Nancy Mann Jackson

For Years, Most Landfill operators have tracked densities and compaction of waste by using ground surveyors and aerial topography. While these methods can help track and improve a site's performance, they also can be labor-intensive and time consuming. For many landfill operators, global positioning system (GPS) technology is reducing the amount of time, labor and expense associated with such monitoring — and achieving results never before experienced.

Two years ago, at the Greater Lebanon Refuse Authority's (GLRA) landfill in Lebanon, Pa., officials replaced ground surveys with GPS devices on the site's bulldozer, track loader and compactor. “Within the first month, our operators found a mistake they'd been making in filling,” says Larry Taylor, senior staff engineer for GLRA. Basically, the GPS system enabled the landfill's workers to discover that the waste was being filled in at less than the targeted 3:1 slope ratio and taking up too much ground space. If that had continued for much longer, the landfill's ability to develop future cells would have been impacted.

“It was caught in sufficient time to go back and correct the filling,” Taylor says.

GPS uses both U.S. and Russian satellites to pinpoint the precise location of an object. In landfills that use the technology, a common installation includes an on-board computer and GPS unit in the cabs of compactors or dozers, a wireless link from those on-board computers to an office computer, and a GPS base station and antenna on the site. Working together, the on-board units and the base station can calculate not only the latitude and longitude of the equipment, but its exact elevation above sea level. The measurements of cell heights and slope angles can give landfill operators a highly accurate view of how well their equipment is doing its job.

Enjoying the Benefits

In addition to correcting mistakes, many landfill operators are finding that outfitting their equipment with GPS devices can streamline and improve their operations in other ways. Three years ago, Brownwood, Texas, bought a compactor equipped with a GPS unit and a bulldozer with a GPS device and a 3D machine control system for its landfill.

The 3D machine control has been especially effective by allowing the operator to see his current elevation, which results in better compaction, says Todd Thompson, Brownwood's landfill supervisor. “The greatest advantage to the system is keeping track of the elevations so you know where you are all the time, and the compaction rate of the waste,” he says. “It makes it so much easier on the operators. They don't guess. They can look at the system and know.”

The Oneida-Herkimer Solid Waste Authority (OHSWA) in Utica, N.Y., had a compactor outfitted with GPS technology from GeoLogic Computer Systems two years ago. The system “allows the operator to know exactly where he is in the landfill, at the edge of the waste or the waste limits,” says Bill Rabbia, director of OHSWA. “But most importantly, it provides real-time, instantaneous measures of compaction. The operator can watch a color-coded screen, which changes colors as he reaches [the desired level of] compaction.”

Such real-time knowledge about compaction levels allows the landfill to conserve fuel and reduce wear and tear on the machine because operators know exactly when they've achieved the target compaction levels and don't have to put in unnecessary effort, Rabbia says.

Not only do on-board GPS systems seem to make compaction easier, but they also eliminate some tasks that were once mandatory, such as staking grades when expanding a landfill site. “Because the on-board computer shows a three-dimensional design right in the cab, the operator simply follows the grade lines depicted on the screen to build the lift or landfill cell,” says Daniel Fluman, senior scientist and manager of environmental monitoring for the Delaware Solid Waste Authority (DSWA). Additionally, a grading module in the software allows DSWA operators to perform on-the-fly design changes within the interior of the build-out.

Monthly surveys also are rendered obsolete. “The GPS is constantly updating its position in a data file,” Fluman says. “This file is downloaded to the base station computer twice a day. This allows operators and managers to track landfilling activities, calculate volume consumed, estimate remaining landfill cell capacity and generate reports quickly without having to wait on monthly land or aerial surveys.”

In addition to managing where the trash goes into the landfill, operators must plan for how stormwater can get out of the site — and the high-tech systems also are helpful with that task. “Stormwater management is easier because swells are better controlled,” Taylor says. “We can tell operators we want this particular area to slope this way or that way, and they can make it happen.”

As GLRA continues to use the technology and manufacturers continue to refine it, Taylor and his staff keep finding new benefits. “The system has the ability for me to put a warning zone around [vertical gas] wells that stick up so that vehicles get a warning when they get too close,” Taylor says. Soon, he'll also have the ability to place warning zones around each piece of equipment so operators will be warned if they accidentally get too close to each other.

The GPS system also serves as a helpful supervisory tool. “The software has the ability to see how much the machines are moving,” Taylor says. “I was able to look at what [the operator] was doing on Saturday. I can pull up the screen right now and see where they're working; I can look at how they're filling, what they're filling and how much, all in real time.”

Getting Your Bearings

When shopping for a GPS system, there are several items to consider. “Make sure that the GPS system you choose meets the survey standards needed to meet your goals,” Fluman says.

In addition, before installing a GPS-based system, Fluman says landfill owners should have a complete site survey and build-out design prepared to be uploaded to the machine's computer, as well as enough radio repeaters to cover the entire landfill area. “If the base station can't see the signal, it can't register data,” he says. “Also, provide ample storage space on your hard drive. Daily files collected by DSWA routinely exceed six megabytes for 30 acres of coverage.” The more acreage covered, the larger the daily storage requirements.

Like any change in operations, transitioning to a GPS system requires time and is sometimes met with opposition by landfill personnel. In Lebanon, “it was easy for one operator,” Taylor says. “He is younger and was more enthused. He would sit in the compactor and read the books [to learn about the system]. The other [operator] was older and less willing to change.”

GLRA's vendor, Caterpillar, offered on-site training for equipment operators. Then they “went away for awhile, and then came back again,” Taylor says. “That was really good because [by the time the trainers returned], the guys had used it for awhile and they had different questions, and they were more comfortable asking their questions.”

A new GPS system may pay for itself within the first month, as Lebanon's did, but operators still should work to maximize the use of the system. A good way to start is to “learn the system's capabilities and software, and appoint and train several operations personnel to learn the system as well as to take care of daily file maintenance,” Fluman says.

Landfill operators should set realistic goals and timetables, Fluman says, including the following:

Like most useful technologies, GPS-enabled landfill equipment isn't mastered immediately, and over time may become more valuable. “I have yet to reach the system's full capacity,” Thompson says. “There is so much the system can do.”

Nancy Mann Jackson is a Florence, Ala.-based contributing writer.