Global Positioning Systems(GPS) originally were designed for use by the military for a variety of functions, from battlefield management to missile guidance systems. Now, the technology's precision is being brought to the landfill, where it's making a difference in site management.
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.
GPS Comes to Lycoming
Lycoming County, Pa., operates a 100-acre landfill that receives 1,200 tons of solid waste per day. According to Dave Bonus, operations manager of the facility, the county purchased a GPS system from Caterpillar in 2003.
“What we found out prior to using the system is that the [compactor] operators never had any idea of how well they were doing their job except by doing a monthly volume calculation or a yearly fly over,” he says. “In my opinion, that was a little too late to see what the densities were. You couldn't recoup that airspace. So we got them on the compactors and trained the operators.”
The GPS system consists of a touch screen located in the cab of the compactor. The screen color starts out showing red, but when the waste has reached its ideal density, the screen color changes to green. “The system measures the deflection of the wheel into the waste,” Bonus says.
“They're looking at three or four passes to get that green screen, then they know that they can move on to another area of the working face,” he adds. The system also allows the facility's compactors to “talk” with each other so that they don't duplicate work.
Lycoming County also has placed GPS units on a bulldozer and an excavator at the landfill. “Mainly, why we got it on the excavator was to install the horizontal gas lines into the two [horizontal gas collection] fills,” Bonus says. “It gives them a lot more accuracy when installing the lines, and we also use it to install leachate recirculation lines in the landfill as well.”
Way Up North
The Carleton Farms Landfill in Carleton, Mich., is Fort Lauderdale, Fla.-based Republic Services' second largest landfill, accepting 7,000 to 8,000 tons per day of municipal waste and incinerator ash from metropolitan Detroit and Canada on a six-day-per-week schedule. The 402-acre landfill, which has been in operation since 1993, receives more than 300 trucks per day, with almost all of the waste being delivered in transfer trucks.
Since 2004, the landfill has used the Geologic GPS system on two compactors and a mobile unit mounted on a four-wheel drive ATV. “We use [GPS] to look at density and the lift areas on a given day,” says Brian Ezyk, Republic's area engineer for the site. “We also use the GPS on the compactors to locate special waste such as asbestos.”
Landfills in Michigan are required to track asbestos. When a load of the material arrives at Carleton Farms, scale house personnel will radio a compactor operator. The operator will then travel to the exact disposal site, observe the placing of the material and radio the real-time coordinates back to the scale house.
The site has the highest compaction rate of any landfill in the company, which Ezyk attributes to the use of GPS as well as to the types of waste the facility receives and the height of the landfill. “While I think 2,400 pounds per cubic yard is a very high number and people won't believe it, we can't discount the fact that the GPS is very beneficial, [and] we immediately see how much compaction that we're getting on the working face.”
Ezyk adds that the GPS unit on the ATV is valuable for locating items on site, such as underground pipe.
A Variety of Applications
The Rumpke Sanitary Landfill in Hamilton County, Ohio, is the largest landfill in the state by volume and is permitted to accept up to 10,000 tons of waste per day; on average, it takes in about 7,500 to 8,500 tons daily.
The landfill uses GPS in a variety of ways. The first is a roving Trimble 5800 with a TSC2 data collector that the facility uses for site surveys in order to reduce third-party survey expenses.
“The first year we hoped to realize a $30,000 to $40,000 dollar reduction in third party survey costs,” says Larry Riddle, manager of the landfill. “Today we are saving approximately $60,000 per year with the rover type system.”
The site also uses GPS on a Bomag compactor and on a dozer. “Having a surveyor with the rover, a dozer and a trash compactor equipped with the system allows for rapid real-time data collection without the expense of a third-party surveyor,” Riddle says.
“We still use a third party surveyor for certification surveying, but we find that we are using the third party much less because we can put the fill, clay barrier and drainage layer on very close to final grade prior to the third-party survey, which reduces our cost considerably.”
At the Greater Lebanon Refuse Authority's 160-acre landfill in Lebanon, Pa., GPS is playing a role in the site's expansion. Like the other facilities described here, the landfill also uses the technology for compaction and dozer operations.
At the site, the contractor's design plans for the expansion are transmitted to the GPS units on the contractor's construction equipment. “The design file goes out to the equipment itself and then they build to the design,” says Larry Taylor, senior staff engineer at the site. “There's not a lot that I need to do except monitor how they're doing.”
Lynn Merrill is a contributing writer based in San Bernardino, Calif.