THE IDEA OF USING costly satellite technology and NASA-level software programs to design a landfill was practically unheard of just a few years ago. However, as older cells near capacity and potential expansion sites become more scarce, tools such as computer-aided design and drafting (CADD) software, geographic information systems (GIS) and global positioning systems (GPS) units are winning hearts and minds throughout the industry.
By making precise measurements and using complex computer algorithms, these systems are helping landfill operators to delineate wetlands boundaries, determine setback criteria, improve waste compaction, manage airspace down to the centimeter, design final cap slopes, and monitor gas production and waste settlement, to name just a few uses.
“With the CADD modeling, [designing a landfill] is so much easier,” says Andrew Nickodem, manager of Midwest waste services for the engineering firm Earth Tech, headquartered in Long Beach, Calif. “In the past, we would have a big file box full of all the data that you need — the number of homeowners in the area, the terrain, the wetlands — and we'd have to put it all together by hand. Now, we can have the relevant technical information stored in one database.”
GIS models, which are created with the help of satellite-driven GPS data-gathering devices, take the CADD modeling one step further by analyzing and displaying geographically referenced landfill information. By emphasizing the spatial relationships among the data collected, GIS can integrate this complex information into easy-to-read maps and reach conclusions about those relationships over time.
“I estimate that in the next five to 10 years, GIS will be used at virtually every landfill,” says Robert F. Hasemeier, senior project engineer for the Harrisburg, Pa.-based engineering firm Gannett Fleming. “The technology is becoming too available, and landfills are making the right investments.”
More than Maps
Earth Tech uses three-dimensional CADD modeling packages for virtually all of its solid waste clients, Nickodem says. As the landfill grows, the CADD models can be updated with new gas wells and leachate extraction points, “so you can make sure you're not encroaching on any of the easements, permit boundaries or setbacks,” he says.
Surveyors gather field data to update the CADD topographic models, either monthly or quarterly, and to monitor waste compaction at the site, says Kevin McKeon, manager of Earth Tech's Northeast waste services. The company then uses this data to produce isopach maps, which indicate the varying thicknesses of waste across each landfill cell, showing where and when all the waste cuts and fills have been made, he says.
With help from CADD, “project managers can operate much more efficiently,” Nickodem says. “Clients often wait until the last minute to start construction of the final cover. They used to have remaining airspace estimates in intervals of six months or a year. Now they can plan down to the month.”
In a simplified comparison, while CADD models provide detailed pictures of landfill sites, GIS is a database made up of many layers of these pictures. Originally designed for county governments to analyze their land use options, GIS maps are also being modified for offsite landfill planning purposes to determine baseline utility locations, identify resources and help plan capital outlays for potential new landfill cells.
Earlier this year, the Greater Lebanon Refuse Authority (GLRA) in Lebanon, Pa., wanted to evaluate whether the county should expand its 412-acre property to build a new cell or relocate to a new greenfield site elsewhere in the county. After collecting data from several Lebanon County variables, including population density, utility locations and wetlands, Gannet Fleming “queried the data and produced a colorized GIS map that showed that there wasn't much land left to expand on,” Hasemeier says. The company recommended that the GLRA buy more land near their current facility rather than look for more distant county sites.
Pennsylvania's 1,200-ton per day Lanchester Landfill, run by the Chester County Solid Waste Authority, has benefited from two different GIS studies of its landfill gas collection and leachate recirculation programs, says Bob Watts, the authority's executive director.
Using algorithms produced by GIS databases, route alignments were performed for a new landfill gas recovery system at three of Lanchester's five landfill cells, Hasemeier says. “Just 24 months after we were contacted [by Chester County], they began putting gas into the pipes,” he says. “We finished with 75 easements in that time.
“This year, we've expanded the gas collection and picked some sites that were in need of additional wells,” Watts adds. “We also found some old wells that were not producing anymore.” With some wells, GIS analysis determined that the valves were all the way open but the methane concentrations were too high, “indicating that there was not enough of a vacuum to draw in air in that section,” he says. “With GIS, we can address problems before they happen.”
GeoSyntec Consultants, based in Boca Raton, Fla., also has worked with Chester County for the past two years, providing GIS analysis of the landfill's leachate recirculation project. Through regular monitoring of selected trenches and along the perimeter of the site, crews are using ArcView GIS software to track the movement and settlement of waste over time, says Douglas Mandeville, an engineer in the company's Columbia, Md., office.
After recirculating 7.5 million gallons of leachate since the program began, GIS has provided “a 3-D visualization of the geometry of the trenches,” Watts says. “It also gave us peace of mind — something that you can see visually — so you can tell that the movement is mostly vertical, not horizontal.”
Currently, it is still too early to use GIS data to determine what effect the recirculation is having on Lanchester's waste settlement. “The effects may not be immediately apparent,” Mandeville says, “but we can tell from the data that we are keeping good controls on where the leachate is going and not contributing to any environmental problems during operation of the system.”
Eyes in the Sky
To make GIS, CADD or any other kind of high-tech mapping tool work most efficiently, many landfills are turning to the GPS satellite network to provide geographic information for various landfill parameters. The sophistication of available GPS units varies widely and depends mostly on the type of job that is needed.
In its most basic form, GPS technology can fit in the palm of your hand, Hasemeier says. Small “sportsman grade” units can be taken out in the field to record groundwater monitoring wells, mark wetlands boundaries or, “generally, to put more details on the maps, like ditches, fences and other features that may not show up on aerial surveys.”
Other, more complex GPS systems can be mounted onto earthmoving equipment and linked to a software interface to record movements in real time. Since 1998, Larry Taylor, site engineer for the GLRA, says he has used two of these types of GPS systems at his 366-ton-per-day MSW landfill: An AzTech Software mapping-grade unit for the landfill face, and a Leica Geosystems survey-grade unit to monitor the soil taken from the site's borrow area.
The AzTech unit, mounted on the GLRA's bulldozer, is accurate to “within a couple of feet,” Taylor says, and is used to map the daily grid and to put his crews “in the right ballpark” when locating gas collection pipelines. The Leica is accurate down to a few centimeters.
Craig Asman, operations supervisor for the Evergreen Landfill in Northwood, Ohio, says subcontractors come to his facility about two or three times a week with survey-grade GPS systems to help calculate the angle of the slope. However, since the landfill is permitted to accept special and industrial wastes, one of the most valuable GPS uses is the tracking of incoming asbestos loads.
“Up until about five years ago, it was all done by a surveyor who would come out with a slew of stakes to make grid points and all the coordinates would be recorded by hand,” Asman says. “Now, we just walk to where the asbestos load was dumped, hit a button and it's recorded.”
Meanwhile, to improve site waste density, the Lanchester landfill has been using Caterpillar's Computer Aided Earthmoving System (CAES) for the past five years. A TV monitor mounted in the cab of the compactor, and linked to a central computer, tells the operator when the waste has achieved maximum density so he can drive to another spot on the landfill face.
“We've estimated that our compaction has increased by 10 to 15 percent,” Watts says. The system also has made it easier for the Lanchester crews to configure the top of each lift at a three-degree angle so that rainwater runs into diversion ditches.
“After each rain event, we used to have to spend a few days fixing the erosion problems,” Watts adds. “Now, it's rare that we have to deal with erosion at all.”
Justifying the Cost
Like most worthwhile technology, tools such as CADD, GIS and GPS provide great benefits in efficiency and labor savings, but also big initial price tags.
According to Taylor, costs for a typical GPS mapping system are in the $15,000 to $20,000 range. For survey-grade, costs are more like $50,000, he says, while the compactor-mounted units reach into the $100,000 range. “The learning curve for new systems is steep,” he adds. “It often takes a full week to evaluate all the features, and I just don't have time.”
For some landfills, simplicity is the key. “We use a Gorman handheld GPS unit that costs $500 and provides good coordinates,” Asman says. However, he concedes, only the larger landfills can afford to use GPS systems every day to monitor density. “I think you need to handle able 3,000 to 4,000 tons per day to make it cost-effective,” he says.
Angela M. Gerdeman, senior project manager for Hull & Associates, based in Toledo, Ohio, says that both GIS and GPS have been very effective in the early stages of landfill permitting. “With GIS, you're able to quickly see changes and how field data come together,” she says. “It helps you modify the footprint and avoid permitting headaches.”
During the recent siting process for a new residual waste landfill owned by an Ohio-based power company, “GPS allowed us to quickly identify two large wetlands,” she says. “Since it was in a densely wooded area, it would have been 10 to 20 times more costly to do this surveying by hand.”
“With regard to costs, the real savings is in the level of details on construction quantities,” McKeon says. “Construction costs vary locally, and you have to take that into account. CADD models provide a higher accuracy in bid document preparation that, in turn, results in a more competitive bid process.”
Another positive aspect of the CADD and GIS models are their potential for representing complicated engineering concepts in a bold, graphic manner. “The waste business is primarily a service industry,” McKeon says. “We are required to make presentations using color drawings that can be easily displayed for community relations purposes.”
For some landfills, the benefits of CADD, GPS and GIS have yet to outweigh the initial costs. While Mandeville says his company does not have an actual dollar figure in terms of monetary savings with GIS, he says the technology “has had a huge impact on our efficiency and the cost to provide our services over time. Also, we feel like it's helped us avoid problems during construction, operation and monitoring that could have been costly to remediate.
“For it to really be beneficial, [GIS] takes a lot of attention,” he adds. “You can do a full monitoring of groundwater, leachate and landfill gas generation, but it doesn't do any good if you take time to input a lot of data and then stop. The real benefit is in keeping up with it.”
Randy Woods is a Waste Age contributing editor based in Seattle.