When traffic is a problem or revegetating a site is impossible, solutions can still be found.
The EPA National Ambient Air Quality Standards define particulate matter as “both solid particles and liquid droplets found in air.” Further, particles are differentiated into “fine” and “coarse” classifications. Fine particles (PM2.5) are those less than 2.5 micrometers in diameter, while coarse particles (PM10) are between 2.5 and 10 micrometers in diameter. The EPA standards for air quality were first issued in 1971, with subsequent revisions in 1987, 1997, and 2006. The latest revision reduced the allowable amount of PM2.5 in the air, while retaining the already-existing 24-hour standard for PM10 particles, but eliminating the previous annual PM10 standard.
Typical sources of fine particles include motor vehicles, power plants, wood burning, and certain industrial processes. Coarse particles are commonly created from crushing or grinding operations, and they appear as dust from both paved and unpaved roads. Both types of particulate matter put heavy machinery at risk of premature repair and replacement.
From a health standpoint, PM10 particles are small enough to be inhaled into the respiratory system, where they can accumulate. PM2.5 particles, due to their extremely small size (less than one-seventh the width of a human hair), can lodge deeply in the lungs, according to EPA documents. Health dangers from long-term exposure to the larger, coarse particles are unclear, but the tiny, fine particles are associated with multiple ailments including asthma attacks and cardiovascular disease, particularly for the elderly and children.
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Photo: Patricia Armstrong-Stott |
| Wind and sand create problems for the 800-acre cranberry farm. |
Decreased visibility is another concern with excessive fugitive dust, putting both drivers and pedestrians at risk. Thus, adequate dust control remains an important issue for a variety of construction sites, farming operations, and other businesses and municipalities.
Watering of dust-prone surfaces has long been a simple method of reducing airborne dust particles, but due to the necessary frequency of application, it can also be expensive, time-consuming, and labor-intensive. As an alternative, a variety of soil stabilizers and dust suppressants exist on the market designed to meet the needs of demanding environments and operations. Some of these dust-control products are applied directly to the surface in varying concentrations, while others are tilled into the soil.
Desert Dust
SunCal Companies develops large master-plan residential communities such as the Terra Lago Project in Indio, CA, and an ongoing development in the Coachella Valley in the Palm Desert and Palm Springs region of southern California. “Dust is a big problem here,” explains Gary Williams, vice president of project management for SunCal. “We have loose, granular soil and high wind in the desert.”
Water trucks are used at times for dust control, but Williams has come to rely primarily on Envirotac II from Environmental Products & Applications. “I’ve used a lot of different products, but this is the best,” he says.
After mixing the Envirotac with water, Williams applies the solution with either a water truck or a hydromulching machine. The concentration he uses depends on what type of dust control is needed. “It’s water soluble, so it can be easily mixed to the desired concentration. In a low concentration, we’ll use it as a 90-day Band-Aid, but in stronger concentrations, it can last for years, if undisturbed,” Williams says. “And it dries quickly, within about a day in the dry desert climate.”
Having used Envirotac for seven or eight years, he finds that the frequency of application depends mainly on whether the surface is disturbed with vehicular or other traffic, and to what extent.
Williams is quick to note that “in California, people are very environmentally conscious, and the state requires permits for anything applied to the ground.” But he has done his homework and is satisfied that his dust-control solution “is completely innocuous, completely biodegradable, and completely safe for humans and animals.” He is especially cautious because his projects involve the construction of thousands of residential lots where homes will be built and families will live.
Canadian Cranberry Farm
In the small town of St. Lucien, QC, about 130 kilometers (80 miles) northwest of Montreal, sits an 800-acre farm operated by L&S Cranberry. Three hundred seventy-one of those acres are cultivated, all devoted to producing cranberries. Farm manager Patricia Armstrong-Stott explains the problem she faces.
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Photo: US Gypsum |
| A binder was hydraulically applied to the farm's sand piles. |
“The farm is approximately 2.5 kilometers from one end of the farm to the other, and it is all open. We have two big sand piles at the front of the farm, which were dug out to make our water reservoir deeper, and when it is extremely windy, the sand does tend to blow a lot,” she says. “The farm is built on sand, including our bogs and roadways, so blowing sand at times has been a real problem. When the winds are blowing extremely hard, unfortunately, our neighbor has received a lot of this sand. We had to find some way to control this problem because of the complaints we have had.”
Seeding the sand piles is not an option, she notes. “We cannot plant vegetation on our sand piles, as this would contaminate the sand for any further use. We use our sand to sand our cranberry bogs every year, and any vegetation would then be transferred to our bogs and we would end up with a nightmare in weeding.”
To solve her problem with blowing sand, Armstrong-Stott turned to Airtrol Geobinder from US Gypsum. It is designed to form a crust-like barrier that she felt might be ideal for her needs. Workers first had to flatten the tops of the sand piles to provide access. They then sprayed the material from a hydroseeding truck, applying the Airtrol directly to the surface of the piles without any tilling. The product has worked well, even resulting in a visit from a nearby television station. As Armstrong-Stott notes, “The product is supposed to be good for 6 to 9 months, but we find that because of the quantity of rain that we had last year, the duration rate was about 6 months,” after which it had to be reapplied. Prolonged heavy winds also tend to erode the crust over time, she says. But she can now manage the farm, instead of worrying where her sand piles are blowing.
Miami of the Midwest
Miami County, KS, located about 30 miles south-southwest of the Kansas City metropolitan area, is the second-fastest growing county in the state. But because its roads were originally designed primarily for farm use, about 77% of the road miles in the county are still unpaved gravel.
Road blading is a thorny issue for the Miami County Road and Bridge Department. Blading involves digging up and rebuilding the ditch on either side of a road, thereby reestablishing the ditch line. “This is a big deal for us,” says Department director J. R. McMahon. Permits must be obtained, and the more time his department has to spend on obtaining permits, the less time is available for other road and bridge maintenance that needs to be done.
In addition, McMahon says that “blading can be as destructive as constructive” because it involves cutting gravel and moving it from one place to another, with dust flying all over. This is a frequent source of complaints from residents. Yet, due to wind damage and vehicular traffic, he has found that many roads must be bladed repeatedly, often as frequently as once or twice each month.
With an increasing population comes increased traffic, and increased airborne dust from these gravel roads. “When a road that is monitored exceeds an average daily count of 300 vehicles, that road goes into the county’s dust-control program,” McMahon says.
To reduce the road dust, McMahon has been using North American Salt Company’s DustGard, provided by Scotwood Industries Inc. in Overland Park, KS. Designed to increase road stability and improve dust control, DustGard is a liquid form of magnesium chloride that is produced from naturally occurring minerals in Utah’s Great Salt Lake.
After eight years of experience with the product, McMahon has obtained best results by applying a half-gallon of DustGard per square yard, letting it sit, then applying a second coat about a week later. This process typically takes place during the spring months.
As proof of its effectiveness, McMahon notes that once the DustGard has been laid down, blading frequency is normally reduced to just once every year or two. “It stays on after blading, and reduces the incidence of rocks being blown around,” he says. “It does a great job of controlling dust.” McMahon generally applies the product annually to about 45 miles of road in Miami County.
DustLess in New Hampshire
New Hampshire may be known for its beautiful forests and clean air, but it still has its dust problems, as Jack Eaton can attest. He is the general manager of Certified Erosion Control of New Hampshire and has been asked to provide dust abatement for a variety of venues.
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Photo: DirtGlue Enterprises |
| A treated surface on a work site in Guatemala |
At equine arenas, an untreated surface will throw up a good deal of dust as the horses go through their competitive paces, but it is important that any treatment leave the footing stable. As Eaton explains, “Horse owners are very particular about the footing at equine competitions.” In addition, horses are very vulnerable to respiratory diseases, so a dust-control system is needed that can withstand constant surface disturbance, without plumes of dust being sent airborne.
Previously, he used calcium chloride as a dust suppressant, but found that he had to continually add water. For the past 18 months, however, he has been using ArenaKleen and its cousin product, DustLess, both from DirtGlue Enterprises. These products are applied directly to the surface, without the need of tilling into the ground. “They are more effective and longer lasting than calcium chloride,” Eaton says.
“Horses and people may walk on areas treated with Arena Kleen or DustLess immediately after application,” he notes. “The ArenaKleen or DustLess application may take a period of time to finish migrating evenly through the surface it has been applied to, but traffic of any kind will not affect this process.”
There appears to be no known respiratory or dermatological toxicity to worry about.
“ArenaKleen was developed specifically for use with horses and contains nothing that would be harmful to horses,” Eaton says, echoing the manufacturer’s claims.
“ArenaKleen does not change the characteristics of the footing it is being applied to,” he continues. “It makes the soil particles unable to become suspended in air, but this does not change void space between particles or increase the adhesion of particles to each other, which would add to compaction of the surface. Most other dust-control products rely on their ability to attract or retain water to achieve the same result; generally, these require repeat applications of water during dry periods to remain effective. The soil particles are suspended in the water, and this can lead to compaction of varying degrees within a surface.” If a hard, uniform surface is required, he points out, DirtGlue could be used to achieve this type of surface. “The product is an acrylic latex polymer that binds particles together to form anything from a light crust on a soil surface to a drivable roadway, depending on application rates and techniques.”
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Photo: EarthChem |
| Areas with little traffic are treated with liquid applications. |
Larry Dolan of DirtGlue Enterprises adds that “ArenaKleen and DustLess, because of their light molecular weight, will not coat the particles, but absorb into them, thus, keeping them heavy and ‘damp.’ This will enable the fine particles to remain in the soil, eliminating dust and providing a more stable footing or driving surface. These products, unlike a water application, will not result in particles suspended or floating in the liquid, causing varying degrees of stability and dust control as the water evaporates.” These two products, he notes, do not evaporate.
At this point, Eaton has applied both of them as one-time applications at a number of arenas, but expects that he’ll likely need to do an annual “touch-up.” Besides equine environments, Eaton has also used DustLess on roadways and parking lots with similar success.
Nuclear Toxins
Located along the Columbia River in Southeast Washington, the 586-square-mile Hanford Nuclear Reservation is home to nine nuclear reactors. The US Department of Energy reports that the site contains “more than 50 million gallons of high-level liquid waste in 177 underground storage tanks, 2,300 tons of spent nuclear fuel, 12 tons of plutonium in various forms, about 25 million cubic feet of buried or stored solid waste, and about 270 billion gallons of groundwater contaminated above drinking water standards, spread out over about 80 square miles, more than 1,700 waste sites, and about 500 contaminated facilities.”
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Photo: Midwest Industrial Supply |
| Untreated stretches of land can cause severe dust problems. |
If ever there was an environment in which strict dust control was needed, this is it, with its soil highly contaminated. Envirocon’s construction manager Rick Park is the person charged with the task of dust abatement, and he has been working with the cleanup of the Hanford plant for the past 11 years.
“The soil in this area is granular and sandy, with winds up to 40 miles per hour,” he notes, which complicates matters. For areas that are disturbed regularly, he has used calcium chloride, although this proved to be an expensive method of treatment. “When I really needed to lock down the dust,” Park says, “I used Soil-Sement,” produced by Midwest Industrial Supply. “It’s very long lasting. But for areas with little traffic, I’m using EarthBound, applied from a water truck.” Its cost is significantly less than the alternatives.
The EarthBound material, from Earth Chem, is available in either a powdered form (to be mixed with water) or a liquid form. Park expects that for his specific project, the liquid form may be the superior type to use.
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Photo: Midwest Industrial Supply |
| Once treated, unpaved roads can stand up to heavy vehicles. |
As of press time, he is anxiously awaiting the results of his applications to see if the product works sufficiently well in the presence of heavy winds.
Gummy-Bear Dust Control
Not far from the offices of Midwest Industrial Supply, the manufacturer of multiple dust-control products, stands a plot of land with a serious dust problem. Mike Blackmer, general manager of Universal Metals in Canton, OH, explains, “We have a steel-cutting operation with a lot of land that is unpaved.” If left untreated, “the dust would get 2 to 3 inches thick and create a cloud of dust” anytime it was disturbed.
Initially, Blackmer tried a tar product. He was satisfied with the dust control it offered, but a major problem was that the material “tracked up on vehicles, forklifts, and shoes.” Eventually, Blackmer turned to Midwest Industrial’s EK35 for the approximately 2 acres of land in question. “It already comes mixed in their truck, and when applied, it gels up, and keeps the dirt down. It’s worked great.”
The EK35 takes about four hours to dry, so Blackmer usually arranges to have it applied during an “off-shift” so it’s already dry by the time most of the staff comes in. He uses one application in the spring and another in the summer, and has done so for the last few years.
He’s found that this product works well for both heavily used areas and undisturbed patches. In contrast to the problems he had with tar tracking everywhere, he comments, “The EK35 doesn’t do this—it stays put.” It slowly works its way into the ground, and as Blackmer describes, “Once it’s put down and solidifies, it’s kind of like a gummy-bear consistency.”