Using Drones for Landfill Mapping
What you should know about this emerging technology
National surveys show that more than 65% of landfills develop an annual topographic map, and most of those topo maps are created using traditional aerial photogrammetry. This is a process that two years ago we would have called “state of the art.” Today, we call it “old-fashioned,” because we can now produce those same maps using what are technically known as Unmanned Aerial Vehicles, otherwise known as drones.
Drones are becoming more and more mainstream, with talk of instant delivery by Amazon, and the ability for filmmakers and video hobbyists alike to produce dramatic aerial footage for a low cost. Drones are cool and fun to fly, but there is much more to the technology than just the fun factor. In fact, drones are often faster, more accurate, and less expensive than traditional methods of data-gathering. Early discussions about the how to use drones at solid waste facilities were filled with skepticism: Would it work? …Could it work? Much like early application of GPS to provide surveying guidance on heavy equipment, many people are skeptical.
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This is a Déjà vu’ moment—we’ve been here before. Back in 1991, I was involved in developing some early prototypes of GPS equipment for landfill compactors and dozers—making presentations to Waste Management and Caterpillar. Shortly thereafter, Caterpillar came out with their CAES GPS unit. Today, seeing GPS units on heavy equipment is commonplace, but in those early days there were plenty of experts who said it was interesting, but couldn’t be done…and certainly would never catch on for landfills. What they missed seeing was the energy that could propel a new technology into its full potential.
Yes, drones are fun to fly, but that doesn’t mean they are toys. These are state-of-the-art instruments; they are tools. A modern drone is equipped with a very sophisticated GPS system, gyroscope, accelerometer, and a robust communication link. There is more computer horsepower in one of these drones than NASA had when it sent Neil Armstrong to the moon.
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And, it’s not just the drone. If you want to generate an accurate topographic map of your landfill, you must also have a high-quality camera (20+ megapixels), an interface program, and controller—so you can communicate with the drone from the ground and set up a flight plan to take aerial photos. Once the flying part is done, you’ll need a sophisticated program to process the photos and convert them from photos into a point cloud, from which you can generate a three-dimensional model, topographic map, etc.
Of course, you’ll also need a CAD (computer-aided design)program and a fast, powerful computer. Our company, Blue Ridge Services Inc., received an FAA (333) exemption in 2015 to fly drones commercially—and was one of the first to use drones for landfill mapping. That requirement was recently eliminated, but you still must take an FAA (Federal Aviation Administration) test and be certified in order to fly drones commercially. I know, it sounds a bit funny. Any 10 year old can fly a drone right out of the box, but your engineer needs to take an FAA test to fly a drone commercially.
The Flight Process
The process for producing a topographic map with a drone is similar to the process used by the old-fashioned aerial photogrammetry systems, where a pilot flew an airplane over your landfill and snapped photos. It’s just that the drone process is much more automated and significantly safer. Drone pilots don’t die in airplane crashes. The biggest risk is that the drone could fail in flight, fall out of the sky, and hurt someone. That’s not likely to happen—but it could. And just to be on the safe side, all of our drones are equipped with parachutes, which deploy automatically when the parachutes’ accelerometer senses a too-rapid descent.
That’s right—even these drone parachute systems are smart. In the instant they sense that the drone stops flying and starts falling, the parachute deploys. And your drone will come floating down out of the sky, like a small, mechanical paratrooper.
Drone mapping is also fast. Once the ground control points are set, the pilot opens the protective case, pulls out the drone, spends about 10 minutes programming the flight, and then launches. Flying a small site might take 15 minutes. A larger site could take an hour or more. Drones can fly large areas, but it may require multiple flights that are digitally stitched together. The area that can be flown in a single flight is limited by battery life. Multi-rotor drones (with 4+ motors) typically have 15–20 minutes of flight time, while fixed-wing drones (with only 1 motor) may fly for 30–45 minutes. Once the flying is done, the drone goes back in the case, and that’s it.
All of the necessary data from that flight is stored in a tiny SD card on the drone. That information is transferred to a computer, and the previously described processing begins.
Once the processing is done, the map preparer must clean up the data. Remember this process is automated, and the software doesn’t know the difference between a GMC pickup and a pile of concrete rubble. It treats everything as topography. That means the technician deletes the contour lines that define the pickup and makes adjustments to sift through the noise created by trees, brush, or other heavy vegetation. Every site—and every project—is a little different, but with a typical flight, the process takes a week or so.
Let’s Talk Accuracy
When it comes to selecting a method to map your landfill, you have a lot of options, many of which affect accuracy. How high do you fly? How fast do you fly? What percentage of overlap do you select for the individual photos? But most importantly, what type of camera and lens do you use? Now, we’ve heard a lot of different opinions about the accuracy that drone maps can provide.
Even the drone manufacturers will quote accuracies of 1 inch (2.5 cm), 4 inches (10 cm), 6 inches (15 cm), or even 1 foot (25 cm). Accuracy quotes are all over the board. So why the discrepancy? I don’t know, but the interesting thing is: When we ask these folks what sort of testing they have done to confirm those accuracies, most of them confess that they have done no accuracy testing. These accuracies are theoretical.
Our company is currently in the process of conducting detailed accuracy tests to determine just how accurate our drones are when it comes to gathering data for topographic maps. We are testing several different flight/camera scenarios. As of press time, we have not completed that analysis, but when it’s finished, I’ll post something here.
Drones have potential applications beyond topographic mapping. Drones and mapping technology are being used at waste facilities to improve the quality of fill sequence planning, conduct time-motion studies on machine productivity, and allow for in-depth analysis of traffic patterns, cell construction, litter control, and more. Drones can also be used to quickly measure stockpile or compost windrow volumes—something that can help facilities manage inventory. Finally, drones equipped with thermal imaging cameras can detect surface heat that could indicate a sub-surface landfill fire.
Just a Passing Trend?
You might be asking: is this drone stuff for real? Well, you can bet your microprocessor it is. It is as real as the GPS in your car or tractor. It’s as reliable as the computers we use in our offices and smartphones. And it’s as mainstream as the Wi-Fi you use to connect to your home network, office network, or to get online at your local coffee shop.
Some folks just don’t take to technology as quickly as others. It has taken 25 years for GPS to be considered normal on heavy equipment—and now most heavy equipment manufacturers offer GPS equipment as an option on their machines, and GPS has become an integral component of waste facility operations.
I have been utilizing drone technology for my clients for some time, and in my opinion, drone technology is not only here to stay, but also has vast potential to improve many aspects of the solid waste industry. So does that mean every landfill should have a drone? It depends. If you want have a drone in order to get a birds-eye view of your cell, traffic patterns, or a wetland area that you can’t drive to, then sure, a basic drone would work. And, oh, did I mention drones are fun to fly?
You can get a quality drone, camera, gimbal, and controller—which is what you’d need to fly up into the air and get video of your operation—for under $1,000. If you want to create maps, a basic system will run you $15,000–$20,000, depending on whether or not you already have a fast computer and AutoCAD.
As a point of reference, we have invested approximately $50,000 into our company’s drone program. We have four drones in our fleet—three multi-rotor units and one fixed wing. Two of the multi-rotor drones are set up with GoPro cameras and are used for time-motion studies, facility observation, and basic recon. We used them when we conduct a comprehensive operations review (CORE Assessment) and also as a great visual aid when providing field training. The third multi-rotor drone and the fixed wing unit have high-quality cameras and are used for mapping.