They’re coming and there’s nothing that can be done to stop them. No, it’s not the in-laws visiting for the holidays, but rather a much quieter species invading to wreak havoc on the lives of construction and demolition operators—in the form of small particles known as "fines."
These dust-sized particles at a recycling facility are nothing to sneeze at. What may begin as a minor problem can become a headache for some C&D debris processors. Fines can clog machines, cause added wear and tear on equipment and contribute to health problems of workers.
The particles, which can accumulate on a job site and in and around equipment, can cause operators and processors to scratch their heads as to the best ways to handle amassed quantities of fines.
It is a problem that is not exactly being swept under the rug, but at the same time there are no apparent "fast-track teams" working to formulate industry-standard procedures for dealing with the particles.
REDUCTION AT THE SOURCE
A trial and error approach to handling fines seems to be the action taken by some C&D operators. Several factors have to be taken into consideration when deciding the best way to dispose of and handle fines, including safety for workers who handle the fines, the cost of disposal or recycling of the material, and finding equipment that can make management of fines easier and more efficient.
Since there are few equipment companies making units that specifically deal with the handling of fines, some companies take existing equipment and attempt to modify it to meet their needs. "There is not really anyone out there building [fines-related] equipment specific to the wood industry," says Richard McCandless, recycling and marketing manager at Kroeker Inc., Fresno, Calif. "We are trying to make equipment and modify it to our needs. You tweak or modify to make it [the equipment] fit your application."
McCandless says Kroeker Inc. has been modifying equipment in an attempt to find a more efficient way of handling fines for about two years.
Tom Goodrich of Needs Inc., a mixed C&D processing company based in Johnston, R.I., has taken a similar approach to handling fines. "Over the past couple years we have engineered water misting systems to keep dust down," he says. "In this industry, or at least our facility, the latest development is the introduction of water. I do know that in most of this industry a lot of this has been pure research and development, almost trial and error."
Equipment companies are just beginning to produce equipment that addresses the handling of fines. "The problem with mixed C&D is that you have such a variety—wire, pipe, rugs, metal and wood—a real mixture and a lot of screening equipment that may work well with gravel or dirt materials must be modified to work with a mixed feedstock," says Goodrich.
Many companies have also decided to market some of the equipment they have designed to handle fines. "I think what you’ll find is the manufacturers are beginning the curve of trying to keep up with the modifications," Goodrich says.
Once the original equipment makers saw the modifications being made by recyclers, they too incorporated some of the same ideas and other processors into their own pieces, Goodrich says. "That’s typically the way equipment is developed in the industry,"
A well-designed system can help reduce the amount of fines at a facility, says Scott Jable, Midwest regional manager for Van Dyk Baler, Chicago, Ill. (The company also markets Lubo sorting and screening equipment to the North American market.) Jable says the use of screens can help make the fines into a usable material, suitable for backfill or as a road base.
He also notes that while the shredding or grinding process creates some fines, others are produced during the demolition process and hauled onto the premises of C&D recycling companies. When the fines are not taken out of the load before materials head to the grinder, "they can wreak havoc on those pieces of equipment," he says. "It makes the blades wear faster," as well as causing other wear and tear on machinery.
In Europe, Jable has seen completely enclosed indoor facilities that can eliminate some of the problems found at outdoor facilities, such as blowing dust that can cause irritation to surrounding residents. But, as successful as that approach has been in Europe, Jable says he doesn’t think the trend will spread as fast to the United States. "It would take quite a bit to happen in the United States—it is an expensive proposition," he says of indoor facilities. "A lot of things that have happened in C&D in Europe have already happened here, but that one would take some time."
In an effort to reduce the dust produced by fines, some companies are using water. Russel Hawkins, vice president of Allied Recycled Aggregates, Commerce City, Colo., says containing the fines is not that hard to do, but finding something to do with them afterward is more of a challenge. "Generally most of them are dealt with using water," he says, "an H2O spray. You can add a detergent material that is a wettener, but containing them isn’t all that tough."
Common ways of dealing with fines, Hawkins says, are bag house systems or scrubber systems, which are required by some states. Working in metropolitan areas can also bring with it stricter regulations.
WHERE TO PUT THEM
What many C&D companies are doing with their fines is using the material for landfill cover, says Jim Cullom, of Flo-Cait Environmental Services, Holland, Mich. "Generally what they do with the fines, because they are still [a commingled stream] with wood and stone and dirt, is about 90% of it goes for landfill cover," Cullom says. "And most landfills take it for nothing or charge a minimal fee to dispose of it."
While reuse can be an option for some fines, it has not become a widespread practice because of concerns of contamination with hazardous materials. "There’s not a lot of reuse because everyone is nervous about lead contamination," Cullom says. "If there was no lead you could use it for back fill material."
One Westboro, Mass.- based company has found that, for now, the best way to dispose of fines is to use them for intermediate daily landfill cover. Ben Harvey, vice president of recycling for E.L. Harvey & Sons, says the company has been using a trommel system to sift through debris and then use the material for cover.
"We run our material through a trommel system that takes out everything ¾-inch or less," Harvey says. "We’ve been using them for intermediate daily landfill cover. That’s all we’ve been able to do with these things on a regular and consistent basis." Because the fines contain a variety of materials, it is hard to find an application for a material that has an inconsistent content from day to day.
And although the landfill application has worked well for E.L. Harvey & Sons as well as some other C&D companies, the ever-increasing tendency of landfills to close is on the minds of processors and operators.
"The landfill cover has worked out good for us, but as more and more landfills close it is going to be more difficult to find something to do with the material," Harvey says. "And at that point I don’t know what to do with the material."
While finding ways to dispose of fines is one issue C&D processors face, another can be the safety of workers from breathing in dust and particles. For workers, the inhalation of dust particles is not healthy. Fortunately, utilizing a mister to dampen the dust can help keep respiratory risks to a minimum.
Other concerns can involve eye safety from flying particles, with safety goggles being the primary method to avoid injuries.
"Dust, splinters and eye irritants can result in demolition material and you also have nails," says McCandless.
Some of what can cause hazards for workers can be the contaminants in or on the materials being processed, such as lead-based paint on the rubble of older buildings or traces of arsenic in some soils. But depending on the application that the fines are to be used in, those safe contamination levels can vary.
Florida has a set of risk-based guidelines concerning the use of fines in applications including as a base under asphalt or as landfill cover material. "For any type of waste or contaminated solid that may have any type of environmental pollutant, there are risk-based guidelines for when the material is safe to land-apply," says University of Florida professor Timothy Townsend. Townsend, along with fellow faculty member Brian Messick, has researched how materials from fines can be recovered and possibly reused.
Some of the variations that can be permitted include, for example, fines that are going to be used as a layer under blacktop could contain more lead than fines that were going to be used for other applications. But, Florida’s contaminant problem is more with arsenic than lead, Townsend says. "We have a very low risk base number for arsenic," he says.
And along with risk-based guidelines, there are also separate guidelines for residential and industrial applications. A complication to the situation can be proving that an industrial application of the fines (as a base going underneath ground level) will remain on industrial land and not become residential after a period of time.
Using fines as landfill cover does not have as many limitations as do industrial and residential applications, he says. "I think the industry is trying to feel out what their true ability to recycle this material is," Townsend says. And the benefit of recycling fines versus the potential risks that it may entail must also be taken into consideration, he adds.
"Folks are still trying to figure out what they can do," Townsend says. "Speaking from the point of view of C&D facilities now, they are still scratching their heads about how much time and effort to put into looking at reuse," he remarks.
The author is assistant editor ofC&D Recycler.