Vacuum Trucks Help New Surfaces Go with the Flow

Who hasn’t been stuck in a downpour?
While those of us lucky enough to have an umbrella are scrambling to get it open, it is what is happening at the other end that can be especially irritating. Rainfall from gutters, side streets, and curbs suddenly washes over our feet, dumping gallons of water down sidewalks and streets and alleyways. Aside from soaking shoes, that same rain collects pollutants, particulates, and grit and efficiently washes it into storm sewers—and that can be a big problem. The federal government has made it clear that municipalities have to cut the amount of runoff going into overloaded sewer treatment plants. When sewer treatment plants are inundated with rainfall, polluted overflow ends up in streams and lakes.

One solution, and an option that has gained a foothold in some parts of the country, is the installation of pervious pavement that is specially designed to allow rain to seep into the ground, naturally filtering particulates and pollutants.

The pervious surface would seem like a perfect way to eliminate storm sewer overflows at septic plants, but there is only one problem. That same surface that allows rainfall to seep through can also get clogged with sediment, sand, and even larger pieces of trash. As a result, the surface is opening up a new market for vacuum street sweepers. In fact, Brian Giles of Elgin Sweepers in Elgin, Illinois, shared that his company is working with the Environmental Protection Agency, engineers, universities, and municipalities to see how pure vacuum sweepers can work in conjunction with other sweepers to maintain and restore the permeability of this new style of pavement.

“The entire world seems to be switching from standard pavement and normal asphalt and concrete because water runs off it when it rains,” Giles explains. “If we allow the pavement to leach, through pervious pavement, it takes care of the runoff.”

Pervious pavement is not practical for super-highways because it cannot currently withstand the weight of heavy trucks. But in cities such as Chicago, street workers are pulling up alleyways and replacing the existing surfaces with pervious surfaces.

“The only way to keep the surface permeable is to suck the dirt out of it.” Giles continues. “You need a lot of power to suck dirt out of six inches of asphalt, and this is a new technology. The EPA has been pushing this permeable surface. We’re working with the EPA, developing the technology to maintain porous pavement, and right now that technology is pure vacuum.”
According to a document prepared by Mark Kinter, a technical consultant for Elgin Sweepers, use of the surface has been growing at a double-digit rate over the last several years. The reason is that the EPA has identified it as a so-called “best management practice” to deal with storm water runoff. “They have been proven to be an effective tool to reduce the quantity of water and accompanying pollutants that is directed untreated to our waterways,” Kinter says.

To understand how pervious pavement works, it is helpful to think of it as a series of layers. Just below the porous pavement, which can look like a brick or traditional ornamental paver, is one layer of stone. A second, different layer is then laid down, followed by a gravel fill, and then a subgrade layer. Under that is the water table, which receives the runoff and slowly lets it seep back into the ground.
Porous surfaces come in two categories               :

The first allows water to seep directly through the material pore surface. Concrete, asphalt, crumbled tire rubber, and other materials can make up that surface, according to Kinter.
The second type is a series of interlocking pavers that allow the rain to flow between impervious blocks. Both need to be kept clean. The first reason is to restore permeability; the second is for aesthetic reasons and to allow the rain to move through the crevices.

Giles explains that the surfaces are opening up a new use for pure vacuum machines. Elgin is the only United States company that manufactures a full-sized pure vacuum sweeper. The vacuum sweepers are the most popular style in Europe but have a relatively small share of the American marketplace—just five percent. Broom sweepers, on the other hand, account for sixty to seventy percent of the market here, and regenerative air sweepers claim a twenty- to thirty-percent share, according to Kinter. While the vacuum machines are best suited for restoration of the permeable surfaces, the regenerative air machines can play a role if the surface is damp.

Kinter says that testing has indicated that if a regenerative sweeper is operated in full regen mode, care has to be taken to prevent injecting fine silt into the pores of the surface with the air blast. “This would tend to occur if the surface [were] damp. When operated in the full vacuum mode, the
vacuum level is generally insufficient to restore a clogged surface, but may produce acceptable
maintenance cleaning.” In other words, regenerative air sweepers are not suitable for restoring permeable surfaces, but they can be a good option for maintaining them.

That view is echoed by Raymond Massey of Schwarze Industries in Huntsville, Ala. Schwarze does not manufacture pure vacuum machines, but it certainly is in a position to sell its line of regenerative air sweepers to municipalities and other clients who are installing the surface. Schwarze sells machines that range from 4.3 cubic yards to 9.6 cubic yards, the smallest of which can reach hard-to-access places such as alley ways and parking lots, where the pavers and permeable pavement are often used.

“If you’re not removing that sediment, it is just clogging up, and that area floods. We’re seeing more and more of it in shopping malls and residential areas. Based on the test results out there, it was proven that a regenerative air sweeper is by far the best sweeper when it comes to just regular maintenance,” Massey says. “On the other hand, a vacuum sweeper, based upon the test results, is the best for rejuvenation.”

According to Massey, Schwarze has no plans to introduce a pure vacuum line. “Most of these areas that have these pavements are very aware of what they need to do as far as a consistent sweeping program. We feel the regenerative air sweepers are providing the [operator] with a best management practice for maintaining the service.”

Haaker Equipment of LaVerne, California, is the number one Elgin Vactor dealer in the country and has been in business since 1972. Owner Bill Haaker says that pervious pavement is popping up here and there on the West Coast. San Diego County, for example, currently has some that it is testing in a lot.

While Haaker appreciates the role that pervious surfacing can play in protecting groundwater, he does not anticipate that its use will lead to the domination of pure vacuum sweepers in the industry. In other words, there is plenty of room for pure vacuum, broom sweepers, and regenerative air sweepers. Vacuum sweepers are one component that happens to be tied to the pervious pavement movement.

“Pervious pavement is an attempt to reduce the amount of storm drain runoff,” explains Haaker. “One of the problems is [that] whatever sediment is on that surface gets into the pre-designed cracks and crevices, so you have to remove and pull that stuff off. As you can imagine, if you broom it, that material just gets smeared over it. It’s like getting an English muffin and spreading butter on it; it gets into the crevices.

“That’s when you use the vacuum-type sweeper such as the Elgin Whirlwind, a machine that can pull that material out and allow that material to return to its permeable state. There are some parking lots that have been reconstructed with the permeable material under the parking spaces. The idea is that the transmission fluid and oils will drip down and get filtered through the surface.”
Pure vacuum styles of machines “are more adept at this type of cleaning,” says Haaker. While the vacuum sweepers have the power to get the material out of the surface, they likely will not completely replace the other styles of vacuums.

“If you’re going into an area that exclusively has permeable surfaces, it would make sense to use it exclusively. The other types of sweepers, such as regenerative air, don’t necessarily hurt these surfaces. It isn’t going to make pure vacuum-type sweepers universally purchased. I do not see it.”

While most people do not realize it, there is an exciting change taking place underfoot—literally. Permeable surface requires pure vacuum technology, at least for restoration purposes. Manufacturers will continue to tinker with their technologies, looking for ways to help operators better maintain the life of porous surfaces. Is a revolution in the works? Not yet. But adjustments are going to be made.
Massey believes “it is definitely going to change the atmosphere of the industry, because it is a surface that will require constant maintenance to function properly.”

 

Story by Marie Elium

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