"I've talked to people from cities where they have a lot of snow. They don't usually lay the rock salt down until snow has started to fall. In Philadelphia, we've started to lay it down a day before the snow even starts."
Mayor Nutter's press secretary, Mark McDonald, said that Streets Commissioner David Perri last month contracted with an engineering firm to study the issue of alternative deicing materials.
"What precipitated that action were the very low temperatures and concerns we may have more weather like that on a regular basis, and the fact that the current kinds of rock salt we now use does not perform well below 20 degrees," McDonald said.
Kenney said the practice of using the rock-salt compound has detrimental effects on the environment, on young people and on pets whose paws can become irritated by the mixture.
Although it's unclear what costs would be associated with using an alternative melting solution, Kenney said his research shows too much rock salt ingested can cause liver and pancreatic failures in animals, and the compounds sodium chloride, potassium chloride and calcium chloride have long-term, known corrosive effects on roads, vehicles and underground utilities.
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