Contractors who use trackout cleanup equipment such as automatic wheel-washing systems merely to comply with environmental site regulations may be taking the wrong approach. Plenty of reasons exist for “taking the high road” and adopting these systems—namely minimizing operating costs, which can allow for more competitive bidding, and maintaining a good company image and relations with neighbors adjacent to sites.

Although different portable construction-site wheel-washing systems’ dimensions and features vary, they are essentially designed so that trucks are driven across a raised metal platform—typically equipped with walls and, in some cases, rails—while side- and bottom-mounted water sprayers remove mud and debris from tires at a high velocity with the walls reducing spray drift. Programmable controls and sensors run the sprayers, triggering optimal water output for a given truck driving across the platform. These systems have either above- or below-ground washwater storage tanks, with the latter design possessing greater storage capacity to handle a higher truck volume. Typically, these systems are equipped with some means of removing solid material from the washwater, such as a conveyor.

J.P. Lake, vice president of sales and marketing Rain for Rent, a provider of temporary liquid handling solutions and carrier of MobyDick wheel-washing systems, reports that these systems are more commonly used in the Pacific Northwest and in the Northeast compared with other areas. He notes that the National Pollutant Discharge Elimination System (NPDES) permit for construction sites touches on this area, but uniform enforcement has not yet occurred.

According to section 2.1.2.3 of the 2012 construction general permit, “Minimize Sediment Track-Out,” ­contractors must “restrict vehicle use to properly designated exit points” and “use appropriate stabilization techniques at all points that exit onto paved roads so that sediment removal occurs prior to vehicle exit.” In regard to mud trackout, contractors must “where necessary, use additional ­controls to remove sediment from vehicle tires prior to exit.” ­Examples of these additional controls include “wheel ­washing, rumble strips, and rattle plates.”

As one would expect, the main reason contractors use these systems is to keep trucks from tracking mud onto surrounding streets—a costly mess to clean up. “The primary reason is for soil trackouts,” Lake points out. Rain for Rent primarily rents out ConLine one-tire-revolution-length in-ground and one-tire-revolution-length surface-mounted units. This series has common core components to make six alternative system designs and can be scaled from one to two tire revolutions for in-ground or surface-mounted applications.

“There are some cities or municipalities that focus on that, especially in high-visibility areas. We’ve seen strict enforcement on university campus construction projects where they don’t want mud being tracked out onto the nearby streets, for instance.”

Ted Ahrens, president of Ahrens Contracting in St. Louis, can attest to the need to keep mud off of streets adjacent to job sites where Ahrens does its demolition, excavation, and environmental remediation work. The company owns two ConLine one-tire-revolution surface-mounted units. “The last thing we wanted was to have offsite tracking,” says Ahrens. “We own our own water trucks, but the downtime involved in cleaning streets and the risk of putting manpower out in traffic to clean the streets were things we really wanted to stay away from.”

Brad Makepeace, project manager at T.A. Loving Co., a general contractor based in Goldsboro, NC, recalls that keeping surrounding streets clean was not the issue when the company was building a three-story, 50-patient bed tower addition to the Johnston Health Clayton hospital in Clayton, NC in 2013–14; keeping a hospital loop road free of mud was. Without the use of a wheel-washing system, by the time trucks got to surrounding streets, their tires would be free of mud—although the loop road would be covered with it. The addition is located at the back of the original hospital building, so trucks covered a lot of muddy ground going to and from the construction area during two winters and one spring season. The soil is a dense red clay that turned to a slick, muddy mess when it rained, causing the mud to stick to the trucks’ tires.

To clean trucks and their tires before they got on the loop road, T.A. Loving purchased a Pro Wash unit from Neptune Automated Wheel Wash Systems. Equipped with a 3,500-gallon water tank, the one-tire-revolution unit is designed to clean up to 25 trucks per hour and uses the same high-volume, low-pressure wash technology as the manufacturer’s larger systems. It consists of a tank and a wash platform that couple and uncouple for transport. To operate the system, T.A. Loving needs an external power source and makeup water. The contractor excavates the tank location, places the tank in the excavation, drops the wash platform on top of the tank, locks the platform in place, and backfills the tank.

Makepeace says that the system has taken care of the contractor’s problem. “Hospital campus work is challenging to begin with, and to affect such a large area around our operations makes it even tougher,” he says.

Primarily for Mud, not Dust
“We are seeing dust control becoming more of a concern for contractors and project owners, but wheel washing doesn’t necessarily help with that,” says Lake. “In some cases, it does help if you are tracking out mud which then dries and then ultimately gets kicked up as cars drive over that mud cake. In some cases, a wheel-wash system can save them money over a traditional gravel approach, rumble strips, wash rack, or street sweepers. Street sweepers can kick up a little dust. Dust control is not the primary reason for using these systems.”

The contractors who spoke with Erosion Control about their wheel-washing systems say that keeping mud off of streets is the main reason they buy or rent them, with dust control accounting for little or none of the decision to adopt them.

Makepeace reports that T.A. Loving makes sure a water truck is available to control dust during a typical project. This was important in the summer of 2014 while the company was building the hospital addition. “We didn’t want to create an issue with parked cars with dust blowing on those or dust blowing into the air-handling units mounted on the roof of the hospital; that was definitely a big factor for us,” says Makepeace, adding that, given how often the company uses water trucks, the wheel-washing system does not do much to control dust.

“The motive for using the wheel-wash system is about 70/30 in favor of controlling mud,” says Ahrens, whose company also owns two MobyDick Dust Control Cannons.

Credit: RAIN FOR RENT
Automatic wheel-washing systems clean truck tires in a fraction of the time it takes for a laborer to do the job manually.

Keeping Trucks Moving and Productive
Along with controlling mud trackout, a much bigger motive for adopting these systems is their ability to keep trucks hauling payloads rather than standing in line awaiting cleaning by a laborer equipped with a pressure washer, points out Dennis ­Stanton, owner of wheel-washing system ­manufacturer Stanton Systems.

Additionally, notes Stanton, these systems keep wastewater off of the soil, unlike manual processes that generate a great deal of mud on a job site. In contrast to manual washing methods that can consume many gallons of water per truck and turn part of a job site into a quagmire, Stanton’s portable system uses two gallons per truck. Most of that small volume of wastewater quickly evaporates, and the system automatically removes solid matter with a conveyor after each truck drives through.

Makepeace says that automatic wheel-washing systems are a better way to go from both an operational and cost standpoint. “We had gone the route of having a temporary laborer stand at the gate with a pressure washer, but that’s not very efficient,” he says. “It takes way too long and the equipment breaks down way too often. The truck traffic tends to back up when you have just one guy standing there with a pressure washer.”

The cost effectiveness of T.A. ­Loving’s system became apparent during the Clayton hospital project. “Not having to pay for a laborer to stand at the gate for 14 months was a big savings, and the system itself was very low maintenance,” says Makepeace. “It stockpiled the spoils with its conveyor system. We would run up and move the pile every few days with a skid-steer loader, and we kept the hopper filled with flocculent additive. It wasn’t anything we had to spend a lot of time on. We knew that, as we haul it from job to job, it will pay for itself pretty quickly.”

Ahrens understands that the costs of queuing up trucks under a manual cleaning process add up quickly. “Definitely, you save on labor costs versus having a laborer clean the tires individually,” he says. “You’re keeping the truck traffic flowing, which, at the end of the day, gives you more trucks leaving the site, which is better all in all because you have more loads. It cuts down on the manpower you need. You can put more manpower to a different area of focus. A laborer does get fatigued by the end of the day, whereas the truck wash does the same thing as it did on the first truck—it keeps going, truck after truck.

“With this system, the trucks don’t really have to stop—they get in a low gear and just keep going,” continues Ahrens. “If you have a laborer and a hose, that truck has to come to a complete stop. In that case, you’re talking at least a minute and that’s if it’s not a real clay mud. With this system, the truck never has to come to a complete stop—it just exits and the next truck is in line to go. When a truck is getting washed by hand, the next one has to wait. During the course of a day, you’re talking about at least 50 loads, and it all adds up.”

Credit: STANTON SYSTEMS

According to Stanton, washing trucks automatically onsite is 10 times less expensive than having to clean the streets. The marketplace also appreciates how efficiently these systems clear a construction site of delivery trucks and concrete trucks. For manual cleaning, the next truck in line usually is held up for 10 minutes or more, compared with about 10 seconds for automatic washing. To calculate how much the last truck in line must wait under this process, multiply the number of trucks in line by 10. Contractors view an automatic washing system as one more tool in running a less expensive job site, which improves their odds of winning bids.

Stanton estimates that contractors can save 80 cents on the dollar versus manual washing—and that’s just on the first project. According to an analysis that was conducted for Stanton, manual truck cleaning costs contractors about five times as much as the investment in a portable automatic washing unit, figuring for the use of a water truck and street sweeper. An additional hidden cost of manual washing emerges in the aforementioned scenario of trucks standing in line for 10 minutes per truck, adds Stanton. These costs really hit contractors during their monthly progress meetings, when they see that actual ready-mixed concrete costs are higher than the price in the bid because concrete mixer trucks have sat in line with other trucks, waiting for their wheels to be washed. After adopting an automatic wheel-washing system, contractors tell him that they get their trucks through in 25 seconds and are better able to control their material costs as a result.

John Jenkins, manager of technical maintenance and special projects for one of Stanton’s customers, O.L. Thompson Construction Co. Inc., a contractor based in Charleston, SC, that provides demolition, clearing, ­erosion control, grading, storm drainage, concrete, and asphalt paving among its services, can confirm the faster throughput of automatic washing. O.L. Thompson was hired as the main sitework contractor for a building project in Berkeley County, SC, for a corporation and set up the wheel-washing unit within a few hundred yards of a four-lane highway. The unit was set up to prevent the trackout of mud onto the highway—and reduce the liability involved in sending sweeper trucks onto the highway. The waste is collected on a concrete slab and most of the moisture allowed to drain off before being collected by small loaders and carried to a spoil area.

Jenkins says that O.L. Thompson purchased the unit expecting it to clean 10 trucks per hour. “On busy days, we can see that many in 15 minutes and the machine could easily process more,” he says, adding that O.L. ­Thompson easily installs and maintains it.

Credit: NEPTUNE
Systems typically are equipped with conveyors that remove solid material from washwater. The spoil piles are hauled away and disposed of according to the site permit requirements.

Not Required but Encouraged
Contractors who spoke with Erosion Control say that automatic truck washing typically is not prescribed in stormwater pollution prevention plans (SWPPPs). But that does not mean that general contractors do not encourage or even require their subcontractors to use them.

Makepeace recalls that, even having used the automatic wheel-washing system for the hospital project, T.A. Loving still made sure that its site contractor protected stormwater inlets and cleaned them after the job. For this project, the site contractor utilized the usual wire mesh stone check dams and hay bales barricaded with silt fence. Additionally, T.A. Loving sent a water truck and a sweeper out to the loop road to keep it clean. “Protecting the inlets is not as serious an issue if the site contractor has a wheel-washing system on site,” says Makepeace. “Those measures are mandated in our bid manual so site contractors that are looking at our work know there is a standard they need to meet in SWPPP reports.”

Ahrens acknowledges that automatic wheel-washing systems can assist other erosion control measures and structures that are put into effect on a job site. “It helps to bridge some of those gaps where you’d normally have an issue, between the inlet protection, asphalt curbs, and a sump pit,” he says. “The wheel wash contains anything that would otherwise go offsite.”

Use of the system is not yet mandatory for a given project in St. Louis, adds Ahrens. “But having two of these units in our back pocket will put our plan ahead of everyone else’s because we have this cleaner way of doing things,” he says, adding that, although a set of rumble strips or clean gravel is mandatory, they aren’t comparable to the effectiveness of the wheel-washing system.

Because manufacturers make these systems portable and easy to set up and tear down, contractors find it easier to adhere to expectations to use them.

Credit: NEPTUNE

“We just felt like from our company’s standpoint, we would purchase something we could take from job to job,” says Makepeace. “It has worked well enough that starting with another hospital project we’re working on now in Greenville, NC, we’re requiring all of our site contractors, whoever is bidding the job, to use a wheel-washing system just like that at our sites. The typical silt fence and gravel beds at the entrances and exits are on the plans as dictated by the civil designer and those are things everybody does,” but the gravel beds are not very effective for cleaning mud off of tires, says Makepeace. He adds that gravel beds are very limited in their efficiency, so T.A. Loving needs to take additional measures to ensure that the company is a good neighbor.

For the Clayton hospital project, “Neptune got us a detailed installation and maintenance manual that our site contractor was able to use to excavate the hole and get it assembled in a matter of half a day,” says Makepeace. “The electrician wired it and we got water to it and it was running the next day. It was a no-brainer as far as installation, and removal was just as quick—load it onto a trailer and move it onto the next job.

Similarly, the Stanton system is prewired and pre-plumbed so that contractors can get it operating in one day. Without needing to visit plumbing houses and electrical supply houses to get the system up and running, contractors can focus on bringing electricity and water to the system. Teardown takes less time than setup.

Public Relations Perhaps the Biggest Benefit
When it comes to being a good neighbor, contractors know that perception is reality. They say that using a wheel-washing system has tremendous public relations benefits.

“It keeps the job site looking cleaner—it’s very, very important to keep the neighborhood that you’re working in happy,” says Ahrens.

“We really just wanted to keep the site as clean as possible for the customer and so we were trying to go the extra mile to make that happen,” says Makepeace of T.A. Loving’s Clayton hospital project. “For one, we didn’t want any issues with the state department of natural resources. But the main reason is just showing the general public, the owner, and the regulatory agencies that we’re making a good-faith effort to keep our area clean. I think for people seeing it onsite it was enough of a wow factor for them to say to themselves, ‘These guys actually care; they took the time to purchase this system and get it in the ground and get it working’—that says a lot.

Credit: NEPTUNE
Typical systems are equipped with side- and bottom-mounted water sprayers that remove mud from tires at high velocity.

“Previously, I had only seen wheel-washing systems being used in more permanent applications with nice concrete approaches on each side, for farms and animal processing operations,” continues Makepeace. “We took a gamble on this more mobile temporary unit and it paid off for us. We’re going to continue to use it. I’m going to request it on every job that I’m part of from this point forward.”

Lake recalls that Rain for Rent evaluated several systems and particularly likes the fact that the ConLine system is modular. Rain for Rent can break it down into components and haul it to job sites. When it is set up, it fits in a small footprint, but it also works very effectively. “It recycles the water,” he says. “We find that contractors like that. They’re not always needing to constantly deal with runoff, like you might if you have rumble strips and a guy with a pressure wand. Where’s that runoff going? That could lead to erosion issues, so the system does mitigate that.”

Lake adds that the system is flexible and can be installed in-ground without much excavation or as an above-ground solution that is designed to handle less heavy mud or soiling and not as much throughput of traffic. The latter system, which is very quick to get set up, suits projects in which the contractor has light truck traffic. Pointing out that what Rain for Rent provides contractors with reflects on the company, he says management is comfortable renting out these systems, largely due to their durability. Having rented them out since 2011, Rain for Rent is also getting high customer satisfaction thanks to the effectiveness and the cost of the system.

Another benefit that Lake has seen contractors get from use of these systems is preventing noxious weeds and seeds from being transferred from one ecological area to another on truck tires. “That’s another ecological aspect we’ve seen in the Rocky Mountains and the forested areas in the country where the Forest Service might be worried about seeds being tracked from one ecology system to another,” he says. 

About the Author

Don Talend

Don Talend specializes in covering sustainability, technology, and innovation.