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Inside a prescribed burn

A member of the South Haven Fire Department uses a driptorch to set fields on fire near South Haven. Photo by Karen Flaten

A member of the South Haven Fire Department uses a driptorch to set fields on fire near South Haven. Photo by Karen Flaten

On a beautiful spring evening in late May, the South Haven Fire Department drove their engines, tankers, and other vehicles to a hobby farm in Fairhaven Township near South Haven. The sirens weren’t on, the lights weren’t flashing. Instead, as a training exercise, they were planning to set a fire – a prescribed burn – on a few acres of grasses and wildflowers that needed to be rejuvenated. As part of the training exercise, they would set the burn, and then put it out – all within the space of a few hours. Prescribed burns are used in land management to clear the area of invasive weeds and woody plants, and revitalize grasses and forbs. According to the Minnesota Department of Natural Resources, prescribed burning is also an ecologically sound way to improve wildlife habitat. Prescribed or controlled burning is known to recycle nutrients tied up in old plant growth, and reduce the risk of large wildfires.

Used by Native Americans centuries ago to free the land of brush and encourage the growth of fruit-bearing shrubs and forage-producing grasslands, controlled burns have become part of forestry management, prairie management, and even wetland conservation.

The acreage north of Fairhaven is enrolled in the Conservation Reserve Program, a program administered by the Minnesota DNR. It is planted in wildflowers and grasses to allow the land to lay fallow, improve habitat for wildlife, provide nesting sites for pheasants and other birds, and encourage habitat for pollinators, such as bees (honeybees, bumblebees and other pollinating bees), butterflies and moths. Under the terms of the land management contract, the acreage must be burned every few years in order to revitalize the plants and kill off invasive weeds.

There are many businesses that offer controlled burns to landowners, but the South Haven Fire Department was pleased to be able to use the controlled burn as a training exercise for the department. Two or three times per year, the SHFD sets and extinguishes prescribed burns, in order to train members, refresh memories, and become familiar with new equipment. Usually the department gets requests to burn fields or grasslands, but occasionally they burn an old house that has been vacant and needs to come down. In general, the all-volunteer fire department requests a tax-deductible donation when doing a controlled burn, which is used toward the fire department’s expenses, such as equipment and gear.

Fifteen of the volunteer fire department’s members attended the training, setting the fire with drip torches and putting it out with every available means. Peyton Polston, the assistant fire chief, was in command, since the fire chief, Kenneth (Oscar) Laney, was unable to be in attendance.

Dana Kjaer, one of two training officers for the SHFD, obtained the permit and set the date. It had been a windy spring, and even though there had been quite a bit of rain, there had also been high winds, which were beginning to fan grass fires caused by sparks or careless burning. So the day had to be perfect – very little wind, not blowing in the direction of any homes or buildings. The firemen knew that if the fire got out of control, it would be very hard to put out.

Since they were using it as a training exercise, the SHFD brought all the equipment they have. There were tanker trucks, fire engines, a “grass rig” (a pickup truck set up for driving across the fields and grassy areas), an equipment van, and a rescue rig, all parked in the driveway.

Some of the smaller equipment included the so-called “Indian Tanks,” portable plastic water tanks which fit into backpacks so they can be carried on the firemen’s backs. The hose from the tank is connected to a two-way pump gun that squirts water no matter which way you pump it, so no time is lost in pumping the water to put out the fire.

“When setting a fire in a field like this,” Kjaer explained, “you first burn a swatch about 10 feet out from the tree line, buildings and anything else you don’t want to burn. Then you start burning towards the area that was already burned. When the fire hits the burned area, it stops – because it has no more fuel to burn.”

The firemen set out into the field to start the burn. There were a couple of men along the edges of the woods, starting the fire with a “drip torch.” They burned the area along the edge of the woods and back behind the barn, then put it out with handheld tanks. Then another fire was started a little ways away from the burned area. The firemen directed it toward the area that was already burned.

“A drip torch,” explained Kjaer, “is like a propane torch but filled with a diesel and gas mixture. When you tilt it down and drip it, it lights everything as it goes to the ground.”

The flames swirled around the men, their trucks, and their equipment. Smoke and flames gave the scene a surreal quality.

The fire department had to be concerned about relative humidity as well as temperature when planning the burn. If the relative humidity is below 50 percent, the dryness of the grass is prone to causing very hot fires. If the relative humidity is above 70 percent the fire will have a hard time catching at all.

According to Kjaer, the best time to set a fire for a prescribed burn is before the sun goes down, because at night the humidity comes up. “One way to think about it,” said Kjaer, “is that the grasses, trees, and pretty much everything organic gives off moisture. During the day, the sun bakes it off. But at night, the moisture comes out.”

The men worked from about 5 p.m. to after 8 p.m., first setting the fire, directing it, then letting it burn, and finally putting it out with their various trucks and equipment. As it got close to sunset, they worked more quickly, so as to be done before dark.

The SHFD used all their equipment on this exercise. They tried out their new fire truck with the joystick in the cab, which lets you control the spray of water from inside the truck. “This one is a good one for ditch fires,” said Kjaer, “since you can easily direct the water while driving down the road.”

They drove out into the fields with the “grass rig,” getting as close as they dared to the leaping flames. The tanker truck refilled the others, as well as filling the “Indian tanks.” The old fire engine, still going strong even though it is over 40 years old, functioned as well as ever.

By the time night fell, they were done, the fields black and burned, ready to grow again once the hot spots had died off. With the humidity rising, the firemen were finished with their training exercise. They had done their jobs, and stopped for a cool drink in the homeowners’ yard, before heading home.

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