Using Drones in the Erosion- Control Workplace
Back in high school, I used to love telling people what my stepdad did for a living. “He’s a photogrammetrist,” I’d say, then enjoy their puzzled expressions. “He makes maps out of aerial photographs,” I’d explain, rolling my eyes. “Everybody knows that.”
I went decades without hearing the term, until I started researching this story. Yes, that was his job during the ’60s and early ’70s, back when even astronauts used slide rules.
The late ’60s was also the dawn of the computer age—they were beginning to take over all technical jobs, including photogrammetry. I recall my stepdad studying Fortran and Cobol (early programming languages), late into the evenings, so he could keep working in his profession.
As he discovered, it was a constant challenge, even then, to keep up with advancing technology. Today, the pace of that change is nothing short of breathtaking, impacting all kinds of industries in profound ways, and the soil-erosion prevention business is no exception. New tools, things that seemed fantastical just a few years ago, are beginning to find their way into contractors’ toolsheds.
Perhaps the most exciting tool to come along in our profession is the unmanned aerial vehicle (UAV), more commonly called ‘drone,’ a small aircraft with no human pilot onboard. A UAV can be remotely controlled, flown by a pilot on the ground using a smartphone, or it can fly itself, autonomously, based on a pre-programmed flight plan.
These devices range from hobbyist or toy models that can be purchased for as little as $100 to professional units costing into the thousands. The exploding market and burgeoning competition amongst the manufacturers who make these little flying wonders has brought prices crashing down, making them affordable for even the smallest operations. Today, a good professional drone can be had for around $1,000 to $1,500.
You may be thinking, “That’s some sexy technology there, and maybe a lot of fun, too, but how can I justify the expense? Will I really have any use for a drone in my business?” That’s the coolest thing about UAVs. Because they seem so exotic, so Mission: Impossible-ish, if you will, it can be hard to see how practical these devices really are. But, at the rate things are going, it won’t be long before a drone will seem as plain vanilla and de rigeur an item for the contractor as a silt fence or coir log is now.
When you buy a drone, what you’re getting is essentially a highresolution aerial photography platform, either a fixed-wing or rotarywing type. The camera is the ‘payload.’ Some UAVs come with dedicated cameras; others give you a choice of cameras and lenses, depending on what you need and what you want to spend.
“With these cameras, you can do photogrammetry,” said Sean Erickson, a UAV technical support specialist at RdO Integrated Controls, a drone distributor in Billings, Montana. The company also provides mapping and other services to the construction, surveying, environmental, agricultural and irrigation industries, among others.
“You shoot roughly 100 photos in a ten-by-tengrid, ten photos wide by ten photos long,” said Erickson. “Then, you run them through software that turns them into a ‘point cloud,’ a three-dimensional model of the ground as the drone flies over it. This 3-d model can be viewed from any angle.”
The software can also create a two-dimensional orthomosaic (a highly accurate digital image that has been adjusted for topographic relief, lens distortion and camera tilt) map, very similar to a satellite image.
But why buy a drone, when you can get satellite images on the Internet for free, using Google Earth?
Well, the images a UAV can get are much better, because it can fly much closer, 400 feet or less above the ground, instead of 22 kilometers away, as a satellite would be.
As Erickson explains, the resolution of Google Earth imagery is typically 12 to 18 inches per pixel. But a drone has the ability to give you images at one inch per pixel. That’s literally 12 to 18 times clearer than any satellite picture, and in real time, where Google Earth images can be weeks old.
“At a very basic level, a UAV can generate orthomosaics for plan overlays and site staging, and most importantly, to estimate lengths, areas and make even more precise, miniscule measurements,” said Nathan Stein, ag solutions manager for SenseFly, a UAV manufacturer based in Lausanne, Switzerland.
Having such detailed data throughout a project can help keep a client updated, and can be used to create an as-built plan, prove environmental compliance and create a showcase, Stein said.
SWPPP inspections made easier
Blanca Hoffmeier owns SWPPP CAL in Thousand Oaks, California. She’s an engineer who started her career analyzing drainage. Finding that dull, she migrated over to doing environmental compliance work.
“I was working for a surveying company. They’d acquired some drones, and since I was the only one at the company who had a private pilot’s license, I was the only one qualified under the FAA rules at that time to be the pilot-in-command.”
She never thought her hobby of flying would ever be intertwined with her professional life, but there it was. While at the surveying company, she started doing SWPPP inspections, and found that she liked it. A year and a half ago, she started her own company and now does SWPPP inspections full time on some pretty challenging sites.
“Doing these inspections, you spend a lot of time driving up and down roads, especially on some of these huge solar farms that are going up everywhere. You have to drive around these sites again and again, looking at things from different angles, to get all the visuals you need.”
Having purchased a drone to take aerial photographs, it occurred to her that she could also use it for the SWPPP inspections. Sure enough, she found that it saved her a great deal of time, mileage and legwork.
“After it rains, you have to go out and check the BMPs,” said Hoffmeier. “It’s always very muddy, of course, and I spent a lot of time stuck in the muck. You end up tracking a lot of that dirt off the sites,” sort of counterproductive to the work of preventing soil erosion. “So for me, using the drone is mostly about not getting stuck in the mud,” she jokes.
Practically speaking, however, she discovered that the drone did a much better job documenting SW- PPPs than she could on foot, taking pictures with her smartphone. The resolution of the images was much higher, and could be taken from angles she couldn’t get.
The rules have changed since Hoffmeier flew her first UAV. You no longer need to be a licensed pilot to fly one; FAA Part 107 got rid of that requirement. The application process has been speeded up, too.
Have drone, will travel
But you don’t have to become a pilot, or even buy a UAV in order to take advantage of the technology.
DroneBase was founded by an ex- Marine who’d used military drones in the Middle East. It puts qualified pilots across the U.S. and in 40 other countries together with jobs, or, as the company calls them, ‘missions.’ “We vet the pilots, making sure they have all the proper licenses, their Part 107s and approvals,” said marketing head Erik Till. “We also verify the quality of their work and their professionalism.”
After doing a test flight to prove their chops, the applicants fill out profiles, including how far they’re willing to travel to complete missions.“Once a customer places an order, we find a qualified pilot in that area, and send the mission to him. We can usually schedule someone in a couple of days, weather permitting.”
If you want to make drones a permanent part of your company, and want to get one or more employees trained to fly them, you might call a company such as Aerotas. This firm works with land surveyors, developers and construction-related companies, getting them up to speed with drone technology.
“Under the old FAA rules, it would take six months and cost $50,000 to $100,000 to get a company started with UAV technology,” said company president Logan Campbell. “Now, a professional program can be up and running in weeks for about $10,000. For that, you get everything you need: the drone, the training, the licensing exam. It’s a complete solution.”
It doesn’t take long to get trained as a pilot. “We’re talking one to two weeks,” says Campbell. “Our system is set up so that after the first day of in-person training, one could go out to a jobsite the very next day and gather good data.”
Operating a drone is actually easier than flying one of those little radio-controlled toy planes, according to Campbell. It’s mostly automated. You go to the jobsite, take out your tablet or smartphone, draw a perimeter around the area you want to photograph, and hit ‘go.’ The drone takes off, takes its pictures, and returns to the takeoff spot when it’s all done.
“Buying a drone is easy,” Campbell says. “The next step, actually processing the data you get from it, takes a little bit more work. That’s what we’re here to help companies do.”
What he’s talking about is that you also need the right software to interpret the data from the photographs, such as a geographic information systems (GIS) mapping program. Companies like his will crunch the numbers for you, for a price. If you’re going to fully integrate drones into your business, though, you’ll need to get that software.
Sarah Haggard, CPESC, owner of deluge Consulting in Bakersfield, California, discovered that for herself. After hearing a lecture on drone technology at an International Erosion Control Association (IECA) conference a while back, she looked into buying one to help her do SWPPP inspections. Ultimately, though, she held off purchasing one, because she realized she also needed the software, not just for herself, but for her clients.
“Say one of them needs to have a specifically-sized buffer around a railroad area, for instance,” said Haggard. “You input the data into the GIS program, and it’ll display it on a map. It produces a visual representation of digital information that makes it easier for a client to understand.”
Finding the right software would take some research. Then, she’d have to learn how to use it. Meanwhile, all the recent rain in California was washing out BMPs right and left, and she was too busy inspecting to do either one.
Soon after that, she discovered that a man in her office building not only owns a drone which he uses for his remote-sensing business, but also the requisite GIS package. The pair have since teamed up. He’s the pilot, and also the data analyst. After doing some planned trial runs with his UAV on two solar farms, to see what kind of capabilities the photographic and sensing equipment has, she’ll have a better idea of what drone-related services she’ll be able to offer her clients.
“There are many applications for drone technology in soil erosion and stormwater work,” says Campbell. He’s trained a number of environmental consultants who wanted to map plant growth in different scenarios over time, and measure water lines at various times of the year.
“The soil-erosion prevention market is a great fit for drone technology,” said Matt Hayes, mapping product supervisor at RdO Integrated Controls. “The types of UAVs we sell and use are surveying tools, and great topographical instruments as well. Not only will they give you a 3d model with measurements in the data, but you’re also going to get very high-resolution 2d pictures.”
Hayes said that you can get very accurate measurements to answer questions such as, ‘What is the degree of slope of this hill, the volume of material in it, and the surface area?’ All of these things can be calculated to land-surveyor levels of accuracy, with very close tolerances.
A contractor could also determine elevation profiles, perform accurate cut and fill volumes, and verify or assess the final grading. Multispectral imaging can be used to detect soil movement.
Cameras with near-infrared band capability can be, and are, used for checking vegetation health and irrigation deficiencies by measuring the NdVI (Normalized difference Vegetation Index) — essentially, the amount of chlorophyll that’s present in plants. The higher the NdVI, the healthier the plants are. This makes it easier to pinpoint dry or less healthy areas that may warrant closer inspection.
You can see where this would be especially valuable in checking areas that have recently been hydroseeded. A drone could save a lot of time and mileage, finding bare spots that might need a second application.
By repeatedly flying over a problematic streambank or beach, a drone can precisely document the rate of erosion over a certain period of time, and do it much cheaper than using helicopters or other manned aircraft. UAV data is used in flood modeling, too, to project how water and mud would flow through the breadth of an area or property.
Is it safe?
Part of the reason for using a UAV is that it can boldly go where no other aircraft or vehicle can, such as very steep areas or crevasses that might be treacherous for human beings.
But even though a drone can fly on autopilot, it’s not like you can control it from miles away while you sit in your office, drinking coffee. You still need someone onsite; in fact, FAA rules require it. Besides, the battery only lasts about 15 minutes before it needs recharging.
Though a UAV is smart, “It’s not a genius,” says Campbell. But it will have a lot of technology onboard, collision avoidance and altitude sensors to avoid obstacles such as trees.
“Ultimately, this is why you still need to have someone on the jobsite.
Part of our safety training is making sure you know not to fly it at 50 feet, if there is 150-foot structure on the site.”We’re just beginning to scratch the surface of all the potential uses for drone technology in our industry. It’s exciting, and yes, even kind of fun. Can you envision yourself flying one someday?