More than a mere household inconvenience, dust can be a problem tied to erosion, road safety, and human health. You can’t build anything without stirring up a little dust-but safe and cost-effective cleanup has to be part of the plan.
Clean Sites, Clean Machines, Clean Products
Rather than surrounding themselves with asphalt, many industrial plants lay down gravel for local traffic. Gravel is convenient, less expensive, and porous, but when the weather’s dry, dust can be a problem.
“Gravel roads, made of limestone, get ground up to a dust,” says James Bellamy, superintendent of the maintenance department for PTC Alliance in Alliance, OH. “We used to use [liquid] asphalt to keep the dust down, but it was so messy, and when we’d walk on it, we’d track it into the plant. We now use Road Pro NT, from Midwest Industrial Supply.”
Located in Canton, OH, Midwest Industrial Supply developed the polymer-modified asphalt emulsion, which reduces the human health risk and environmental exposure to polynuclear aromatic hydrocarbons (PAHs). Polymers enhance the weatherability of treated surfaces and help lock the hazardous constituents into the asphalt. Road Pro NT also helps ensure compliance with the Clean Air Act regarding PM10 emission requirements. PM10 particles are between 2.5 and 10 micrometers in diameter.
“It’s a liquid; they apply it for us,” explainsBellamy. “Midwest comes with it premixed in a tanker truck and sprays it on. Doing our whole yard takes about two hours. We used to get three applications a season per year, starting in April, with touch-ups through the season-depending upon the weather, of course. You can even apply it after rain-or, if it rains a couple hours after application, it’s already set. We try to have the application done after 5 p.m., as it’s better if truck traffic doesn’t go right over it. By the next day it’s fine. We also have train tracks that run beside our yard, and Midwest hand-sprays the gravel between the rails.”
Bellamy has many reasons for applying Road Pro NT. “We were concerned with air quality as much as the mess. As we make steel tubing, our customers don’t like it if there’s dust on the products we send them. Employees’ cars would get dusty as well, which they didn’t appreciate, since stone dust can damage vehicles’ finishes. We’re located near residential areas, too, so I’m sure the homeowners appreciate having less dust.”
The gravel, mostly ground-up limestone, is laid upon the area’s sandy-clay soil. With heavy truck traffic, PTC Alliance must replace the limestone every so often.
“We’re not worried about any residual effects of Road Pro NT in our soil; our environmentalist has gone over this with a fine-toothed comb-we feel very safe,” says Bellamy. “It’s worked as good as anything we’ve tried, yet has nothing sticky, like the road tar we used to use. Once it’s dried, we don’t even know it’s there. It makes the dirt heavier than it was-any dust kicked up falls right to the ground, so it’s not blowing around.”
“Old” Dust a Particular Problem
There’s no mess like an old mess. Knoxville, TN’s Safety and Ecology Corp. (SEC) is involved with site cleanups all over the US and Europe, and while it’s reclaiming a site, dust from decades-old trash and other materials must be contained.
“We use Earth Chem’s soil stabilizers every day, at the end of each shift,” reports Preston Anderson, who works at SEC’s field office in Richland, WA. “At this soil remediation site, we need to make sure things don’t blow. Right now we’re digging up old trash burial grounds. The large items are put into containers for disposal. But during the excavation process, we don’t want materials in the pit to blow out. After the landfill is cleaned up, then we take the land as close to its original vegetation as possible.”
Earth Chem Inc. of Fort Collins, CO, manufacturers soil stabilization polymers for use in agriculture, fire rehabilitation, and construction. Its products include the soil stabilizers/mulch tackifiers EarthBound and SOILPAM.
“We have a lot of oversight on these sites,” continues Anderson. “Local residents get upset to see dust, which comes up quickly, as this area is fairly arid. We put the stabilizers down to keep the dust controlled-as much as we need, depending upon the weather conditions. We mix the Earth Chem product with water, then apply it using a water tank truck. It’s great stuff: It does the job well, and it’s biodegradable.”
Desert Dust a Difficult Dilemma
Arid portions of the country experience near-constant dust problems; not only is the soil dry most of the time, but it’s also difficult to get soil-trapping vegetation established. Whereas water can be used to control dust in some parts of the nation, in the desert it’s not only deemed wasteful but also a waste of time, as evaporation rates are nearly instantaneous.
“Once you disturb the natural crust by grading, the developer or builder has to get an Arizona Department of Environmental Quality permit and, in the Phoenix area, a dust permit from the Maricopa County Air Quality Department,” explains Joe Pampinella Jr., senior vice president of CNS Management Corp.’s southwest regional office, which serves arid states from New Mexico to California. “Using water to keep the dust down is a typical dust method; however, it is not allowed here as a BMP [best management practice].”
CNS Management sells products and consults on compliance for environmental health and safety as well as Leadership in Energy and Environmental Design (LEED) compliance. “We deal with all real estate related issues, from ground-breaking dust to occupants’ indoor air-quality issues,” says Pampinella. “For dust control, we use Apex Resources Inc.’s products, which have been blended differently for a desert environment. What we use is called AZ Dust Blend.”
Louisville, KY’s Apex Resources Inc. manufactures DustFloc, which effectively reduces PM10 fugitive dust. A blend of natural and organic polysaccharides, environmentally safe, and nontoxic, DustFloc binds soil particles together, provides dry and wet strength, and has reworking capabilities. The long-lasting product works well with soil types of various pH levels.
“It’s very difficult to apply liquid products in the desert; humidity levels are often below 7%, making it difficult for liquids to be applied correctly,” says Pampinella. “We blend Apex’s product differently, to adapt to the desert, and we also modify the application method, to compensate for the lack of humidity and dry conditions. We still spray it with water trucks, however, which increases efficiency and yield per acre and helps reduce the “cost per acre applied’ tremendously. Apex is a food-based product with a little bit of what I’d call “steroids’ in it,” he chuckles. “It’s safe to put down, with no negative impact on environment, employees, or the equipment.”
Pampinella’s procedures reduce the amount of water needed onsite, while complying with a site’s stormwater pollution prevention plan (SWPPP).
“In a daily process application, we’ve cut water-truck usage by a least a third, and we can also go to weekly stabilization for less active areas. There’s also a final dust stabilization for your NOT [notice of termination] and a yearly application method for dust permit closure.
“Or, we can re-establish the crust with a the AZ Dust Blend product,” he adds. “That’s a big factor right now with sites that are being mothballed-if you don’t secure the soil, you must have a dust-control coordinator on site.”
Every project in the area has two main challenges: the need for dust control to meet Maricopa County permit regulations, and the need to meet erosion control BMP requirements to follow the SWPPP. “Of course, if you’re in a drought situation, there’s less worry about the SWPPP,” he notes. “When grading a large tract of land-since you have most likely installed sediment basins, which are dry-the dust will kick up. “˜Moondust’ is how it’s referred to here, as it’s the consistency of talcum powder. Even adhering to a 15 mile-per-hour speed limit, vehicles can kick up dust, and dust opacity is a great concern in the dry seasons. Moving over the site with equipment, you pulverize the soil further-you can easily see it. We have a lot of clay; it’s an expansive soil. On a job site that’s been touched, just look at the tire marks-they make mounds 3 to 4 inches thick of this “˜talcum powder.’ It takes nothing to get that dust airborne. With our procedures, we can address several compliance issues at one time: We control silt runoff if there’s a water event, and we also stop dust moving from wind events.”
All of CNS Management’s projects encompass 1 acre or more, but most are developments of 20 acres or larger, often a strip mall shopping center or a residential project. “Big tracts of land are being developed here,” Pampinella says. “Our last project covered 125 acres-a residential section, within a 500-acre tract.”
He explains how most local projects unfold: “You grade the site first, so you have dust and SWPPP issues to address immediately. In fact, until you get to the point when vegetation is reestablished, there are going to be dust and SWPPP issues. Your crews are constantly disturbing the soil as you’re grading-even just moving through the area to get from one end of the work site to the other. We also use Apex’s AZ Road Blend product, which uses the same basic materials, so we can stabilize a road for temporary operations and reduce both dust and track-out.
“Here, a construction site can take 18 to 24 months to complete,” he continues. “Overall, the less land disturbed, the lower the requirement for dust stabilization. Typically, a crew will stabilize and close, or back off, an area and leave it stabilized until the final BMP is put in place. But on something like a road project, crews are constantly grading-and requiring water 12 to 15 times a day-to keep the dust down. Our process uses fewer water trucks and drivers-companies don’t have to purchase a lot of water trucks. If we can use AZ Dust Blend during these temporary periods, we eliminate the need to put in temporary vegetation, which wastes a lot of water to get them established in a desert environment. AZ Dust Blend is less costly, with the same net effect: low erosion and low dust loss.”
Pampinella has used Apex for over a year. “My background is in environmental health and safety; I’ve been in the environmental business 20 years. I started in oil spills, which led me in a direction that brought me here. Ten years ago I was working with chemical companies on products for this dust problem. I’ve been a board member of the University of Stony Brook’s Division of Occupational Medicine for over 10 years, working there with leaders to find ways for a company to profit from meeting compliance challenges set by EPA and OSHA.”
Compliance is a challenge, because so many regulatory entities are involved.
“California, Nevada, and Arizona are currently involved with dust regulations, in addition to SWPPPs. Under the Clean Water Act, a SWPPP requires sediment to be controlled, to prevent its impact on our waterways and local inhabitants. Dust regulations are prompted by the Clean Air Act, and they often note the PM10 levels in a city as well as ozone. Dust has an impact upon the PM10 particulate measurements. Particulates adversely affect one’s health, as they can carry fungus and bacteria. Currently, the Centers for Disease Control is investigating valley fever, a fungus that lives in the dirt and is respirable-so there’s lots of reasons to reduce airborne dirt.”
There is some crossover between the various regulations, he points out, which can be confusing. The dust control regulations under the Clean Air Act cover some of the same topics as a SWPPP. For projects that are striving for LEED certification, reducing water usage during construction can be a concern as well.
If guidelines aren’t met, someone must pay-literally. “Federal highway dollars are the typical monies that are withheld if the states are not complying with air objectives. The counties-Maricopa, for example-have averaged over a half-million dollars per month in fines and penalties to put this program in place and are currently using helicopters for visual air confirmation of “˜hot spots.'”
Controlling dust is a dirty job, and Pampinella’s one who does it. “I work to stop dust, stop erosion, and implement something to help keep workers and the public safe. Everyone seems to benefit when you control dust.”
Mulch in the Wind?
Apex Resources’ DustFloc is also used to keep larger particulates out of the air. Richland, WA’s WildLands Inc. is in the land restoration business, using a variety of products and procedures to achieve that end.
“We do hydroseeding, as well as install plants in the ground, for federally funded riparian restoration,” says senior restoration ecologist David Bradney. “We also have experience in gas pipeline projects, and in the wind energy industry, which has expanded and is going strong in our part of the world.”
Bradney gives more details on wind energy projects. “Roads to-and construction on-the wind farms, disturbed a lot of soil. The major portion was the electric cable trenches, which run from the turbines to the collection points. WildLands has worked on about 15 sites, which have varied in size from 60 to a couple hundred turbines. Soil disturbances can cover several hundred acres per project, as the contractors put down roads and concrete pads for the turbines. Once the roads and infrastructure are installed, the sites are slightly smaller, but the smallest one we’ve worked on was 50 acres.”
Often, turbines are sited on agricultural land. “In those instances, farmers will till them up and replant, so we don’t have to go into those sites. We’re doing our work as part of the Conservation Reserve Program. Columbia Gorge is a hot spot for turbine installations right now, and there are others in the Snake River and Kittitas Valley. We’re also reclaiming sites in northeast Oregon, near Le Grand.
“We come in at the end of construction to reseed,” he continues. “We sometimes drill seed, but we also hydroseed and apply mulch. Sometimes during construction we’ll put down temporary dust control measures, such as DustFloc, which is a great wind-erosion-control tackifier. I’ve found it works really well; it’s more expensive but works better than guars, especially since it’s really windy on wind farms! I don’t particularly understand its chemistry, but I can put in less DustFloc [than other tackifiers] and have it hold together both wood fiber and paper-the items that make up the mulch we hydroseed-really, really well. It’s worth paying a little more for the end result-no redos, and it also helps hold the seed down. I can go back a year later and see a nice layer of mulch still intact. I can mix DustFloc right into the hydroseeding mulch. It doesn’t make a crust that inhibits rainfall, and it doesn’t form little pellets, like guar can do. We’ve been using it since 2005; we’ll try anything to improve our performance.”
Trained as a botanist, Bradney uses a great deal of native seeds in his applications. “The “˜native’ definition isn’t very strict, but it depends on the sensitivity or rarity of the vegetation. For some projects, such as those in the Kittitas Valley, we use seed as local as possible.”
For flat ground, Bradney uses 50 pounds of DustFloc per acre and “a bit more for slopes.” With those turbines churning up all that air, are there application problems? “Wind turbines don’t hinder application, but you have to be careful and know which way the wind is blowing,” he says. “Our crews are very good at working in these conditions; we’ve never had to redo anything for dust control. For the final seeding, the only problem is that we can get tremendous rain. You always have to watch the weather-and we’re located in Washington’s “‘dry’ area!”
Damper Climes Still Make Dust
Despite its high humidity, some parts of Florida still produce large volumes of dust. “Because dust control is not enforced as much as it is out west, our customers only call when they are facing fines and work stoppages,” reports James Griffin, vice president of Bio Mass Tech Inc. in Land O’ Lakes, FL. “Our typical dust-control project will consist of a high-profile project, such as Tampa Airport Interchanges.”
Griffin’s environmental services firm uses Soil Stabilizer M10+50, an all acrylic, redispersible liquid soil stabilizer manufactured by Enviroseal Corporation of Port St. Lucie, FL. This polymer modifier can bring dramatic improvements in adhesion, abrasion resistance, flexural strength, and exterior durability that are associated with acrylics-with the convenience and cost effectiveness of a one-pack system.
“We’ve been using Enviroseal products for four years now, and it’s our opinion that theirs are by far superior to the others on the market today,” Griffin says. “We apply M10+50 with our Finn Titan HydroSeeder. This 4,000-gallon HydroSeeder gives us the ability to cover up to 4 acres per load, which is critical when working on time-sensitive projects.”
He describes the Tampa airport project: “Bio Mass Tech was contracted by Flatiron Construction Corp. to stabilize all the exposed slopes of the project. With constant winds coming off Tampa Bay, the exposed slopes were generating dust that was blowing across Courtney Campbell Causeway and even reaching the runways. This was a very sensitive project due to the air traffic, along with the vehicle traffic from the causeway. Bio Mass Tech chose to use M10+50, with a once-and-done application that lasts up to six months. The results we achieved allowed Flatiron Construction to complete vital portions of their project in time for Super Bowl XLIII.”
“Season”-ing With Salts
As they take much less traffic, rural roads are often unpaved; gravel serves the purpose. However, during hot, dry summers, even the least amount of traffic can stir up huge clouds of dust. Add more traffic during a construction project, and that dust becomes a major problem.
“We spray gravel roads and industrial sites for dust, plus we sell the dust-control items to other suppliers,” says Paul Heffron of Heffron Services Inc. in Van Meter, IA. “We use magnesium-chloride salt. When dissolved in water, it’s hygroscopic; when sprayed on a gravel road, it gives the road a near-concrete hardness for two to six months. The same product is used in fertilizer blends-so, when it does dissipate, it’s a natural source and goes right back into the soil.”
Heffron uses North American Salt’s DustGard. Based in Overland Park, KS, North American Salt produces a variety of products, including road salt and potassium sulfates. Produced from naturally occurring minerals in the Great Salt Lake, DustGard is an environmentally friendly dust control and soil stabilization product often used in sensitive areas, such as on US National Forest roads. The company says DustGard can lower costs by reducing the need for blading, watering, and gravel replacement; reducing vehicle maintenance costs by lowering the levels of dust that clog filters, bearings, and machinery; and reducing the cost of cleaning vehicles, equipment, property, vegetation, and living sites. It also prevents costly soil erosion caused by destructive wind conditions.
“Our dust-control season starts in May and runs through October,” Heffron says. “At least half of our business is homeowners who want us to spray the roads-at least 500 feet of their frontage. We work closely with county engineers; crews will come out and grade the road, fix potholes, and so on, then maybe in spring or midsummer we’ll spray the gravel. There are also a lot of small towns around, and we’ll cover their streets that aren’t paved.”
When a lone pickup truck can stir up a dust devil, imagine the cloud generated with a building boom. “Our highest-profile project was spraying the wind energy farms of Mid-American Energy. When they were being built, the biggest issue was that they were all being placed in relatively remote Midwest rural areas, and there weren’t any paved roads to the sites. During the construction process, that caused lots of traffic on unpaved roads. In addition to the nuisance of dust, a safety issue crops up-when you get 100 concrete trucks on a gravel road that normally gets 15 cars a day, clouds of dust can affect safety and quality of life.”
With such traffic, why weren’t paved roads installed? “The roads were only going to see heavy use for three or four months, during construction, and then traffic would return to normal levels. It would have been too expensive to replace all those limestone gravel roads. Only access routes would be left there when the site was done.” He adds that the excavation for the turbine pads stirred up even more dust.
“We went in and applied DustGard right after the grading was done. For such a large project, we used several large semi-trailers retrofitted with tanks and three 7-foot booms, as this is a liquid application. We sprayed from the back of these, with a computer-controlled sprayer. The computer was programmed with all the pertinent information-the GPS coordinates of the site, the miles per hour of the truck, the gallons of mixture per yard that needed to be applied. The whole process is automatic; drivers never had to leave the truck.”
Heffron’s firm has been using North American Salt products for five of its six years in business.
“DustGard is excellent,” he says. “I’ve tried other stuff that doesn’t work as well.” What about the cold months-does Heffron use other North American Salt products? “We sell de-icing products in the winter, but we don’t spray them ourselves-that’s vacation time!” he chuckles.
