Sacramento District removes ordnance, preserves native plants with controlled burn
February 12, 2010
- US Army Corps of Engineers uses controlled burn to expose unexploded ordnance.
- Burning central marine chaparral actually helps the plant species.
- Ordnance removal is part of comprehensive ordnance removal program at Fort Ord, Calif., closed in 1994.
SACRAMENTO, Calif. - Many people might think that burning vegetation pollutes and damages the environment. In reality, it can be good for the environment. In one particular case it has solved a problem at Fort Ord, Calif.
Fort Ord, the former Army base, is currently being cleaned of residual ordnance by the Sacramento District of the U.S. Army Corps of Engineers.
Fort Ord, closed in 1994, had been an active training base for the U.S. Army and Army Reserve since 1917, at one point serving as the home of the 7th Armored Division (Light). An important part of Army training involves the firing of small, medium and large weapons. An assessment of the training areas in 1995 at the fort revealed unexploded ordnance still lying on the ground.
"Normally, an average of about 10 percent of ammunition expended does not explode," said Clinton Huckins, ordnance disposal expert with the Corps of Engineers. "The fuse just does not activate the explosive material. So it's unexploded and still dangerous, even if it's been lying around on the ground for decades."
But getting to the ordnance to remove it wasn't easy. Brushy thickets of central maritime chaparral, or CMC, blanket the area - preventing access by the public, but also by ordnance removal specialists. CMC is an extremely rare plant community that used to be prevalent in some parts of California. At Fort Ord, it is prolific - one of the largest remaining contiguous concentrations of CMC in the state.
The majority of the ordnance impact areas are covered by dense stands of CMC, some of it up to 10 feet tall. One possible solution was to cut back the CMC to reach the ordnance. But a different, more environmentally-friendly approach was taken to tackle the problem: a controlled burn.
"Periodic fires are a natural part of California's natural history," said Bill Collins, wildlife biologist at Fort Ord. "CMC, like many other plant communities, has evolved to not only survive fires but to benefit from them.
"Fire stimulates the release and germination of CMC seeds, which ensures the habitat will persist," said Collins. "It would be much easier to cut back the CMC, but many of the seeding plants would not survive. Weeds and non-native species would invade the area."
In view of this and the fact that burning would be more effective than cutting back the CMC, officials decided to burn approximately 6,800 acres of CMC on Fort Ord to better reach ordnance lying on the ground or buried underneath it.
"Our goal is to burn off about 800 acres per year," said Chris Prescott, senior project manager for the Corps of Engineers.
This may seem like a simple goal, but the requirements associated with the burn are very complex. Burning affects air quality in the surrounding community, so weather conditions have to be such that smoke is blown over the ocean, away from populated areas. That means off-shore breezes, a condition where breezes blow from the land toward the ocean, have to prevail.
Those conditions exist in the Fort Ord area from July to November. During the winter months, rain makes the plant material too wet to ignite. Humidity is an important factor, as well. With high humidity, the wet vegetation will not ignite; too low and the CMC will ignite too quickly and fire could spread beyond the burn area.
Another problem is availability of firefighters, helicopters and associated infrastructure necessary for safety reasons during a burn.
"California's fire season runs from June to December of each year," said Prescott. "So, if there is a large fire somewhere in California, no one is available to help us and we can't have a burn."
Since the inception of the program in 2001, ordnance specialists have cleared nearly 2,500 of the 6,800 acres, finding over 12,000 unexploded ordnance items and 89,000 pounds of munitions debris. Of the 2,500 acres, approximately 500 acres were burned off last year and work is under way to clear this area.
The planning and conducting of the burn is a very complicated process for the Corps. Before every burn, the Corps must coordinate with the California Department of Toxic Substance Control (DTSC), in case any toxic substances are located; the U.S. Fish and Wildlife Service, to ensure that rare, endangered and threatened species are protected; the Environmental Protection Agency, to monitor the overall environmental impact of the burn; the California Air Resources Board and Monterey Bay United Air Pollution District, for concerns over smoke from the burn; and the Federal Aviation Administration, whose concern is the possibility that smoke could obscure visibility at nearby Monterey Airport. All these agencies have a voice in approval for a burn.
Besides the agencies, Jack Riso, chief of the Presidio of Monterey Fire Department, has a long list of responsibilities associated with every burn. One is to insure the fire occurs in such a way that it is hot enough to send smoke straight up into the air. If the fire is not hot enough and there is too much smoke, nearby residents, especially those with breathing difficulties, could be negatively impacted.
Riso also performs a pre-inspection of the burn site to check the slope of the hills, how dry and dense the vegetation is, its proximity to residences, the presence of fire breaks, and whether the fire will be able to escape to non-burn areas.
Another key player in a burn is Barry Callenberger, a contract burn specialist with 37 years of experience as a wildland firefighter. His job is to mix the proper prescription of fuel for the burn so that the burn is neither too hot nor too cold.
"We start by measuring the moisture content of the live vegetation," said Callenberger. "Moisture content in the vegetation can be as high as 150 percent, when it's raining. For a good burn, the moisture content should be from 100 percent down to 50 percent. Anything below that is too dry and the vegetation will burn too hot and stand a greater chance of burning out of control."
Once good moisture content is available, Callenberger checks the weather forecast from meteorologists at the Naval Post Graduate School in nearby Monterey. With this information, Callenberger then uses a computer model called "Behavior" to better predict the result of a burn. Since the weather patterns in the Monterey area are so variable, notice for a burn is set one to three days before.
"In 2009 we had a good burn," said Prescott. "With 90 percent of the vegetation consumed by fire," he added, "It resulted in an easier clean up of ordnance and recovery of the area for future use as a wildlife habitat."