Efficiency, Flat-Out

Aaron DeWeese

The advent of the Subtitle D age has put airspace at a premium.

Although construction costs vary from site to site, the per-acre price tag on this new breed of landfills can total more than $1 million, mainly due to the installation of liners and other protective devices mandated by environmental laws.

"The days of the small community dump are over," says Judy Caron of Caron Compactor Co., Modesto, Calif., manufacturer of compactor wheels and blades. "I say 'dump', because that's what they were. But today with Subtitle D, the industry is realizing the name of the game is conserving airspace."

Most Subtitle D landfill operations now have some sort of density monitoring/management program in place. Commonly, aerial photographs are taken on a periodic basis to determine a landfill's compaction ratio. But for some landfill operators, this monitoring practice alone is not enough.

"We were doing [density surveys] based solely on aerial fly-overs," says Richard Allen, site engineer for the Salt River Landfill, Scottsdale, Ariz., which is owned by the Pima-Maricopa Indian Community.

Compaction is a major concern for this 2,000 ton per day site that serves two American Indian communities, the city of Mesa, the town of Gilbert and several regional commercial haulers.

Allen says his goal is to start spending more time on surveys. "We're planning on physically surveying subcells," he says. "We're trying to prolong the life of our landfill as much as possible."

Ideally, most landfill operators would like to achieve at least 800-pound to 1,000-pound compaction rates to maximize airspace - efforts that have created a large-scale reevaluation of traditional landfill equipment uses.

According to Murl Kelley of the North American commercial division of Peoria, Ill.-based Caterpillar, achieving increased compaction rates can boost potential landfill life.

For example, by increasing compaction from 1,000 pounds per cubic yard (lbs/cy) to 1,200 lbs/cy, a potential 1.9 years can be added to the life of a landfill averaging 104,000 tons per year, according to a Caterpillar study. The life span increases to 7.6 years if a 1,800 lbs/cy compaction rate is achieved.

"It kills me when people think they can get the same compaction rates with a bulldozer as with a compactor," says Lesley Baily of Al-Jon, Ottumwa, Iowa. "There are still a few out there using bulldozers, but I think, partly through the efforts of organizations such as SWANA [Solid Waste Association of North America] and its landfill management training programs, there's just a lot more education on how valuable airspace is."

Bigger is Better Landfill efficiency boils down to compaction. At one time, landfill operators might have been content with making occasional, casual passes with a bulldozer over vast, exposed mounds of loosely packed garbage. Now, they're rolling compactors repeatedly over smaller working faces, squeezing as much airspace out of each acre as possible.

As landfill operators become more cognizant of the airspace/density equation, the industry is moving toward larger compactors. The norm has progressed from 30,000-pound to 70,000-pound compactors, says Jim Smith of Landfill Construction Equipment, St. Louis. "Airspace is more expensive now."

Some operators are purchasing above the norm. For example, Jim Rodriguez of CMI, an Oklahoma City-based compactor manufacturer, reports increased demand for its 70,000-pound and 100,000-pound units.

It makes sense: the heavier the compactor, the higher the density achieved with fewer passes. And with the added costs of operation and labor hours, bigger machines have become a necessity for many landfills.

"Even landfills with smaller volumes are recognizing the need for higher compaction rates," Bailey says.

According to Kelley, increased sales of larger compactors have not been at the expense of smaller compactors, whose sales still are "ample."

Weight isn't Everything "It's not just about weight, but weight properly applied," Rodriguez says. While the trend may be toward heavier compactors, experts agree there's no substitute for operator expertise.

"Our density studies indicate that we're achieving comparable compaction with a 45,000-pound compactor as we do with a 70,000-pound compactor," says Matt Dillard, vice president of operations for Cleveland, Tenn.-based Santek Environmental Inc., operator of several government-owned landfills in the Southeast. "Maintaining good compaction still boils down to the machine operator and proper technique."

Often, achieving desirable compaction has as much to do with the material being compacted as with the compactor doing the squashing.

Several landfills, including the city of Billings [Mont.] Sanitary Landfill, are separating construction and brush waste from municipal solid waste (MSW) to achieve greater compaction rates.

"I'm aware of compaction's importance," says Randy Crable, Billing's landfill superintendent. "We now have recycling and composting to get better compaction and save airspace. Normally, MSW is going to give you the best compaction. The worst is concrete, which doesn't compact much at all; it just kind of lays there."

Weight and machine operator technique aside, which machine achieves the greatest compaction?

"That's a controversial subject," says Caron, who notes that there are plenty of tests available validating one compactor's performance over another's. But there has yet to be a uniform comparison test.

There are two basic compactor designs on the market: the four-wheelers and the three-wheelers.

The verdict is still out on which design achieves better compaction, but finding a level playing field to compare performance is easier said than done.

By the time variables such as waste content, equipment-operator skill, cover-soil quality, wheels and blades are added into the equation, it becomes difficult to compare apples to apples.

For most landfill operators, durability and dependability are perhaps the most valuable qualities of any piece of equipment. One compactor can out-perform another all day long at a waste convention rodeo, but if it can't run 10 hours a day, seven days a week, 52 weeks a year, a landfill operator would be better off with a dependable bulldozer. "A landfill is the most hostile environment you can put heavy equipment in," Caron says.

According to Kelley, the average lifespan of landfill heavy machinery is about 30,000 hours, but that number is relative to the quality of equipment maintenance. "We often see owners who don't maintain their equipment and [find that] it is in need of repair in just a few years," he says.

Preventative maintenance is the key to equipment longevity. Traditionally, landfill operators have kept a close eye on their machinery, changing the oil after so many hours and keeping written logs and mental notes of required maintenance.

While that still might be a practical procedure for landfills that have just a few pieces of equipment, for most operations, computer software maintenance scheduling is now commonplace.

For example, Crable has relied on computers for routine maintenance scheduling for the past three years to ensure that his compactor, dozer, scraper, loader, grader, two water trucks and dump trucks keep a stringent maintenance schedule.

Preventative maintenance also has prolonged the life of Santek's landfill equipment. "The manufactures give guidelines, but we've customized our computer program based on field experiences," Dillard says.

Warranties, Buy-Backs and Remanufactured Equipment Extended warranties don't seem to be popular with either the manufacturers or with landfill operators. Since comprehensive preventive maintenance programs keep the machinery running, extended warranties usually are not cost-effective.

Additionally, site-specific variables make it difficult for manufacturers to gauge machine durability.

Manufacturers' policies on extended warranties vary. For example, although CMI doesn't have a blanket extended warranty, it will enter into agreements with customers based on the size of an order, Rodriguez says.

Many manufacturers offer guaranteed buy-back programs, whereby customers are given a set price at the end of a term, which is commonly three years.

This not only keeps newer, more reliable equipment in the field, but also allows for landfill operators to reassess their equipment needs on a regular basis, upgrading as needed. For example, Allen says he switched to a heavier compactor from his Cat dealer when it came time for the guaranteed buy back.

Many of the returned machines are remanufactured and sold. Besides offering significant savings to landfill operators with budget constraints, reducing the depreciation curve makes economic sense for many.

Buying remanufactured equipment also may be a logical choice for less-used equipment at the landfill. According to Kelley, remanufactured equipment normally has a lower initial cost (60 percent to 80 percent of new equipment's cost), but prices can vary.

Kelley also notes there is a difference between remanufactured and dealer-rebuilt products. "Remanufactured" means the manufacturer is involved with the equipment and is certifying that it is remanufactured to original specifications, according to Kelley.

Dozin' the 'Fill While compactors might be the reigning king of the trash hill, at many facilities, bulldozers, the proverbial jack-of-all-trades, often work side-by-side with their tooth-wheeled cousins.

"We use a Cat D8 when the compactor is down and toward the end of the day when the volumes are up," Crable says. "It takes some of the stress off the compactor. We usually run the dozer two to three hours a day."

Some landfill equipment uses are site-specific. For example, before Santek assumed operation management of a landfill in Leflore County, Miss., cover soil had been collected using a track hoe and dump truck. After assessing the facility's sandier soil, Santek staff decided to use a tractor and scraper instead, which resulted in significant cost savings by reducing operational hours.

The change in equipment has worked well this summer, Dillard says, but the verdict is still out on how well it will work in the winter.

With the Carbone ruling prohibiting solid waste flow control, the best marketing tools any landfill has in securing waste streams are competitive tipping fees.

Landfill operators increasingly are called on to maximize efficiency while simultaneously keeping equipment costs down.

Whether it means having four 100,000-pound compactors running 12-hour shifts on the working face, or tag-teaming a 40,000-pound compactor with a dozer, the key to any successful operation is having the right equipment for the job at hand.