Controlling Fugitive Dust on Roadways
Climate, traffic, and road composition help determine what to use.
By Carol Brzozowski
...Anyone whose work involves earthmoving activities, construction, or mining knows the problems fugitive dust can cause—from poor visibility to respiratory problems to simply causing a nuisance to people downwind. They're probably familiar with some of the remedies, too, from water trucks to dust-suppressing products. However, dust control is also an issue in places we don't often consider, and some of the work done to solve the more unusual problems in other arenas ends up benefiting the construction and erosion control industries as well.
The military has been dealing with dust control for decades, particularly at airfields. The action of helicopter blades, for example, generates a tremendous amount of dust, particularly in the arid environments of Iraq and Afghanistan, where many are deployed, as well as in desert training sites such as Twentynine Palms, CA, and Yuma, AZ. With an increase in training and operations overseas, the issue became a priority shortly after the wars in Afghanistan and Iraq started.
"The natural sands, dust, and silts that exist in those regions are easily kicked up by the aircraft we are using," explains Barry Spargo, branch head at the Naval Research Laboratory (NRL) in Washington, DC. "We were challenged to come up with solutions for reducing the amount of dust that is created during helicopter landings and takeoffs in the theater and in training for the Marine Corps and the Navy."
Although air quality is part of the equation, dust control becomes more urgent in this type of environment. "While this is an environmental issue and it's something that the Navy continues to address, it's also an operating and maintenance problem and a safety problem," Spargo says. "Whenever you are kicking up significant amounts of dust and dirt, you diminish the visibility significantly and also increase the intake of these particles into engines, so you get engine wear and blade wear. It's a pretty significant problem."
In addressing it, NRL considered the variety of commercial products on the market and how they might be redesigned to meet the needs of the military. "They have to be environmentally friendly and easy to use, and they have to have a low logistical footprint," Spargo says.
Around the country, dust-control issues are escalating, leading to lawsuits and stop-work orders on large construction projects. The EPA is increasingly clamping down on the problem, which is not only a visual annoyance, but a health issue as well in terms of aggravating respiratory problems.
Roads remain a common source of dust problems, and many municipalities report that residential complaints of dust are the catalyst for dust-control actions. Consider Chardon Township in Ohio.
Don Mohney, a road foreman with the township, explains that dry weather had been causing a dust problem on three roads, as well as traffic on a road that wasn't being treated with anything. The heavily trafficked clay-based roads have severe hills, curves, potholes, and washboarding conditions. The township wanted to control dust on the roads and reduce complaints of chemical splashing on cars.
"We have used just about everything available over the years," Mohney says. "I've been here for 23 years. Years ago, we used calcium chloride, and it basically would turn a road to mush if you put too much down, or it would turn the road soft, mucky, and muddy. You would get stuck in it with that."
Mohney recalls that the township reverted to reprocessed used oil obtained through a local company. "We used them for quite a few years, but you never knew what you were getting each time you called them out," he says. "It would either last a week and be gone, or it would take three weeks to soak in, and then we'd get constant complaints about it being on people's vehicles."
Finally, another company presented a solution to the township: a polymer resin, mixed from four to seven parts to one part water. "I found it to be a good product," Mohney says. "We had only about one complaint a year; somebody would get it on their car because they were following the truck right down the road as they put it down, not giving it any time to soak in, and we could only tell them a little kerosene or gasoline would get it off."
The product not only stopped the dust on a dirt and gravel road but also bound the road so that it appeared almost like an asphalt road as the summer wore on.
"It was an exceptional product at a good price," Mohney notes. "They sold the company and the customers to Midwest Industrial Supply, and we've been with them for two years." He notes that the new product, EK-35, is somewhat different because it doesn't need to be mixed with water. The product is formulated with synthetic fluids and rosins, and controls dust and stabilizes soil.
In road experiments in Chardon, dust kicked up into the air 10 feet by a vehicle traveling 35 to 40 mph. After an initial application of EK-35 at the same speeds, the dust would rise 5 to 10 feet and settle back down within 20 feet of the particles' origin. Midwest Industrial Supply designed application rates by the tenth of a mile for each of the roads to address areas such as hills, curves, areas with moisture, and places where vehicles left asphalt for dirt roads. The initial application of the product over 2 miles of three individual roads was in early July 2003, with maintenance applications in late July and September.
"We've used it on those three roads and the yard and it's worked out well," Mohney notes. "We haven't had a single complaint. Even though it really doesn't kill the dust all the way, you can still go down the road after they've done it. What's good about it is you can actually follow their truck as they are putting it down and it will get on your car, but it will wash right off with soap and water."
For Chardon Township, it's also an economical choice. The township's budget for dust control is $14,470, with any job more than $15,000 having to be bid out by the township, so Mohney had to insist the project be done at that rate. He is pleased with the return on the investment.
As for application rates, Mohney asks Midwest to provide coverage twice a year—once before June 1, because the town has a large-scale trash collection on that day and doesn't want a lot of dust resulting from it.
"I try to get it done one more time during the year for two reasons—not just for dust, but to help bind up the road so it'll hold for me in the winter when I'm plowing," Mohney says. "When you get the road bound up, you're not pushing off all your gravel in the low end of the ditch when you plow, so it's a good idea."...
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