Stricter enforcement prompts new control measures.
There used to be a time when companies such as construction contractors were somewhat concerned about dust control, but it wasn’t a top priority.
“Five years ago, you did your dust control plan, but in the last two years, it’s become serious business, and a lot of companies in Maricopa County [Arizona] spend a lot of money,” says Dale Hardin, a project superintendent with McCarthy Construction’s Southwest Division in Tempe, AZ.
Companies that don’t spend the money for dust control may find themselves spending the money for fines instead. During a recent construction project, Hardin says, county inspectors had made inspections at least twice a month to check for dust control violations.
“You get no break,” he says. “Whether you’re the big guy or the little guy—they’re coming after you.
“You’ve got to get the permit, and they are getting you for track-out and the dust. It used to be something you kind of worried about, but you didn’t get nailed a lot. Now it’s the first thing you think about when everyone shows up and starts moving dirt. There’s no option.”
Dust control is a large part of his company’s construction planning now, Hardin notes. Times have changed as laws have tightened up and inspections have become more rigorous.
Indeed, the USEPA in September 2006 tightened the short-term daily standard regulating the amount of lethal soot air particles by cutting it from 65 micrograms per cubic meter to 35. The annual standard remains, despite input from the EPA’s Clean Air Scientific Advisory Committee and the American Medical Association that the long-term standard be reduced from 15 micrograms per cubic meter to between 12 and 14.
Research indicates the tiny particles account for tens of thousands of deaths each year from respiratory and coronary disease through their penetration into the lungs and circulatory system.
The EPA reviews its standards according to current scientific findings every five years as part of the Clean Air Act. The National Ambient Air Quality Standards address fine and coarse particle pollution, known as particulate matter (PM).
PM is a mix of very small particles and liquid droplets in the air, including dust and soot. The standards relate to fine particles that measure 2.5 micrometers in diameter and inhalable coarse particles measuring between 2.5 and 10 micrometers.
The EPA estimates its revised short-term fine particle exposure standard will reduce premature deaths, heart attacks and hospital admissions for those with heart and lung disease and will save between $9 billion and $75 billion a year in health care costs.
States must meet the revised standards by 2015, with a possible extension to 2020, depending on local conditions and the availability of controls, the EPA reports.
In August 2006 alone, Maricopa County, AZ, had collected more than $266,000 in air-quality violation fines, many of which were for lack of dust control, and listed every company that had been fined—several of which have nationally recognized names—on its government Web site. One of the biggest violators was responsible for $47,000 in fines.
Such figures for monthly fines are not unusual for Maricopa County.
“Maricopa County is pretty tough on dust pollution, so the county inspectors wear us out pretty hard,” Hardin says. “But it’s a good thing.”
Hardin was not about to see his company featured on that notorious list when it began construction in late 2005 of the Banner Gateway Medical Center in Gilbert, AZ.
Complying with air-quality regulations means spending thousands of dollars on a construction project such as the new hospital just to control dust, he adds. Costs include the dust control product, the trucks used to apply it, a street sweeper, cattle guards, gravel, and labor.
“Once we cut our roads in on this project, we used Gorilla-Snot [from Soilworks LLC],” he says. “You don’t get as much dust, so you’re not putting down as much water. You do a biweekly treatment. I was skeptical at first because I’d never used it, but we tried it and I’d do it again.”
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Photo: Soilworks |
| A water truck spraying a copolmer product for dust control |
McCarthy Construction applied the copolymer product over a three-month period ending in January 2006. The Gorilla-Snot—an economy-grade version of Soilworks’ Soiltac—was applied as a temporary measure.
“You have to back off as your underground work starts; we are doing a lot of digging every day,” Hardin says. “It’s mainly for haul roads around the site. It keeps the dust down and keeps us from putting so much water down, which also saves me a street sweeper to sweep the mud up.”
McCarthy Construction subcontracted the dust control work through Soilworks. The product was applied with water trucks. Soilworks delivered the material, and the subcontractor loaded up the water trucks to spray the application on the surface.
“I graded the roads first to make sure they were flat before I let them do the Gorilla-Snot spray,” Hardin says. “You try not to drive on it. Soilworks would come in late in the day as everyone was going home and do the work, and in the morning we could drive on it.”
The Gorilla-Snot was applied at a rate of 1 gallon of concentrate plus 10 parts of water per 120 square feet on an as-needed basis at a cost of $1,600 per mile on roads 24 feet wide. An average of 7 miles of unpaved, silt-heavy clay soil heavy haul roads is treated with each site visit.
The product was initially applied at a much heavier rate two weeks in a row and then applied every week or every other week, Hardin notes. “It depends on how it works for you and what you are doing,” he says.
Traffic conditions were a major consideration in its application, Hardin says, because it kept the dust down around the site. “If I had a job with a dirt road that no one was going to disturb for six or nine months, this is the perfect material,” Hardin says.
Prior to using the Gorilla-Snot, Hardin says, his company’s dust control efforts involved running water trucks at about $80 an hour to keep the dust down. The mud created by that action had to be removed by street sweepers for about $75 an hour.
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Photo: Midwest Industrial Supply |
| Preventing fugitive dust from escaping a dried-up pond |
“It adds up. We are pouring a lot of concrete, so we generate a lot of dust and mud,” he says. “The Gorilla-Snot helped us because we didn’t have to water as much. You water about a third to a half, but you cut down on the water.”
In addition, it cut down on equipment and labor costs. “We don’t get the mud tracked out the back, so instead of sweeping eight hours a day, we went to a four-hour minimum,” Hardin says.
A clause in the Arizona Pollution Discharge Elimination System stormwater permit requires the developer or the contractor filing a permit to stabilize any lot or stockpile that will not be used for 14 days, says Tracy Castell, a Tucson, AZ, branch manager for WindSwept Organix.
WindSwept Organix uses MonoSol’s TerraLOC as temporary soil stabilization. The soil-penetrant dust palliative is a solution of polyvinyl alcohol and additives used for loose and dry or slightly damp surfaces.
“We like using the TerraLOC because it is much easier to clean up our equipment, and it is easier to use and more installer friendly,” Castell says.
Castell has applied the substance on the surface with both a water truck and a hydroseeding machine, depending on the terrain and the job, and sometimes will switch between the two on one job. He uses an application of 132 gallons of TerraLOC per acre, which he says is a light application, used particularly for the 14-day rule.
“Typically, we do it to meet the intent of the permit and won’t do a reapplication unless the inspector requires the developer to do so,” Castell says.
As for dust control, Castell notes that just as in Maricopa County, the county in which he operates—Pima County—is starting to crack down just as strictly on violations.
As fugitive dust flew about a Tennessee Valley Authority (TVA) fly ash dredge cell in Harriman, TN, so too did complaints from nearby industrial and residential neighbors, located one-quarter- to one-half-mile away.
Brian Lankford, a program manager for coal combustion byproducts for the TVA, explains there had been a dike failure in one of the dredge cells. The TVA usually dredged to the top, with the water spilling down to the ash pond.
“During the failure, the dredge cells were basically not deep, so there was no water on the top of them and wind would blow across the top of them, capturing a lot of ash, which would blow all over the place,” Lankford says.
There was no relief. In the winter, fugitive dust was created when freezing temperatures caused the ash pond surface to freeze dry. In the summer, dust became a problem when the pond’s water either evaporated or was drained off.
The TVA used Soil-Sement polymer emulsion, manufactured by Midwest Industrial Supply, to address the problem. The product chemically bonded and sealed the surface, preventing wind from lifting fine particles and creating dust. The application was applied twice on the surface with a water truck as a temporary measure.
“It actually bound the ash together and created a small crust on the top of it, which did not allow the wind to take it to other places,” Lankford says.
The Soil-Sement was the only solution TVA considered. “We did a bit of research on binding agents and found this was the only one that offered a one-year guarantee,” he notes.
Given that, the TVA applied the product once in November 2004 and then again in October 2005. The Soil-Sement was mixed with water at a 9:1 ratio, with 1 gallon applied per 200 square feet for a total of approximately 2.5 million square feet. Although the usual application is 1 gallon per 100 square feet, using 1 gallon per 200 square feet—which was determined through an analysis of materials in Midwest Industrial’s soil lab—reduced the TVA’s costs. The application cost about $1,200 per acre.
The TVA has used Soil-Sement in other applications. After its Paradise Fossil Plant, a coal wash plant in Drakesboro, KY, was first idled in July 2005, the fine refuse was being dumped into a pond. The pond dried up, and in March the TVA had the binding agent sprayed in the 80-acre pond.
The TVA works to maintain “no visible dust” air quality in all of its facilities, Lankford says. “We are trying to be proactive with the dust on all of our sites,” he notes. “We want to be environmentally friendly.”
At George Washington’s Mount Vernon Estate and Gardens in Mount Vernon, VA, caretakers are concerned not only about being environmentally friendly but also with preserving the rich history embodied at the facility and its surroundings.
Jim Simms, director of special projects for George Washington’s Mount Vernon Estate and Gardens, had researched various methods of dust control before contacting Environmental Products and Applications in California.
“We have a lot of 18th-century-type gravel roads that become very dusty, and in order to keep fugitive dust down, we apply topical applications [of dust control products],” Simms says.
Dust control has always been a challenge on the grounds, he says. At one time the estate’s caretakers used calcium chloride but ceased doing so when it damaged underground piping and alarm circuitry over the years.
Additionally, “It got tracked into the house and did damage to the carpet and the floors,” notes Simms. “We didn’t use anything for a long time. We had to find something.”
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Photo: Soilworks |
| Copolymer products keep the dust down on dirt roads. |
After Simms contacted Environmental Products and Applications to place an order, the company indicated that it would donate its Envirotac II and its application process to George Washington’s Mount Vernon Estate and Gardens.
“This is George Washington’s home, and John Vermillion, the president of the company, is interested in history and has been interested in helping us keep this place really nice for the millions of people who see it,” says Simms.
The application on nearly 2 miles of road was scheduled for the autumn of 2006, following the busy season. The estate and gardens also at the time was constructing an additional complex: a 66,700-square-foot orientation center, museum, and education center. Simms says any reapplication of the product will be determined by how the initial application fares.
“We get more than 1 million visitors per year,” he says. “That’s a lot of foot traffic. We try to eliminate as much vehicle traffic as possible so that there are not a lot of cars blowing everything around. We have snow removal equipment and things of that nature that tread on the roads. We’ll have to play it by ear and see how long it will last.”
In a 165-acre area of 8,600 acres of open range in Vantage, WA, 172 wind turbines have been erected in the Wild Horse Wind Power Project as part of an effort to provide wind-generated power to the Northwest.
The area has long been known for its vigorous winds, and the topography made it an obvious choice for the wind generation site. The project is in a remote area up on ridges with no road access.
“For them to get all of the equipment and material in to build a wind tower, they have to have substantial roads,” says Eric McCrea, a partner with Wildlands Inc. in Richland, WA. “It’s nothing to see 50 to 100 miles of roads by the time they get a site completed. The wind, of course, is inherent with a site like that.”
Wildlands was called in to administer dust control. The company chose to use DustFloc, manufactured by Apex Resources. The soil stabilizer system is a blend of natural polysaccharides that can be used alone or in conjunction with a variety of fiber sources.
“Throughout the project, we stay on top of all of the temporary construction dust,” McCrea says. The application rate for temporary seeding is 75 pounds per acre of DustFloc, 750 pounds per acre of virgin wood fiber, and 25 pounds per acre of seed.
Wildlands is applying permanent seeding on 400 acres at the site, mixing it with 1,000 pounds of wood mulch. The temporary dust control measures extend beyond that.
“We’ve gone over most of the property twice or so, and as things get torn up, we’ll come back through and do it again,” McCrea says. Wildlands applied the DustFloc on the surface with a hydroseeding machine.
McCrea says his company has offered a six-month guarantee of the product and process, as long as it’s undisturbed. “The only reason we are reapplying it prior to permanent seeding is if they regrade an area or bring it to final grade,” McCrea says. “In the temporary application, they’ll clear an area and grub it or bring it to rough grade, and we’ll do an application. If they come back and break up the final grade, we may apply it again. Other than that, once we apply it during season, it’s good to go until permanent seeding.”
Workers are setting the wind turbines or doing an extensive amount of crane work and are still using water to stabilize the gravel roads, McCrea says.
Traffic is the major factor Wildlands employees consider when working in the area. “There are still clean air policies even though it’s in the middle of nowhere,” he says. “There are all sorts of accommodations we have to make in our schedule as far as construction traffic and the building of the new roads as they are pioneering new roads in.”
McCrea notes that doing a job on a site such as this one is different from other road projects in that only 25% of the site may be accessible by road, and as the roads are pushed farther out, more of the site is available for dust control work.
The amount spent per mile of road on the project varies, McCrea says. “It depends on how intensely the roads are redisturbed and on the equipment they are bringing over at any point in time,” he says. Prices can range from between $600 and $800 for temporary dust control to $800 to $1,200 an acre for permanent dust control jobs, which factors in seed prices, he says. On this particular project, Wildlands used about seven types of seed mixes and organic fertilizer.
“We’re very conscientious of the seed varieties on sites like this due to the different elevations and slope aspects such as north- or south-facing slopes,” McCrea says. “There are also many differing soil types and depths, so your seed blend changes a lot. Normally you’ll go into a large construction project with one, maybe two, different seed blends.”
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Photo: Midwest Industrial Supply |
| Keeping the dust down keeps the air quality up. |
McCrea is finding that air-quality inspections are becoming more strictly enforced—“And not at a slow rate,” he adds. The area has an annual precipitation of 12 inches and a great deal of wind.
As little as five years ago, his company would average about 50 to 100 acres of dust control work a year. These days that number has swelled to 1,200, a factor that is driven by increased regulatory inspections, he says.
DustFloc is McCrea’s product of choice. He favors it for its price and his ability to guarantee it for six months. “We rarely have to go back and touch anything up,” he says. “We do pipelines where we don’t put any wood mulch at all with it, and that would knock that guarantee down to about three months. But it still works great and locks in seeds.
“We’ve used all of the polymers. There are some that work better, but the cost is through the roof. Like everyone, we’re looking for the best product for the cheapest price, and we’ve been really pleased.”
McCrea also relies on input from field personnel. “Guar gum tackifier was the last new product that worked well, but a problem with it is that when you load it into a slurry, regardless of how slow you load it, it has a tendency to ball up, and you don’t get full use of the product,” McCrea says.
He says the biggest difference he’s noted with DustFloc in applying it is the material’s consistency. “The weight of the bags, the amount in the bags, and the product itself is extremely consistent, and that’s pretty important when you have guys who are adjusting their rates daily over a multi-week, -month, or -year project; they can feel confident that they are getting an acre’s worth.”
In the township of Bedminster, NJ, John Mantz, the public works manager, has been using Dow Chemical’s calcium chloride for dust control on 20 miles of unpaved gravel roadways for more than two decades.
Although Mantz hasn’t noted more stringent air-quality regulation enforcement, his city’s dust control efforts are in response to residents complaining that the dust on the roads is so bad they can’t leave a window open.
“The municipality likes to keep that rural characteristic of the town,” Mantz says. “It’s also a large horse community, so they like to keep those gravel roads. In doing so, dust is always an issue, and we try to control it with the use of calcium chloride.”
Bedminster put out a bid for calcium chloride, which is applied by the vendor. It is typically sprayed on the surface. Some companies, however, till the substance into the roadways. “They grind everything together for the blacktop and use calcium chloride as a stabilization agent, unlike a liquid asphalt they would use normally for a sub-base. That process is becoming more prevalent,” Mantz says.
“What I’d like to do as long as time and money permits is to use that same type of process on our gravel roadways. It would be injected into the base of the road material, and then we’d grade it, roll it, and spray it on top of a cap.”
Mantz says the material he’s been putting on the roads has worked well because it’s a sandier type of material that acts as a binder.
“I am very happy with the way the calcium chloride is working as a stabilizing agent along with the dust control,” Mantz says.
Mantz budgets about $24,000 a year for calcium chloride, which translates to $1,200 per mile of road. But Mantz may not spend the entire allotment, depending on weather conditions.
“If the weather conditions are such that I don’t need to use the calcium chloride because it’s been raining every day, then I don’t. I have found that if there’s rain and moisture in the area, it lasts a lot longer. During the dry season, I have to put more applications down.”
Mantz says its application rate depends on road conditions. “If the road conditions are very hard and it’s just a dust-type application, I try to do 1% or 2%, so it’s two-tenths of a gallon per square yard. If it’s a softer material, I try to go up as high as 3%. I don’t like to get much more than that because it starts to run off the road.”
Mantz says he’s never tried any other products because of the diversity of calcium chloride’s applications. “Calcium chloride seems to be a multiuse product that can be used as dust control and can also be used for deicing operations in the wintertime,” he says. “I personally don’t use it for deicing, but I know other municipalities do, and it works pretty well.”
As for the future of dust control, Hardin believes as more environmental inspectors are turned out to monitor air quality—Albuquerque is following Maricopa County’s lead, for instance—it will get more difficult for companies to avoid dust control fines.
“It’s a good thing to keep the pollution and the dust down. You just have to follow the rules,” Hardin says.
And there is now more cooperation among those who perform erosion control services, notes McCrea. He credits the evolution of the International Erosion Control Association (IECA) for that.
“It’s not so adversarial anymore,” he says. “We share more information. When we started in 1987, there weren’t many of us. I think IECA has done a good job of facilitating that. I like what we do and how it’s allowed us to grow. We’ve got a bunch of people who work for us who really like the whole business, so I think there’s a bright future for us.”