Unless you were to scratch and sniff a newly patched pothole, you wouldn’t necessarilyrealize what a dirty little business it is to mend the road ruptures.
You also might not know that a new “green” industry is popping up to reduce environmental hazards, while resulting in pothole repairs that are durable and cost-effective, according to satisfied customers at highway departments in other regions of the U.S.
Traditional cold-patch asphalt mixtures, which are used in winter to fill potholes, consist primarily of stone, sand, a liquid to bond the ingredients as well as petroleum products and other substances that are known human carcinogens.
Thousands of gallons of diesel fuel, kerosene, naphthalene and other petroleum derivatives run off into the environment or evaporate into the air when the coldmix asphalt hardens. The toxic substances are needed to keep the patching material pliable while it is being placed into potholes and tamped down to bond with the existing pavement.
Looking for a cleaner way to go, some transportation agencies are monitoring experiments with alternative materials in other cold-weather climates in the hope of reducing emissions of pollutants to safeguard public health, animals and plants.
At least three manufacturers of cold-mix asphalt that contains safe, biodegradable materials instead of traditional oil-based chemicals approached Chicago officials over the winter offering samples for the city to test.
“This is the first year we have been contacted by the ‘green’ manufacturers,” said Brian Steele, spokesman for the Chicago Department of Transportation.
One ton of conventional cold-mix asphalt contains about 5 gallons of petroleum derivatives on average, according to industry experts. Some of it runs off into sewers, seeps into the ground near roads, leeches into lakes and other waterways or evaporates.
In Chicago last winter, about 400,000 potholes were filled from December 2007 through April, according to CDOT.
That means an estimated 43,000 gallons of petroleum derivatives were “spilled on Chicago streets,” said Warren Day, chief of quality control and product development at Cofire Industries, a Flushing, N.Y., company producing a new environmentally friendly cold asphalt mixture.
Day based his calculation of 43,000 gallons of fuel products used on CDOT disclosing that it put down 8,600 tons of conventional cold-mix asphalt during the five-month period.
Cofire’s product, called GreenPatch, uses biodegradable plantbased solvents instead of fuel, said Glenn Shapiro, chief of product development and marketing.
New York City and others on the East Coast have awarded Cofire contracts to provide GreenPatch.
“We got the New York contract strictly because we were the low bidder, not because GreenPatch is better for the environment,” Shapiro said, adding that GreenPatch has a low vapor pressure, which minimizes the production of ozone.
Consolidated Edison Co. of New York has been using GreenPatch for six months to repair pavement that was cut for utility work, officials said.
“I was very suspect at first, but it sets up beautifully and stands up to Manhattan traffic as well as the stuff we used in the past,” said Mark Sullivan, field operations planner for Con Edison.
“The cost is about the same, maybe a dollar more per bag. But for a buck more to save the environment? It’s a home run. We are developing a pilot program to make GreenPatch our stock material,” Sullivan said.