After the Fires!
The Pioneer Fire that started on July 18 has consumed nearly 200,000 acres in Idaho, and it’s not out yet. At the time of this writing, early October, it was only 71 percent contained.
A raging wildfire like this one will always lead the news, but not much about the blaze will grab headlines after the firefighters go home. Not many people know what happens after the fire is out, except for government officials and a community of soil erosion and hydroseeding professionals who specialize in post-fire reclamation.
The people who do this type of work are passionate about it; they have to be. It’s very hard work, taking place in remote areas. And while the rewards can be great, the risks can be even greater.
“We were working near Cibola, New Mexico, right on the Mexican border, and had heavy equipment stolen in broad daylight,” said John Larson, CEO and founder of Apex Curb & Turf, LLC in Clarkston, Washington.
“The police said, ‘We’re busy; we’ll get back to you in a couple of weeks.’ And the locals warned, ‘Don’t go looking for your stuff—you probably won’t come back.’” “It got so dangerous that we had to hire armed guards to protect us and our helicopters. Later, we found out that we’d been right in the middle of the biggest heroin-importing pathway in the U.S.,” Larson said.
Risky, yes, but not usually this exciting. What happens after a fire depends not so much on one’s ability to dodge possible bullets, but on a number of biological, topographical and budgetary considerations: how big the fire was, how hot it burned, how accessible the site is, and how much money is available for remediation. Most important of all, how close to critical watersheds or homes is the burn area?
“After any forest or wildland fire, ground cover has been lost,” said William J. Elliot, P.E., PhD, a research engineer at the U.S. Forest Service’s Rocky Mountain Research Station in Moscow, Idaho. “Anything you can do to improve ground cover will reduce the risk of erosion, and it’s critical that it be done before the next rainfall.”
Erosion control is almost always necessary after a big fire, to prevent sediment, silt, ashes and other debris from running off and polluting lakes and streams. Ash in the water will increase its pH to unhealthy levels for aquatic life. Sediment fills up reservoirs, diminishing their capacity to hold fresh water. Mud flows can knock homes off their foundations, or bury them, along with whoever’s inside.
The process of deciding what to do starts while the fire is still burning. The Forest Service sends in a Burned Area Emergency Response (BAER) team, consisting of hydrologists, soil scientists, engineers, biologists, vegetation specialists, archeologists and others, to rapidly evaluate the area and specify emergency stabilization treatments.
“I spend a lot of time in helicopters and airplanes,” said Michael Harding, a soil stabilization and revegetation consultant who works out of San Diego, California. One of the leading technical experts in the field of erosion and sediment control—in particular, post-fire hazard assessment and remediation—he’s also a three-time past president of the International Erosion Control Association (IECA).
“Overflights are critical. You need to see the burn site with your own eyes, not a drone’s. While someone flies the helicopter, I hang out the window and get an overview from 1,500 to 2,500 feet.”
“I look at all the drainage points, and figure out where water is going to go, and what in its path needs to be protected,” said Harding. He visits each site at least three times before coming up with a list of recommended BMPs.
The hardest part, says Harding, is getting things done in a timely manner. You only have 120 days after a disaster has been officially declared by a state’s governor; after that, funding is cut off.
That is, of course, if anything is going to be done at all. “On public lands, after the BAER team does its damage assessment, nine times out of ten, they’ll opt to do nothing.” Nature will eventually repair the wounds on her own, within two to five years, But after a very hot fire, one that burns six inches down, scorching the seed bank and killing all the microbial life in the soil, the natural repair process could take twenty years. We simply can’t wait that long when something valuable is at risk—people, livestock, property, or natural resources.
That’s the point where erosion control and hydroseeding contractors are called in. Increasingly, though, it isn’t seeding they’ll be doing. Colby Reid, reclamation division manager at Western States Reclamation, Inc. in Frederick, Colorado, says that Forest Service policy towards hydroseeding has changed over the past ten years.
“At one time, they used to seed everything. But now, everyone is more concerned about bringing in noxious, nonnative invasive weeds. For the most part, in the past five years or so, seeding has been taken out of the equation. The BLM (Bureau of Land Management), though, still does quite a bit of seeding.”
If seeding is done, it’ll usually be with natives and a sterile triticale wheatgrass that has a one-year growth cycle. “The wheatgrass comes up really fast, and has a strong root system that tends to hold the soil a lot better than waiting on the native species to germinate,” said soil erosion consultant Michael Allen, CPESC, owner of Allen Land Services, Inc. in Garden Valley, Idaho. “It functions as a nurse crop, protecting the native seedlings that take much longer to germinate.”
Before any BMPs can be installed, or seeding done on the burn site, crews have to be able to reach them. Roads are typically narrow, and often blocked by fire debris, so first, the crews have to build new ones.
In lieu of seeding, ‘straw bombing’ is the technique that’s mostly used now to provide post-fire ground cover. Wheat and barley straw is generally used, and it must be certified weed-free. It’s called ‘straw bombing’ because mulch and seed is delivered aerially, dropped from planes and helicopters.
But straw can blow away. In the war on post-fire erosion, sometimes you’ve got to make more than one bombing run.
“We were the low bidder on the Schultz Fire near Flagstaff, Arizona, in 2010,” said Larson. “We dropped 3,000 acres of straw from the air. After that, it was hit twice more, by two other companies. The Forest Service paid three times to do that same job.”
Wouldn’t it have been better if they’d just gone ahead and specified seeding? “Hydroseeding would probably have been effective,” said Larson, “but very expensive. We’re talking $3,000 to $4,000 an acre, compared to $500 to $700 an acre to straw-bomb.”
In lieu of straw, wood fiber mulch or bonded fiber matrix is sometimes used, if the budget allows.
Soil particles, stripped of the vegetation that held it in place, will start moving as soon as the first rain falls. Blocking that sediment flow is critical.
Straw bales, sandbags and gravel bags are often employed for this purpose. Harding has even used K-rails, the concrete lane dividers you see on highways, on slide-prone hillsides behind homes.
Allen prefers using burlap-filled gravel bags instead of straw bales. The gravel bags dissipate velocity, where the straw bales are easily undermined. Water can flow under and around the bales, and cause even more erosion.
Harding is credited with inventing burlap gravel bags as an alternative to sandbags. Modern sandbags are made of non-porous geotextiles, and water can’t flow through them. “Sandbags are great for blocking, containing, or diverting flow, but they don’t filter flow,” said Harding.
He explains that, once the area behind a bank of sandbags is full, it’s full. The gravel bags, by contrast, will slowly leak water out, so by the next storm event, they can be back at 100 percent capacity.
The gravel bags act as filters, catching silt as it flows through the burlap and gravel. Each bag is filled about one-third of capacity. When thrown down in a streambed, they’ll meld themselves to the bottom. The burlap will eventually biodegrade, so the bags can be left in place. Sandbags, however, leave behind plastic debris that has to be cleaned up.
Another method for blocking sediment flow is building log or rock check structures on the contours of slopes. Often, felled trees found onsite are used for this purpose.
Jay Selby, owner and president of Selby’s Soil Erosion Control Company Inc. in Newcastle, California, uses a lot of straw wattles for this purpose. They’re also fully biodegradable, and, left in place, eventually disappear.
To break up or not to break up?
Wildland fires have a feature that other erosion control scenarios don’t. A very hot, intense fire releases gases from the waxes and lignins in the vegetation. When these gases settle on the ground,
they make the top layer of the soil hydrophobic, or water-resistant. Instead of being absorbed, water runs off.
“That hydrophobic layer is like a sheet of plastic,” said Selby. “With a normal rainfall, say a quarter-inch, you get a lot of absorption. But if there’s a big storm event, and water hits that non-absorbing layer with some velocity, that’s where massive landslides come into play.”
“Sometimes a forest fire will flashburn through an area, and won’t cause hydrophobicity,” said Reid. Where you see the white-ash ‘moonscapes,’ that’s usually where the hydrophobic soils have been created.
Without physically breaking that layer up, there’s nothing you can really do about it.”
It seems as if it would need to be broken up. But when you’re dealing with hundreds of thousands of acres of marginally accessible terrain, however, that’s not really possible or practical.
Just as well, contends Elliot. “My personal opinion is that it’s a really bad idea to try to physically break up that layer. The soils in those forests have spent the last 10,000 years gradually consolidating.”
“All those little soil particles are snuggling together, and they’re nice and stable; not even rain dislodges them. Then someone comes along and digs them all up, and 10,000 years’ worth of settling is gone. Now it’s easy for them to get detached, because there’s nothing for them to hold on to.”
Nature and moisture will break up that layer over time, but there is a way to speed up the process. A compost tea added to hydromulch slurry can help restore the microbes and mychorrizae that the fire killed. Over time, these organisms will break down the waxy layer.
A tricky business
In post-fire reclamation, nothing is ever simple. “People say, ‘You get all these government jobs and make a pile of money,’” said Larson. “But you can go broke faster than you can believe.”
Harding once worked with a contractor who vastly underbid a job, not realizing everything that was involved. He quit early on, after he realized that he was losing money with every gallon he sprayed.
“Some contractors will deliberately underbid, and try to get away with not using the right type and amount of material,” said Dave Chenoweth, the semi-retired CEO and president of Western States Reclamation. “And some just don’t have the knowledge or experience they need to bid a project of that magnitude.”
He never tries to ‘buy’ jobs by bidding too low; he only bids jobs to make money.
Then there’s getting that money on time. You’d think that government remittance checks would roll in like clockwork. Not so, according to Selby. “We’ve had contracts in the past where they didn’t really have the funding in place. You could work on a project for a couple of months, and not receive a dime. Meanwhile, we have money tied up, which causes a cash flow problem.”
Fire reclamation isn’t for people who like things nice, neat and planned in advance. Since this work is done on an emergency basis, decisions are made on the fly. Selby says that he often doesn’t know exactly how much land he’s going to be hydroseeding, mulching or covering with blankets and wattles, and could easily get stuck with $100,000 worth of site-specific native seed that he can’t use anywhere else.
“You can’t bid these jobs sitting at a computer,” said Larson. “It takes a team of very talented people, and a lot of spreadsheets. We’ll bring in the aircraft people, calculate our flight times and elevations, look at our water sources and try to factor in weather.”
When it’s time for these crews to roll, it’s like a military operation: everything they need goes with them. If something’s missing or breaks down, they can’t just run back to the shop, so they take along enough spare parts to stock a store.
Larson had a particularly nail-biting experience while working on the Charlotte Fire near Pocatello, Idaho, in 2012. There was no money in the budget for aircraft, so the Forest Service called him, because they knew he’d built some very large-capacity hydroseeders (Larson also owns Apex Hydromulchers, a manufacturing company). “I told the agency that, if they could build roads and provide me with cabling, we would yo-yo our large-capacity hydroseeders into the canyons.”
“Yo-yo-ing” means hooking a cable to a tie-hook on the front of a hydroseeder, and winching it down the side of the canyon from a piece of heavy equipment. You spray, then winch the machine back up again.
Needless to say, this procedure isn’t for the faint of heart. But it allowed Larson to complete the job for just under $700,000, considerably below the original $2 million budget.
Fire reclamation is some of the most satisfying erosion-control work you can do, knowing that you’re restoring habitat and bringing back beauty to a once-blackened landscape. But before you try it, make sure you know what you’re getting into.