After two rounds of testing on a handful of ice-fighting products, the city of Spokane will continue to use liquid magnesium chloride de-icer on its winter streets, even though it contains trace amounts of polychlorinated biphenyls, or PCBs.
According to the testing and analysis done by the city, the de-icer has the lowest PCB levels of the six tested. It’s also cheaper, and less is required to melt ice.
The de-icer was called into question after City Council President Ben Stuckart was told the product contained the cancer-causing PCBs, a compound that was produced by Monsanto. Last year, the city sued Monsanto for producing the compound and polluting the Spokane River.
Apart from the lawsuit, the city has a 2014 rule that says “no department may knowingly purchase products” that contain PCBs.
But after the city had six different de-icing products tested for PCBs and delivered the results to the Public Works Committee this week, Stuckart said he is supportive of sticking with the city’s product, which is called FreezGard and is produced by Compass Materials. Magnesium chloride is a naturally occurring salt found in the ocean and ancient sea beds. In Spokane’s case, the product is mined near the Great Salt Lake in Utah.
“It doesn’t quite reach the levels we require if you’re testing the water, but it’s the lowest out of all the options,” Stuckart said. “And it uses the least amount of product. With salt brine, you have to double the amount you use.”
According to Mark Serbousek, the city’s streets manager, the city has used 700,000 gallons of the liquid de-icer each of the past two winters. The city has about $1.3 million budgeted for the product each year.
In December and February, the city collected samples of three liquid de-icers: magnesium chloride, calcium chloride and sodium chloride. Three solid de-icing materials were also gathered: sand and two types of road salt.
The liquid magnesium chloride had the lowest concentration of PCBs at about 0.0004 parts per billion. Road salt from the city’s stockpile had the highest concentration, at 0.025 parts per billion. The current surface water quality standard is 0.00017 parts per billion, according to a briefing paper for the Public Works Committee.
The city’s street department tested not only the PCB levels of the products, but also their effectiveness in melting ice, ease of use and cost. According to the results, magnesium chloride and calcium chloride performed equally well, but magnesium chloride is 33 percent cheaper to purchase. Road salt used by the Washington state Department of Transportation needed greater amounts to fight ice, and it did less to prevent the ice from re-freezing.
The city tested the products’ performance and contracted with a company to analyze the PCB content of the six products. Two labs were used during that testing: the Pacific Rim Laboratory in Vancouver, British Columbia, and Vista Analytical Laboratory in El Dorado Hills, California.
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