Napa Valley Register, 14 October 2011
The city of Napa hopes to pave the way for Northern California when it comes to green paving techniques.
On Thursday, the city held an on-site workshop for public works directors, council members and other decision makers from cities and towns throughout the Bay Area to show them an innovative way to lay asphalt on Golden Gate and Freeway drives in southwest Napa.
The process, called cold-in-place recycling, has been around for about
35 years but is just making its way to Northern California, according to James Emerson of Pavement Recycling Systems, Inc., the Riverside-based company doing some of the work.
Municipal officials watched a machine that dug up pavement, chewed it, then extruded a strip of asphalt as smooth as a baby’s bottom.
“I think this is going to be a big start for Northern California,” Emerson said of the process credited with emitting 80 percent fewer greenhouse gases than traditional paving methods. This method is used widely in Southern California, he said.
With cold-in-place recycling, about four inches of the existing pavement is ground up, crushed and mixed on site with emulsifying agents before being laid and compacted back onto the roadway from which it was taken, said Marlene Demery, a city special projects manager.
“We’re using our streets as our own little urban mine,” Demery said. “We’re mining our own material out of the street.”
Demery said there is nothing wrong with the rock on Napa’s deteriorating roads so it can be reused.
“They’re able to take the roadways that really have a quality product and grind it up rather than going out and looking for new places to quarry road base,” said Napa Mayor Jill Techel, who praised the swiftness of the work. “It’s taking a resource and maximizing it and it’s probably a better quality than if we went out now and got something that was recently quarried.”
Had traditional paving methods been used on the 1.5-mile stretch along Freeway and Golden Gate drives, between 60 and 80 trucks would have been used to haul away the old pavement and bring in new pavement, Demery said. With cold-in-place recycling, only one truck is needed to bring in oil, along with a few pieces of equipment necessary to complete the on-site work.
“If we were to have done it using conventional means, it would have been about three times as expensive as this,” Demery said, adding it also would have taken longer with traditional methods.
“If we were going to do this road conventionally, this probably would have taken three to four weeks,” Demery said. “We’re going to be done in two days.”
Some who attended said they hope to bring cold-in-place recycling to their municipalities.
“We have 40-plus miles of roads that are just neighborhood roads and we’re looking for a really good way to fix those roads; a way that is cheap, effective, environmentally sensitive, cost-effective.” said Moraga Councilmember Howard Harpham. “We’re here to look at this and say to ourselves, ‘Is this something we could use? Is this something our citizens would support? Is this a good way to fix the systemic problem our town faces?’”
Harpham, who attended the workshop with some of his town’s staff, said cold-in-place recycling offers the “greatest promise.”
Much of Napa’s work is being paid for by a $2 million federal Innovative Climate Change Grant it shared with Sonoma County, which did its cold-in-place paving last week, Demery said.
The grant included $40,000 for public education in hopes other municipalities will begin using the technique. In addition to Thursday’s workshop, Napa and Sonoma will be making a video of the process.
San Rafael-based Ghilotti Bros. Contractors is the main contractor on the work, for which Napa and Sonoma have allocated a combined $2.8 million, according to city staff.
Northern California has not embraced cold-in-place recycling yet, so it’s difficult to get Southern California contractors, who own the equipment necessary for cold-in-place recycling, to travel the distance to do the work, Demery said. She hopes more cities will begin to use the method so local companies will start investing in the equipment.
“When you can pave three times as many roads with it, it’s something you can’t ignore,” she said. Roads fixed through cold-in-place recycling hold up as long as those paved through conventional methods, she said.
“We’re really in a position where we can’t do the thing we always did, which was to mill and fill and overlay,” Demery said.“That’s prohibitively expensive.”
Motorists could drive over the pavement laid Thursday that night, Emerson said. Paving was scheduled to be completed Friday.