When the Fire's Out
Hydroseeding, hydromulching, and other techniques on wildfire-damaged sites
Red and orange filled the sky last autumn in southern California, but it was the unrelenting flames of extensive wildfires, not leaves changing their seasonal colors. When all that is left in wildfire-damaged areas is ash and charred soil, is it better to seed or just help nature take its course by providing a stable environment for the seed left in the soil to thrive? This is one of many questions posed in the state as workers mobilize their erosion control efforts.
Many areas are still coping with fire damage. For example, the Ammo Fire in San Diego County burned more than 21,000 acres, the Santiago Fire in Orange County blazed across 28,400 acres, and the Poomacha Fire in San Diego damaged more than 49,000 acres, according to statistics released by the California Department of Forestry and Fire Protection. In October, CNN reported that as a result of the wildfires, more than 500,000 people were forced to evacuate their homes in the hardest-hit area of the state, San Diego County. The bill for such destruction is steep: The October 2007 wildfires caused more than $1 billion in damage, according to the Arlington, VA–based conservation organization, The Nature Conservancy.
Erosion has already occurred in some areas of southern California that at press time had experienced a large rain event, explains John Munn, a Sacramento-based soil scientist with the California Department of Forestry and Fire Protection. Munn served as an advisor to the Burned Area Emergency Response (BAER) team that was involved with the Canyon Fire in Malibu, CA.
“It’s worse than average,” he says of the 2007 wildfires. “I don’t know that you could say it was worse than 2003. It’s a bad year for anybody whose house burns down.”
Following the October 2007 California wildfires, California Governor Arnold Schwarzenegger called upon the state’s Blue Ribbon Fire Commission to assess the next steps that will be taken at all governmental levels to prevent and battle future fires. In November, the House-Senate Conference Committee approved $500 million for risk recovery, emergency fire suppression, and recovery needs related directly to these southern California wildfires.
Several conditions in fall 2007 created the ideal setting for the spread of these blazes.
“Southern California is a fire chaparrals area,” says Ron Dietz, president of Dietz Hydroseeding of Sylmar, CA, explaining that there were extreme Santa Ana wind conditions blowing 70 miles per hour, making the spreading fires virtually unstoppable. These are usually dry winds in very low humidity. “They increase the temperature. We’ve had a drought situation. Even some of the areas that burned in 2003 reburned. The issue is that they are building homes more into these areas that are native wildfire areas. It’s like building in tornado alley. Where you decide to build your structure is impacted by the natural conditions.”
When wildfire does produce extensive damage, as is the case from the October blazes, temporary measures may be used to protect areas vulnerable to mudslides or ash washed down a hillside by heavy rains.
Straw wattles or silt fencing may be needed for erosion protection, depending on the situation’s severity, according to Gary Weems, president of Hydro-Plant. Sand bags, too, may be used when there is a risk of heavy rain. In high-flow water areas, erosion control blankets would be a consideration, says Dietz, whose company is also working with residents of Orange County affected by the Santiago Fire.
“Sand bags or gravel bags can be used at the bottom of slopes in place of straw bales,” he says. “When you get into straw bales, they really should be maintained. That’s another consideration. If any material gets behind that, it fills it up. Then a big rain comes, and it breaks loose and goes all at once. That’s why they really don’t like to use it until they really have to.”
For post-fire recovery sites where hydroseeding is an option, seed choice is very important to the well-being of the area.
Workers at S&S Seeds, a wholesale native seed and erosion control supplier based in Carpinteria, CA, provide guidance for companies working to hydroseed post-fire recovery sites. “We are filling various seed mix prescriptions, ranging from true California native species like Cucamonga brome and small fescue to non-native sterile cover crops like QuickGuard,” says Bruce Berlin of S&S Seeds, referring to recovery efforts from the 2007 fires. “Each different agency or region is developing its own particular seed mix components based on the site criteria and plant pallet.
“Our company has the ability to help them with the seed counts, seeding rates, and supplying the mix components. We are the largest supplier/producer of native seeds with origins in southern California. Timelines and product availability do enter into the criteria for both product and seed selection. You have to be able to supply the materials immediately so the slopes can get protected and covered prior to the onset of fall rains.”
Photo: Ted Stallings
|A fleet of grounded AT-802 Air Tractors|
Berlin notes that seeds grown commercially in other regions are not, in many cases, acceptable for use in sensitive California habitats.
Dietz Hydroseeding is helping private landowners in Malibu recover from the October fires, using a bonded fiber matrix and, in some instances, a seed mix.
“If you’ve got a homeowner who has a half-acre site and they want to protect a quarter acre, it’s viable for them to use the more expensive product to get better protection,” says Dietz, referring to the hydromulch mixtures added to the affected areas and noting that the company is using some native grass seeds, including Vulpia and some nassellas, in that area as part of the mix. “In the Malibu area, there are a few areas that are using native seeds. Grasses tend to germinate and grow quicker. You get a lot more plants per square yard than shrub seeding. Some of the homeowners want to put wildflowers in [such as] California poppies.”
Most people today not only seek a quick ground cover but also a suitable native occurring naturally in the burn zone, says Berlin, unless it is “a non-interfering-with-native annual such as the QuickGuard.” Berlin also stresses that, in some instances, seeding is not an agency’s first choice.
“Contrary to what many people believe, the Forest Service does not automatically reseed burn areas,” he says. “The BAER teams evaluate the seed bank and erosion control concerns and then develop a plan to address potential erosion and sediment control concerns.”
Devastation and Recovery in South Lake Tahoe
Beginning on June 24, 2007, and continuing for nearly a month until it was controlled July 19, the Angora Fire in South Lake Tahoe, CA, burned 3,100 acres, 2, 736 of which were National Forest System lands. More than 250 homes and 75 commercial structures were destroyed. Soil on the burned sites needed to be stabilized quickly because many more homes were threatened by potential sediment and runoff. The Angora Fire was the most destructive blaze to occur in the Tahoe Basin in more than 100 years.
Photo: Ted Stallings
|These aircraft are indispensable tools for applying hydromulch.|
The US Forest Service named Aero Tech, based in Clovis, NM, the prime contractor to provide aerial hydromulching services to stabilize the site and protect it from erosion.The hydromulch would be used to trap moisture and foster an environment where new growth could be established.The company subcontracted Loomis, CA–based Selby’s Soil Erosion Control Co. to aid it with mixing operations. Other contractors had set straw wattles in place as a temporary emergency measure on the site, and on September 12, Aero Tech began using its five AT-802 Air Tractors to treat 636 acres that were affected by the burn.
Workers hydromulched areas near the South Tahoe High School, Angora Ridge Road, an area close to Angora Lakes, and an area near Highway 50. The magnitude of the project was its biggest challenge, with many airplane loads that needed to be completed each day.
“We applied approximately 2.3 million gallons of mulch to the mountainside in 14 days. We did 3,187 airplane loads,” says Ted Stallings, Aero Tech’s president, adding that the company used a 60% wood, 40% paper hydromulch mixed with Super Tack, a combination he described as typically standard for use on post-fire sites. “Getting maintenance completed at night on the aircraft, everything just had to go perfect, and it did.
Photo: Ted Stallings
|The result of the Angora fire that had started as a result of an illegal campfire|
“The Forest Service told us that the Angora Fire was the largest, most successful aerial hydromulch project to take place in the state of California. We are the first contractor that has been awarded straight 10s across the board.”
The decision to hydromulch a post-fire site without using seed is something Stallings says is practiced on about half of the post-fire recovery work that his company performs. This depends on how hot the fire-damaged area became and if the germination in the soil has been destroyed.
Dietz agrees. “The native seed palate is designed to survive,” he says. “There are even seeds that are post-fire germinate.”
Protecting Homes in San Diego County
In 2003, wildfires damaged more than 200,000 acres in San Diego County, explains Chuck Austin, owner and president of Great Circle International based in Hygiene, CO, which worked to protect 1,200 of those acres from erosion. These fires, he says, were slower than those during the fall of 2007. They damaged many homes and impacted high-priority watersheds located above many homes.
At Scripps Ranch, an upscale housing development in San Diego, Great Circle International worked to protect 220 acres from erosion.
“We used Super Tack. On that particular site, we used regular wood fiber hydromulch, EcoFibre by Canfor. We mixed in a particular [native] seed mix for the county, and we mixed in mycorrhizae,” says Austin, referring to the soil fungi. “We tried it. It really didn’t gain us much. We aren’t using it this time.” In fact, following the 2007 fires, which he says were fast and not quite as hot as those that blazed through in 2003, his company isn’t planning to use seed.
|One of the canyon areas along Lake Wolfard Road in San Diego County|
“The key is actually the mulch and the tackifier holding the stuff in place. We got pretty much the same results in sites where we put seeds,” says Austin, who said this allows an area that can recover on its own to do so. Rarely, he says, does it get too hot to burn up all of an area’s seeds.
Hydro-Plant, a San Marcos, CA–based hydroseeding services company, treated the Cedar Fire, also located in San Diego, following the same wave of wildfires.
“We’re usually ready to go before the agency is. San Diego County and City hired us during that fire,” says Weems, noting the company has six 3,000-gallon Bowie hydroseeding machines it can use to treat large sites. “We apply a mulch and a binder on the burn areas. [We used] EcoFibre, and the binder was Super Tack.”
EcoFibre mulch is manufactured from whole wood chips. Super Tack, produced by Ranchester, WY–based Rantec Corp., is a guar-based tackifier that is 93% soluble.
As in South Lake Tahoe, Hydro-Plant didn’t seed certain damaged areas. “They put a seed mix in some areas, and in other areas they did not, depending on the terrain, how steep it was, and how hot it got,” he says, noting that the mix included four to five different native species determined by a biologist. “If it was a grass burn or a chaparrals burn, it may not have been hot enough to kill all the seed.”
If the area was wooded, however, says Weems, the fire probably did get hot enough to destroy the seed. The primary concern for workers at the Cedar Fire site was to hold the ash and stabilize the ground before heavy rains began, threatening roadways and structures below the site.
“Ash moves pretty easily,” notes Weems. “By putting in the mulch and the binder like a blanket on top of it, it helps control that erosion until the new plants pop out of the ground. It can take awhile.”
After the site was treated, there was “virtually no erosion in 90% of the area,” he says.
Protecting Science From Nature
Another example of extensive hydromulching to protect fire-ravaged soil from erosion took place during the winter of 2005 at the Santa Susana Field Laboratory in Chatsworth, CA.
“It’s a site we were working for Boeing and NASA. We did 872 acres in 14 days,” says John Larson, owner of Apex Curb & Turf based in Asotin, WA. “We actually did about 335,000 gallons of hydromulching.”
Apex worked in cooperation with American Civil Constructors, which is headquartered in Denver, to stabilize the soil in the area that had been damaged by the Topanga Canyon Fire.
While Apex works on approximately 60 federal contracts annually, this project was the most complicated it had ever performed. Security checks were tight at the site where rocket testing takes place. Larson explains that Boeing had its own photography crews onsite, and his company was restricted from taking its own photos. About eight days of onsite training with Boeing took place prior to the project, and the hydroseeding workers wore badges. Adept at having to mobilize quickly, the teams were able to begin within 24 hours after being contracted for the project, which continued through the Christmas and New Year holidays.
“We provided all of the bonding and insurance. We provided about 75% of the labor and manpower,” says Ron Dean, an estimator for the environmental restoration department at American Civil Constructors, who adds that the company also provided some mixing trucks as backup that were never used on the project. A combination of wood and paper fiber mixed with water was used, along with a product called SoilSET, from Sequoia Pacific Research Co., as part of the slurry. No seed or fertilizer was used.
“Very little of any of this work in California has seed in it,” says Dean, noting that some interest groups in the state have difficulty agreeing on what can be classified as a native seed. “They are so afraid of planting something that will encroach on the natives that are there that they don’t choose to [seed] anything.”
In many cases, even though the fire has passed through, “There is still a pretty good seed bank in all of those treated areas,” according to Dean. “Once the rains came, the grasses there took off. There’s a lot of scrub brush up there. A good portion of that all came up from the roots with the topsoil gone.”
The client was pleased when the project ended. “Boeing sat us down at the end of the project and said it was the most organized contract that they’ve ever had on that site since they’ve been in business,” says Larson.
Additives That Can Be Used For Stimulating Growth
Mycorrhizae are soil fungi that are sometimes added to the soil following a fire.
|The Hydro-Plant truck along Lake Wolfard Road|
“Mycorrhizae are naturally occurring soil fungi that would typically exist in a healthy living soil. In many cases, adding commercial mycorrhizae is not needed, provided you have healthy topsoil to begin with,” explains Berlin of S&S Seeds. “Mycorrhiza has shown itself to be effective at getting roots established and providing greater nutrient-holding and soil-holding abilities. In many cases the fires burn so hot that the soil, and the organic components within the soil, including any seeds and any mycorrhizae, are killed.”
Varying opinions exist on when and where it’s appropriate to add mycorrhizae to fire-damaged soil, according to Dietz. It’s particularly beneficial to add the fungi on a site where there has been grading or cut soil, he says.
“After a fire, you’re dealing with an existing topographical area. Nothing has changed as far as the grade. There is still seed there,” explains Dietz. “There are still roots from the shrubs that burned.”
Chemical strategies can also be considered for boosting growth speed and sustaining vigorous plants, according to Don Bandoni of Helena Chemical Co. based in Memphis, TN. “With the fire, they get free nutrients on the soil,” he says, noting that nutritional products like Ele-Max nutrient concentrate can also be added in small amount to a hydroseeding solution. “When it’s cool, roots are slower to grow. This way they’ve got some [nutrients] right there on the surface. If you put too much on, you can burn the seeds, but you can add a minute amount to allow the seeds to grow as best as they can.”
Retaining moisture at the surface, he explains, also provides the seeds with a better opportunity for germination.
Naturally occurring rainfall—in moderation—can also protect soil from erosion on post-fire sites. “Everything being done now is preventative to keep the potential for mudflow at a minimum,” says Dietz. “In the event we get really heavy rains, then repairs [to stabilize the soil would be necessary]. We had a rainstorm last weekend, and the rain was more than we expected. They are predicting rain this weekend. If it doesn’t come too fast, it could be really helpful.”
The next steps in the recovery of the post-wildfire regions of southern California have been set into motion. Hazardous material must be removed from around homes that were damaged by the fires before hydroseeding is done in those areas.
After a wildfire a BAER team usually will assess a burn and recommend the best treatment for controlling erosion, explains Stallings. The team will consider aspects of a site, in particular the steepness of its slopes. In southern California, straw wattles and ground hydromulching were put into place initially in many locations.
“The assessments have been done,” says Munn. “The reports are complete.” People in the affected areas are currently in the phase of implementing the recommended changes, he explains, including everything “from local governments completing the culvert cleanouts they were involved in … to developing bids for some of the larger projects, which might include following through with putting down erosion control measures.”
The BAER assessments found an increased need for emergency notification. “The assessments that were recently conducted also identified needs to provide early warning for people in places identified as potentially hazardous, particularly where, as a result of the fires, stream flows increased,” says Munn. “There were evacuations in areas of the Santiago Fire. The bottom line is, where we don’t have time to fix a problem, we want to make sure that people have the opportunity to get out of the way.”
Time frames for site erosion control measures are also being established. “I think with most of the work, the target is to get it done in less than six months,” says Munn. “Some were long-standing problems, where culverts were undersized, where channels were undersized. Those kinds of things take time.”
Sometimes, a company will be contracted when the methods it used on past post-fire recovery sites is deemed the most effective way to treat the current fire-damaged area.
“Due to the success of the Angora hydromulch project, the Forest Service wants us to apply the same mulch mixture on the San Diego burns,” explains Stallings, who added that at press time the company expected to receive a “proceed to work” notice to begin applying mulch. “The San Diego hydromulch project will require approximately 4.5 million gallons of mulch to be applied aerially in approximately 25 days, so we have asked Western States Reclamation and Erickson Air-Crane to help us. We have a long and great working relationship with both of these companies, and it will require the expertise of everyone to make this a success.”
Learning from the past can be the key for people in wildfire-damaged areas as they move forward.
“Fires are a natural part of the environment in southern California. These areas will recover,” says Munn. “If fire becomes more frequent than natural, the vegetation in them will change. But they will recover. It’s a matter of learning from what has happened this year and in past years and trying to improve the situation in the future.”
Author's Bio: Based in Morgantown, PA, Tara Beecham writes frequently for Forester publications.