind blows, he said.
“I think there are too many variables. If we’re going to ban it, then we should know why we’re banning it,” he said. “I’m not convinced at all, personally, that mag chloride is harmful enough not to use it.”
The Colorado Department of Transportation apparently believes mag chloride is safe, noted Councilman Tony Hershey. CDOT uses great quantities of the de-icer on highways and interstates.
“Where is the proof that this stuff is dangerous?” he said.
“There’s no proof,” Cassin responded, “but the evidence from that study is concerning.”
Ultimately, Hershey agreed that the city should “err on the side of caution.”
“We’re picking our poison here,” said Councilman Jim Markalunas.
In the end, the council directed Reid to use a combination of CMAK and sand mixed with sodium acetate pellets – an alternative Snowmass Village has used with success instead of mag chloride.
The cost will be somewhere between $50,000 and $100,000, Reid estimated. The cost of a year’s worth of mag chloride is about $4,275.
In addition, the city needs a new street sweeper, at a cost of about $140,000, especially since it will use more sand with CMAK than it would with mag chloride, Reid said.
The use of sand contributes to another Aspen pollution problem – high levels of particulates in the air.
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