Jan. 13, 2014 03:33

Controlling Dust

When the Santa Ana winds kick up the dust here in Southern California, I’m reminded of a quote by the poet T.S. Eliot: “I will show you fear in a handful of dust.”

Most people outside of the erosion and sediment control business might not understand the fear that dust particles can create. As someone who is in that business, however, you know many reasons why dust is something to be dreaded, and respected.

You understand that construction, revegetation, and slope stabilization work always produces dust and, as the contractor on a project, it is your responsibility to contain it. It’s your job to manage the hundreds of billions of dust particles, smaller than the thickness of a human hair, that will be kicked up when the earth is disturbed.

Once airborne, these microscopic particles can float into and contaminate other areas. If it rains, that same dust—now saturated—will quickly turn into sediment runoff, picking up debris and polluting the nearest water source.

Each state has strict environmental open-air dust control regulations relating to water and air quality. If the conditions listed in those regulations are not met, fines can and will be imposed. If, at a jobsite, your control measures fail and you can literally scoop up and hold a handful of dust, your company could pay dearly.

Patrick Duhaime, a dust-suppression product line manager for Company Wrench in Carroll, Ohio, believes the responsibility goes deeper than just controlling dust to meet minimal requirements. “It’s bigger than our jobs, because it’s a health issue for all of us,” he says.

Take, for example, cigarette smoke. It contains 187 known carcinogens, but which one(s) of them might send your DNA into a tailspin? It’s the same thing with dust.

The fear T.S. Eliot may have been talking about is the fear of not knowing what’s in it.

So, a handful of dust in your profession is very much a thing to be feared. That is, unless you know the proper ways to handle and contain it.

Luckily, there are a whole range of tools and types of dust suppressants available for the contractor who is looking for good dust controls. Bob Vitale, CEO of Canton, Ohio-based Midwest Industrial Supply Inc., says, “Our company provides dust control products for the construction industry, industrial facilities and military bases.

We’ve been in business since 1975 and specialize almost exclusively in controlling dust.”

“There are thousands of possibilities for the formulation of dust control products,” says Vitale. “We’ve found more than 50 different dust control agents that work well.” Over the years, his company has found that each construction site has its own unique requirements and special considerations.

“These differences are the key to help you in selecting what types of products you are going to use to meet the dust control requirements of the job.”

Duhaime concurs with that statement. He adds, “In dust management, the biggest part is in planning and finding the right tools and equipment for each job and jobsite.”

So, how should you go about attacking dust? Fortunately, there are a lot of products available to help you do your job. One exotic formulation even comes right out of the tap.

Using the wet stuff

No surprise—it’s water, the oldest and safest dust control product around. Putting plain old water on the ground, either by spraying it out of a backpack mister or a truck, or using an in-place irrigation system, is one of the easiest and most cost-effective means of controlling dust. And, it can be done at almost any site.

Almost. “But some sites need more water than some delivery systems can provide. This was the problem our clients were having,” said Duhaime. “The small electric misters they were using just weren’t powerful enough, and weren’t doing the job.”

Company Wrench used to specialize in demolition products.

Their customers were having problems dealing with the dust created by large demolition projects. To tackle this challenge, the company bought some used snow-blowing equipment and developed a dieselpowered dust suppression unit.

“It’s an air/water cannon,” continues Duhaime. “You have air going through a turbine at about 120 mph, and water pressure that is busted at 150 psi; the net effect is you get a mist that will go about 300 feet. This fine, atomized mist just attaches to the dust.”

“We feel that the mist yields a better result than just putting water on the ground, because that sometimes causes working hazards,” he said. “It can simply get too wet for crews or equipment to work in and around.”

Duhaime makes a good point.

You need to be careful, and aware of the quantity of water being applied. You want to prevent an excess of water, which can lead to erosion problems. If water is applied in abundance, it can result in runoff from the site or vehicles tracking mud onto public roads. Applying water to exposed soils can also be quite time-intensive.

Chad Falkenberg, CEO and chairman of Chandler, Arizonabased Soilworks, a company that controls dust worldwide, agrees with Duhaime’s concerns. “The problem is, when you’re spraying water on a roadway, you can create additional problems. When you get a road wet, it loses its strength. Although you’re controlling the dust, you’re creating mud, potholes and diminishing the surface friction.”

Jeff de Laveaga, director of business development for Soilworks, adds, “The reason roads develop ‘washboarding’ is because the water has nowhere to go. We believe water is a temporary fix, but not a solution.”

One option to control dust is by spraying a bonded fibre matrix solution.

“Our customers also find water doesn’t last very long,” said Falkenberg. “The water is just going to evaporate and disappear quickly, particularly if you’re working in an arid climate.”

And sometimes, it’s simply not available. In many states, water has become too precious and expensive to use in this manner. “We have many clients who live in areas with water shortages, where using water may not be an option,” said Falkenberg. “So we offer solutions that minimize the use of water, if not eliminate it. We have developed spray-on chemical soil treatments, such as tackifiers, soil stabilizers and chemical adhesives, including anionic asphalt emulsions, latex emulsions, resin-water emulsions and calcium chloride.”

Using Chemicals

“Our primary focus is on dust control and soil stabilization,” Falkenberg says. “We distinguish between the two things. The first is where we’re creating a surface crust on the ground to control dust; and the second, where we’re treating the soil by going three-dimensional and into the ground in order to stabilize a certain depth of the soil.”

“To do so, we created and use synthetic, engineered copolymer emulsions and synthetic fluids,” continues Falkenberg. “The copolymer emulsions are formulated adhesives that glue and bind soil particles, aggregates and particulates together to form a surface crust. They can also be mixed into the surface for soil stabilization and solidification.”

“Our products are prime products, not byproducts,” says de Laveaga.

That’s an important distinction, since there’s a complete difference between the two. Most polymers are industrial byproducts. For example, when polymer companies rinse out their tanks, they are left with various contact adhesives, latex paint and similar chemistries as waste products.

Back in the day, these were normally disposed of in water treatment facilities. Then, the companies discovered that this waste material could be used as topical treatments to control dust on construction sites. It worked well, because the mixture would form a film or crust on the surface.

However, as we mentioned earlier, each jobsite is unique, and many times not all of the chemistries in those byproducts were appropriate for every soil. “In other words,” says Falkenberg, “you didn’t know if one day you were going to get contact adhesive, where the results would be sticky. You didn’t know how stable it was going to be in the sun, how long it would last or what type of odor the product might have.”

“The problem was the lack of consistency and repeatability, because there was no formula,” he adds. “What we brought to the industry is a formulated copolymer emulsion, a product that provides consistency—Soiltac.”

Through field trials conducted at the U.S. Army Corp of Engineers’ Research and Development Center, Soiltac quickly gained credibility. The Army wanted to see if it could hold down dust that’s kicked up during helicopter takeoffs and landings.

“The product worked so well, it was selected to be deployed throughout the world,” said Falkenberg. Recently, it was used at a UN mission in Sudan, Africa, where three “super-camps” for refugees were being built. It kept the desert dust at bay as roads, runways, berms, ditches, campsites and trails were being constructed.

The product comes in powder form, making it lighter and easier to transport. “It can be broadcast over a treatment area and hydrated with water that mixes into the soil,” says Falkenberg.

Midwest Industrial Supply also makes chemical controls. “The product we use the most is Soil Sement,” says Vitale. “We created the product using unique polymer chemistry, and it has been widely used around the world, in all types of applications and construction sites.”

The product is sprayed on an area that’s freshly graded. It then creates a “bound matrix” across the surface. “It absorbs into the surface materials, and the combination creates a seal so fine particles can’t blow out.”

When construction is complete, the treated surface can then be planted. “Often, when the time comes to vegetate the area, they will even put some of the Soil Sement into the hydroseeder and use it as a tackifier,” says Vitale. “The seeds and moisture will be held in place until the seed germinates.”

“When it comes to chemical applications, there’s a belief that all dust control products are the same,” continues Vitale, “but there is nothing further from the truth. There are hardly any two types of products that are the same, and every product requires some knowledgeable practices to make them work effectively.”

Another aspect to consider when using chemical applications is the expense. Costs for chemical dust control measures can vary widely, depending on the specific needs of the site and the level of dust control desired.

“Remember, the key variable you have to consider when you’re using chemicals, or even water, is what the local conditions of the site are,” says Duhaime. “Your site might experience more rain, more wind, or contain more topsoil than other locations. It’s vitally important for you to consider this.”

He cites the following example: “When applying water, our cannon will shoot 300 feet. But, because it’s an air/water cannon, if you have a 15 mph headwind, you’re only going to get half of that 300- foot output. So it really depends on the local conditions.”

Vitale says that dust control is a threefold process. “First comes selecting the right product; second, knowing how to use the product correctly; third, having the discipline to use the product properly in order to get the best effect.”

Remember the fear that T.S.

Eliot mentioned? “We don’t fear dust,” says Falkenberg. “Because we’ve been able to control dust for miners, they no longer have to wear dust masks. We’ve stopped military personnel from getting sandblasted when their aircrafts land. And, we’re saving lives by eliminating ‘brown-out’ conditions (similar to white-outs, only with dust instead of snow) that cause aircraft and vehicle crashes.”

However, a word of caution: be careful when considering chemical applications. Check to see whether the chemical is biodegradable or water-soluble, and what effect its application could have on the surrounding environment, including water bodies and wildlife. Use them sparingly; their misuse can create additional surface water pollution from runoff or contaminate ground water. Chemical applications might also present a health risk if excessive amounts are used.

Controlling dust, especially—but not exclusively—on construction and revegetation sites is imperative. For sites where you’re doing revegetation, it helps plants grow so they retain the topsoil; on construction sites, it will save you from heavy fines and work stoppages. Best of all, controlling dust helps all of us breathe a bit easier.

Also in Soil Erosion News

In many ways, we are fortunate that, in our chosen profession, we are able to help people when certain disasters occur: the tornadoes in Missouri, Oklahoma, Louisiana and Georgia, the flooding in Louisiana, the snows in the northeastern part of the country, the rain in California, and the snow in Colorado....

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