Peter Candelaria says he’s very passionate about dust control.
“People came to Arizona during the 1950s and 1960s because they had pulmonary issues, whether it was allergies, asthma, or sinus problems. They came here because we had clean air,” says Candelaria, who was born and raised in Arizona.
But like many states with pleasant climates, Arizona became a magnet for immense population growth. Resulting construction brought on the very dust problems those relocating were fleeing when they left other states.
“We’re very dry and arid, and once you stir the dust, the particulates will stay in the air for a great length of time. The smaller the particles, the greater the time it takes for it to eventually settle down,” points out Candelaria. “The more we scurry about, the more we suspend the particles.
“People took [the clean air] for granted,” he says. “I want to be part of the effort to bring that back.”
As the general manager for Earth Bound Environmental in Litchfield Park, AZ, he’s doing just that. The company provides full-service engineering, including a variety of dust containment solutions.
“Dust control and the application of dust palliatives is no longer just spraying water on the disturbed earth surface,” says Candelaria. “It’s changed. It’s become complicated.
“We look at our client’s project and determine the different products that are available that would suit the purpose [for which the client is] needing the dust control,” he adds.
Choices include polymers and organic fluids, depending on the job considerations. Dust control may be provided during the construction phase or at the end of the project.
“Sometimes we do surface stabilization using polymers to stabilize the dirt surface; a lot of this is being done adjacent to runways or taxiways at airports,” says Candelaria.
Earth Bound Environmental has created a joint venture with DirtGlue Enterprises to help contractors and landowners to find the most economical solution to their dust issues, he says. DirtGlue offers a variety of products, including DirtGlue Polymer, used for roads, stockpile capping, erosion control and hydroseeding, mining, and military applications; PM Tac, a medium-duty polymer emulsion to control fugitive dust at construction sites or in similar situations; DustLess, an organic fluids blend that needs no water for application, used on unpaved roads, parking lots, service lots, and storage lots; ArenaKleen for horse arenas and stables; and PotHoleGlue, which binds to existing asphalt.
Maricopa County, AZ, has been in conflict with the EPA over dust issues, says Candelaria. “There hasn’t been a serious effort to control dust in Maricopa County; therefore, there have been mandates. Arizona is now in jeopardy of losing federal funds because we’re in violation of the air-quality standards that the Environmental Protection Agency has established.”
However, the county has become more stringent, says Candelaria. It now requires entities to obtain a dust permit for a clearing of more than one-tenth of an acre, digging a trench with motorized equipment, or constructing a road.
“Dust in Maricopa County is a big issue,” says Candelaria. “It’s all about economics. Most people will complain about the guidelines and air quality and why we need to do this. Everybody points fingers-such as, “˜What about the farmers?’
“We didn’t have dust when Arizona was just thousands of acres of farmland, so we can’t blame farmers,” he continues. “For contractors in general, it’s a cost issue. They want to be able to be competitive and get the job, but they feel all of this extra effort for dust control is a cost. They find themselves in a bit of a tiff with the authorities, and here come the fines. But they have to be proactive, because once you get fined, you’re going to be on the radar screen.”
Earth Bound Environmental is involved in helping develop specifications for the application of dust palliatives to help contractors “and to understand we’ve got to do something about this, or else we face consequences,” says Candelaria.
“As you open one door, all of a sudden there are several more in front of you to be opened, and you proceed with means and measures of what needs to be done to keep all of this in check,” he says.
He references one Texas contracting company that had been shut down for a number of violations, including dust problems. “We went to bat for them-they were from out of state and didn’t understand the local regulations,” he says. “We got them into compliance. It cost them money they didn’t figure on spending, but it’s doing due diligence-taking into account the overall planning of how the job is going to be handled.”
Contractors will take time to figure out where they’re going to obtain materials and how they will transport them, consider the financials for each month of the project, and figure out what they’re going to turn in for receivables at the end of the month, Candelaria points out. “They’re very detailed about everything, and here’s this sensitive subject called “˜dust control’ that people don’t plan for and they don’t know how they’re going to handle it,” he says. “It’s always a secondary thought. They just think they’ll have their water truck and spray as they go. You have to do the same preplanning for choosing your dust control product as you do choosing your equipment.”
Candelaria is now a big fan of organic fluids, which are derived from alkanes.
“An organic fluid reminds me of an olive oil,” he says. “A polymer has a shelf life as far as the application of it. All of the moisture will evaporate out of it. It will leave behind either a film to coat the top of the dirt surface, or, if you mix it in, it becomes bound to the soil. It evaporates. It has a cohesiveness that binds particles together to keep them weighted down so they don’t fly up into the air.
“If you were to take a cup of olive oil and pour it out onto dirt in your backyard, you would see that the olive oil does the same thing. It weighs the particles down. But it doesn’t bind them. The soil is free and loose and it moves around, but the oils keep the dust particles weighted so that they don’t become airborne.”
Candelaria points out that when dirt is being moved about, it needs to be done as quickly and efficiently as possible, causing the least disruption and creating the least dust problem.
“That’s why I’m now promoting organic fluids to help control dust, versus using water or polymers,” he says. “People need to understand that there are different methods and different products, and each one is produced for a certain purpose. We all need to be more open minded about what we’re doing in trying to put the right product in the right place.”
Earth Bound Environmental subjects products to independent lab testing.
“We spend our own money going to labs and setting up different field conditions with different soils, and then we produce laboratory results of the different products so we can go to our clients and tell them how it performs and what we recommend,” says Candelaria.
“We’re about performance and getting the client onto the right path. Each product has its own use,” he adds. “The bottom line in the homebuilding industry is you don’t need the high-test stuff. All you need to do is hold down dust for a period of months while you’re building a home. We make evaluations based on client need and the duration of the activity.”
The criteria one must consider in knowing which dust-control product is most appropriate for a particular application depends on the end result, says Candelaria. “Are you going to do a surface stabilization? There’s no question you’re going to be using some type of a polymer,” he says. “Then you go through your soil classification and figure out all of the things to make sure you have what you need. Then you have the site-you’re going to move dirt. When you do that, you need construction water, there’s no question. You have to have the moisture in the material.”
With polymers, one must pay heed to traffic, says Candelaria. “With organic fluids, not as much,” he adds. “They’re made to take on whatever traffic there is. Whatever soils your roads can handle traffic-wise as far as volume and weight, you’re going to build that surface to handle it, so you’re going to apply the DustLess or the polymer. You just have to do preplanning. It’s difficult to say what you should do in any case because there are variables. In drier climates, I personally like the organic fluids. We’re looking at some work from the Bureau of Land Management that has hundreds of miles of dirt roads. They won’t want to be going out every two weeks in areas where there is a lot of rainfall. Maybe we have to look into surface stabilization or roadway stabilization.”
Using as little water as possible in executing dust control is becoming more desirable, especially as it relates to regions in which there are ongoing water shortages.
“In Arizona, water is a big luxury. We’re eventually going to run out. The Colorado River can only supply so much. Lake Meade is at its lowest point,” says Candelaria. “We, along with DirtGlue, are promoting waterless dust control, especially in the Southwest. We don’t live in the Midwest or along the eastern seaboard where water is in abundance and so it’s more a conservancy issue.”
Whether the dust control product is sprayed on or tilled in depends on the material being used, he says. “The polymer is a product you can spray on or mix in,” he says. “If you do a mix-in, that’s more of a surface stabilization-you’re going to bind all of the particles and keep them in place.
“The topical [application] is spraying it over the top. It dries off, and eventually you put traffic on it, which eventually grinds it down and the polymers become dust along with the soils. The topical is a short-term solution; the mixing is the long-term solution.”
Organic fluids such as DustLess are applied topically. “Organic fluids weigh particles down and keep them weighted,” says Candelaria. “Eventually the sun’s rays break it down and it does blow away. It can last for about a year before [it becomes necessary to] reapply it.”
There are several approaches to grading and erosion control: one is to do the grading work in stages so that as little ground as possible is disturbed at one time. Another-which in some cases can be cost-effective-is to do all the grading at once and apply suppressants to control the dust.
Candelaria, who has previous experience working for major US construction companies, says one of the ways those companies would save money was to pre-wet the soil, “so when we’d go to move the earth material, it was wet and we wouldn’t create a dust hazard.”
He adds, “Whether to do grading in smaller amounts is one of those things you have to balance in excavation. If you’re doing a road or any construction site, the earth is contoured the way it is, so you’re going to make an excavation and place it in a field area. You now have two areas you need to prepare. How you plan and execute that is exactly what we’ve tried to help with.”
Earth Bound Environmental has been working on several projects where dust control is critical. One involves dust containment for the tailing ponds at the Freeport-McMoRan Copper and Gold mines.
Dust is detrimental to solar panels, and Earth Bound is also working with DirtGlue in a solar plant construction project in Imperial Valley, CA.
“We’re going through all of the geotechnical testing, classification of soils, what we really want to do, and what it’s really going to cost,” says Candelaria. “The bottom line is whatever is spent to construct the solar plant will be passed on to the consumer. We’re cognizant of that, and we don’t want this burden on consumers. We’re trying to do this as effectively as we can. That’s where we do the due diligence and look at all of the different products and then make recommendations.”
The impact of dust on solar panels depends on the type of solar project, he notes. “Some of the solar projects are mirrors that collect the sunlight, directing it to a focal point that creates the heat that then heats the water and creates the steam for the turbine. If there are particles in the general area, one of our options is to put up wind breaks to control the dust.”
Surface stabilization is another option by which Earth Bound binds dust particles on the surface to counteract wind blowing through the area.
“Once these particles are suspended, they eventually do come back to the ground. On the way to the ground, they collect on the surface of the panels-whether it’s a solar panel that generates electricity or a mirror-and the efficiency then is lost. The more dust, the less efficient they become.”
Another project on which Earth Bound Environmental is working on is an addition to an existing gas-fired electric power plant owner by Salt River Project in Casa Grande, AZ. He says the Salt River Project, a public power and water utility, is a leader in dust control.
“They are currently active in the search for new products for dust control and surface stabilization to include new and innovate means and methods,” he says, adding that Salt River Project also is involved with the revision of existing dust control specifications for the Maricopa County Association of Governments and its own specifications. Earth Bound Environmental and DirtGlue also are involved in the process.
Landfill Dust
Nick Clapper understands the importance of keeping dust at bay.Clapper is a planner/engineer with DelHur Industries in Richland, WA. His company does mine site reclamation, dam modifications, and landfill cell construction and closures.
On a recent job expanding a landfill, DelHur used EarthBound from Earth Chem, a manufacturer of soil stabilization polymers for use in agriculture, fire rehabilitation, and construction.
“At the site, it’s very windy, and maintaining the dust is a requirement of our client to meet federal regulations,” says Clapper. “It’s very important to keep the dust down, because if it gets too dusty, they’ll shut us down.”
DelHur has numerous water trucks scattered throughout the site during construction.
“As we’re constructing, we’re excavating dirt, we’re moving it around, and we’re adding water to it to keep the dust down during construction, but as a final product we add in the EarthBound,” he says. “It’s real sandy and dusty, but we spray on the product with a water truck. It locks down and limits the dust.”
EarthBound has been subjected to field tests by the Texas Transportation Institute, with results showing that the product supports effective vegetative growth and reduces soil erosion by 85% on 2:1 slopes.
The soil stabilizer and mulch tackifier binds paper and wood-fiber mulches to the soil and is manufactured to last four to 12 months in the soil. Usage requires five to 20 pounds per acre. It can be applied with seed or mulch, or alone for temporary soil stabilization.
Battling Spider Mites
Meanwhile, in California, spider mites have been a vexing issue for vineyard operations.
According to an article posted on the University of California’s California Agriculture online site, grapevines in the San Joaquin Valley are most often attacked by two spider mite species. Willamette mites can cause leaves to yellow, but rarely build up to densities causing economic damage. Pacific spider mites, on the other hand, can cause leaves to turn brown and abscise prematurely, reducing the fruit’s sugar concentration and reducing vine growth and crop yields the year after infestation.
Recently, Valley Farm Management in Soledad, CA, used Soilfloc 30 EVT tablets from Hydrosorb in an effort to control dust that kicks up from unpaved roads on the property, which contributes to the spider mite problem.
“The mites are everywhere,” says Dustin Rubbo, a viticulturalist for Valley Farm Management. “They’re in the wind. They’re so tiny they get blown up with all of the dust. They can cause pretty good damage.”
Soilfloc 30 EVT tablets are effervescent water-treatment tablets. The water-soluble, linear polyacrylamide (PAM) is used not only to improve water quality by flocculating and settling suspended clay particles in runoff water, but also as a temporary dust control additive for water trucks, reducing water truck trips by up to 70%.
Rubbo says Valley Farm Management tried the Hydrosorb product after one of the company’s distributors presented it as a solution to the dust challenge. Seven tablets per 2,000 gallons of water are used and applied on the unpaved roads. A driver takes the water truck on weekly rotation among all of the Valley Farm Management ranches.
Valley Farm Management oversees 2,800 acres of vineyards, which are serviced through about 10 miles of unpaved roads.
“We tried it out and it seemed like it worked,” says Rubbo a month after the process was initiated. “It kept the dust down for a couple of days and cut out a little of our water application.”
Rubbo points out that Valley Farm Management is also using fewer chemicals to combat the spider mite problem and is thus spending less money.
The use of the Soilfloc 30 EVT tablets also mitigates another problem: water conservation demands in a part of country that has experienced little rain. In California, water is “liquid gold”; it costs about $900 per acre-foot of water to run a water truck eight hours a day, says Sandra Miller of Hydrosorb.
“It’s a temporary dust product that can cut down water truck needs 30% to 50%,” she adds.
Rural Kansas Roads
In Miami County, KS, about half of the population lives in rural areas, while the other half lives in more densely developed communities. The county has 250 miles of paved roads and 515 miles of gravel roads. Homeowners and businesses along the unpaved roads often complain not only about chuckholes and ditch problems, but also about dust.
Miami County’s Road and Bridge Department began spraying North American Salt’s magnesium chloride product, DustGard, on its roads as a maintenance tool. It helps reduce dust on roads with traffic counts exceeding 300, says James Rice, a road foreman and supervisor.
“Then, a couple of years ago, we started using it for a maintenance tool for those roads where we were getting the work request complaint calls on a regular basis, and it’s dropped those down to nil,” Rice says.
“When we repair the road, we improve the drainage ditches, put some material on the road, and then put down our magnesium chloride. It’s reduced those calls by at least 95%, if not more.”
DustGard is used as both a dust control and road base stabilizer. Hygroscopic characteristics help it attract moisture and maintain natural surfaces for long periods of time without the need for reapplication.
Rice says Miami County applies the DustGard once a year. “We put it on a half-gallon per square yard. That’s a little heavier than most people [apply it], but we’ve had good success not having to do re-applications,” he says. “Usually we do about 50 miles a year, and usually two or three miles we might have to do over again. Those are usually our very high-traffic roads or a road that got rained on right after we put applied it the first time. We’ll do a half-application in those cases.”
Miami County has a chip seals dust control program whereby it converts some of the magnesium chloride-treated roads to chip sealed roads, using the chip seals to improve drainage structures.
A Four-Year Construction Project
For Henry Martinez, who owns water trucks and also is a supervisor for Ashby USA, Soil-Sement from Midwest Industrial Supply is the dust-control product of choice. Martinez has been working four about four years on the Roripaugh Ranch project, an 800-acre master planned community in Temecula, CA, with homes, a school site, and parks.
Soil-Sement is a polymer emulsion designed to significantly reduce PM10 and PM2.5 particulate matter in an environmentally friendly way. It dries clear after application.
Martinez is using dust control in the flat areas and erosion control on the slopes. He says Soil-Sement was chosen because, at one time, he had used a mulch tackifier that he found to be “messy.” In contrast, Soil-Sement “breaks up really good” when mixed, he notes.
In the beginning, the construction site had a significant dust problem, “but as soon as we sprayed the whole site with Soil-Sement, we had very little dust,” Martinez says. The Soil-Sement is sprayed on with the water truck and has been reapplied once a year in keeping with the city’s requirements.
Trying New Products
Sometimes, choosing what form of dust control to use is not a clear-cut decision and involves weighing the benefits against the drawbacks.
For years, the Larimer County (Colorado) Road and Bridge Department had been using the salt compound magnesium chloride for dust control and road stabilization on unpaved roads. Dale Miller, the department’s director, says it was a cost-effective and efficient way of controlling dust.
Several years ago, however, members of the public voiced environmental concerns about the use of magnesium chloride causing damage to vegetation, getting into stormwater runoff, and-when used on asphalt roads-leaching hydrocarbons into the environment.
There had been no definitive scientific study to address those concerns, so Larimer County teamed up with Grand County to engage in a long-term study through Colorado State University’s Department of Bioagricultural Sciences and Pest Management.
Three years into the five-year study, findings showed that magnesium chloride-based products can move from treated roads into adjacent soils. Trees take up soil magnesium and chloride through roots, and the substances accumulate in leaves.
“We’ve learned that the magnesium chloride can cause trees to suffer stress, but have not gone all the way to say it causes death,” says Miller, adding that long-term drought also has been a challenge for trees in Colorado. He says that there have been no findings indicating the use of magnesium chloride leads to a negative effect on streams or aquatic life.
The Colorado State University Extension recommends the use of non-chloride-based products to avoid chloride toxicity in roadside trees. The county intends to phase out all use of magnesium chloride by 2012.
Miller says it’s unfortunate that the county can no longer use magnesium chloride as dust control. “Other than its effect on roadside vegetation, it’s our product of choice,” he says. “It’s more affordable, cheaper and more effective than anything we’ve tried. We’ll try any product that comes to our attention to try to find something that’s environmentally friendly, affordable, and effective.
A few years ago, Larimer County stopped using magnesium chloride in forested areas and areas with steep grades. The county has a standing offer to any company with a new product: The county will give the company a mile of road with nontreated gravel on it on which to apply the new product.
“If it works, we’ll pay for it,” says Miller.
Recently the county has been applying X-hesion DC from EnviroTech Services in Greeley, CO. X-hesion DC is a non-chloride form of dust control and road stabilization created from agriculturally derived complex organic polymers, which bind base materials together while maintaining a water-resistant and flexible road surface.
“It does a reasonable job of stabilizing,” says Miller. “We pay more for it [than for magnesium chloride] on a per-mile basis.”
The market for dust control in Colorado is good, notes Miller. Colorado cities and counties are required to apply dust control treatment on any urban road that hosts more than 150 daily trips and rural roads that exceed 200 trips. Reapplication of dust control depends on such factors as the weather, the roadbed, traffic volume, load, and speed. Thus, he says, some roads are treated once a year; others can be treated up to six times a year.
