Burning a Slash Pile

Spring, 2009
Gary Sager

Doing a safe burn involves careful planning, including knowing the regulations for your area. For Gallatin County outside city limits, a permit is required and some subdivisions place further restrictions on burning. Permits can be obtained online at www.burnpermits.mt.gov or at locations listed at the Bridger Canyon Fire Department web site. The permit lists a number of requirements that should be carefully reviewed. Before starting each burn, the burn permit must be “activated” online or by calling in with the burn permit identification.

You are liable for damage caused by a burn that gets out of control, so proper preparation and monitoring are important. Check your insurance policy to make sure you are covered. You may want to consider alternative methods for dealing with slash.

Preparation for a safe burn starts when the slash pile is created. A very good resource for preparing slash piles and burning them is on the Larimer County Web Site. One need only make a few obvious substitutions to that information to plan and execute a safe burn in one's own county. Additional recommendations are:

1. Have enough helpers to work in shifts. Use FRS or GMRS radios to communicate with your backup workers.
2. Wear clothing that will withstand heat and sparks; dense wool or cotton is okay, leave the synthetics at home unless they are specifically fire resistant.
3. Call and warn neighbors who might see the fire or smoke.
4. Prepare shelter and a comfortable rest area near the fire.
5. Be prepared to spend the night if the fire continues to burn beyond sundown. Keep this in mind when you choose where to place the pile; it's most convenient to monitor from your home or a camper vehicle.
6. Keep track of tools; it is easy to lose them if it snows.
7. If the fire is not close to a water source, a backpack sprayer is handy but it can freeze up when it is cold. Alternatively, use “stream machine” style water guns and buckets of water; keep the guns dry until needed so they don't freeze.
8. Have a party! Use the fire to prepare lunch and dinner.

Unfortunately, the slash piles on our property were created by a person who did not follow the guidelines outlined in the web site linked above and did not fulfill their contractual obligation to deal with the slash. As a result, we have been breaking the piles up when possible and taking great care when burning problem piles. If you hire someone to do forestry work on your property, make sure they have proper permits from the forest service for doing the work and make sure they are responsible for and insured for taking care of the slash. Monitor the work to insure that slash piles are properly located, constructed and burned.

The following account documents the burn of a pile we created by breaking up a larger pile and is therefore close to ideal.

Our Burn

On March 25, the weather forecast looked ideal for a burn: little wind with snow flurries for the day and a snowstorm approaching in the evening. Furthermore, there had been a wet snow the night before. This pile was a 10 minute hike from our house, so we used radios to communicate with our support team.

8:15AM — Arthur shoves burning cardboard into a dry spot on the south side of the pile to get it started. We had called in the burn at 7:30AM. For good measure, we called neighbors who might see the flames or smoke. Rather than pour diesel onto the pile, we save up cardboard and use it to start the fire.

This slash pile was about the right size and had very few needles in it. We started the fire near the top and on the down-wind side in hopes of reducing the flare up that occurs as the loosely stacked wood catches. It was quite cold, but we were soon ditching our jackets as the heat from the fire built.

8:30AM — Arthur monitors the start of the burn. This picture of the north side shows how much snow had accumulated on the pile and how much was on the slope above the pile. We like the snow because it helps slow down the initial burn and keeps the fire from spreading.

In the background at the left of the picture is a large slash pile with a small alcove we hollowed out to shelter in during the frequent snow flurries. We hope to break the large pile up into smaller ones this Summer so we can burn it in the Fall.

8:45AM — The fire flares up. This can be the most dangerous time for the fire. If the wind starts blowing while the flames are high, the snow on the branches of nearby trees, the high humidity and the moisture content of the needles help keep them from catching, but we would have preferred to have this pile further from trees. The heat from this fire may kill the lower branches of the tree enveloped in smoke (update: the tree was not as close as it appears – it did fine).

Gary stood by with a backpack sprayer to douse any small fires started by the sparks. The smoke is caused by the melting snow. In another 15 minutes, the fire was much smaller and there was very little smoke. As the fire burned, we cleared the brush around the fire to reduce chances of spreading.

12:30PM — Things are pretty calm now. Note how the fire has melted the snow for quite a distance around. The fire was still very hot; we could only stand to be near it 15 seconds at a time as we shoved burning material toward the center. We wore our heavy clothing and face masks to protect us from the heat rather than the cold!

When the weather is nice we bring potatoes, brats and other fixings up and prepare dinner by wrapping food in foil and baking it in the ashes. However, at 3:15PM snow was accumulating around the site and there were no flames or smoke, so we built a moat of snow around the perimeter and went home to rest. By the time we got home, it was snowing heavily. We kept track of the wind that evening and night; if it picked up we would return because the wind can re-ignite a fire. And we returned periodically just to make sure things were going well.

8:00AM Next Morning — The pile of ashes was still hot enough to remain dry in spite of the snow and the cold; it was 9°F at the time the picture was taken. A new accumulation of snow greatly reduces any chances of the fire spreading even if the wind picks up.

One of the burns we did 3 weeks ago was still steaming. It looks like something one expects to see in Yellowstone Park! The reason it continued to steam in spite of several snow falls and cold weather is this was a poorly constructed pile: there was a large mass of wet fir needles at the bottom and they slowly burned as the heat dried them out. We had to camp out overnight twice to monitor this burn. Even though there were three wet months ahead, we wanted to make sure this one was out, so we emptied the backpack sprayer on it every time we went to check it and shoveled snow onto it until the snow no longer melted.

Parting Shot
3 Days and 7 Hours After Start