After the Burn,,, Contrlolling Erosion
Wildfire! Whether it's the recent Waldo Canyon wildfire outside Colorado Springs, Colorado, the High Park fire south of Tulsa, Oklahoma, or something smaller that doesn't make the evening news - almost no natural or man-made disaster is as destructive as wildfire.
The problem is far more widespread than you might imagine.
According to the National Interagency Fire Center, this year has already seen almost 10,000 wildfires in July alone, wreaking havoc on more than 204 million acres. Not that 2012 is exceptional, either. In fact, it’s been relatively calm. By way of contrast, the year 2006 saw more than 15,000 fires in the month of June.
Most of these fires you never hear about, though the destruction is not merely from flame and smoke. With trees and plant material gone and hillsides denuded, burn zones are prime candidates for flashfloods, landslides, and other debris flow. One good post fire pounding rainstorm can touch off a mudflow that contaminates streams, rivers, and lakes.
Mother Nature spirals out of control. While firefighters are the ones protecting lives, homes, and terrain as the conflagration is raging, it’s up to us as soil erosion professionals to bring our expertise to the aftermath. There’s much work to
be done to make sure to limit damage, to the extent that we can.
Start by mapping the damage. On the same day the Waldo Canyon fire was contained, the local Burned Area Emergency Recovery (BAER) team released an edition of a map that to an untrained eye looked like the top view of a fireworks burst. In reality, every color indicates the level of burn severity. Blue means low intensity severity, the yellow means moderate, while red means high. Considering that the Waldo Canyon fire burned for 17 days, killed two people, torched nearly 29 square miles, and destroyed more than 346 homes, there was a lot of red and yellow on that map.
This map was the starting place for the recovery and erosion control process; similar maps guide professionals all over the country— and the world—as they work to help nurse the land back to health. “We look at the areas that were most severely burned, because they’re going to have the least amount of protective cover, and then we’ll start our assessment from those areas,” says Craig Sponholtz, Dryland Solutions, Santa Fe, New Mexico.
The beginning of a post-fire rehabilitation project is dependent on two things: budget and access, reports Julie Etra of Western Botanical Services, Reno, Nevada, and a member of the International Erosion Control Association. Budget sets up the playing field and dictates how much you can do. Access to the burn zone can be problematic. Mountainous terrain, private property considerations, and coordination with federal, state, and local officials can all pose difficulties and delay reparative measures.
Delay can hurt the recovery, particularly during slow-moving and hot wildfires that create intense gases; soil changes its chemistry when those gases bind to the particles. Some areas may burn so hot that the soil turns waxy and no longer absorbs water. This is called hydrophobicity.
“When you put a drop of water on hydrophobic soil it runs right off, and it takes with it anything it can grab,” says Penny Luering, national program leader for the Burned Area Emergency Response Service. “That means there’s more soil and debris in the streams and channels. Once it gets into the channels, it starts to carry rocks and ash. It becomes very powerful and can do a lot of damage, not only because of the force, but because of the volume.”
Hydrophobic layers vary in depth. The effect doesn’t wash away after the first rainstorm either, says Sponholtz. It may take up to as long as one to two years. Those oils in the soil have to dissipate on their own over time. On a limited basis, it’s also possible to turn over or roughen the soil with a spade or a steel rake like you’re working a garden,
to break up that hydrophobic layer.
Once the soil can support life, the next step is to seed. “There’s improved technology with seeding,” says Luering. She explains that the same traditional cereal grain used to grow crops like barley, oats, and wheat are useful in the aftermath of a wildfire. They germinate quicker and grow faster. “We can use those in the mountains, and get ground cover within a couple of weeks by using the quick-grow cereal grains.”
Etra recommends that whatever mix you choose should be dependent on climate. An annual rye that works well in Nevada, for instance, won’t work in Southern California. Regardless, “Using some inexpensive cover crop should always be in your mix, and it shouldn’t compete with your native species,” she says.
It’s a bit of a race against time.
At the same time that you’re thinking about reseeding, Mother Nature is doing it the old-fashioned way, with wind-borne and animal-borne seeds and spores. Weeds can result, but weeds are not always a problem. Often, they’re native to the area and can contribute to the quick establishment of ground cover.
On the other hand, sometimes Etra will go into post-fire areas where the land has been so charred that native plants can’t germinate. The introduction of non-native weeds—whether by Mother Nature or by the hand of man—can result in explosive growth that crowds out more desirable species you want to plant. In fact, Colorado now requires contractors to use weed-free mulch on public land after a wildfire.
Mulch comes into play very often when the fire has burned so hot that—hydrophobic or not—soil nutrients are gone. Plants can’t live on water alone; if the soil is sterile, they’ll die.
“An alternative to seeding is to lay down woodchips, mulch, or biological compost,” says Sponholtz.
“Anything you can do to get biology into the soil will help and it starts with organic mass. Don’t use fertilizer; it’s just a very temporary fix.
When a forest burns, it’s an incredible nutrient release. So it’s not that its nutrient deficient, the problem is that a lot of those nutrients get flushed out of the system very quickly.”
Assuming that the soil can support plant life, the type of application can be just as important as what you use to nourish the soil. According to Etra, there are three kinds of vehicle application: broadcasting, drill seeding, and hydroseeding. Broadcast seeding is something you can do with a little machine that’s attached to the back of a pickup truck. You can also do it by hand, just like you were going to seed a lawn. A crew following behind will spread the seed with rakes or a tractor-driven harrow. Etra warns that broadcast seeding can also be a waste of money if you can’t cover your seeds.
Drill seeding is a farmer’s method; you put the seed in the hopper and it makes a little trough that the seed drops into. It has limited use, since you can’t dig into rock, but if you can make it work, it’s very effective, she says. You shouldn’t use this equipment on steep or rocky terrain because the equipment could flip and injure the operator.
Hydroseeding is a quicker and more efficient way to go, especially on sloped areas. If you’ve added a bonding agent, it will hold the material to the area you sprayed, especially in steeper areas. It’s a popular method, especially in areas that more prone to rain.
“We did quite a bit of hydroseeding with the fires I was just on,” says Etra. “Since we couldn’t get a truck on those back roads, we did a lot of broadcasting and we drill seeded in some of the flat areas.”
Hydroseeding can be applied aerially, as well. According to Luering, it’s quite expensive, and you usually see it in areas like road cuts, where there’s absolutely no vegetation. It may come with a high cost, but there are places that are worth the value.
While you have your mind geared to revegetation, keep your eye on the weather, Leuring suggests. Agencies like BAER do soil treatments quickly, so they can beat inclement weather that can wreck reseeding and mulching. If you reseed or mulch and an intense rain follows shortly after that, your investment is washed away. Hopefully, it will be a gentle rain.
Before seeds are planted, Etra says, you may want to check on the water supply and any infrastructure leading up to that water supply. “In terms of remediation, I think that is the most important thing to protect,” she says.
Case in point: when the High Park wildfire passed through northern Colorado near Fort Collins, ash affected rivers and creeks that pulse through the state. After the fire was contained, there were complaints that the water looked like oil more than anything else. As a result, cities located downstream of Cache la Poudre Canyon decided not to use that river as a source of drinking water. If you can’t use local water to assist in the reseeding, you either have to find another source or pray for gentle rain.
Reseeding and mulching occur as part of a multi-faceted post-wildfire recovery effort. For example, Sponholtz says, “If we know an area’s going to experience a lot of intense flooding and a road crosses a creek multiple times, we try to accommodate that without losing the road.”
Following any fire that will require soil erosion countermeasures, response speed is key—not just to prevent a possible landslide, but so that you can get in on the profit to be made doing at least some of the work.
Post-fire contracts are usually filled on an emergency basis. You’ll often find listings online at government sources for just three to five days, unlike the usual 30-day listing. For example, the federal contract offered at www.fedbizopps.gov for some of the reseeding of the 350-square mile Whitewater- Baldy fire in New Mexico was posted on June 22nd, with a response deadline of noon on June 28th.
Often, one of the requirements in these situations is that contractors must be able to start immediately. According to Luering, “If you can’t do that, then you shouldn’t even submit a bid.”
That said, if you can start immediately, and have the capability to do the work, there’s real profit to be made. With fire season not even close to over, and almost 10,000 wildfires in the month of July alone, that’s lots of post-blaze soil erosion control, mulch-spreading, and reseeding to be done.