Essential and Effective Techniques for Controlling Fugitive Dust
Years ago, dust was an accepted result of construction, of driving on unpaved roads, and of some industrial activities. In 1970, the Clean Air Act changed that. Three types of particulate matter (less than 10 microns, less than 2½ microns, and lead) were classified as health hazards. State and local governments were tasked with monitoring air for particulates and other pollutants.
In the last few years, many municipalities and county and state governments have tightened air-quality standards even more. Control of particulates becomes a big part of planning for any project or for a facility. The public is also more aware of the hazards of dust. People will complain if a facility near their home or business is producing dust or if truck traffic on an unpaved road is raising dust clouds nearby, on a daily basis.
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Dust and erosion control are two sides of one coin. If proper erosion control measures are in place, dust control will often follow. They are both the result of good soil stabilization methods. Planning and application needs to take place before the dust begins to blow.
The products for dust control vary by the type of site and coverage needed, whether long term or continuous. The purpose of the application is also important. Is the goal to stabilize a slope until vegetation can be established? Or, is it to control dust on a road that must withstand heavy truck traffic? Does a facility need to control dust from industrial processes?
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Many dust control products are chemicals that are applied to the soil, while others are mechanical systems for spraying water. The chemicals used differ. Some are adhesives, which tie aggregate and fines together, leading to a durable and dust-free road surface. They might consist of polymer or asphalt emulsions.
Another set of emulsions are resins, such as lignin sulfonate, which holds fibers and soil together, reducing dust and erosion.
Some salts, such as calcium chloride, magnesium chloride, and sodium chloride, are hygroscopic, meaning they pull moisture from the air. With concerns about adding chloride to the environment, they must be used carefully to avoid contamination of water sources, but they are an excellent choice if used properly.
Oil Field Roads
In 2011, Jason Ramsey and Brian Coleman started Ramco Environmental, with sites in Arkansas and Ohio. They saw the need for dust control along roads used by oil and gas companies and built their company to fulfill that market.
Oil companies typically use unpaved roads, either local county roads, or roads they create to reach a new rig or pumping pad. Many of the sites are in remote areas with only unmaintained roads. Initially most of the companies used water to handle dust control. But water was needed for fracking operations, leaving little for spreading on roads, especially if it had to be applied several times a day. Heavy truck traffic was causing significant air-quality issues for residences and farms along these roads. Different dust control products were tried, but during rain events, it was hard to keep the products on the road. Some water-soluble materials ran off into creeks or ponds, causing problems for livestock that relied on those water sources.
Ramco Environmental chose to apply PennzSuppress D, an emulsified resin-based dust control product. PennzSuppress D works as a dust control agent as well as a soil stabilizer. It is a blend of asphaltenes-free resins that promote penetration into the ground, as well as superior bonding and elasticity. The components include a paraffin resin with a blend of wetting agents, emulsifiers, and dispersants. The emulsifiers coat the resin particles so that they stay in suspension in water, leading to excellent penetration into the road surface. The product binds the fines into the aggregate of the roadway, keeping them from being blown around or running off in rain events.
In testing, PennzSuppress D has reduced fugitive dust by 98%. It forms a long-lasting surface that is moisture-permeable, but will not wash away and is not corrosive to vehicles.
The amount of product used depends on the soil conditions. Typically it is diluted from four to 10 times. In drier climates, more water is used to lower the viscosity and allow better penetration.
PennzSuppress D is being used on haul roads by companies other than those in energy. One project involved a half-mile-long unpaved haul road that carried heavy truck traffic near a coal-fired power plant in Missouri. The road was well graded with medium-grade aggregate. However, the fly ash that was being transported mixed in with the aggregate and produced a very fine dust. Ramco brought in a tank of PennzSuppress D to be applied at a one-to-nine ratio, with water and at a rate of 0.46 gallons of the mixture per square yard. Three applications were made with drying time in between. The solution quickly penetrated the road surface without puddling.
During the drying time, Ramco had the trucks drive over the roadway to force the solution deeper into the road surface. Once the road is fully treated, maintenance treatments will keep it stable and dust free.
Roads can also be built and stabilized using PennzSuppress D. The liquid product is mixed with the aggregate before it is spread on the roadbed. Equipment required is an application truck and a road grader. Once applied and compacted, the aggregate mixture provides a durable, dust-free surface. Ramco customers have found that this system works well, even on roads with numerous curves and hills.
In 2014, unpaved roads in Allegheny National Forest were exceeding Pennsylvania DEP air-quality compliance because of dust. An energy company has several wells in the area and the truck traffic was causing fines from the roads to enter protected drinking water sources. Using PennzSuppress D to stabilize the roads brought the energy company back into compliance and the truck traffic could continue.
Colorado Sand Mine
Transit Mix Aggregates-Daniels Sand Division operates a mine near Colorado Springs, CO. The mine is a natural sand deposit, some of the best quality found in Colorado. Grant Smith, mine and production manager, says, “Dust control is a hot topic, and becoming more front page as states and counties increase enforcement.”
He needed a way to extend the time between passes with the watering truck on haul roads and around the plant areas. The sandy soil plus the usual breezy to windy conditions seen along the Colorado Front Range called for strong dust control measures. With summer temperatures, the situation worsened. The water truck driver was making five to seven passes a day. Another complication was that the truck driver had a double-duty job; he watered the roads and was also responsible for cleaning and washing many areas around the mine and plants.
The search was on for a product that was environmentally friendly, cost effective, and easy to apply and maintain. The choice was X-Hesion Pro from EnviroTech Services, based in Greeley, CO. The product is an extra-low-chloride polymer, which helps limit the amount of chloride entering the environment. X-Hesion Pro effectively binds the fine particles and aggregate into a strong matrix. It is also very effective at drawing in and retaining moisture to keep the connection strong and reduce dust.
Applying PennzSupress D on an unpaved access road
EnviroTech Services personnel came to the mine and began the initial application with a 50/50 blend of X-Hesion Pro and water. The mine then took over maintenance of the roads and now has a bulk tank for the X-Hesion Pro onsite. The maintenance mix for summer conditions is a 10% dilution applied once a week. Smith thinks he might be able to extend the time between maintenance passes during fall and winter when there is more rain and lower temperatures.
He says the product keeps moisture in the road as designed, and adds that it has improved road conditions. The roads are composed of mostly sandy soil with small spots of clay. When only water was added, the clay spots became slimy and slick. Now, they perform well in dry or wet conditions.
“All in all, X-Hesion Pro has made our dust control measures and program more cost effective without a large change to the processes,” says Smith. The new process also cuts down significantly on the costs for fuel and water for the water truck.
GelTrak kept neighborhood dust complaints to a minimum during temporary construction.
Solid waste landfills must not only control odor, but also maintain dust control to be good neighbors. For many landfills around the country, the choice is Soiltac, manufactured by Soilworks of Gilbert, AZ.
Soiltac can be applied to the earthen caps that cover landfill sections. The product consists of long copolymer molecules with multiple links and cross-links. The concentrate is mixed with water, with the ratio depending on the site and use. The mixture is sprayed on the soil by water truck or sprayer applicator. The white fluid begins to disappear, but the soil surface will appear darker. The mixture penetrates into the soil, forming the flexible solid mass that will capture and encase fines so they cannot escape as dust. After it dries, Soiltac is transparent.
The product is non-corrosive to equipment and will not rinse away in rain. It can last from weeks to several years, depending on the concentration of the application.
Reclamation In The Oil Fields
Chief Oil and Gas wanted to reclaim the Dacheux Water Transfer Pad at a well in Cherry Township-Sullivan County, PA. The company needed a time and cost-effective way to revegetate the bare pad and the slopes around it. Erosion control blankets were considered, but the final choice was EarthGuard Fiber Matrix, a product from LSC Environmental Products of Bakersfield, CA.
EarthGuard Fiber Matrix combines 100% wood fiber with a soil stabilizer. The stabilizer is designed to directly impact soil to corral any fines, and to keep the soil structure intact, protecting it from wind and rain. It consists of high-molecular-weight polymer emulsions. The product can be used for winterization, without seed, to protect bare soil, slopes, and stockpiles during the rainy season. It can also have added seed for quick growth when the conditions are warm enough. For seed establishment, amendments can be included to give the seeds a good start.
Penn Line Service performed the application at a rate of 10 gallons and 2,500 pounds per acre. Other products often require heavier loading of fiber.
After five weeks, significant growth had occurred, making the pad and slopes stable for the winter ahead.
Keith Kimball, construction inspector for Chief Oil and Gas, says, “I have been very happy with EarthGuard’s overall performance. We save money and get the results that we are looking for.”
A temporary lime rock road was being used at a golf course in Florida, On Top of the World Communities and Related Entities in Ocala. Golf course superintendent Andrew Jorgensen, CGCS, explains, “We were faced with numerous complaints from the nearby residential community associated with dust from construction traffic while using this temporary roadway.” Seeing the need for dust alleviation and for a short term of 60 to 90 days, he decided to use GelTrak, manufactured by Ecologel Solutions, LLC of Ocala.
GelTrak is an environmentally friendly dust suppressant that mixes hygroscopic and humectant chemicals with plant-based binders. The product keeps soils damp by pulling moisture from the air and the surrounding soil, and it adheres fine dust particles to larger particles. According to Sarah Spatola of Ecologel Solutions, “By utilizing subsurface moisture and relative humidity to help maintain nominal surface dampness, GelTrak reduces watering requirements by up to 50% or more.”
Application was accomplished by using a small tractor to pull a water tanker with a high-volume flood nozzle. The product was mixed with water at a dilution of 50 to one, and applied at the specified rate of 55 gallons per 1,000 square feet for the first application. The road should be damp to wet, but with no standing water, before application.
Jorgensen says the course plans to make applications every six weeks or as needed during the dry season as long as the road is still in use. The application will be effective for up to three months, depending on rainfall and traffic. Results are amplified by each application.
The product reduced the amount of dust to virtually zero and greatly reduced the number of complaints. GelTrak is biodegradable and not hazardous to plant, animal, or marine life. Jorgensen says, “We intend to continue using GelTrak in other areas where construction is within a close proximity of the nearby residential community.”
Credit: RECLAIMED AGGREGATES
Atomized water droplets control dust without creating mud.
The Right Equipment
Dust control does not always mean adding resins, polymers, or tackifiers. It can mean water transformed into an atomized mist.
Reclaimed Aggregates Inc. (RAI), a company in southern California, recycles old road surfaces into new, providing substantial savings. In the
past, when California roads needed replacing, the pavement was torn up and trucked to landfills. New materials were brought in to rebuild the road. RAI provides a more environment-friendly process of reclaiming the used asphalt or concrete and recycling it into Class II base, or crushed miscellaneous base (CMB). The process saves money, but at several stages, dust is created. Dust from the operation at the five-acre Chula Vista plant causes problems with air-quality standards.
The plant receives dozens of trucks each day delivering asphalt and concrete chunks from demolished roads. The pavement debris is dumped onto a 200- by 200-foot receiving area. Front loaders move it to a crusher or to a storage pile. Facilities manager Robert Erautt explains, “The offloading process creates a tremendous amount of dust, and that was causing issues for our neighbors who run large vehicle salvage lots.”
At first, the company tried a sprinkler system to settle the dust. However, Erautt says, “It just saturated the material, creating a lot of mud, but the dust still remained an issue.” After some research, the company found DustBoss suppression equipment and decided to give the DB-45 a try.
The DB-45 from Dust Control Technology (DCT) of Peoria, IL, atomizes water droplets to a size of 50 to 200 microns. In contrast, sprinklers send out droplets of 2,000 to 6,000 microns.
The tiny mist particles from DustBoss are similar in size to the particles of fugitive dust, so the water is able to make contact with the dust particles and pull them out of the air. The atomized mist also produces large numbers of the water particles without saturating the debris or causing mud. DCT president Laura Stiverson says, “The size range is critical to avoid the ‘slipstream’ effect that large droplets from sprinklers have on airborne dust particles.” Water particles larger than 200 microns can cause dust particles to swerve, but not contact the water. The dust remains in the air.
The ability to atomize the water means that less water is needed. The DB-45 propels the mist out 150 feet and can cover a 12,000 square foot area. It can also oscillate to cover as much as 74,000 square feet. Stiverson says, one advantage is that the equipment runs without requiring constant adjustment by an operator. DCT manufactures a variety of sizes of DustBoss equipment, so a fit for many situations can be found. The company has personnel who can help customers determine what size is needed, based on working conditions.
Dust suppression cannons manufactured by DCT can be mounted in several ways. A three-wheeled carriage allows greater mobility and can be easily moved by hand. The skid mount is useful for stationary positioning; the unit should be placed above the source of dust. A tower mount can place the unit up to 30 feet in the air. Trailer or vehicle mounts give the most mobility for operations such as highway coverage.
Erautt says that using the DB-45 has made a big difference. “On hot dry days—which we get a lot of around here—a little breeze can carry dust a long way. We just turn on the atomizer and you can see the mist pull the dust out of the air.” Most of the time, the unit stays in one place, but the position can be changed if needed. “We leave the machine running most of the day if it isn’t raining,” says Erautt. “We haven’t had a single call from our neighbors about dust from the day we added it.”
Dust Control Best Practices
Whatever product is the choice for your project, the experts in this article had some advice.
- First, if road preparation is poor, the result will be bad no matter what product is used or how well it is applied. The best results require quality aggregate, good road preparation and compaction, and appropriate application of the dust control product.
- Be sure to exactly follow the manufacturer’s instructions on dilution and application of the product. A solution that is too strong or applied too heavily can lead to slick roads. One that is too light wastes product and fails to accomplish the goal of dust control.
- Apply again as needed. This will vary with topography, temperature, and weather conditions.
- If you consider the cost of dust control products over plain water, they may seem expensive. But these compounds greatly reduce the amount of water needed, and decrease fuel costs for water trucks, making them a cost-effective fix.
Dust control is a top priority for projects of all kinds. The public will complain if dust is filtering down into their houses or businesses. Fines can result from not meeting local or EPA particulate matter standards. These products can avoid these issues and contribute to a successful completion of your project and good relationships with neighboring residences and businesses.