Thinking about buying a landfill compactor? Manufacturers and end-users offer opinions on choosing, and using, the right machine to improve density and conserve air space.

By Penelope Grenoble O’Malley

Compaction pays for itself,” says Johnny Poole, executive director of the Cedar Grove Landfill in Lamar County, GA. “It’s the one thing you can control in a landfill.” Poole takes in 250 tons of mixed MSW and C&D a day. His operator typically makes more than five passes in the landfill’s 120,000-pound Al-jon 600 and the landfill keeps the trash damp by circulating leachate.

“We’ve got wet garbage, we’ve got a narrow working face, we spread it thin and I over-roll it. But I wouldn’t trade all of that for my 1,800-plus pounds per cubic yard any day.”

In landfills, compaction has become the name of the game.

“What they should be looking at when choosing a compactor,” says Bernie Melcher, vice president of the solid waste division at Al-jon, “is first of all, weight. We’re seeing a lot of customers using bigger compactors, even those where their peak times are spread out and they could maybe use a smaller machine. They’re doing this because a heavier machine gives them a better compaction ratio. When you’re deciding what machine to buy, you have to take into consideration how much revenue is coming in the gate and what kind of compaction numbers you’re looking for.”

Compaction has become the name of the game in landfills. Landfill managers will offer compaction numbers as justification for everything from the size of the machine they prefer to wheel configurations to how many passes their operators make. Mark Hiatt, president of Road Machinery Services, Inc. in Statesville, NC (which has cornered the market for CMI Terex in the Carolinas), puts it another way. “Other than raising prices,” says Hiatt, “the way to maximize your revenue throughout the life of a landfill is to get more tons or pounds of material into whatever number of cubic yards you have. If you can increase your density even a little, the dollars can be phenomenal.”

The common wisdom is that good compaction is a function of thin lifts and three to five passes with the right size machine. But a trip around this country’s landfills suggests the common wisdom is subject to a range of interpretation. Like Poole, Jerry Johnstone in Conway, SC, keeps his two 81,000-pound Al-jon 81 Ks constantly moving. In Waterloo, NY, operators shut down their Geologic-GPS-equipped Al-jon 600 based on vertical drop rather than number of passes. At the High Point Kersey Valley Landfill in High Point, NC, Landfill Superintendent Steve Pendry thinks 4-6 passes over 500 tons of MSW is optimum. The landfill is uses two Terex 390s and keeps one for backup.

At Lycoming County Resource Management Services in Williamsport, PA, Operations Manager Dave Bonus reports that each time a manufacturer comes out with a heavier model machine, he buys it, because “with the weight of the machine, you can get better densities.” The landfill runs two Caterpillar 836s equipped with CAT’s Computer Aided Earthmoving System (CAES) to compact 1,200 tons a day. “We run both compactors at the same time,” says Bonus. “We push off the pad with a Caterpillar D-8, which spreads the waste in 2-foot lifts. Then the compactors level it off.” In Fresno, at the landfill operated by the Fresno County Department of Public Works, three Caterpillar 836s and one 826 compact over 1,600 tons of MSW a day. The oldest of the 836s is used for backup, and the lightest is used in small areas.

“In the late ’80s, early ’90s, we were getting compaction rates of about 800 to 900 pounds per cubic yard,” says Fresno County Public Works Engineer Frances Coward. “Then we bought the 826 and we were doing something like 1,200. Now, with the big machines, we’re about 1,400 pounds per cubic yard. And we’ve gained in the neighborhood of 10 to 13 more years of site life.”

“It used to be,” says Caterpillar Waste Industries Manager Tom Normoyle, “that lots of waste businesses thought they made their money on tipping fees. Now they realize the airspace is where their money is. So compaction has become much more important. When they’re buying a machine obviously they need to consider tons per day and compaction cycles and the number and size of their peaks, but they also have to take into consideration the facility’s resources. If you’re personnel-limited more than capital-limited, that will change the structure of what you can use. If a site does 500 tons a day, for example, and has one operator, they’d be borderline for an 816 compactor, but an 826 would easily handle it. And you can’t just look at today. You have to look 10 years down the road, or whatever you think the life cycle of the machine is going to be at your site.

“A system-matching approach is also significant. Size your dozers and your compactors to handle your peaks and valleys. And you want to be sure you’ve got the correct complement of machines. You don’t want a dozer with a 5-yard blade and an 836 that’s equipped with a 25-yard blade. The dozer will be struggling to keep up with the compactor.”

At 250 tons a day, Poole exemplifies Normoyle’s logic. “I thought we were a small landfill and couldn’t afford a big heavy machine. My only regret is I didn’t buy it earlier. With the 600 we extended the life of the cell from 5.9 years to 8.3 years because of increased compaction.”

“People spec for tons a day,” says Jim Caron, president of Caron Compactor Co. “But this isn’t the way trash comes into the landfill. You’ve got to structure your operations to handle the peaks. Many times I’ve seen operations that have the proper equipment but they don’t use it right. A lot of people have two compactors and use the second one for a standby. But the standby needs to be readily available. It needs to be out near the face and the operator needs to be in the unit running it during the peak periods. You can’t spread trash 2-feet thick and do an adequate job. The wheel drum is basically rolling on the surface and the only way it’s going to do its job is to penetrate the trash and work the bulk of it to break it down. If the trash is too thick it can’t do that, and you get a sandwiched layer that isn’t compacted.”

Compaction dynamics affect everything from size of machine to the number of passes it will make.

Mickey Cereoli, national sales manager, landfill and stabilization, for BOMAG Americas Inc., agrees that speccing a machine to handle peaks is the way to go. “To maximize your return on investment, a compactor must be sized not just for daily tonnage but also delivery rate. This is how smaller landfills can make a mistake by buying a too-small machine. Typically on a 300-tons-per-day site, approximately half of the daily tonnage will be delivered during two peak times, one in the morning and one in the afternoon. A 60,000 pound machine is too small to correctly spread, place and compact trash delivered at that rate. A better model would be a 70-80,000 pound machine. Machines of this size can extend the life of a small landfill far beyond what was initially projected. They are also typically the optimum size for most mid- to large-sized landfills that run multiple machines. Larger, high-volume sites that take in 1,000 tons or above a day need a compactor in the 100,000-pound-plus class.”

Richard Allen, solid waste operations manager at the Charlotte County Zemel Road Landfill in Charlotte County, FL, agrees with the importance of the machine keeping up with the pace of volume coming in. “It has to be able to process what’s coming in fast enough to keep the working face cleared off and allow the customers to come in and dump and get out.” For Allen, cost is the other criteria—“I have commissioners I have to answer to.” Allen is looking for a compaction rate of 1,200 pounds on the 800-1,000 tons a day, and he figures he achieves it in 4 to 5 passes with a CAT 826 and an 80,000-pound BOMAG.

In North Carolina, Johnstone runs two 81 K Al-jons on the combined MSW and C&D on he takes in and holds one for standby. For him, volume is the deciding factor on which machine to purchase. “If we were handling 12-14,000 tons a day instead of 700 tons a day, we’d be wanting to have a 120,000-lb machine. But given our tonnage, buying a larger machine would push the economics of scale out of whack.” Once the machines are out on the site, Johnstone subscribes to the rule that you run them all day. “Fuel costs are not that big an issue when you need to keep the compaction up. Right now we average around 1,500 pounds per cubic yard. The 17-acre cell we went into in 1998 was scheduled to close in August 2004. Given our compaction practices, it lasted until July, 2005. I don’t even want to tell you what that’s worth dollarwise. It’s roughly 200,000 tons of garbage at 29 cents a ton.”

With 6,000 tons a day to handle at IESO Seneca Meadows Landfill in Waterloo, NY, landfill manager Kyle Black says maneuverability is an important issue. “We’re a large-volume landfill and we do a lot of outside slopes, so we’re looking for a compactor that’s not only going to be able place the waste to maximize density, but one with good maneuverability. We try to keep our working faces very tight in order to control the waste placement, so a highly maneuverable compactor is very important to us. Air space is our lifeblood. We don’t have time to wait for settlement.”

Seneca Meadows takes in about 3/5 MSW plus processed and unprocessed C&D and industrial waste. Black currently has two Al-jon 600s and two more coming. Seven 91K/525s are gradually being replaced with the larger machines.

“If you figure in the cost of the machine and the fuel and maintenance,” Pendry says of the big Terex compactors he prefers, “you could conceivably buy a machine that was more than you needed. But if you’re looking at the long-term benefit of the life of your facility, I’d much rather have 1,400-1,500 pounds per cubic inch than 850-1,100.”

Landfill managers with GPs on their machines can't say enough about results.

What Al-jon’s Melcher describes as uptime, most landfill managers described in terms of service, parts availability and the intended lifetime of the compactor. Allen writes his specs so the manufacturer is responsible for cleaning wheels, and he wants his machine to be “open” so his mechanics can get at components. In Fresno, Coward is looking for machine longevity and good local service. “We want a reliable piece of equipment and good turnaround for maintenance. Plus we’re looking at the overall cost of routine maintenance for things like oil change, gear change, transmission change, and engines.” Fresno uses CAT’s buyback program and typically keeps its machines seven to eight years. In Lycoming County the landfill keeps compactors two years or 5,000 hours. The landfill also takes advantage Caterpillar’s buy-back program—and its government discount. Kyle Black figures operators put about 3,000 hours on the Al-jons at Seneca Meadows Landfill, which puts them on about a 3-4-year cycle. Just about everyone agrees that the optimum situation is to have a spare for when the primary machines are down for maintenance and repair as well as for covering peak periods.

Although landfill operators use manufacturer buyback, there is also the option of buying a reconditioned or rebuilt machine from Herculaneum, MO-based Landfill Equipment. “A rebuilt would be similar to buying a new machine,” says company spokesperson Danielle Gunter. “A reconditioned machine, which we also offer, would be used more as a backup. There are some small landfills that take in 100 tons or less of trash a day where new machines are just too expensive, so they buy a rebuilt machine. We offer a standard warranty with a rebuilt machine, and they can buy an extended warranty if they want it. On one of our rebuilt machines you’re probably looking at useful life of 5,000 hours. Cities and municipalities who don’t want to spend $700,000 for a new machine can get one for $400,000.” Landfill Equipment also offers rentals in the case where they’re rebuilding a machine for a customer or if one of a landfill’s regular machines goes down or burns, or in case of other emergencies. After the recent tornados in Missouri, for example the state Department of Natural Resources allowed a county to open up an old landfill, and Landfill Equipment rented the operation a machine.

Among the benefits of CAT's CAES systems are lowered fuel and operating costs and better predictions about airspace.

At CAT, Limer has his own perspective on rebuilt machines. “Let’s say they’ve got x amount of air space left and they’re currently using a ’26. What if they bought a rebuilt ’36, which is less expensive? How much will that give them in terms of longevity of their landfill? What’s the extra cost in maintenance and upkeep on the ’36 versus the timeframe for expected closure? Maybe they’re got to raise the gate fees a little bit to offset it.”

Next to compaction rates, wheels rank high in the landfill lexicon of what’s important for minimizing downtime. In Florida, Allen specs 50 cleats on front wheels and 60 on the back. “We found that the Bomag is a better finished product with those types of cleats.

In Fresno, Coward says a primary reason they spec Caron wheels is because the tips are easy to replace. “Caron’s wheels have replaceable teeth, so you don’t have to buy a new wheel. All you have to do is replace the teeth. You don’t have to have someone come and unweld the tips. You just punch out the pin, put on a new cap and punch the pin back in. There’s nothing worse than a down piece of equipment.”

Jim Caron wants his customers to remember that the critical factor in achieving high density is “regular, predictable reduction in the particle size of the material you’re working with, which you accomplish by matching the right wheel pattern to the material being compacted and to environmental conditions. We have different sized tips for the same model, and it depends on the circumstances,” says Caron. “If your machines are working in something like cohesive clay, for example, you have to modify the wheel patterns to accommodate these conditions.” Coward says Fresno takes in a lot of wire from vineyards in the area and likes Caron wheels because of their wire guards. He also says the harder tips that are made possible on the Caron wheels because of the snap-on feature increase longevity in the landfill’s abrading sandy soil. The Lycoming Landfill takes in 12% of its daily waste in sewage sludge and runs a Caron sludge pattern wheel to accommodate it.

Poole swears by narrower wheels than a machine would typically be fitted with. “A wider wheel gives you more coverage, but it also spreads that weight out over a wider footprint, so it lessens your compaction. If I ran a big landfill, I’m going to weigh pretty heavily the productivity of the machine. We’re a small-volume landfill and productivity is not as critical as compaction, because I’m trying to conserve airspace, which means I want to cram as much garbage into each cubic yard as I possibly can. So when I go shopping, I compare pounds per linear inch. On my Al-jon 600, I went from a 48-inch wheel to a 40-inch wheel. I cut down 16 inches on my productivity, but I increased my compaction from 1,000 to 1,250 pounds.” In Terex country, Pendry likes the single pass machine. “The wheel configuration leaves less room for operator error. He doesn’t have to figure out exactly where he last compacted and move over.”

Don Harris, engineering and compliance manager at Sprint Fort Bend Landfill outside Houston, TX, runs CAT tips on his 836 compactor. He says he can tell immediately when his operators are running without the cleaning bars he specced. “I can tell the compaction isn’t going down that much. You don’t break the stuff up with the weight of the machine. You do it with the tips.”

Matching dozers to compactors is a key component of landfill opeartions.

What other bells and whistles do landfill managers consider important when speccing a machine? The Lycoming landfill in Pennsylvania and the Fresno landfill across the country in California use Caron’s double-U blades to funnel trash directly under compactor wheels, because they think this gets them better compaction. In South Carolina, Johnstone insists that his engine warranty includes starters, alternators, water pumps, and also electric components and hydraulics. He requires manufacturers to guarantee wheels and cleats for 10,000 hours or four years whether the machines are working on MSW or C&D. Most landfills want backup alarms, warning horns for operators, and auto-reversing fans. At BOMAG, Cereroli cautions landfill operators to look for machines that are designed exclusively for tough landfill conditions, an important aspect of which is that engine compartments are completely sealed against trash and debris that can cause overheating and fires. Allen wants a closed undercarriage and always specifies “a bathtub-like chassis.” Some landfills managers want GPS.

“I don’t care how many passes you make over the trash,” says Rich Limer, waste industry account manager for Caterpillar. “What I care about is that you make the right amount of passes over the trash. GPS is about optimization and building a landfill to design. A lot of sites do flyovers on a quarterly or yearly basis. But by that time, it’s too late. The compaction is lost.”

Landfill managers who have GPS on their machines can’t say enough about their compaction numbers. Added benefits are lower fuel and operating costs, plus reliable predictions about air space. “This surprised us,” says Harris. “We didn’t really factor this into our decision-making, but it turned out to be a huge cost savings in fuel and equipment. GPS allows you to concentrate your efforts where they need to be because you have feedback telling you this is an area that hasn’t closed for compaction yet or this is an area where you’re not getting any more compaction. Quit wasting the tips on your compactor, quit eating up your machine time.

“Back in the old days a guy would get on that thing and he’d face north and south and run it that way all day long. Six months later one side of the compactor would got worn tips and on the other side the tips would be brand new because he never turned the darn thing around. We were able to recover our GPS costs in less than six months when we considered airspace savings, fuel savings, labor, equipment and time. If I can carry the savings over the next 50 years, which is the life of the landfill, that’s $18 million dollars.”

Maneuverability is both an art and a science.

Harris is running CAT’s CAES on an 826 compactor.

“What GPS does, says Jack Maclean of Geologic Computer Systems Inc., located in Waterford, MI, “is measure vertical change. We’ve perfected a method that gives us changes in vertical position sufficient to indicate when there is no more change, which indicates to the operator in the cab that he’s got as good as he’s going to get. By maximizing density with a constant monitor, every place the compactor runs you make the landfill live longer. And it doesn’t make sense with fuel costs where they are today, the maintenance per hour of machinery and the cost of ownership to keep a machine running when you have no benefit.”

“This landfill opened in 1978,” says Bonus at the Lycoming operation in Pennsylvania. “We were supposed to be closed five, six years ago. We’re trying to do everything we can with alternative daily covers, tarps and now the GPS system. We’ve seen a 12%–14% increase in compaction with GPS. We were getting 1,300-1,400 pounds per cubic inch, and now we’re averaging right about 1,600-1,650.

“I don’t care if you’re a big landfill like ours or a small municipality,” says Black at Seneca Meadows who has invested in Geologic’s system. “You’re looking for return on investment. Once you get the base units on, you’re going to want to order the machines with them. It’s not a big project to wire them, and adding a harness for a GPS system isn’t that big a deal. If we save 3% of air space over the next three or four years of site life, they’ll more than pay for themselves. The better you pack it in, the more you can put in there. The more you can put in there the longer the site life. The longer the site life, the cheaper the site is to run.”

Penelope Grenoble O’Malley specializes in environmental topics.

MSW - July/August 2006