Monitoring and Improving Compaction at Landfills
Landfill managers continuously seek increased efficiency and greater compaction and airspace, but as technology improves, some of the ways they achieve those ends have changed.
Caterpillar has begun making equipment “smarter” in engine and powertrain logic to get more passes across the waste with less fuel, according to Tom Griffith, senior system application specialist with Caterpillar Inc. At transfer stations and material recovery facilities (MRFs)—where material is stockpiled and sorted, and feed lines and outbound trucks are loaded—doing the job quickly with less tire spin and using less fuel is critical.
It’s important to have quality, reliable, right-sized equipment for optimal efficiency and compaction, but due to many waste applications having more and more diversion, Griffith says that cleat designs need to change to help with traction and shredding. “In the past few years, we have changed cleat offerings and ‘solutions’ that customers can utilize in many specific applications, depending upon their wastestream and site dynamics,” he says.
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Similarly, James Caron, president of Caron Compactor Co., says that, although landfill managers should initially consider size/weight/horsepower and proper utilization, and that compactor maintenance—including but not limited to wheels—will help achieve higher density, they should also consider different designs (teeth and patterns) for more site-specific improvements in density.
Caron’s ongoing research resulted in the recent introduction of a new tooth design to aid in increasing density, while simultaneously providing higher wear life. “Replacement cost and wear life are all part of the equation,” he says, suggesting that the return on investment for spending a little more on quality equipment means increased savings in air space. His company also produces specialized track shoes for crawler tractors to aid in achieving this goal.
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The Human Element
All of the best equipment and latest technology in the world won’t suffice unless trained staff understand how to use it and implement best practices. Equipment, training, and technology work hand-in-hand to reduce costs, improve efficiency, and increase profits.
One way to help operators do a good job is to provide them with ergonomic and intuitive cabs and systems. This helps the operator “stay relaxed while maintaining a higher level of efficiency,” explains Griffith.
It also helps their customers lower their bottom line, he adds.
Proving just how important it is to have the “total package” of equipment and trained employees, Griffith says that Cat has worked with several customers looking for complete solutions—i.e., equipment and experienced waste specialists who work closely with them to improve operational efficiencies.
Information From Above
One way that landfill managers and equipment operators can improve efficiency is to use information to better manage airspace. There have been culture changes in the industry, says Kevin Garcia, business area manager for paving and specialty construction with Trimble Geomatics & Engineering. “We never thought we’d run out of landfill space. Now we are having to carefully plan and manage that space.”
But, as Jim Greenberg, product manager/civil engineer for Trimble Geomatics & Engineering, says, “You can’t improve what you don’t measure.”
And, landfills are measuring a lot more frequently these days. “They used to get information quarterly; now they can get it hourly if they want. That allows them to affect change more quickly.”
Almost every landfill gets an annual fly-over, says Lauren Elmore, president of Firmatek, a stockpile measurement and inventory management company that has been using applicable mining principles and analyzing data to assist landfills. But, instead of doing it annually and working all year from one set of numbers, landfill managers are now getting quarterly—or monthly, even weekly—measurements, utilizing rovers, GPS, or drones. This helps them keep closer track of density.
Firmatek uses lasers to scan the site and create a three-dimensional (3D) image. The laser is mounted on a truck that drives around the site to collect 36,000-plus data points per second.
“It can create a 3D image of the landfill or just the active area,” explains Elmore, adding that the procedure is typically performed quarterly to track and update designs and progress.
“Using drones and mapping more frequently increases density,” she continues. “It allows the client to make more accurate decisions, because he knows what issues he’s facing. He can see where it’s filled in. The manager knows the weight and can get the density number and air space number.”
The cost averages $3,500–$4,500 per visit. A drone could be cheaper, Elmore acknowledges. “Drones are a new entry into the market; they are a cost-effective way to get information.”
Whichever method they choose, Elmore says most clients do it quarterly. “It can expand the life of a landfill; that’s the payback.”
Droning On and On
When it comes to choosing between mapping and drones, Caron says the latter constitutes the latest and best technology available. Drones fly at lower altitudes (200 feet on average), compared with aircraft flown at greater heights and at higher expense. In addition, drones are more convenient to scheduling changes to accommodate weather conditions.
Unmanned aircraft systems provide a “great snapshot of the entire site,” states Greenberg. They provide valuable real-time information, as well as greater visibility and detail.
“It provides precise measurements,” elaborates Garcia. “It can measure the grades of roads, side slopes of a cell, trends.… You can see new material and the settling and erosion of cells. It provides a lot of data in a 3D image—it’s a fascinating tool. It captures the whole thing in one shot.”
Most importantly, it indicates volume and weight, and calculates compaction, allowing a landfill manager to predict the remaining life (volume) of a cell by extrapolating how many years until it’s full. “Landfills are permitted to build to a specific elevation, so this is important information,” explains Garcia.
One advantage is that a survey isn’t needed (except to set up the control points), nor is weight from the scales. “You can create an accurate topo map with images taken at the right spots,” says Greenberg. The drones can even calculate the volume and measure changes in the borrow pit, adjusting for density by taking into consideration how cover dirt affects density.
It provides the metrics to make decisions, Garcia says. “On a regular basis, it can provide information more quickly, more easily, and with greater detail.”
Garcia says drones weren’t a core business for Trimble until recently, but now there is a lot of interest in them.
Similarly, Elmore contends that not a lot of landfills are using mapping technology. “We do about 50—it’s not a big market share.”
GPS and machine control software aren’t viewed as absolute necessities in waste applications, believes Griffith. He cites cost, lack of understanding of their capabilities, and misunderstanding of the training requirements as some of the customer concerns he’s heard.
“I have been with three customers recently [who] tell me their operators ‘are good enough, [and] they don’t need GPS to tell them what to do or where to go.’ This type of misunderstanding is common.”
GPS is there to “aid” the operator and help him perform his operations safely and quickly with less fuel—at less cost. If operated and managed correctly, Griffith says, most GPS units will pay for themselves in less than a year. “Most customers have seen more than 10 to 20% increase in density, no matter how good or experienced their team is.”
Technology informs the operator and provides guidance on the equipment that allows operators to focus on other details, but ultimately, an operator’s expertise is still needed.
“It’s a training tool,” indicates Greenberg—”a benchmark for operators. It can make a good operator better.”
The biggest issue with GPS technology that Caron sees is software management. “Most sites that benefit from this are ones that have people on board or consult with engineers to adjust and maintain these useful tools. Machines can only provide their best results if the operators understand their objective and, with or without technology, use these products to their fullest capacity.”
Misunderstanding of machine systems, office systems, and capabilities is the main drawback of any technology, Griffith suggests. Nevertheless, he says, “I’m hearing of more and more sites either utilizing drone companies, or that have their own drones for a multitude of reasons, not the least [is for] tracking density.”
Working face teams are being held to a specific density number to meet. If they exceed that number, they are rewarded. “Landfills that have a beginning, and in final plans now, are able to play ‘what if’ games for future [daily/weekly/monthly] fill plans with either computer technology, by utilizing GPS rovers or on machine technology,” says Griffith.
Machine systems can map and be run to specific, or “on-the-fly” designs more readily. Daily mapping can be offset to help with drainage and cover placement or removal shared between machines to aid in more efficient operations.
Part of a Plan
Greenberg discusses a four-part solution:
- CCS: a compaction control system that works on compactors to help operators assess the level of compaction
- Cloud-based applications that let the office see what’s going on in the field, providing two-way data via cell or Wi-Fi. “The bottom of the track is mapped,” he explains.
- Office software in the business center that reads cell designs
- UAS, aka drones: fly-overs for surface reporting. Each compactor has a GPS receiver to transmit information in real time, with precision to the centimeter, vertically. “If a compactor runs over new materials and it sinks vertically, that tells the operator if it’s compacting, based on the number of final passes,” explains Greenberg. “If you’re trying to compact too much material, it issues a warning to thin out the material.”
This plan allows managers to see trends—days when a lot of material comes in, the level of compaction, and more. It raises questions: Do you have the right equipment on hand? Do you need more equipment? Do you need more personnel? Do you need to put the material to the side?
As Greenberg says, “It’s not obvious that you’re not doing a good job until.…”
Keeping on top of the landfill, so to speak, helps managers do a good job, and be more efficient and accurate.